Griffin’s COVID-19 Response

GGSPro Tech Tips

Weed Control in Mum Fields

Weeds are generally not a problem in greenhouse crops, but a mum field presents an entirely different challenge. With seeds blowing into the crop on a continual basis and a likely well-established seed bed under the crop before the mums even hit the ground, active weed control is well worth the effort. Fortunately, we have strategies and products which offer great performance for this application.

Mechanical Weed Control

Weed pressure can be reduced in your mum field by placing a barrier between the crop and the soil. A deep gravel bed will help to reduce weeds compared to bare ground. However, a ground cover fabric provides a physical barrier which is far more effective. Remember that the pad area should be cleared of all debris and accumulated soil and media prior to placing the crop. If not cleared, these areas will provide an ideal location for weeds to take hold. It also helps mow the perimeter of the mum field regularly to reduce weed seed production immediately adjacent to the field.

Chemical Weed Control

Despite the best efforts at mechanical weed control, weed pressure on a mum field very often requires treatment with pre- and post-emergent herbicides. It is far better to prevent weeds instead of trying to control them later when the only option is to send a crew out to weed the crop.  

Existing weeds are treated with a post-emergent spray prior to placing the mums. Contact with crops must be avoided. A pre-emergent herbicide may also be mixed with the post-emergent. However, best control is achieved when a post-emergent product is applied just before the crop is placed and quickly followed by an over-the-crop application of a pre-emergent product. This strategy minimizes the time interval during which weed seeds can germinate following the post-emergent application and effectively prevents germination in the pots and at the drain holes. If a longer interval is expected between the initial post-emergent application and crop placement (more than 7 days), tank mix a pre-emergent product with the post-emergent product to avoid the need to treat newly germinated weeds at the time the crop is placed.

When using a pre-emergent over the crop, control is best if the media is allowed to settle prior to the application; two irrigations will generally do the trick. If using Barricade, Fortress, Pennant Magnum or Snapshot for this application an overhead irrigation is required, though ½” or more of rain within two weeks of the application satisfy the moisture requirement. Fortress and Snapshot recommend rinsing granules off foliage to reduce the chance of injury.

As with all other pest control products, rotation is important to prevent the development of resistance.

 


Not all products are registered in all states. Some pesticides are restricted use in some states or regions and not others. It is the responsibility of the applicator to read and follow all label directions, remembering that labels may change. Other products may be safe and effective.


Pythium Root Rot Diagnosis and Treatment Options

Oospores
Root rot diseases are mostly caused by soilborne fungal pathogens. Pythium is a water mold pathogen and is most commonly associated with root diseases/damping off in ornamental and vegetable production. As a naturally occurring soil pathogen throughout the world, the organism survives in soil as dormant thick walled resting spores known as a chlamydospore. In soilless media or in plant roots, Pythium survives as oospores and/or sporangia. When contact occurs with roots of seedlings/plants of a susceptible host, root exudates stimulate germination and depending on the environment this can occur in as little as 1.5 hours or take days to weeks for pathogen penetration and symptoms to occur. 

Pythium Root Damage - Outer Root Sloughed off Leaving
Inner Root Cortex
Under ideal temperatures and conditions of ample soil moisture, Pythium oospores will produce zoospores during sexual reproduction and fertilization. Zoospores swim and can be easily carried within surface water, capillary mats and growing media. As Pythium invades the roots, slowly nibbling away at the root epidermis, the death of root cells occurs. Once the root system is compromised, roots characteristically turn brown and the outer root tissue sloughs off leaving the inner cortex. Pythium is capable of causing crown rot as well as resulting in a lower stem canker. Symptoms of mild yellowing and wilting especially during the day at first, recovering at night are become noticeable. As more roots are affected, uneven growth, stunting or total plant collapse can occur.

Petunia with Pythium Root Rot and Fungus Gnat Larvae Present
The spread of Pythium in greenhouses and nurseries is mainly through contaminated soilless media. It is also readily spread on tools, hands, shoes and in contaminated irrigation water. Shoreflies breed in puddling water and algae under benches can harbor the pathogen spores on their legs and spread freely throughout the greenhouse. Fungus gnat larvae can cause damage to roots providing entry for the pathogen into roots as well as being capable of ingesting spores and spreading the pathogen throughout the media. Do not forget that plant material itself can harbor the pathogen which can be brought in on transplants and/or cuttings. Remove any diseased plants immediately and follow up with control strategies. 

Optimum soil temperatures vary with the pathogen species with our most common greenhouse species being P. aphanidermatum preferring 95°F, P. irregulare 75-80°F, and Pythium ultimum 50-86°F. Environmental stresses caused by over fertilization that contribute to high soluble salts, poorly drained soil media, overwatering, as well as strong wet/dry media moisture cycles need to be averted. Cultural practices that include sanitation can help exclude root rot pathogens into production. Starting with clean, unused plastics is ideal. If plastics are to be reused it requires a two-step process of cleaning before disinfesting. The cleaning step can be accomplished with Strip-it Pro, Horti-Klor or rigorous hand cleaning. Sanitizing options include Greenshield II, KleenGrow, SaniDate 5.0 and ZeroTol 2.0. A 10% bleach solution can also be used but requires extra steps to ensure the safety of workers.

Phytophthora which is another water mold pathogen closely related to Pythium is often suspected of causing root rots particularly in nursery crops but has been reported on many herbs, edible and potted plants. For this reason, testing for confirmation of either pathogen can only be done via a microscopic examination or test kits purchased through Agdia, Inc. Fungicide treatments are similar in many cases, but rates will vary depending on the pathogen detected.

There are several choices of chemical and biofungicides labeled for Pythium that are all applied as drenches. When selecting fungicides, plant age, plant safety, disease pressure, rate, soil moisture and MOA should be assessed prior to using. The label specifics the drench volume for most products and is based on container size. Re-application intervals, REIs and MOA rotation requirements are spelled out on the label. Biological fungicides always must be applied preventatively as they have no curative properties. For growers who prefer the microbial fungicide approach, a trend of using a chemical fungicide initially to eliminate pre-existing soil borne pathogens is then followed up with the biological fungicide 1 week later with good results.  Depending on the microbial fungicide chosen, reapplications may be needed every 2-3 weeks while others can last up to 12 weeks. All labels must be examined carefully for crops being treated and application intervals.



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Phytophthora Root Rot and Aerial Blight Management

Derived from the Greek word “Plant Destroyer” the genus Phytophthora affects crops worldwide causing economic losses. Thriving in wet conditions, it is a very fast moving pathogen to susceptible crops. Phytophthora is being classified as a water mold and more related to algae then fungi. Overwintering as chlamydospores, oospores or sporangia that can persist and survive in the soil for years. The chlamydospores are produced asexually and can directly produce sporangia which release zoospores that swim through water to reinfect plants with ease.  The thick walled oospores also produce sporangia which release swimming zoospores that enable spread under idea temperatures and moist, wet conditions. Spores are disseminated by water, rain, irrigation runoff, by humans and even wildlife such as snails. In greenhouses, shorefly and fungus gnat larvae can carry chlamydospores.

There are more than 60 recognized Phytophthora species; at least 10 have been reported on potted plants. Many Phytophthora species are specific to common plant genera: azalea, bacopa, calibrachoa, dogwood, gerbera, lavender, pansy, petunia, poinsettia, rhododendron, vinca, and many herbaceous perennials and vegetable crops, particularly tomato.

Phytophthora on Rhododendron, APS net
The four key pathogen species: P. cryptogea, P. infestans, P. parasitica and P. ramorum, are each capable of causing mortality over a wide range of host plants. P. cryptogea has been associated with tomato, petunia, begonia, cineraria, gerbera and other hosts. Optimum temperatures for growth are 72-78˚F but sporangia can form as low as 40˚F. P. infestans is the pathogen that caused the potato famine and impacts tomatoes causing the destructive late blight, preferring cool spring/fall weather (60-70˚ F days, 50-60˚ F nights). P. parasitica which is more common in potted plants prefers temperatures of 78-90˚F but can colonize in the absence of symptoms at lower temperatures. P. ramorum is associated with foliar blights and dieback of nursery host plants particularly causing the Sudden Oak Death of several oak tree species. 

Phytophthora
Phytophthora root rot in Verbena
is a common root and crown pathogen of many ornamental and edible crops. Phytophthora root rot appears darker in color with less sloughing off of roots than Pythium. Stunting and wilting often occur, and crowns may break off easily at the soil line. When above-ground infections occur, known as aerial Phytophthora, plants often exhibit a rapid wilt with a characteristic bleaching of leaves starting at the leaf base. Leaf spotting, leaf drop, dull-colored isolated branches/stems or stem lesions are other pathogen indicators. On some plants (e.g., tomato), whitish sporulation can be observed under high infections, though this is somewhat uncommon. 
Sanitation is the link that breaks the chain of the reinfection process. 



Control options

Phytophthora sporulation on tomato leaves
Management of Phytophthora root rot is similar to Pythium root rot management. Avoid fertilization that contributes to high soluble salts, poorly drained soil media, overwatering, as well as strong wet/dry media moisture cycles. For aerial Phytophthora, practices that reduce humidity within the canopies by adequate spacing and facilitating good air flow. Avoid late-day irrigation and saturated conditions that leave wet foliage going into the night. Both fungi are soil-borne and rely on movement through splashing and running water to spread.

Products for Phytophthora must be carefully chosen and rotated, due to resistance reported among some Phytophthora species. To reduce further resistance, rotation with other MOA products will improve performance. For aerial Phytophthora, foliar sprays are recommended. While the table below is provided as a summary, growers must read and follow the entire pesticide label. Products other than those mentioned may be safe, legal and effective. Not all products may be registered for use in all states. Contact GGSPro as needed for further guidance.

There are several choices of chemical and biofungicides labeled for Phytophthora when applied as drenches. When selecting fungicides, plant age, plant safety, disease pressure, rate, soil moisture and MOA should be assessed prior to using. The amount of drench volume is dictated by pot size and reapplication intervals as well as REI (reentry interval) are dictated by the product label. Most fungicide labels allowing making 2 applications before rotation to another MOA. Biological fungicides always must be applied preventatively as they have no curative properties. For growers who prefer the microbial fungicide approach, a trend of using a chemical fungicide initially to eliminate any potential soil pathogens and follow up with a biological fungicide a week or two later has provided good results. Depending on the microbial fungicide chosen, reapplications may be needed every 2-3 weeks while others can last up to 12 weeks. All labels must be examined carefully for crops being treated and application intervals.




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Bring Down the Intensity this Spring with Shade

Plan to shade your crops and spare them, and yourself, the pain of sunburned foliage. Greenhouse operations can get tense in early spring as the intensity of the workload, space crunches, and insect populations all start to build. The increasing intensity of the sunlight can also be anticipated.  Each spring GGSPro sees examples of sunburned crops during this early spring transition. Below are some tips to help you avoid the setbacks and costs of a sunburned crop.

Timing the Shade

In the early spring light levels increase rapidly. The more northern the location, the more rapidly the daylength increases over the spring months. At the same time as the duration is increasing, the intensity of the light is also increasing. The cumulative effect is calculated in the Daily Light Integral (DLI).  Mapping DLI data by month shows the seasonal progression, as illustrated below from the work of Dr. Jim Faust’s lab at Clemson University.

These data can be used as simple guides for shading decisions, even if over simplified.  Deep shade plants and many ferns are best shaded at DLIs in the 30-35 range (Kelly green).  Shading should be applied over sun-sensitive and light shade loving crops when your location falls into the range of 35-40 DLI (lime green) in the maps. Most sun-loving plants will benefit from 30% shade at DLIs of 40 and above (yellow to orange shades). Remove the shade when the DLI falls below the trigger level you used in putting it on.  These guides are perhaps over-simplified but provide a starting point for planning and scheduling. Note that the light level in the maps can be, and normally are, significantly reduced inside the greenhouse by the glazing, settled dust and pollen, and overhead infrastructure.


From: Faust, James E., and Joanne Logan. 2018. Daily Light Integral: A Research Review and High-Resolution Maps of the United States. HortScience 53(9): 1-8

Choosing Shade Percentage

The table below can serve as a guide for choosing the appropriate shade percentage from cloth or liquid shade products, for various crops. 


Shading Products

Black shade cloth is available in percentages from 30-90% shading and widths up to 88 ft. In addition to the standard black shade to cut the light intensity, several options are available with additional functional features.  

White light-diffusing fabrics
Colored fabrics for light spectrum management 
Aluminum knit heat-reduction fabrics
 
Griffin also carries liquid products for shading

Kool Ray from Continental Products in 1- & 5-gallon containers
ReduSystems products for shading and heat reduction in 15-liter buckets. 

Call Griffin to discuss your specific shading needs. 

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An Aphid BCA Guide for Dummies

Available in every bookstore or on the internet are the famous “For Dummies” reference books, helping readers with non-intimidating instructions on various topics. Discussed in this article today is the GGSPro version of “An Aphid BCA for Dummies.” BCA stands for Biological Control Agents. Successful pest control with predatory insects is possible, but sometimes, when aphids will not yield to BCAs alone, compatible pesticides can be used without crashing an entire BCA program. 

Before starting BCAs for aphid control, stop pesticide applications not designated as compatible 8-weeks prior to releasing unless you are using compatible pesticides (see below). Make sure you ask your supplier for pesticide records for all incoming plant material.

Next, follow these four principles:

    1.Commit time to scouting weekly with trained personnel that can correlate pest identification and risks.

    2. Place BCA orders to begin releases at the beginning of production based on desired sq ft.

    3. Check viability of BCAs upon arrival and release on a predetermined schedule (release frequency and rates may need to be modified depending on pest pressure development)

    4. Follow up with routing scouting and evaluations and keep records. 

Aphidius wasp, aphid mummy, Aphidoletes and lacewing larvae (left to right). Photo credit: GGSPro and Cornell IPM

The most reliable aphid parasitoids belong to the Aphidius genus. Aphidius colemani is released for smaller aphids like the green and melon aphids, while Aphidius ervi is used for larger aphids like foxglove and potato aphid. The Aphelinus abdominalis, also an aphid parasitoid species, targets larger second and third instar aphid nymphs. Both parasitoid species lay their eggs inside the aphid where it then hatches and the larvae consumes the body. The Aphidius forms a tan colored aphid mummy while the Aphelinus produces a distinctive black mummy. Releases are done on a biweekly basis until the first sighting of an aphid. Then, plan on three weekly releases before going back to biweekly releases. Ideal temperatures are 65-85oF and 70% relative humidity. Lower or higher temperatures outside this range will delay parasitoid development. 

The predatory midge, Aphidoletes or the Chrysoperla carnae/rufilabris (common name - lacewing), are used for hot spot areas along with the continued parasitoid wasp releases. Both will prey on all species of aphids. Additionally, both require warm temperatures of 70-80oF and 80-90% relative humidity. Aphidoletes will enter diapause under cool temperatures and low light condition. Releases are biweekly to weekly for Chrysoperla and weekly for Aphidoletes for 3-4 weeks or as needed to clean up an infestation. 

When our biological enemies do not provide adequate control, careful choices and timing of low toxicity pesticides will provide a back up to biological control. This should allow a reduction of pest reproduction so that within 1-2 weeks, a return to BCA releases is possible. The GGSPro department can provide tailored compatibility charts to reduce harmful effects on your BCA program from pesticide applications.. 

The safest choices typically include biological insecticides like Ancora, BotaniGard WP, Velifer, or Venerate. These can be tank-mixed with an Azadirachtin IGR (Insect Growth Regulator) like AzaGuard, Azatin O, or Molt-X. Insecticides with short residual toxicity include: Suffoil-X/Ultra-Pure Oil, Kopa/M-pede, Endeavor (spray/drench), Kontos (spray/drench), and PyGanic. Avoid tank mixing insecticides with fungicides when using BCAs because less information is available for fungicides. Try to always spray before new BCA releases rather than after. Omit use of surfactants when possible as these can have a negative impact on BCA populations.


Product NameMOASizeCommentsItem Number
Apheline
NA
250
Mummies/adults
SB0202-01, 30AD25
Aphidoline BioAphidoletes
1K 2K
Pupae
SB0151-01, BB-0006, 30AA2
APHIDIUSforce C BioAphidoletes
500
Mummies/adults
30AC5, BB-0005,
Apheline APHIDIUSforce C
1K
Mummies/adults
SB0102-04, 30AC10

Other sizes and packaging of Aphidius mixes are available. Contact GGSPro


Product NameMOASizeCommentsItem Number
CHRYSOforce R
1K
Larvae
SB0301-04, 30LWB
CHRYSOforce R
1K
Eggs on cards
30LWE

Other sizes and packaging of Chrysoperla larvae and eggs are available. Contact GGSPro
Product NameMOASizeCommentsItem Number
Ancora
UNF
1 lb
Spray
70-1166
BotaniGard WP
UNF
1 lb
Spray
70-12521
Endeavor
9B
15 oz
Spray or Drench
70-1655
Kopa
UN
2.5 gal
Spray
70-1970
Kontos
23
8.45 oz
Spray or Drench
70-19601
M-Pede
UN
2.5 gal
Spray
75-10262
PyGanic 5.0
3A
1 qt
Spray
70-2687
Velifer
UNF
1 qt
Spray
70-9540
Venerate
UNB
1 qt
Spray
70-9461
Azatin O
UN
1 qt
IGR, Spray
70-12301
AzaGuard
UN
1 qt
IGR, Spray
70-1224
Molt-X
UN
1 qt
IGR, Spray
70-2400
Suffoil-X
UNE
2.5 gal
Spray
70-4040
Ultra-Pure Oil
UNE
2.5 gal
Spray
70-21401

This information is intended to help reduce aphid outbreaks that may occur during implementation of BCA programs. It is the responsibility of the applicator to read and follow all label directions. Labels do change without notice. Pesticides other than those listed may be safe, legal and effective.

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Preventing Disease In Propagation

Many growers start crops from unrooted cuttings. High humidity and warm temperatures in propagation promote rooting but can also promote disease. Disease progression in propagation can be swift, so it is important to recognize and treat problems quickly and consider preventative treatments.

Sanitation is the first step in preventing disease in propagation. Prior to sticking the first cutting, take time to clean and sanitize benches and irrigation systems. Remove all debris and use a chemical cleaner, such as Strip-it Pro. After cleaning, sanitize with KleenGrow, SaniDate 5.0 or ZeroTol 2.0. Never stick cuttings in reused media. If trays are reused, be sure that they have been properly cleaned and sanitized.

Dorotheanthus, Rhizoctonia Web Blight Disease

 
Damaged tissue is more susceptible to disease, so stick cuttings as soon as possible and hold under appropriate conditions when necessary. Most importantly, keep cuttings cool and moist until they are stuck. It is also wise to stick the most sensitive cuttings first. Geraniums are a special case, as they are sensitive to ethylene in shipping, can yellow easily and should always be stuck first. Minimize the yellowing by spraying with Fascination at 2 ppm as soon after sticking as possible. Apply with CapSil for best results. Avoid spraying so heavily that it runs down the stem into the soil as that can slow rooting. Fewer yellow leaves mean less plant stress and less susceptibility to disease.

The most common diseases to initiate on the propagation bench include Botrytis, Phytophthora, Rhizoctonia and bacterial disease. Empress Intrinsic, Pageant Intrinsic and Mural are good options for a preventative spray/sprench for fungal pathogens. Broadform can be used as a spray only. All those products contain strobilurin fungicides which have been shown to enhance rooting in many species of plants.  

Stem cankers are often the result of a Botrytis/Rhizoctonia complex. Fortunately, several of our top choices for Botrytis also control Rhizoctonia, including the strobilurin fungicides listed above. Other Botrytis and Rhizoctonia rotation options include: Affirm, Cease, Palladium, Triathlon BA and Stargus. In propagation, a sprench or drench application over the small plants will also provide good control of stem cankers. (Broadform and Palladium can only be sprayed.)

Phytophthora is a fast-moving disease with hallmark symptoms including bleached or necrotic tissue moving up from the stem or petiole into the leaf. Petunias are particularly susceptible to Phytophthora and should be scouted regularly to support early detection. Segovis is an outstanding new Phytophthora product giving several weeks of control from a single application. It can be applied as a spray or drench. Phosphonates such as Fosphite and Phostrol are effective and can also enhance rooting. Fenstop and Segway O provide additional rotation options for Phytophthora control. 
Like Phytophthora, bacterial diseases can move very quickly in propagation beds. Tell-tale signs of a bacterial infection include slimy areas on stems and/or dark, slimy leaf spots. Bacterial leaf spots caused by Xanthomonas often display a yellow halo around dark colored centers. Bacterial infections in propagation are best treated by quickly removing symptomatic plants. Treatments include KleenGrow which as some curative activity and Cease or Triathlon BA as preventatives. Copper bactericides such as Badge SC, Camelot O, Grotto and Phyton 35 can be helpful, especially when tank mixed with Protect DF. ZeroTol 2.0 can be used as a quick surface clean-up for bacterial ooze and for general sanitation.

Pythium is not typically seen in early propagation, so we do not typically treat preventatively. If needed, Fenstop and Segway are effective and provide good plant safety on young, tender cuttings.

It is the responsibility of the applicator to read and follow all label directions. Labels do change without notice. Pesticides other than those listed may be safe, legal, and effective.

Products Mentioned In This Article

Product NameDescriptionItem Number
Affirm
FungicideFungicide
71-1131
Badge SC
Bactericide, FungicideBactericide, Fungicide
71-1205
Broadform
FungicideFungicide
71-1290
Camelot O
Bactericide, FungicideBactericide, Fungicide
70-21202
CapSil
SurfactantSurfactant
74-1541
Cease
FungicideFungicide
71-13301
Empress Intrinsic
FungicideFungicide
70-1510
Fascination
PGRPGR
73-1910
Fenstop
FungicideFungicide
71-14801
Fosphite
FungicideFungicide
71-1520
Grotto
Bactericide, FungicideBactericide, Fungicide
71-2030
Kleengrow
Bactericide, Fungicide, SanitizerBactericide, Fungicide, Sanitizer
74-21101
Mural
FungicideFungicide
71-1690
Pageant Intrinsic
FungicideFungicide
71-26801
Palladium
FungicideFungicide
71-2685
Phostrol
FungicideFungicide
71-2725
Phyton 35
Bactericide, FungicideBactericide, Fungicide
71-2732
Protect DF
Bactericide, FungicideBactericide, Fungicide
71-2748
SaniDate 5.0
SanitizerSanitizer
71-35001
Segovis
FungicideFungicide
71-3100
Segway O
FungicideFungicide
71-31102
Stargus
Bactericide, FungicideBactericide, Fungicide
71-2950
Strip-it Pro
CleanerCleaner
74-2124
Triathlon BA
Bactericide, FungicideBactericide, Fungicide
71-3040
Zerotol 2.0
Bactericide, Fungicide, SanitizerBactericide, Fungicide, Sanitizer
71-35501
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The Relationship Between Water Quality and Fertilizer Programs

The Importance of Water Testing

Testing your irrigation water can help determine an appropriate fertilizer program that sufficiently meets nutritional requirements while managing optimal substrate media pH. There are many labs available that offer water quality testing; regardless of the lab you choose, make sure some specific horticultural parameters are measured. These include pH, alkalinity, electrical conductivity (EC), primary (nitrogen, phosphorus, potassium) and secondary (calcium, magnesium, sulfur) plant macronutrients, as well as micronutrients such as iron. Sodium and chloride, which can be negative to plant growth in large quantities, are also valuable to measure. The quality of your “clear water” or water directly from your main irrigation source (wells, ponds, city water, etc.) without any additional inputs (fertilizer, acids, bases) should be determined year to year as  water quality can change over time. At a minimum, it is a good idea to have your water tested annually.

Alkalinity and Substrate pH 

Alkalinity is a measure of the dissolved bicarbonates and carbonates (calcium, magnesium, and sodium) in water. More simply put, alkalinity can be seen as a fertilizer salt that is not taken up by the plant that makes a critical difference in the availability of other plant essential nutrients by altering the pH of the growing media. These carbonate species create a basic environment in the media, the higher the alkalinity, the greater the increase in media pH over time. Alkalinity can also be described as buffering capacity, or resistance to pH change. Low alkalinity water offers little or no resistance to pH changes coming from acids (sulfuric acid) and fertilizers. High alkalinity water overwhelms the effects of the acids and bases and becomes the controlling factor of media pH.

Fertilizer Rotation 

Fertilizers can have a significant impact on raising or lowering substrate pH. The relative “acid forming” or “basic forming” ability of a given fertilizer is primarily determined by the percentage of ammonium to nitrate in the fertilizer. For example, fertilizers with high amounts of ammonium forms of nitrogen (21-7-7) are considered acid forming fertilizers, whereas fertilizers containing predominately nitrate forms of nitrogen (15-0-15) are considered basic forming. The relative acid/basic forming ability of a fertilizer can typically be found on most fertilizer labels below the guaranteed analysis (Figure 1). Please reference Table 1 for examples of acid and basic forming fertilizers. 

Figure 1: Example fertilizer label for Jack's 20-10-20

Figure 2: Iron deficiency due to high soil pH in calibrachoa














Figure 3: Iron and manganese toxicity due to low soil pH in geranium
Bringing alkalinity back into the conversation, we can now combine our understanding of how both alkalinity and fertilizer choice influence substrate pH. Each plant species has an optimal substrate pH to be grown at for all the macro and micronutrients required to be available for plant uptake. Poinsettias for example have an optimal substrate pH of 6.0 to 6.5. If we go below or above this range, micronutrients can become in toxic or deficient in the plant, respectively. We can manage substrate pH by rotating between acid and basic forming fertilizers in an appropriate schedule based on the alkalinity of the irrigation water. As shown in Table 2, a poinsettia grower with an alkalinity level of source of 100 ppm CaCO3 would irrigate their crop twice with an acid forming fertilizer and then use a basic forming fertilizer on the third irrigation. 



Adjusting Substrate pH with Acid

For water with alkalinity greater than 150 ppm CaCO3, injection of technical grade sulfuric acid is recommended to neutralize alkalinity and help keep media pH within the optimum range. Sulfuric acid may be added to most acid forming fertilizers (20-10-20 or 21-5-20) but is not compatible with any fertilizer containing calcium (15-0-15, 15-0-0), which are typically basic forming as well. Reference Table 3 for rates of continuous sulfuric acid injection based on alkalinity level. Please contact GGSPro for recommended rates when using other types of acids (phosphoric, citric), suggestions on where to have your water tested, or if you have any questions on fertilizer rotation programs.


Products Mentioned in this Article


Item DescriptionItem Number(s)
20-10-20 (25lb bag)
333614, 31-140200, 67-2316
15-0-15 (25lb bag)
33626, 31-140100, 67-2340
21-5-20 (25lb bag)
33602, 31-140306, 67-2308
Sulfuric Acid (1 gal)
75-5030
Jack's Potassium Bicarbonate (1lb, 25lb)
91-2190, 91-2191
BioSafe CalOx (2.5 gal)
75-0525
Printable version

Poinsettias - Tips for End of Season Success

This is the time of year where poinsettia growth has come to a crawl, and bract develop is in full swing. Bract development and overall poinsettia health during the late season can be managed through a combination of cultural and chemical practices. This article will outline some techniques and considerations for ensuring end of season poinsettia quality. 


Bract Development and Temperature 

Temperature has a direct effect on bract expansion, color, maturity, and durability. Night temperatures are critical for bract expansion, with 65-68°F being ideal for most varieties. Higher night temperatures can encourage weak bracts, dull color, bract edge problems, and foliar diseases. Night temperatures that are too cool can cause bracts not to size up properly. White flowering varieties can also look green or yellow if night temperatures are too cool. Day temperatures should be kept relatively cool to reduce stretch and increase stem strength. 




Average daily temperature (ADT) has the largest impact on the rate of bract expansion and saleable color date. The stage of bract development is the best indicator of when to change temperature requirements (Table 1). Stage 3 should begin when bracts are ~75% of finished size. Stage 4 represents the time when bracts are nearly fully expanded or at saleable quality. For example, early flowering varieties may enter stages 3 and 4 up to 2 weeks earlier than Table 1 indicates. Temperatures below 60°F in stage 4 can increase the risk of Botrytis on bracts. Maintaining dry air during the last stage when the coolest temperatures occur may be difficult with reduced heat. Cooler air temperatures increase the relative humidity in the plant canopy, which in turn makes condensation more likely. Free moisture on plant surfaces favors Botrytis development.

Average daily temperature (ADT) has the largest impact on the rate of bract expansion and saleable color date. The stage of bract development is the best indicator of when to change temperature requirements (Table 1). Stage 3 should begin when bracts are ~75% of finished size. Stage 4 represents the time when bracts are nearly fully expanded or at saleable quality. For example, early flowering varieties may enter stages 3 and 4 up to 2 weeks earlier than Table 1 indicates. Temperatures below 60°F in stage 4 can increase the risk of Botrytis on bracts. Maintaining dry air during the last stage when the coolest temperatures occur may be difficult with reduced heat. Cooler air temperatures increase the relative humidity in the plant canopy, which in turn makes condensation more likely. Free moisture on plant surfaces favors Botrytis development.


Maintaining Bract Health

Figure 1. Bract edge burn

During the end of the season, healthy bract development is key to a quality product and long-term shelf-life. The biggest issues to look out for is Botrytis and bract edge burn, which can go hand in hand. Botrytis is a quickly spreading fungal pathogen that can propagate in damaged material caused by bract edge burn. Bract edge burn is caused by a calcium deficiency. Both of these issues can be prevented by using foliar applications of calcium and fungicides. We recommend weekly sprays with calcium chloride dihydrate rather than calcium nitrate, because calcium nitrate can occasionally cause additional bract damage. Weekly foliar sprays of calcium chloride dihydrate at 0.5 oz per 3 gal or 16 oz per 100 gal should be applied at onset of bract color. Affirm WDG, Astun, Medallion WDG, Palladium, or Spirato GHN are all effective, bract safe options for preventing and controlling Botrytis. All of these

Figure 2. Poinsettia bract with Botrytis

applications should be used in conjunction with a surfactant such as CapSil (¼ tsp per gal or 4 oz per 100 gal) to reduce any potential for residues. CapSil should not be applied more than once per week during bract development.






Increasing Bract Size with Fascination

Inadequate bract expansion can be caused by a number of reasons including but not limited to: a

Figure 3. Spikey bract effect with Fascination spray
lower than ideal ADT (Average Daily Temperature) and excessive or late applications of PGRs. Foliar sprays of Fascination can be successful in increasing bract expansion but carries certain risks with it. Over-applications of Fascination at this stage of development can lead to weakened petioles, overly large floppy bracts, a change in bract color, and accelerated cyathia abscission. Consider these to be rescue treatments for when the risk of unsaleable plants due to small bracts outweighs the potential risks. Conduct trials on a small number of plants before widespread applications. Bracts sometimes have a “spikey” appearance soon after the treatment, but they usually flatten out within a few days. Fascination can be sprayed at 3ppm from first color to mid-November. Concentrations should decrease to 1-2 ppm during mid-November to December 1st. It is important to wait at least 5 days to evaluate changes in growth before reapplying if needed. 


Nutrition

Once poinsettias have essentially stopped vegetative growth and put their efforts in flowering, their overall nutrient requirements should be cut in half. Applying too much fertilizer during the bract development stage can lead to off colored bracts, salt stress, and disease issues such as Botrytis and Pythium. Please refer to Table 2 for general recommended feed rates based on dates during the late season. 




*All of these recommendations are based on top irrigation. For sub-irrigation, typically ½ as much fertilizer is used. Early cultivars go to clear water ~7-10 days earlier. The recommended schedule will need to adjusted if black clothing plants.

Nutrient deficiencies that do occur during the later portion of the season need to be corrected immediately to prevent a decrease in plant quality. Most of these issues can be prevented by making sure your crop is appropriately fed and soil pH is in the correct range leading into flower. We recommend testing your tissue and soil prior to first color in order to correct any issues before bracts begin developing. The most common deficiencies typically fall under the category of molybdenum (Mo), manganese (Mn), magnesium (Mg), iron (Fe), and calcium (Ca). Mn, Mg, and Fe will increase in availability to the plant as soil pH goes down, while Mo and Ca will decrease in solubility. Utilizing a micronutrient package such as S.T.E.M. or M.O.S.T. in combination with adjusting soil pH within 6.0 to 6.5 can help correct all of these deficiencies except Ca. Calcium deficiencies can be corrected by using a calcium containing fertilizer such

Figure 4. Pythium root rot causing plant wilting
as 15-0-15 and foliar sprays of calcium chloride dihydrate as described previously. 


Late Season Pythium 

There are various Pythium species that can cause root rot issues throughout the season. Most often, we can prevent root rot by supplying the appropriate concentration of fertilizer based on the stage of growth as described above and maintaining an appropriate irrigation frequency. Applying high amounts of fertilizer can lead to salt stress and damaged root systems. These conditions are ideal for Pythium to colonize and overtake the plant. Pythium can also be prevented with scheduled fungicidal drenches. Table 3 shows a recommended drench program for preventing root rot issues throughout the season. 








Mentioned Products

Product NameItem Number
Affirm WDG
71-1129
Astun
71-1190
Medallion WDG
71-16502
Palladium
71-2685
Spirato GHN
71-2948
Banrot 40 WP
71-1210
Fenstop
71-14801
Segway O
71-31101
Subdue Maxx
71-2979
Terrazole L
71-3025
Terrazole WP
3183862
Truban 25 EC
71-3070
Fascination
73-1910
CapSil
74-1541
Jack's 15-0-15
33627
Peters ICL 15-0-15
67-2340
Plantex 15-0-15
31-140100
S.T.E.M.
67-2344
M.O.I.S.T.
33633
Calcium chloride dihygrate
35315
Printable version

Heat Stress in Plants

All good things are best when used in moderation, as the saying goes. That is certainly true of heat in the summer, as we can all attest. As the temperatures soar plants can take a turn for the worse, a condition generally termed ‘heat stress’. Several common crops cultivated over the summer season provide well-known examples of the effects of non-lethal heat stress. Tomato crops set fruit less efficiently, poinsettias
Heat distortion of chrysanthemum foliage. 
and chrysanthemums can develop strappy foliage and experience delayed flowering. These effects occur when the local temperature the plant is experiencing is higher that the inherent stability of the plant’s cellular DNA, protein enzymes, and membrane structures.

The process of photosynthesis is the first to be affected as temperatures rise. The enzymes involved in photosynthesis, are heat-sensitive and denature, or unfold, easily. Plants try to protect themselves physically by changing leaf orientation and size, and plant morphology under prolonged stress. Furthermore, plants change their biochemistry in order to preserve their normal cellular functions. Plants express heat-shock proteins to stabilize the enzymes of photosynthesis and other processes, they produce enzymes to deactivate oxidizing molecules, and shore up cell membranes with more saturated and less fluid lipids to mitigate damage. (Think of lard or shortening versus vegetable oil.)

 
Lack of chlorophyll due to heat stress in geranium.
The severity of heat stress is a function of both the high temperature and its duration. Also note that the leaf tissue temperature is what matters, and it is not the same as the air temperature on your thermometer. Plants cool their foliage by transpiration of water though the stomates, up to the point when water conservation becomes a greater need than cooling. Once stomates close and transpiration stops, the leaf temperature can climb to more than 10 degrees above air temperature due to radiant heating by the sun. Shoots and foliage are generally more tolerant to heat events than the roots are.




Heat stress due to the root zone temperature (RZT) of woody ornamental plants in outdoor production has been well characterized by Ingram, et al. 1,2 The RZT is driven primarily by direct sun on the sidewalls of the growing container. The low angle of the sun in spring and fall seasons allows more radiant energy to directly impact the pot sides. The sun’s angle, combined with clear dry days, can lead to high RZTs. Surprisingly, soil temperatures equivalent to the highs mid-summer have been shown to occur anytime from late spring through October, depending on location. 

The RZT in full sun production settings regularly tops 120⁰F and can reach 138⁰ F on the sun-exposed side of the pot, even in northern climates. Furthermore, it was shown that RZT will consistently exceed 104⁰F for 5-10 hours a day in some part of the container under field conditions. Temperatures of 120-130⁰F directly damage the roots of woody ornamental species in just a half hour, while 100⁰-104⁰ causes physiological changes and indirect damage to the roots in 5 to 6 hours. 

From: Reducing Heat Stress to Container-Grown Plants,
Kentucky Cooperative Extension Circular HO-119
written by Dewayne L. Ingram, John Ruter and
Chris A. Martin, 2017.
Re-growth of the roots on one side of the container
and death of roots on the other side as the sun
angle changes with the season.



The temperatures above indicate the majority of container-grown woody ornamentals in nursery production have roots functioning somewhere below their potential maximum. In a greenhouse, the solar heating of containers is reduced compared to field production due to diffusion of the light by greenhouse covering and convection cooling by mechanical or natural ventilation. Even so, slowed growth and reduced nutrient utilization are commonly seen in greenhouse crops in the heat of summer. 

So, how can a grower mitigate the conditions leading heat stress? Ingram, et al detailed a number of methods that can be used to moderate root zone temperatures in woody ornamental container production, elements of which can be related to horticultural production in general.

    • Shade the production area to prevent direct sun; start young plants pot-to-pot; shade the sidewalls of the outside rows; space plants for mutual shading; use pot-in-pot systems. 
    • Pot color choice - green, white, or other light colored containers can be 9-18⁰ degrees cooler than black pots. Fiber pots insulate the soil, making them the coolest option available. 
    • Squat containers will be cooler than tall containers of equal volume due to less sidewall area. 
    • Avoid production on highly reflective mulches or ground covers; woven black cloth reflects less heat to the pot wall, yielding cooler soil, than reflective white gravel or shell. 
    • Pre-dawn irrigation reduces the maximum daily high soil temperature slightly, but not enough. Cyclic watering throughout the day has little impact; watering a small amount to cool the soil in the heat of the day drives surface heat deeper and is not effective. 

Mineral nutrients can also increase a plant’s tolerance to heat and other abiotic stresses. Calcium has been shown to reduce plant stress and increase heat tolerance in a number of genera, from poinsettia to rhododendron. Calcium supplied in the nutrition plan can be supplemented with foliar sprays of calcium salts. This application method is very effective for pumping the plant tissues with calcium, and has used extensively for blossom end rot and other calcium deficiency issues. The preferred application is calcium chloride dihydrate due to its lowered potential for foliar damage compared to calcium nitrate. 

Silica is also protective against abiotic stresses in plants, including heat and drought stress. Silica can be incorporated in the nutrition program, drenched in the media, or applied as a foliar spray. Sil-Matrix is a formulated spray product, while AgSil16H can be applied by any of the above methods. 

The benefits of calcium or silica mineral supplements are not long-lived and applications should be repeated every 1-2 weeks to maintain effective levels, especially when using foliar sprays. New research into the plant benefits of these two minerals seems to continually provide additional reasons we should use them.

Referenced ProductsPackage SizeItem Number
Calcium chloride dihydrate
1,4,25 lb options
35315, 35316, 35317
AgSil 16H
50 lbs.
67-1000
Sil-Matrix
2.6 gal
71-2940

Log into Onliant for full list of our shading products, ground covers and container selections

1Reducing Heat Stress to Container-Grown Plants, Kentucky Cooperative Extension Circular HO-119 written by Dewayne L. Ingram, John Ruter and Chris A. Martin, 2017.

2 Ingram, D.L., J. Ruter, and C.A. Martin’s 2015 Review at: https://journals.ashs.org/hortsci/view/journals/hortsci/50/4/article-p530.xml

Printable version

Fall Pansies - Fighting Black Root Rot and Phytophthora

Few crops can compete with the performance of pansies and violas during the fall season! For many regions, fall pansies are a landscape staple, providing impressive color through the autumn and winter months. In northern regions, pansies provide fresh fall colors and can overwinter to provide an early burst of color in the spring. Plant breeders have ensured there’s a lot to enjoy: a myriad of colors, flower sizes, and new plant habits. From the grower perspective, pansies also provide a welcome profit center that’s independent of spring. 

Even with improved genetics, pansies are still a cool-season crop. Fall-flowering crops are typically started when the weather is quite warm, even hot, and therein lies the challenge from a disease-prevention standpoint. Two diseases of the root and crown area earn mentions for being particularly challenging for fall pansy production: Thielaviopsis and Phytophthora.

Black Root Rot: Thielaviopsis 

Thielaviopsis, also known as Black Root Rot, is a wasting disease of pansies that’s inhibited to some extent at a soil pH below 5.8. Warning signs include roots that darken and are reluctant to
Pansy, Thielaviopsis
grow out of the original plug. Infestations are often random in appearance with stunted pansies right alongside plants that are thriving. Unless you have a microscope and can identify Thielaviopsis spores in the roots, suspicious plants should be sent to a plant diagnostic lab for positive identification.

Plants infected with Thielaviopsis cannot be salvaged, meaning fungicide treatments can only be used to protect adjacent healthy plants. Given the susceptibility of pansies and the environmental stresses early in production, GGSPro recommends a preventative fungicide drench soon after transplanting. The products we recommend for Thielaviopsis also control Rhizoctonia.

Phytophthora

Phytophthora is seldom found in winter/spring-grown pansies but can cause substantial losses in late summer and early fall. Warm temperatures and abundant splashing water favor this fast-moving algae. The Phytophthora zoospores (swimming stage) can readily move about and enter healthy plants via the drain holes in pots and flats. For this reason, growing the crop up off the ground is very desirable. Benches are ideal; however, inverted flats or 1” PVC pipes under the flats will serve the purpose.

Effective fungicides may be applied to address Phytophthora, but to be successful it’s important to reduce the risk for spread. Learning to identify the early symptoms as well as the conditions that make disease expression more likely is also key. Watch for sudden stem constriction and collapse at the crown. Rootshield Plus is a fungal-based preventative fungicide that includes Phytophthora prevention due to the addition of a second strain of Trichoderma to the original formulation. It’s also labeled for the prevention of Thielaviopsis. Chemical control options appear in the table below.

Pansy Care: Additional things to look for

Pythium

Pansy, Anthracnose (Colletotrichum sp.)
Pythium is another water mold that can cause root rot in fall pansies. Over-fertilization, poor drainage that leads to containers in standing water after heavy rains and irrigations and heat stress can predispose fall pansies to this common foe.

Foliar diseases become more prevalent as the crop progresses and the weather cools. Anthracnose (Colletotrichum), Botrytis, and Cercospora are among the troublemakers.





Anthracnose

Pansy, Cercospora
Anthracnose symptoms on pansies generally appear as large necrotic and chlorotic lesions that are somewhat irregularly shaped. Often, faint concentric rings can be detected within the necrotic tissue. Botrytis can be especially problematic as early blooms begin to senesce and “melt,” sometimes involving adjacent foliage. Cercospora often manifests itself with dark purple spots, some of which have tan centers, giving rise to the “fish-eye” description.

Much more information on these and other diseases that affect pansies is available through GGSPro and the GGSPro 5th Edition Reference Guide, which includes cultural and chemical controls, as well as helpful diagnostic pictures. 

The tables below also contain fungicide suggestions.

Products for Pansies Root and Crown Diseases

Apply as soil drenches except as noted.


FungicideMOACommentsItem Number
Thielaviopsis
Affirm
19
Chemigation label approved
71-1129
Cleary’s 3336 EG
1
Max label rate, re-apply in 3 weeks
71-2550
Cleary’s 3336 F
1
Max label rate, re-apply in 3 weeks
71-2575
Medallion
12
2 oz per 100 gals rate
71-16502
Mural
7 & 11
Broad-spectrum control
71-1690
OHP 6672 F
1
Max label rate, re-apply in 3 weeks
71-2670
OHP 6672 WSP
1
Max label rate, re-apply in 3 weeks
71-2672
Orkestra Intrinsic
7 & 11
Broad-spectrum control
71-2200
Rootshield Plus G
UN
Pre-incorporation
71-27911
Rootshield Plus WP
UN
Best applied at time of transplant
71-27951
Spirato GHN
12
Formerly called Emblem
71-1570


FungicideMOAP= Pythium
Ph= Phytophthora
CommentsItem Number
Actinovate SP
NC
P
Best applied at the time of transplant
71-1118
Adorn
43
Ph
Foliar spray or drench
71-1130
Areca
33
Ph
Foliar spray, avoid open bloom
71-1180
Aliette
33
Ph
Foliar spray, avoid open bloom
71-11352
Banrot
1 & 14
P, Ph
Soil drench, use max label rate
71-1210
Broadform
7 & 11
Ph
Foliar spray aerial Phytophthora only
72-1290
Fenstop
11
P,Ph
Foliar spray or drench
71-14801
Fosphite
33
Ph
Foliar spray or drench
71-1520
Heritage
11
Ph
Foliar spray or drench, preventative
71-1400
Kleengrow
NC
P,Ph
Do not combine with fertilizer
74-21151
Micora
40
Ph
Foliar spray or drench
71-1655
Orkestra Intrinsic
7 & 11
Ph
New product, trial for plant safety
71-2200
Orvego
40 & 45
Ph
Foliar spray or drench
71-2300
Phostrol
33
Ph
Foliar spray or drench
71-1520
Rootshield G
NC
P
Pre-incorporation
0
Rootshield WP
NC
P
Best applied at the time of transplant
71-27901
Rootshield Plus G
NC
P, Ph
Pre-incorporation
71-27911
Rootshield Plus WP
NC
P, Ph
Best applied at the time of transplant
71-27951
Segovis
U15
Ph
Foliar spray or drench
71-3100
Segway
21
P, Ph
Foliar spray or drench
71-31101
Stature SC
40
Ph
Foliar spray or drench
71-14652
Subdue MAXX
4
P, Ph
Some resistance reported
71-2978
Terrazole L
14
P, Ph
Stronger vs Pythium
71-3025
Truban EC
14
P, Ph
Stronger vs Pythium, no tank mixing
71-3070
Truban WP
14
P, Ph
Stronger vs Pythium
71-3065

Products for Common Pansies Foliar Diseases


FungicideMOAAnthracnoseBotrytisCercosporaItem Number
Affirm
19
x
x
71-1129
Astun
7
x
71-1190
BotryStop
NC
x
71-1260
Broadform
7 & 11
x
x
x
71-1290
Camelot O
M1
x
x
70-21202
Cease
44
x
x
x
71-13301
Daconil Ultrex
M5
x
x
x
71-1420
Daconil Weatherstik
M5
x
x
x
3117025
Eagle
3
x
x
71-1435
Fame
11
x
x
71-1505
Grotto
M1
x
x
71-2030
Heritage
11
x
x
71-1400
Kalmor
M1
x
x
71-2050
Medallion
12
x
x
x
71-16502
Mural
7 & 11
x
x
x
71-1690
Nordox
M1
x
x
71-1700
Orkestra Intrinsic
7 & 11
x
x
x
71-2200
Pageant Intrinsic
7 & 11
x
x
x
71-26801
Palladium
9 & 12
x
x
x
71-2685
Phyton 35
M1
x
x
71-2737
Protect DF
M3
x
x
x
71-2748
Spirato GHN
12
x
x
x
71-1570
Triathlon BA
44
x
x
x
71-3040
Trigo
3 & 11
x
x
x
70-3035
Zerotol 2.0
NC
x
x
71-35501

Read and follow all label directions. The label is the law! Products other than those mentioned may also be safe and effective. Some pesticides may be restricted-use or unregistered in certain states.


Printable version

Insect Pest Control Roulette

Late spring and early summer are just around the corner, which means some of the most feared pests of ornamental crops are not far behind. Oftentimes it feels like a game of “Insect Roulette”—never knowing what pest you will find and when (not to mention, which crops will fall victim). However, by understanding the important phases of insect development (i.e. life stages) and what damage insects cause, growers can shift focus from damage control to damage prevention, ultimately saving time and money.

Pest Stages: Metamorphosis

Figure 1 - Example of Incomplete
Metamorphosis 
First, growers must be able to recognize the difference between simple or incomplete metamorphosis and complete metamorphosis when scouting. The process of how insect transitions during its life stages are known as metamorphosis. When the life cycle entails an egg, nymph, and adult, with no pupa, this is a simple or incomplete metamorphosis. Insects such as aphids, grasshoppers, plant bugs, planthoppers, spider mites, and stinkbugs all have this gradual metamorphosis where the young look similar to the adult. (See Figure 1.) Chemical controls are typically active on all life stages but may show higher efficacy at some stages.

Figure 2 - Example of Complete
Metamorphosis 
On the other hand, complete metamorphosis is when an immature pest looks completely different than the adult, with a life cycle of an egg, larva stages, a pupa, and an adult. The key difference is the pupa stage, which is the last stage when a protective shell or a silken cocoon is formed and the winged adult emerges. Butterflies, beetles, moths, sawflies, thrips, weevils, and whiteflies are all examples of complete metamorphosis. (See Figure 2.) Chemical insecticides targeting the larvae may often provide the most effective control. Separate products are often required for adult control.
Growing Degree Days effect on Pests
There are several valuable tools growers can utilize to indicate pest activity. A pest predictive calendar correlates when susceptible life stage(s) of pests are active by using plant phenology and growing degree days (GDD). Also, since every insect requires a consistent amount of heat accumulation to reach a certain life stage, the Growing Degree Days (GDD) is a tool that models this heat accumulation over a 24 hour period above a specified base temperature of 50oF. Check your state agriculture department and/or extension service to see if they offer plant phenology calendars and pest emergence information for your area. To determine a GDD in an area, use a min/max thermometer placed outside in the production area. Then apply the GDD formula, which is:

(Low temperature + High temperature) / 2 – 50o F = Total GDDs.

It’s also worth noting that as the summer season progresses, increasing temperatures often means shorter insect life cycles. Therefore, knowing which pests have one or two generations vs. several generations annually will help focus scouting efforts.

Plant Pest Identification
In addition to knowing how insects develop differently, growers should look for clues as to what insect is present when scouting. Most plant damage is caused by insects’ mouthparts (See Table 1). Piercing/sucking insects will cause off-colored, stippling or streaking of foliage as plant cells nutrients are being removed. However, insects with chewing mouthparts cause holes in the leaves, leaf margins, or stems.
The table below provides information summarizing the key points of this article along with a representative sample of Griffin’s chemical options. With this knowledge, let’s grow more confidently and hopefully stay ahead of the “Insect Roulette” game.

Table 1 – Pesticide Foliar Spray Options
Common NameLife Cycle*DamageChemical ControlItem Number
Aphids
I
Piercing/sucking mouthpart; Curling, 
deformed, yellowing leaves
Altus 
Pradia 
Tristar
70-1161 (64 oz)
 70-2630 (qt)
 70-85221 (qt)
Beetles
C
Chewing mouthpart; Holes or skeletonized 
leaves; bark beetles bore holes into bark,
 look for frass and/or sap
Discus L
Mainspring 
Sarisa
70-14091 (gal)
70-2331 (pt)
70-2975 (64 oz)
Grasshoppers
I
Chewing mouthparts; holes in foliage 
and flowers; worse in dry weather
Acephate 
Pycana 
Tristar
71-1105 (lb)
70-2655 (gal)
70-85221 (qt)
Moths
C
Chewing mouthparts; eat leaves, roots, 
and can bore into stems; wider host 
range than caterpillars
DiPel Pro 
Pycana 
Venerate CG
70-1450 (lb)
70-2655 (gal)
70-9461 (qt)
Plant Bugs
I
Piercing/sucking mouthpart; stipple 
foliage, distorted foliage
Altus 
Pradia 
Pycana
70-1161 (64 oz)
70-2630 (qt)
 70-2655 (gal)
Plant Hoppers 
(including leafhoppers)
I
Piercing/sucking mouthpart; may have 
waxy coating; jump when disturbed
Discus L 
Flagship 25WG
Tristar
70-14091 (gal)
70-1700 (8 oz)
70-85221 (qt)
Sawflies
C
Chewing mouthparts; larvae consume 
needles/leaves quickly one branch at a time
Conserve 
Pycana 
Sarisa
70-1365 (qt)
70-2655 (gal)
70-2975 (64 oz)
Spider Mites
I
Piercing/sucking mouthpart; Chlorotic 
spots, whitish stippling; bronzed appearance
Shuttle O 
Sultan 
Suffoil-X
70-30151 (pt)
70-3045 (16 oz)
70-4040 (2.5 gal)
Stink Bugs
I
Piercing/sucking mouthpart; causes 
distortion, sunken areas, scarring
Azera Pro 
PyGanic 5.0 
Sarisa
70-1232 (qt)
70-2687 (qt)
70-2975 (64 oz)
Thrips
C
Piercing/sucking/thrashing mouthpart; 
whitish/silvery stippling or streaking; 
the presence of fecal spots
Mainspring 
Pradia 
Pycana
70-2331 (pt)
70-2630 (qt)
70-2655 (gal)
Weevils
C
Chewing mouthpart; chew distinctive 
notches along leaf margins; 
grubs injury roots/crowns
Flagship 25WG
Mainspring 
Sarisa
70-1700 (8 oz)
70-2331 (pt)
70-2975 (64 oz)
Whiteflies
C
Piercing/sucking mouthparts; yellowing, 
chlorotic spots on upper leaf 
surfaces, honeydew/sooty mold
Ancora 
Pradia 
Tristar
70-1166 (lb)
70-2630 (qt)
70-85221 (qt)
* I=Incomplete, C=Complete
All recommendations for insecticides are for foliar spray applications. Most foliar sprays listed will perform better with a surfactant, such as CapSil to increase coverage and reduce visible residue. Some product labels state that surfactants should not be added. CapSil rates: ¼-1/2 tsp/gal or 4-8 oz/100 gal, (# 74-1541, 1 gal).
Information in this bulletin is believed to be correct, but it is the responsibility of the applicator to read and follow all label directions. Labels do change without notice. Pesticides other than those listed may be safe, legal, and effective.

Printable version

Extending Shelf Life and Marketability of Spring Plants

With the uncertainty surrounding the beginning of the Spring 2020 plant selling season in many parts of the country, it is understandable that growers are interested in any strategies that may extend the shelf life of the crops they have worked so hard to produce. The discussion below will not apply to all crops in all parts of the country, but most growers will find tips for increasing the length of time that crops remain in a marketable condition and thereby reduce shrinkage.
Using Temperature as a Tool- Researchers have told us that the average daily temperature is the best predictor of the rate of plant maturity. With that in mind, there are some things that growers can do to manipulate the temperature to slow down crops safely. It is important to recognize that crops vary greatly in their tolerance to cooler temperatures and this needs to be taken into account.
An article titled, “Growing Your Crops Above Their Base Temperature[i] by Drs. Roberto G. Lopez and Erik S. Runkle, Michigan State University, lists minimum base temperatures for many greenhouse crops. The authors describe the base temperature as the species-specific temperature at which plant development stops. Based on their work, there are a number of crops that will not tolerate cool production temperatures for extended periods of time. Ageratum, angelonia, browallia, celosia, gerbera, gomphrena, hibiscus, pentas, portulaca, vinca, and zinnia are crops that may tolerate being grown a few degrees cooler than normal as they approach maturity, but larger temperature drops may have undesirable consequences. 60°F nights with days as close to that temperature as the weather allows should be tolerated for a few weeks. Most other crops will tolerate night temperatures in the 50’s with cool days. As temperatures cool, the relative humidity in the greenhouse increases, leading to more condensation on plant surfaces. Botrytis can make penetration into healthy tissue with just a few hours of free moisture on leaf surfaces. Good air movement via horizontal airflow HAF fans at night helps to reduce the relative humidity within the plant canopy. Provide plenty of ventilation during the day to keep the crops cool and the foliage dry. During multiple days of dark wet weather, bump the heat up a few degrees at night to help dry out the air. If drip irrigation is not available, limit overhead watering to morning to allow the foliage and flowers to dry before nightfall. There are several bloom-safe fungicides with different modes of action that can be used to prevent Botrytis. Foliar sprays of calcium chloride have been shown, through research done by Dr. Jim Faust at Clemson University, to combat Botrytis. GGSPro can assist you in putting an effective rotation together.
Figure 1. Calibrachoa is an example of a cold tolerant plant


Benefits of Outdoor Production- On the other side of the spectrum are plants that growers report are much more tolerant of cold temperatures and will typically survive frost and light freezes without significant damage. These crops would do well placed outside on gravel pads or ground cover fabric. The combination of cooler temperatures, higher light levels, and wind exposure slows down plant development while producing well-toned superior quality plants. Cold frame structures with roll-up sides can provide excellent production conditions for these crops, with the added benefit of protection from heavy rain and unseasonably cold temperatures. Even cold-tolerant crops need to be hardened off for a period of time before facing frost and freezing temperatures. A week of night temperatures in the low 40’s is generally sufficient. For added protection keep an eye on weather forecasts and look for a string of 3 nights that are predicted to have above freezing temperatures to allow for further hardening off when the crops are first placed outside. The fungicide Pageant Intrinsic (BASF) has been shown to increase cold tolerance by a few degrees for a number of plants. Apply 2-7 days before the plants experience a frost or freeze.
Spring annuals generally regarded as tolerant of a light freeze after proper hardening off include:


·       Alyssum
·       Bidens
·       Calendula
·       Calibrachoa
·       Diascia
·       Dianthus
·       Dracena
·       Dusty miller
·       Nemesia
·       Osteospermum
·       Pansy
·       Petunias (except some veined flower varieties)
·       Phlox
·       Snapdragons
·       Stock
·       Vegetables (cole crops, lettuce)
·       Verbena
·       Violas


The following plants should tolerate a frost, but avoid a hard freeze:
·       Argyranthemum
·          ·      Bacopa
·          ·      Bracteantha
·          ·      Lobelia
Putting crops out early is not without its risks. One grower shared this picture after an April snowstorm and freeze. Despite the icy appearance, the entire outdoor crop pulled through with minimal damage.
Plant Growth Regulators- PGR’s can be used to extend crop shelf life by reducing internode elongation that may otherwise lead to over-crowding, leggy plants, and diminished appearance. Selecting the proper PGR, rate and application timing for each crop is important as there is no “one-size-fits-all” recommendation. The GGSPro 5th Edition Reference Guide has an updated and expanded chapter featuring crop by crop recommendations for many annuals and a selection of perennials. The Grower Talks Magazine’s, “Plant Growth Regulators for Annuals” guide by Dr. Brian Whipker, NCSU, is another outstanding resource for PGR information. Crops moved outside will require fewer PGRs than the same crops grown in heated greenhouses. As a rule of thumb, PGR drench applications hold plants longer and have less impact on bloom date and bloom size when compared to foliar applications. Soilless media with pine bark will generally require higher PGR drench rates than other mixes, all other factors being equal. Paclobutrazol is widely used as the drench treatment of choice, especially for growers new to PGRs, because it can be used on so many ornamental crops and rates are well established for most crops. Bonzi, Pac O, and Paclo Pro all contain that active ingredient.
Larger Containers Increase Shelf Life- Consumers looking to make up for lost time may be more inclined than usual to purchase larger containers of spring color. This could work out in favor of growers since larger containers are easier to maintain for longer periods of time than small ones. Consider bumping up to larger containers to extend shelf life and meet consumer demand.
Alesco to Prolong Bloom- Alesco is a unique product applied as a foliar spray that can provide significant benefits for many crops. Applications are inexpensive and can add up to 3 weeks of shelf life depending on the variety and environmental conditions. This happens by reducing petal shatter, bud abortion and extending flower longevity.
GGSPro can be reached at ggsprotech@griffinmail.com or by calling 800-888-0054 extension #89129.


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The ABCs of BCAs

Biological Control Agents, or BCAs, refer to a group of living organisms that growers use to control pest pressure in greenhouses and nurseries. From parasitic wasps to microscopic nematodes, BCAs combat a wide range of common horticultural pests. Currently, BCA use is experiencing a surge in popularity. Much of this popularity comes from the recent legalization of hemp and cannabis production, though these are by no means the only crops to employ them. Growers turn to BCAs when they are seeking to reduce pesticide use, increase worker and bee safety, or even to become more environmentally friendly. This bulletin will address several important reasons to consider implementing BCAs as part of your integrated pest management (IPM) program and how to get started with an individualized BCA plan.
These days, growers choose BCAs over traditional pesticides for a wide range of reasons. Environmental sustainability has moved high up on the list of priorities for many. Switching to BCAs as a method for achieving sustainability, when properly done, directly competes with traditional chemical applications in effectiveness against pests. A huge drawback of chemical pesticides remains their tendency to affect more than intended once they have been applied, either through run off or over spraying. Chemical pesticides may remain in soil for a long time, contaminate groundwater, or spray drift can affect organisms outside the treated area. This unquestionably leads to both environmental and worker safety hazards.

Worker safety with BCAs can be seen in their application methods. With typical BCA applications, workers can directly handle BCA materials with no physical or health safety concerns. BCAs are usually highly species specific when choosing their targets, and simply migrate or die when their prey targets are no longer found. BCAs must be native to North America to be sold in the US, meaning introduction of an invasive species is not a concern. Pest specific targeting also leaves bees unaffected by most BCAs. Finally, pesticides run the risk of facing developing resistance in their target pests. Most pesticide programs recommend regular rotations to avoid overexposure of a single mode of action. For BCAs, there really is no developing a resistance to predation.
BCAs are typically offered in bulk or sachet form. Bulk forms come in containers holding a carrier material such as bran or vermiculite, and an estimated number of BCAs per volume. Bulk options work well for growing areas containing large numbers of small plants. Sachets target larger plants or areas of production where plants are touching. Since sachets provide an enclosed breeding colony for their insect predators, they provide 4-6 weeks of BCA activity at a higher cost. Bulk options are more cost effective but often applied weekly with a shorter period of activity. The range of options allows for greater customizability for specific operations and is a great asset when using BCAs.
Deciding between BCA delivery methods and rates may seem overwhelming; GGSPro provides all the information you need to make a decision based on your needs, budget and labor requirements. Griffin has worked with many growers to develop effective BCA plans. To begin, GGSPro or your local sales representative need certain information to provide the best possible plan for your operation. This information includes:

·       Number of greenhouses
·       Size of each greenhouse and the total growing space
·       Previous chemicals used (if starting a BCA plan mid-season) and chemicals commonly used
·       Type of crops being grown
·       Major insect pests historically seen or currently seeing in production
·       Media used for growing crops
·       Temperature ranges

Griffin provides a wide ranges of BCA products from various suppliers including, Bioline, Beneficial Insectary, BioBee, and others. Griffin can also advise you on how quality check and release your BCAs as well as determine which pesticides are compatible with your BCA program.
In conclusion, BCAs can be applied to almost any greenhouse operation and effectively replace chemical pesticide programs while being consumer, worker, and environmentally friendly. If you are looking to start a BCA plan, simply reach out to your Griffin sales rep or the GGSPro team to get started.


Figure 1. A parasitic wasp (Eretmocerus eremicus)
 laying eggs under whitefly pupae


Table 1. BCA options for common pests (Consult Griffin for specific products and rates)

Target Pest
Type of BCA
Aphids
Parasitic wasps, lacewing, and larvae (bulk release)
Black Vine Weevil & White Grubs
Nematodes
Fungus Gnats
Nematodes, predatory beetles, and mites
Leafminers
Parasitic wasps
Mealybugs
Predatory beetles and larvae
Spider Mites
Predatory mites
Thrips
Nematodes, predatory beetles, and mites
Whiteflies
Predatory bugs, beetles, parasitic wasps, and mites

Figure 2. Sachets on sticks containing predatory mites
used for annual young plant pest management

Figure 3. Bulk release bottle of Aphidius ervi,
a predatory wasp used for aphid control
Figure 4. Bulk release material containing 
predatory mites for whitefly and thrips control
Figure 5. Beneficial nematodes used for 
fungus gnat and thrips control




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Plant Lighting – Introduction into Supplemental and Sole-Source Lighting

Introducing Lighting Units

The previous lighting article focused on photoperiodic lighting. This article will focus on supplemental and sole-source lighting strategies. Utilizing these lighting techniques requires thorough understanding of what light is and how it is quantified. There are some standardized terms and units that are used in today’s industry, which can help you maximize the benefits of plant lighting (Table 1). 


Fig1. Photosynthetic  Active Radiation (PAR) Spectrum
(400-700nm) Photo provided by Dr. Erik Runkle, MSU

Light is a form of energy measured in photons. Photons can travel in different wavelengths and these wavelengths are measured in nanometers (nm). The wavelength that light travels in can be broadly described as light quality. Humans can visibly see photons traveling in wavelengths ranging from 380-770 nm (i.e. the visible light spectrum). Within this range, plants utilize photons within 400-700 nm (light qualities of blue to far-red) for photosynthesis (Fig. 1). We call light within this range photosynthetic active radiation (PAR).

It is important for growers to know how much light plants receive for a given area, so light intensity measurements are typically reported as a density (amount of light given off every second per square meter of growing space). We call this photosynthetic photon flux density (PPFD).




Fig 2. Supplemental lighting during winter
months for young plant production
Supplemental Lighting and Sole-Source Lighting

Supplemental lighting is the use of artificial light to supplement PPFD provided by sunlight. The purpose of supplemental lighting is to add additional light at intensities high enough to increase photosynthesis and improve plant quality in situations where sunlight is limited. During periods where light levels are minimal such as the winter (due to a lower photoperiod) or cloudy days, supplemental lighting can provide additional PPFD to plants to carry on with adequate rates of development.




Fig 3. Indoor vertical farm with sole-source lighting


Sole-source lighting is the use of artificial light without additional PPFD from sunlight to produce any or all stages of a crop. This form of lighting application has been utilized in environmental controlled settings such as factory farms, indoor grow operations, and vertical farms. This is the most expensive plant lighting application. These costs are attributed to high capital and installation costs of the light modules themselves and electrical costs required to operate the lights on a daily basis. For supplemental and sole-source lighting applications, achieving a target DLI is very important. The target DLI a grower should strive for is crop and crop stage specific (Table 2). DLI is essentially the total amount of PAR light one square meter of growing space receives over a single day (mol∙m-2∙d-1).



Griffin offers a wide range of lighting products and services to meet all your photoperiodic, supplemental, and sole-source lighting needs. Please reach out to GGSPro or the Griffin CEA division with any questions or inquiries you may have regarding plant lighting.


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Plant Lighting - Introduction into Photoperiodic Lighting

Overview

Light is an essential input for driving plant growth and producing a high-quality product. The major light sources for growing plants include sunlight and plant lighting technology. Growers can use plant lighting in three major ways:

Photoperiodic Lighting - manipulating vegetative and reproductive stages of plant development through day/night length control
Supplemental Lighting - adding additional light to increase total crop photosynthesis and quality 
Sole-Source Lighting - growing plants in completely artificial light 

This article will focus on photoperiodic lighting and how it is utilized in plant production. There will be a follow-up article on utilizing supplemental and sole-source lighting over the coming year. 

Photoperiodic Lighting

Fig 1. Photoperiodic lighting to keep young plants vegetative
Photoperiod can be defined as the number of hours of light a plant perceives on any given day. The number of hours of light/darkness a plant receives per day can directly influence flowering response, stem elongation, and dormancy. Typically, photoperiod is naturally controlled by the most common light source for plants, the sun. Depending on where your operation is located geographically, your photoperiod can vary by several hours throughout the year and even growing season.

A majority of plants we grow are separated into three photoperiodic requirement categories: plants requiring daylengths less than a given amount of time are short-day (SD), plants requiring daylengths more than a given amount of time are long-day (LD), and plants that do not require a given daylength to show a response are day-neutral (DN). A majority of LD plants require greater than 12 hours of daylength to initiate flowering while most SD plants require less than 12 hours to initiate flowering. Photoperiod requirements can be species specific and even vary between varieties. 





Examples of Photoperiodic Control in Production


Fig 2. Black cloth used to force SD plants into flower
Running lights from 10pm to 2am will keep SD plants vegetative. This practice is commonly used to extend the vegetative phase and prevent plants from flowering or going dormant. Keeping plants vegetative provides more time for plants to increase in size as well as allows precise control on when plants flower. Extending photoperiod is also useful for propagation during the fall and winter months. It is important to keep young plants vegetative to encourage adequate rooting and development. The most common light sources used for extending photoperiod include incandescent, high pressure sodium (HPS) Beamflicker, metal halide, and fluorescent bulbs.

Scheduling plants is vital to meet consumer needs. There are times when the natural photoperiod is greater than 12 hours and growers need to force SD plants into flower. Growers can decrease natural photoperiod by pulling black cloth over the crop in the morning and evening hours on a daily basis. This will extend the “nighttime” period and force SD plants into flower. 


Griffin offers a wide range of lighting products and services to meet all your photoperiodic, supplemental, and sole-source lighting needs. Please reach out to GGSPro or the Griffin CEA division with any questions or inquiries you may have regarding plant lighting.


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New Products from the Softer Side of Pest Control

The trend in new pesticide introductions for commercial greenhouse and nursery operations is towards “softer” pesticides, many of which are approved for organic production. Many consumers and producers are asking for these types of products and the market has responded to this demand in a significant way. A few notable introductions into this category of pesticides are discussed below.

Sil-Matrix is based on a liquid concentrate of potassium silicate. It is an EPA registered fungicide, insecticide and miticide. Silicon research is being conducted in a number of places and as a result many plant health benefits have been described. Sil-Matrix is applied as a foliar spray for the control of aphids, spider mites and whiteflies as well as important foliar diseases such as Botrytis and powdery mildew. It is labeled for use on ornamentals and many edible crops including certain vegetables, berries, vines and fruit trees. The addition of a high quality surfactant such as CapSil improves coverage and reduces visible residue on plant surfaces. Sil-Matrix is OMRI listed and benefits from a 4 hr REI and can be used up to the day of harvest.

Item 71-2940 Size 2.5 gal

Spider mite, 5 days after Velifer treatment - Photo credit BASF
Velifer is a new microbial insecticide and miticide based on Beauveria bassiana strain PPRI 5339. The formulation is described as an oil dispersion, with the oil being plant based. Velifer is labeled for greenhouse use only, for the control of aphids, mealybugs, mites, thrips and whiteflies. It can be used on ornamentals, fruits, vegetables, herbs and spices. GGSPro recommends a program for Velifer that includes tank mixing it with an azadirachtin based IGR such as: AzaGuard, Azatin O or Molt-X to further enhance performance. Contact GGSPro for more tips on maximizing the effectiveness of microbial insecticides such as Velifer.  BASF has produced a list of pesticides that are compatible with Velifer. Velifer has a 12 hr REI and can be used up to the day of harvest.

Item: 70-9540 Size: quart

FireWorxx is a fast acting, non-selective broadleaf weed, grass, algae and moss killer. On a warm sunny day results can be seen in a few hours, but never longer than 2 days. It can be used in and around ornamentals and edible crops, so long as all contact with desirable foliage is avoided. FireWorxx can also be added at a 1% rate to improve the performance of other herbicides such as glyphosate, (Round-Up, etc) and glufosinate, (Cheetah Pro, Finale). FireWorxx is an OMRI listed product with a 12 hr REI.

Item: 72-1608 Size: gal

Dahlia, Powdery Mildew
EcoSwing is a botanical extract from Swinglea glutinosa.  If that is a new plant name for you, you are in good company! Swinglea is a type of citrus. EcoSwing acts as a contact desiccant and cell wall disruptor to fungal hyphae. EcoSwing is primarily a preventative fungicide with some curative activity versus Botrytis, downy mildew of basil, powdery mildew and brown rot. EcoSwing can be used on ornamental and food crops in greenhouses, nurseries and landscapes. It is OMRI listed with a 4 hr REI and it can be used up to the day of harvest.

Item: 71-1455 Size: quart


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Algae Is A Slippery Slope


Algae on a walkway
Algae on a floor or walkway is a known slipping hazard –it ranks right up there with cartoon banana peels! That is no laughing matter in your production areas. On the soil surface in pots, algae can interfere with water penetration and drying of the soil. Its’ growth robs the plant of nutrients, and decreases the soil oxygen levels. Algae can also grow on the foliage, blocking light for photosynthesis. As if interfering with growth is not enough, algae also provides a hatchery and a food source for both fungus gnat and shorefly larvae wherever it exists. In hydroponic production, algae can have an even more interesting effect. The unwanted growth can cause extreme pH swings in recirculated hydroponic systems. The pH swings occur with the light and dark cycles as photosynthesis is carried out by the algae.  How can this green pest be prevented and, once present, how can it be controlled?

Preventing establishment of algae is the best practice, after it takes up residence, a grower is sliding down that metaphorical slippery slope. It can be hard to reign in the green slime.  Prevention begins when the system or structure is recently cleaned and sanitized, or is new in the case of soil-less media or rockwool cubes. Algae reproduces by sporulation and by simple cell division. Spores can be airborne and can cling to greenhouse surfaces, including the greenhouse plastic, leading to recurring issues. Thorough cleaning using an acid or chlorine-based product, followed by a disinfecting sanitizer is necessary to eliminate the spores on surfaces. Request the GGSPro bulletin: Hard Surface Sanitation Practices for more information. 


Algae on a basil float bed

Algae in the water system the leading cause of algae on the soil surface and provides a continual source of algal inoculum for hydroponic systems, drip irrigation systems, walkways and other greenhouse surfaces. Water systems are best cleaned when no plants are on the line or in the greenhouse. To break down the algae, biofilms, and mineral deposits that build up even when ‘clean’ water is used, strong cleaners are required. An empty production area is also best for cleaning surfaces, floors and bench supports. For some growers seasonal breaks provide the perfect opportunity for cleaning and sanitation. For growers in perpetual production, it is worth the effort to make a day, or even part of a day to clean the irrigation system and production area surfaces.


Cleaning Algae from a Water System, No Plants Present


ProductRateUse NotesItem Number
Cleaners
GreenClean Acid Cleaner
2.5 oz/gal (1:50 direct injection)
Soak up to 8 hrs
74-2040
SaniDate 12.0 OMRI listed
12.8 oz/100 gal (1:1000 dilution)
Soak 12-48 hrs. Does not remove mineral scale
71-35351
Strip-It Pro
2.5 oz/gal (1:50 direct injection)
Soak overnight
74-2125
Treat water system, irrigation lines, drop tubing and emitters (no lead emitters). All products are allowed in food packaging areas. Rinse the products through opn flush valves to prevent clogging. For GreenClean and Strip-It Pro acid cleaners, rinse further until the water has neutral pH at the last outlet on the line.


Cleaning Algae from Surfaces, No Plants Present




ProductRateUse NotesItem Number
Cleaners
GreenClean Acid Cleaner
3-8 oz/gal
Use as spray or foam. Contact time 10-15 min. Avoid soft metals and painted surfaces
74-2040
GreenClean Alkaline Cleaner
4-8 oz/gal
Use as spray or foam. Allow a contact time 10-15min.
74-2045
GreenClean Pro OMRI listed
Granular Use: 0.5-2lb/1k sq ft Liquid or Foam Use: 0.5 lb/gal
Use as granular control on floors; spray or foam with a foam agent for vertical surfaces. Break up thick clumps of algae as cleaning occurs. No use on painted surfaces.
74-20521
Horti-Klor
2.5-7.5 oz/gal
Use as spray, foam or dip. Rate based on soil level.
74-2105
Strip-It Pro
2.5-8 oz/gal
Use as spray, foam or brush application. 5-30 min contact time.
74-2125


Treat floors, hydroponic troughs of channels, sidewalls, benches, and supports. Rinse copper or aluminum, which are soft metals as soon as possible. These are strong cleaners, obey all label precautions and personal protection equipment requirements.

Once algae has been dealt a deadly blow, a sanitizer should be used to finish the job by disinfecting the cleaned system or surface, see chart below.  


When algae control is needed in and around crops, many of these same products are used for preventative maintenance against algae, either periodically, or by continuous injection in the water.  Furthermore, SaniDate12.0 or ZeroTol 2.0 can be used to clean irrigation lines while ‘in use’. After soaking with one of these oxidizers, the bulk of the algae and sanitizer is flushed through an opened drain valve before irrigation, since it will not be fully broken down. 


Controlling Algae in the 
Presence of Plants



ProductRateUse NotesItem Number
Cleaners
Eco-Clean
0.25 oz/100 gal
Water treatment only, not a sanitizer. Vegetable extract inhibits biofilm and algae adhesion to maintain water system by continuous injection in clean system. Safe for all plants including food crops.
74-2040
Kleengrow
Mist Propagation 1-2 time/week: 6 oz/100 gal or .06 oz/gal Soil surface sprench Weekly: 0.06 oz/gal Biweekly: 0.12 oz/gal Drip or Flood irrigation systems Weekly 12.5 oz/100 gal or 0.12 oz/gal
Sanitizer for surfaces, irrigation lines, crops. No direct contact with or irrigation of food crops. Use low rate for continuous water injection or propagation mist. Use high rate for weekly or biweekly spray applications to control algae on soil surface. Test crops for phytotoxicity. Do not mix with fertilizer if contacting foliage.
74-2045
SaniDate 5.0 OMRI listed
Surfaces: 0.5-2.2 oz/gal Irrigation water: Periodic or continuous 0.58-4.65 oz/100 gal Evaporative Coolers: Weekly: 0.16 oz/gal
Sanitizer for surfaces, irrigation lines, water treatment, continuous injection. Add foaming agent for vertical surfaces. Consult BioSafe for rates based on water quality and additives for continuous water injection. Not labeled for direct crop use.
74-20521
SaniDate 12.0 OMRI listed
Non porous surfaces: 0.21 oz/gal Hydroponic systems: 0.26-0.64 oz/100 Cleaning irrigation lines: 0.64 oz/100 gal Irrigation water: Periodic: 0.32-12.8 oz/100 gal Continuous (starting point): 0.13 oz/100 Evaporative Coolers: Shock at 0.2 oz/gal Maintain at .03 to 0.06 oz/gal
Sanitizer for surfaces, irrigation lines, hydroponic and irrigation water treatment, continuous injection. Add foaming agent for vertical surfaces. When cleaning irrigation lines, flush though drain valve before irrigating crops. Consult BioSafe for rates based on water quality and fertilizers used for continuous use. Not labeled for direct crop use.
74-2105
ZeroTol 2.0 OMRI listed
Surfaces: 1.25 oz/gal Foliar/ Soil Surface Spray: 0.5-1.25 oz/gal Cleaning Irrigation lines: 1.25-2.5 oz/gal (direct inject @ 1:100-1:50, respectively) Irrigation water Clean water: 1.25 oz/100 gal Contaminated: up to 25 oz/100 gal Evaporative Coolers: Shock at 1.25 oz/gal Maintain at 0.25 – 0.66 oz/gal
Sanitizer for use over plants, surfaces, irrigation lines, water treatment, continuous injection. Add foaming agent for vertical surfaces. When cleaning irrigation lines, flush though drain valve before irrigating crops. Consult BioSafe for rates based on water quality and additives for continuous water injection.
74-2125
All rates are the final concentration, per gallon or per 100 gallons.

Cyclamen Production - Plan Now to Succeed

The traditional use of cyclamen was focused on cool season container crop production due to its preference for lower production temperatures. Innovative breeding and marketing strategies by specialized growers have been successful at expanding the production season, supporting year round cyclamen sales. It is now common to see cyclamen offered twelve months of the year, especially in smaller pots which bring a consumer friendly price point in the retail market.
Rainier White Cyclamen - Syngenta Flowers
Landscape use of cyclamen has also exploded in the last five to ten years, especially in more moderate southern and coastal climates. Some cyclamen varieties tolerate temperatures in the mid to low 30s with continuous blooming and good disease tolerance. Regardless of the end use, production is a lengthy process. Germination and fertility needs are unique to this crop, though success can be achieved with an understanding of the plant needs and utilizing plugs.

Pot Size
Recommended pot size for finishing depends on the variety being grown. It is advisable to follow these suggestions as small varieties will not grow in proportion to larger pots and large varieties will overwhelm smaller pots. If a large flowered variety is desired for a 4-5” pot, select a compact standard/intermediate plant type with large flowers which has been bred for this purpose. Avoid growing a full standard cyclamen in pots smaller than 5” or plants will be top heavy, prone to water stress and petiole stretch.

Growing Media and Transplanting
A well-drained, soil-less mix is recommended for finishing. A mix containing composted pine bark is desirable due to its natural ability to suppress disease. In preparation for transplanting, dibble the pots to match the liner size. 
Liners should be transplanted prior to heavy rooting and petiole stretch. Handle the liners with care and avoid forcefully pushing the root systems through the media. Liner depth is critical and should be transplanted at the same level as the corm in the liner: do not bury or further expose the corm. Grading the liners by size at transplant will make moisture management easier during finishing.


Fertilizer
Calcium Deficiency
Ideal cyclamen media pH during finishing is 5.5-6.0 and the EC should be 1.0 to 1.2 using 100-150 ppm constant liquid feed. Nutrient deficiencies appear slowly in cyclamen and are correspondingly slow to correct. Fertilizer choices for cyclamen should focus on calcium and potassium nitrate-based feeds to achieve a nitrogen to potassium ratio of 1:2 and low phosphorus to avoid soft growth: 14-5-38 rotated with a 15-0-15. Isolated, single applications of ammonium-based feed such as 21-5-20 should be used only if leaf expansion or plant size is lacking. Continuous use of ammonium feeds will result in soft growth, decreased uniformity and poor quality plants. Strong transpiration should be encouraged to reduce the risk of calcium deficiency: well drained media, avoidance of saturated media, and good air movement above the crop.

Temperature
Cyclamen prefer cool conditions, with night temperature of 65⁰ F during finishing. Towards the end of the crop, night temperatures may be lowered into the low 60s. Ideal daytime temperature should not exceed 68⁰ F, with growth ceasing at temperatures above 80⁰ F. Growers unable to avoid temperatures above 80˚ F will experience a delay in flowering and should allow for as much as four weeks of extra crop time. Crops are especially sensitive to heat stress just before or soon after transplant.
Average daily temperature at or below 60⁰ F will also stall growth. This temperature response can be used to the grower’s benefit: crops may be held at 50-55⁰ F nearly indefinitely with slow, but continued, flower production. Crops will be more prone to Botrytis at temperatures below 60˚ F. Increased air flow and variety selection for less dense habits for winter production can both help to reduce Botrytisinfection.

Photoperiod and Lighting
Cyclamen flower independently of photoperiod. Flowers will appear at the sixth and subsequent leaf axils in response to accumulated light and degree days. Higher leaf counts translate to higher flower counts, and liners grown under longer days will flower more quickly than those grown under shorter days.

Plant Growth Regulators
Cyclamen growth is best managed through control of moisture, fertility, spacing and light. Most traditional plant growth regulators afford marginal to no control. While gibberellic acid (GA) was occasionally used historically to hasten flowering and promote a more uniform flower flush, the practice has generally been abandoned. Breeding has improved crop uniformity and the risks of improper application of GA far outweigh the benefits.

Pests and Diseases
Botrytis is not uncommon due to the dense plant canopy. Look for grey fuzzy growth under the canopy. Flower damage shows as darkly pigmented areas or dark spotting on the petals. Remove senesced leaves and flowers, reduce humidity, increase air flow, and balance media moisture with transpiration to avoid favorable conditions. Rotating between fungicide applications may also be beneficial, though it can be challenging to penetrate the plant canopy. Bloom safe options include Affirm, Astun, Broadform, Medallion, Mural, Orkestra Intrinsic or Pageant Intrinsic, Palladium and Spirato GHN.
Fusarium
Vascular disease caused by Fusarium is more serious in a cyclamen crop, though less common. Latent infections occur, with delayed expression of sudden leaf yellowing and wilt. On-site diagnosis involves slicing firm corms parallel and perpendicular to the soil surface: reddish/brown or purple/black discoloration indicates infection. Roots may appear healthy. There are no curative treatments for Fusarium. Discard effected plants and apply a preventative fungicide drench. Options include Cleary’s 3336, Empress Intrinsic, Orkestra Intrinsic, Heritage, Medallion, Mural and Spirato GHN for protection against Fusarium.
Bacterial in nature, Erwinia causes soft rot and rapid collapse. Attacking the cyclamen crown, Erwinia generates an unpleasant odor and softens the corm. Immediately discard effected plants and preventively treat remaining plants. Copper containing products, such as Camelot O, Cease, Kalmor, Phyton 35 and Triathlon BA are prevention options against Erwinia; there are no effective curative options.
Erwinia
Anthracnose diseases affect cyclamen causing brown spots on leaves, as well as drying and distortion of young petioles, flower buds and older tissue. Control includes foliar sprays of Heritage, Medallion, Mural, Orkestra Intrinsic, Palladium, Spirato GHN or copper containing products such as Camelot O, Kalmor, Nordox, and Phyton 35.
Most common insect pests include thrips, cyclamen mites, broad mites, fungus gnats and shoreflies. Thrips feeding can cause white streaking on flower petals. Cyclamen and broad mites cause severe distortion of young tissue and twisting of flowers on the petiole. The presence of fungus gnats and shoreflies is an indication that the crop is being grown too wet.

 Please consult the GGSPro Insecticide and Fungicide Options Bulletin for rates and other detailed information regarding effective treatments for all disease, insects and mite pests mentioned. The GGSPro Team is available to discuss pesticide and biological control strategies.

Product Name
Item Number
14-5-38
JP14538
15-0-15
33627
21-5-20
33602
Affirm
71-1131
Astun
71-1190
Broadform
71-1290
Cease
71-13301
Camelot O
70-21202
Cleary's 3336
71-2575
Empress Intrinsic
70-1510
Heritage
71-1400
Kalmor
71-2050
Medallion
71-16502
Mural
71-1690
Nordox
71-1700
Orkestra Intrinsic
71-2200
Pageant Intrinsic
71-26801
Palladium
71-2685
Phyton 35
71-2732
Spirato GHN
71-2948
Triathlon BA
71-3040

Garden Mum Disease, Insect, and Mite Control Options

MOA Codes appear in “( )”

Chrysanthemum White Rust
Chrysanthemum White Rust (CWR)
Apply a foliar spray of a strobilurin fungicide while the rooted cuttings are still in the tray. Broadform (7&11), Fame (11), Heritage (11), Mural (7&11), Pageant (7&11), or Orkestra (7&11) are all good options. Surfactants such as CapSil should not be used with these products. Thorough crop preventative sprays need only to be made if weather conditions are forecasted to be favorable for CWR development. Rainy and cool conditions for more than 24 hours would be a reason to make the treatment before the forecasted weather sets in. Daconil Weather-stik* (M5) or Protect DF (M3) are reasonably priced protectants. If CWR is known to be in the surrounding area, a second application of a strobilurin is recommended. Eagle (M3) is the only curative product and should be saved in the unlikely event CWR is detected in your crop.
*Avoid open blooms with Daconil products.

Additional foliar diseases
Bacterial Leaf Spot
For overhead irrigated crops or prolonged rainy conditions late in the crop, bacterial leaf spot (Pseudomonas chicorii) and fungal pathogens such as Botrytisand aerial Rhizoctonia can threaten a garden mum crop. This is most likely to occur later in the crop when the crop canopy is dense and air movement into the center of the plant is limited. For bacterial leaf spot, Cease (44) and Triathlon BA (44) can be used as preventatives. At the first sign of bacterial disease, a tank mix of a copper (e.g.- Kalmor (M1), Nordox (M1), or Phyton 35 (M1) and Protect DF (M3) should be applied with CapSil (except no CapSil with Phyton 35). An important part of fighting bacterial leaf spot is to make note of vulnerable varieties and work them out of your program.  Aerial Rhizoctonia often occurs with Botrytis so we recommend fungicides that control both. Some excellent options include: Affirm (19), Broadform (7&11), Daconil Weatherstick* (M5), Medallion (9), Mural (7&11), Pageant (7&11), Palladium (9&12), Orkestra (7&11), or Spirato GHN (9). CapSil is recommended for Affirm, Medallion, Spirato GHN and Palladium.
* Avoid open blooms with Daconil products.

Fusarium
There are no curative fungicides for this disease, but the following soil drenches can be applied preventatively: Cleary’s 3336 (1), Mural (7&11), Heritage (11), Medallion (9), and Spirato GHN (9). PreFence (NC) is a biological fungicide that can be applied preventatively. For a thorough discussion of Fusarium in garden mums, request the bulletin titled, “Defense Against Fusarium Wilt in Chrysanthemum” by Joanne Lutz.

Pythium Root Rot
Pythium
Drench soon after transplanting with Segway (21). Rootshield Plus G (NC) can be pre-incorporated into the soil mix without being damaged by Segway. Rootshield Plus WP (NC) can be applied as a soil drench within a week after the Segway drench if desired. From that point on we recommend a “see and treat” protocol. If another drench is required, one of the etridiazole products could be rotated: Banrot (1&14), Terrazole (14) or Truban (14).

Insecticidal drenches
Due to bee safety concerns with neonicotinoid drenches [e.g.-Flagship (4A), Marathon (4A) and generics, Safari (4A)], GGSPro advises that they only be applied during the first two weeks after transplanting so that the bee hazard diminishes before open bloom occurs. Kontos (23) applied as a drench is effective against many garden mum pests including: aphids, leafhoppers, leafminers, spider mites, thrips, and whiteflies. Mainspring GNL (28) as a drench is effective against: aphids, beetles, caterpillars, leafhoppers, leafminers, and thrips. Endeavor (9B) as a drench is a bee safe option for aphid control.

Aerial Rhizoctonia Web Blight
Insecticidal sprays
Aphids- Altus (4D), Aria (29), Endeavor (9B), Kontos (23), Tristar (4A), and Ventigra (9D) have favorable bee safety profiles when used as directed. All of these products benefit from the addition of CapSil.

Caterpillars- Conserve (5), DiPel Pro DF (11A), Mainspring GNL (28), Pedestal (15), and Tristar (4A) are effective and have favorable bee safety profiles- (check EPA bee box provisions on the Mainspring GNL label for specific instructions). All of these products benefit from the addition of CapSil.

Leafhoppers- Altus (4D), Kontos (spray or drench) (23), Sanmite SC (21A) and Tristar (4A). Some of these products have specific instructions regarding pollinator safety. All of these foliar spray products benefit from the addition of CapSil.

Blotch Leafminer

Leafminers (inc. blotch type)- Adult stage: Avalon Golf & Nursery (3A) and Conserve (5). Larval stage: Avid (6), Citation (17), Kontos (drench only) (23), Mainspring GNL (drench only) (28), Minx 2 (6), and Tristar (4A). Some of these products have specific instructions regarding pollinator safety. All of these foliar spray products benefit from the addition of CapSil.

Spider Mites- Akari (21A), Avid (6), Kontos (drench only) (28), Minx 2 (6), Sanmite SC (21A), Savate (formerly Judo) (23), Shuttle O (20B), and Sultan (25). Some of these products have specific instructions regarding pollinator safety. All of these foliar spray products benefit from the addition of CapSil.

Thrips- Avid (6) or Minx 2 (6) tank mixed with Azatin O (UN), AzaGuard (UN) or Molt-X (UN); Hachi-Hachi SC (21A), Kontos (drench only) (23), Mainspring GNL (28), Mesurol (1A), Pedestal (15), and Tristar (max label rate only) (4A). Hachi-Hachi SC and Mesurol are highly toxic to bees and should not be used immediately prior to or during open bloom. Mainspring GNL has specific bee safety instructions in the EPA bee box. All of these foliar spray products benefit from the addition of CapSil.

Whenever practical GGSPro encourages growers to scout and rely on a “see and treat” approach to disease, insect, and mite control.

Not all products are registered in all states. Some pesticides are restricted use in some state or regions and not others. It is the responsibility of the applicator to read and follow all label directions.

Product NameMode of Action (MOA)Item Number
Disease Control Options
Affirm
19
71-1131
Banrot 40 WP
1&14
71-1210
Broadform
7&11
71-1290
Cease
44
71-13301
Daconil Weather-stik
M5
71-1420
Eagle 20 EW
M3
71-1435
Fame SC
11
71-1505
Heritage
11
71-1400
Kalmor
M1
71-2050
Medallion
9
71-16502
Mural
7&11
71-1690
Nordox 75 WG
M1
71-1700
Orkestra Intrinsic
7&11
71-2200
Pageant Intrinsic WG
7&11
71-26801
Palladium WDG
9&12
71-2685
Phyton 35
M1
71-2732
PreFence
NC
71-2771
Protect DF
M3
71-2748
Rootshield Plus G
NC
71-27921
Rootshield Plus WP
NC
71-27961
Segway
21
71-31101
Spirato GHN
9
71-2948
Terrazole L
14
71-3025
Triathlon BA
44
71-3040
Truban 25 EC
14
71-3070
Truban 30 WP
14
71-3065
Insect and Pest Control Options
Altus
4D
70-1161
Akari
21A
70-1160
Aria WDG
29
70-3399
Avalon Golf & Nursery
3A
70-1210
Avid 0.15 EC
6
70-1185
AzaGuard EC
UN
70-1224
Azatin O
UN
70-12301
Citation WSP
17
70-13501
Conserve SC
5
70-1365
DiPel Pro DF
11A
70-1450
Endeavor WDG
9B
70-1660
Hachi-Hachi SC
21A
70-1795
Kontos
23
70-19601
Mainspring GNL
28
70-2331
Mesurol 75 WP
1A
70-2325
Minx 2
6
70-2398
Molt-X
UN
70-2400
Pedestal SC
15
70-2950
Sanmite SC
21A
70-2915
Savate
23
70-2980
Shuttle O
20B
70-30151
Sultan
25
70-3045
Tristar 8.5 SL
4A
70-85221
Ventigra
9D
70-9550
Surfactant
Capsil
N/A
74-1541

Defense Against Fusarium Wilt in Chrysanthemum

Joanne Lutz, GGSPro Technical Specialist, GGSProtech@griffinmail.com, 800-888-0054 x 89129

Fusarium species are found worldwide as plant pathogens and saprophytes (a fungus living on dead or decaying organic matter). The genetic diversity of Fusarium oxysporum pathogen is economically important in greenhouse production. Losses of chrysanthemum grown outside in containers occur yearly because of the persistence of the pathogen Fusarium oxysporum f.sp. chrysanthemi. The first reported case of Fusarium on chrysanthemum in the US was in 1932 in Florida.

Symptoms of Fusarium Wilting in
Chrythsanthemum

Symptoms start as a yellowing chlorosis of leaves on one branch or section of plant. Depending on the cultivars, symptoms can appear first on the new growth, or at the base of the plant. Loss of turgidly of leaves, stunting, and failure to develop normal flower buds are other indications that Fusarium has invaded the plant. As disease progression occurs, there may be noticeable wilting due to the pathogen clogging the vascular xylem tissue.

Vascular Streaking within Stems
Fusarium is not easily diagnosed because of its resemblance to Pythium root rot. Both pathogens can turn roots brown, exhibit yellowing leaves and wilting. Pythium root rot slowly nibbles at the roots, leaving the inner root cortex. Wilting generally is not observed until the fungus has taken over the root system. If you cut a chrysanthemum stem open, you may be able to see vascular discoloration of dark brown to brownish black tissue. Having an accurate diagnosis is important because early symptoms may look and act like a nutrient deficiency.

1 Advance Fusarium revealing
White Mold on Stems
If factors such as high nutrient availability, high humidity and temperature levels above 90oF predominate, advanced infection of Fusarium may be seen as white to pinkish mold developing along inside stems. At this point, it best to discard the plant to reduce spread. 

Severity of symptoms are related to stress factors such as dry/wet cycles (soil moisture), heat (temperature) and the cultivar resistance. Understanding the disease cycle of Fusarium is important. It starts within the root systems. Fusarium oxysporumproduces three kinds of spores: microspores, macrospores, and chlamydospores2. Microconidia are one-celled spores that upon germinating, produce one germ tube to infect crops. Macroconidia are one or two-celled spores that germinate rapidly within 4-7 hours and also produce germ tubes to infect plants. When nutrition, temperature, fertilizer salts and/or amino acids are available, macroconidia are quickly converted to chlamydospores.

Chlamydospores are thick-wall vegetative cells that exist either singularly, in pairs, or in clusters within hyphae in media allowing Fusarium to survive for long periods of time. These spores withstand extreme heat, desiccation, and waterlogged conditions for extended periods of time and have 100 times more energy than microconidia1. As spores land on growing media, the conidia infect plants through roots via wounds or natural openings. Fusarium can be windblown in infected plant debris and dust. Fusarium sp. in general can survive on seed coats, on corms/bulbs, and in roots. Fusariumcan be found in irrigation water, and irrigation equipment and pipes, where it is spreads via water movement. Fusariumcan be spread via and insect transmission (fungus gnats and shoreflies). Pathologist agree that in our industry, most transmission can occur from infected cuttings and substrate media. Because growers have almost no way to successfully identify infected stock without culture indexing or DNA-based assays, Fusarium management should begin with purchasing  from a reputable source, using appropriate growing methods, and practicing sanitation at the beginning and between production seasons.

Providing an ideal soil, fertilizer program, and growing environment are imperative to preventing Fusariuminfection during production. Containers should provide good drainage, contain at least 15-30% perlite (e.g. Premier ProMix HP, BX, BK25, Lambert LM-16, LM-11, and PC -15), and avoid heavy peat-based medias. The ideal soil pH should be 5.8-6.2. Plants grown in more alkaline conditions have shown to compete better against Fusarium. Using fertilizers containing higher percentages of nitrate nitrogen are preferred; avoid fertilizing with ammonium sources of nitrogen. Plants may be infected and not show symptoms until the proper environmental conditions have been met or the plant has been put under stress. Conditions for optimum pathogen development in a chrysanthemum crop is 84-95oF day and 75-84oF night including both air and soil temperatures. Symptoms are not often seen at milder temperatures.

Avoid handling the cutting/liners roughly, as damage roots allow easy access for pathogen entry. Stimulate rooting with applications of Essential Plus or Fosphite. Once the plant is infected, the plant will fail to produce a marketable plant and should be removed immediately. The method of drenching remaining asymptomatic plants alone with fungicides has not been proven 100% successful. Fungicides applied preventatively labeled for Fusarium include:  Cleary’s 3336, Medallion/Spirato GHN, Terraguard and strobiluron based fungicides such as: Empress Intrinsic, Fame SC, Heritage, Mural, Orkestra Intrinsic, and Pageant Intrinsic drenches. Plant protection is often implemented with the addition of biofungicides to protect crops against Fusarium wilt. These include Actinovate, Companion, PreFence, PVent, RootShield, and RootShield Plus. Research studies continue to enhance the benefits of adding biological fungicides with registered fungicide to yield significant reduction in fusarium disease development.

Fusarium can survive on various surfaces such as wood, concrete, and polyethylene film. Plastic is the easiest to clean with wood being the most difficult. Applying Strip-it followed by KleenGrow is very effective on all three surfaces. Other effective products include GreenShield II or SaniDate 5.0.  When possible, avoid growing directly on wooden or soil surfaces as chlamydospores may be present deep in soil/wood (survive for 5-10 years in the soil) and resurge any time2. Drip irrigation systems should be cleaned before and after the production season to reduce the risk of chlamydospores survival.

1Morel Diffusion –Fusarium EM18, 7/2012,



Chemicals Labeled for Fusarium Prevention

ProductSizeItem Number
Cleary’s 3336 F
1 qt, 2.5 gal
71-2575, 71-2585
Cleary’s 3336 EG
5 lb
71-2550
Empress Intrinsic
24 oz
70-1501
Fame G
25 lb
71-1500
Fame SC
16 oz
71-1505
Heritage
4 oz, 1 lb
71-1404, 71-1400
Medallion WDG
8 oz
71-16502
Mural WG
1 lb
71-1690
OHP 6672 L
2.5 gal
71-2670
OHP 6672 WSP
2 lb
71-2672
Orkestra Intrinsic
16 oz
71-2200
Pageant Intrinsic
1 lb, 12 lb
71-26801, 71-26821
Terraguard SC
1 qt
71-3018
Spirato GHN
1 pt
71-1570
RootShield Plus G
10 lb, 40 lb
71-27911, 71-27921
RootShield Plus WP
1 lb, 3 lb
71-27951, 71-27971
PreFence
5 gm, 25 gm
71-2770, 71-2771
PVent
0.5 lb, 1 lb
71-2775, 71-2776
Greenshield II
1 gal, 30 gal
74-36601, 74-36611
KleenGrow
5 gal, 30 gal
74-21151, 74-21301
Strip-It Pro
5 gal, 30 gal
74-2125, 74-21230

It is applicator’s responsibility to read and follow all pesticide label instructions. Labels can and do change without notice. Not all of the products mentioned in this bulletin are registered for use in all states. Some pesticides are restricted-use in some states or regions and not others. Contact GGSPro or your state’s Department of Agriculture to verify registration status. Pesticides other than those mentioned may be safe and effective.
Printable version

Beautiful Disaster: How to Defend Against Spotted Lanternfly

SLF nymphs, first instar
Many insects hatch and emerge at this time of year. The early nymphal stages of the spotted lanternfly (SLF) are easily recognizable. These wingless planthoppers are small, black and white. As they grow in size to the fourth instar by July/September, they develop a red pattern that covers most of their body. During these instar stages, they range in size from 1/10” to 5/8” and will crawl or jump on many of our favorite woody and edible crops. From the USDA’s perspective, the SLF is not a welcome indication of spring.
SLF nymph, fourth instar
Photo credit: UMass Extension

SLF are native to China and Vietnam and feed on more than 70 plant species as phloem feeders. They’re known to move 3-4 miles a year, mostly by being excellent hitchhikers. Therein lies the challenge: how to quarantine a pest that’s now detected in seven states (Pennsylvania, Virginia, New Jersey, Delaware, New York, Maryland and Connecticut) since its first detection in Pennsylvania in September 2014.

Adults emerge by mid-July and are exquisitely beautiful. The wings are gray with black spots at the front and speckled bands on the last 1/3 of the wings. When wings are spread, the base of the hind wings is scarlet with white spots in the front, and white with black bars at the rear. The abdomen is yellow with black bars.

Major plants at risk to SLF damage include 
tree of heaven, maples, grapes, apples, hops, 
SLF adult
Photo credit: Penn. Dept.
of Agriculture
ornamentals, Christmas trees and species relevant to the lumber industry. Unfortunately, SLF adults can impact quality of life in quarantined areas. As the adults feed via a piercing-sucking mouthpart similar to a straw, they excrete copious amounts of honeydew that drip onto plants, cars and hard surfaces. This byproduct can attract ants, bees, hornets and wasps to feed on the sap. Extensive feeding can result in wounds, wilting and death of branches on young trees. Honeydew on leaves can also reduce the overall quality and limit photosynthesis.
Insects that resemble SLF include green stink bug nymphs and ticks. If you suspect you may have detected SFL, take a photo and send it to your state department of agriculture for verification. Keep the insect in a sealed bag and put it into the freezer.
Green stink bug nymphs

To limit the spread of SLF, actionable quarantine and shipping restrictions have been implemented. For details on regulatory articles, see the www.northeastipm.org or visit www.agriculture.pa.gov for information on the permit process for businesses operating within a regulated area.

Learn to identify the tree-of-heaven (Ailanthus altissima), which is used as a monitoring host tree. The SLF prefers to feed and mate on this specific tree species. To establish a trap crop for SLF, land owners should leave in place male trees that are at least 10” in trunk diameter, and clear all other male and female trees. This facilitates the use of systemic chemicals to limit the exposure of non-target organisms, as few other pests feed on these trees. Application must be repeated annually until no SFL adults are detected on a property.

Removal of trees-of-heaven is a mechanical option to eliminate breeding sites for SLF. Chemical options include spraying targeted plants mid-May through August. Systemic insecticide drenches (e.g., dinotefuran, imidacloprid) are most effective when applied in spring and early summer, before adults build up their populations. The most effective option in controlling SLF are foliar-applied chemicals that contain bifenthrin, carbaryl, dinotefuran or imidacloprid. Basal bark treatments and stump treatments with approved herbicides are among the methods available to remove unwanted trees. Contact GGSPro for more details.

It’s the responsibility of the applicator to check labels and state laws for regulated application sites. Some products may be restricted use. Always read and follow all label directions. The label is the law! Products other than those mentioned may also be safe and effective. Some pesticides may be restricted-use or unregistered in certain states.

Products for Control of SLF Adults (Apply as soil drenches)

ProductMOADescriptionItem Number
Mallet 2F T &O
4A
1 gal
70-2340
Marathon 1% G
4A
5 lbs
70-23752
Safari 20SG
4A
3 lbs
70-29951

Products for SLF Nymphs (Apply as foliar sprays)

ProductMOADescriptionItem Number
Avalon Golf & Nursery Insecticide
3A
1 gal
70-1210
Mallet 2F T &O
4A
1 gal
70-2340
Marathon II
4A
250 ml
70-23712
Safari 20SG
4A
3 lb
70-29951
Sevin SL
1A
2.5 gal
70-3002
Talstar Pro
3A
1 qt
70-34052

Printable version

Good to the Last Raindrop: How to Protect Crops Through Prolonged Wet Weather

In many parts of the country, last spring was so wet that you had to laugh to keep despair from setting in: “Some growers only had two rain storms last season. The first one lasted for 52 days and the second one only lasted for 40 days.”

We kid but, of course, we know soggy spring weather is no joke. A greenhouse filled to capacity with pot-to-pot mature plants in full bloom is not a good place to ride out a long spell of cool, damp weather. Such persistent conditions can provide a launchpad for Botrytis and aerial Rhizoctonia.

There’s no time like the present to prepare for soaking spring rains. Since we can’t control the weather, the best we can do is limit the associated risks. When cloudy, wet weather sets in, disease scouting and control become top priorities.



Botrytis on marigold

Understanding Botrytis and aerial Rhizoctonia

Botrytis and aerial Rhizoctonia share two favorite things. The first is full greenhouses, where air movement is limited or, at worst, inadequate. The second is free moisture on leaf surfaces.

Botrytis symptoms can vary in appearance due to several factors including where on the plant it occurs and the current environmental conditions. Symptoms can occur on leaves, stems, fruit, buds and blooms. Expanding brown lesions of decaying plant material are sometimes covered with white/grey spores when environmental conditions are favorable for disease development.



Aerial Rhizoctonia on Vinca minor
Aerial Rhizoctonia is considered a web blight, although the webbing is often not visible. Most often, it appears as an expanding circle of rapidly collapsing plant tissue under crowded conditions, including stem cankers that girdle stems.

Effective fungicides are available but if the greenhouse environment isn’t also carefully managed, those products may fall short. What follows are best practices to mitigate foliar disease risk in your greenhouses.


Controlling variables in the greenhouse

It’s inevitable that, even during long wet spells, the crops will eventually need to be irrigated. The opportune time to irrigate is in the morning, giving foliage the best chance of drying by nightfall. Under these conditions, drip irrigation and sub-irrigation are greatly beneficial as they minimize wet foliage. When you’re considering irrigation equipment for the future, remember these weather patterns; the upfront cost can be a wise investment in the long run.

Similarly, it may be tempting to turn the heaters off at this time of year to save fuel. However, the increased disease risk may cost more than the fuel. The cooler the air is, the less moisture it can hold. If there’s more moisture in the air than it can hold, condensation begins to form on the cooler leaf surfaces.

It’s best to maximize air movement with HAF (horizontal air flow) fans and adequate crop spacing. Doing so makes temperatures more even throughout the crops, reducing cool spots where condensation may form.

Conversely, heating the air allows it to hold more moisture and reduce condensation. Leaf wetness is the enemy when it comes to many foliar diseases. The expense of running some heat in the greenhouse is dwarfed by the potential of losing crops that are so close to the finish line.

Should you ventilate when it’s raining? If it’s raining, misting or foggy outside, it’s best to keep the greenhouse closed up and run some heat to dry the air a bit. If daytime conditions are overcast but not raining, ventilate the house to expel airborne disease spores and reduce relative humidity.

As old blooms begin to decay, they’re quickly colonized by Botrytis, which turns them into spore-making machines. Taking the time to deadhead spent blooms and remove them from the growing area is cheap insurance.



Preventive and curative fungicide options

Even with the best cultural controls, fungicides sprays are often still necessary. Having optimized the growing environment to every extent possible, it’s time to consider fungicide spray options.

Any fungicides used at this stage will need to have a good record of bloom safety and leave little or no residue. Using CapSil or another high-quality surfactant will help reduce the visible residue that can be left behind. (Not all fungicides should be used with surfactants. Check the label.)

Wet sprays contribute to leaf wetness, which can be slow to dry. For short-duration rainy spells, it may be best to withhold treatment until the sun shines again. When the forecast calls for three or more consecutive rainy days, it may be best to treat anyway.

Consult the GGSPro Technical Reference Guide for a comprehensive list of fungicide options, including rates and use patterns.

Not all products are registered in all states. It is the responsibility of the applicator to read and follow all label directions, remembering that labels may change. Other products than those listed here may also be safe and effective. Rates, application methods and edible status are detailed in the product label.



Product NameMOARate/galRate/100 gal
Comments
Item
Number
Affirm
19
½ - 1 tsp
4 - 8 oz
Some edible crops on the label
71-1129
Astun
7
2/3 - 1 tsp
10 - 17 oz
Systemic action provides
curative preventative control.
71-1190
Broadform
7 & 11
¼ - ½ tsp
4 - 8 oz
Do not use with an organo-silicon
surfactants. Fogging prohibited.
71-1290
Cease
44
1.25 oz
1 gal
Labeled for several edible crops.
OMRI-listed.
71-13301
Decree
17
2 tsp
1.5 lb
Labeled for several edible crops.
Resistance has been reported.
71-1440
Mural
7 & 11
¼ - ½ tsp
4 - 7 oz
Do not use with an organo-silicon
surfactants. Injury observed on African
violets, ferns and rex begonias.
71-1690
Orkestra Intrinsic
7 & 11
½ tsp
8 oz
Do not use with an organo-silicon
surfactants. Injury observed on
wintercreeper and nine-bark. Spotting
has occurred on impatiens and
petunias. Fogging prohibited.
71-2200
Pageant Intrinsic
11 & 7
1 - 1 ½ tsp
12 - 18 oz
Do not use with an organo-silicon
surfactants. Injury observed on
wintercreeper and nine-bark. Spotting
has occurred on impatiens and
petunias. Fogging prohibited.
71-26801
Palladium WDG
9 & 12
½ - ¾ tsp
4 - 6 oz
Do not use as a seedling treatment of
impatiens or NGI. Sensitivity has
occurred on Superbells Coralberry
Punch calibrachoa and all geraniums.
71-2685
Triathlon BA
44
4 tsp
64 oz
Labeled for several edible crops.
OMRI-listed.
71-3040

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Into the Great Wide Open: Tips to Transition Spring Crops from Greenhouse to Outdoors

As the greenhouse fills with new plantings and partially finished crops are screaming to be spaced, moving finished product outside can open up valuable heated space. However, moving plants outdoors early in the season comes with risks as well as potential rewards.

The primary risk is, of course, cold damage due to frost or freeze. Rewards include heated space available for younger plants, better holding ability among the finished plants and stronger weather-acclimated performance for the final customer. Through careful selection of cold-tolerant plants, active management and emergency actions as needed, the risks are diminished and the rewards become a win-win for both the grower and end user.



Hardening off involves physical changes in the plant that can be seen and felt as the plant begins to acclimate to lower temperatures. These changes typically require a minimum of 7-14 days with temperatures above freezing and below 50˚F.
Every plant grown in a warm greenhouse over the winter -- whether an annual, a hardy perennial or woody plant -- must be “hardened off” before exposure to the realities of early spring frosts and possible freezing temperatures. Hardening off involves physical changes in the plant that can be seen and felt as the plant begins to acclimate to lower temperatures. New leaves thicken and darken in color, and stems of new tips mature and stiffen. These changes typically require a minimum of 7-14 days with temperatures above freezing and below 50˚F. More on that below.


Freeze damage on calibrachoa
The most important factor for success is choosing which crops to transition outside and when. The most cold-tolerant crops should be the first to move outside. Woodies and hardy perennials are easy choices, but annuals fall into many categories of cold tolerance. The most tolerant include alyssum/lobularia, annual phlox, antirrhinum (snapdragon), bidens, calibrachoa, diascia, dracaena spikes, dusty miller, lobelia, mimulus, nemesia, osteospermum, pansy, petunia, verbena and viola.

Cold-tough annuals and hardy perennials can be transitioned much the same way. To maintain the foliage in good condition, prevent frost exposure and frozen rootballs during the hardening time. When temperatures are mild (38-45˚F nights) plants can move directly outdoors. For temperatures of 33-37˚F, when frost is likely if the wind is calm, cover crops with row cover or frost cloth, or provide other overhead protection to prevent potential frost formation on the foliage. A cold frame also works well for this purpose.


When light freezing temperatures are expected (28-32˚F), a closed cold frame will provide a few precious degrees of warmth to plants on the ground. Frost cloth or a winter blanket, spread in mid-afternoon to trap radiant heat, will generally maintain overnight temperatures at the foliage of 3-6 degrees higher than the surrounding air, depending on the weight of the cloth. Be sure to support heavier cloth off the top of the plant canopy to reduce damage.



When repeat or hard freezes are expected, hardening can be carried out in a greenhouse maintained at 40-45˚F. When an occasional unexpected or brief freeze pops up in the forecast, growers may need to resort to emergency measures.
When repeat or hard freezes are expected, hardening can be carried out in a greenhouse maintained at 40-45˚F nights. However, when the occasional unexpected and brief freeze pops up in the forecast, sometimes the protections above can’t be employed.

In this case, the grower may resort to emergency measures. The traditional action is to use overhead sprinklers to prevent freeze damage. This works because, as the water begins to freeze on the leaf, it releases a small amount of heat. As long as a thin layer of water is present, the plant will be protected from freezing, whether the water is landing directly on the foliage or on the outer layer of ice that will form over the plant. The constant freezing of water throughout the night will maintain the plants above the critical temperature.



When using the sprinkler method,
continue applying water until the
protective ice melts in the morning.
The sprinkler method only works when the water application is started before frost begins to form, and is continued until all ice has melted off in the morning. Once frost or ice has formed on plants, it’s too late to turn the water on. Evaporating water causes cooling and actually causes the tissue temperatures to plunge further, making damage more severe. With the sprinkler method, growers must also manage the risk of plants breaking under the weight of the ice.

Another emergency measure that can be employed is a foliar application of a strobilurin fungicide such as Pageant or Mural (MOA 7 +11). When sprayed within 24 hours of a freeze event, these fungicides effect physiological processes in the plant, such as slowing water transpiration. This tactic can impart several degrees of cold tolerance, in addition to disease protection. Spray Pageant at 12 oz/100 gallons (3/4 tsp per gallon) or Mural at 6-8 oz/100 gallons (3/8
 to 1/2 tsp per gallon).

The hardening process should be actively managed according to the weather forecast, closing and venting cold frames, or covering and uncovering as necessary to protect the plants during periods of low temperatures.


Well-hydrated plants will withstand the cold better. Desiccation is often a major contributor to cold damage. Make sure outdoor plants are well watered and the foliage is dry before temperatures drop. Once the plants are thoroughly hardened, they’ll survive exposure to cold temperatures down to the limit of their genetic tolerance. Light overhead protection during cold snaps will still produce the best foliage and quickest flowering.



Product Name
Description
Item Number
Pageant Intrinsic
1 lb
71-26801
Mural
1 lb
71-1690
Winter protection fabric*
15' x 150', 6 oz per sq yard
81-730400
Heavy frost cloth*
15' x 300', 1.25 oz per sq yard
78-2045
*Additional sizes available. Contact your Griffin sales representative for details.


Printable version

Geraniums: A Crop Culture Tune-Up

Well-branched, uniform geraniums ready for retail sale
We can all agree: Geraniums have created quite a legacy for themselves. Our industry has seen a tremendous number of new plant species over the years, and gardening trends certainly come and go. Through it all, the venerable geranium – including zonal, ivy and hybrid types – maintains its status as a staple of the garden center.

Producing top-quality geraniums requires close attention to detail. Not everyone can do it well! But for the growers who do, their attentiveness is rewarded. Let’s review some of the finer points of geranium culture. Are there details you haven’t considered lately? Is there an opportunity to fine-tune production of your next crop?


Soil mix and pH

Soil mixes should be well drained and be maintained at a soil pH in the range of 6.6. pH control is crucial because geraniums are very susceptible to iron/manganese toxicity at a soil pH of 5.8 or lower. Monitor soil pH weekly to prevent problems before they occur.


Temperature

The most economical geranium production takes place at average daily temperatures in the range of 65-70° F. Typically, this means night temperatures between 62-65° F and day temperatures in the range of 68-70° F. Crop timing for a 4.5” pot is 6-8 weeks.

Although geraniums can be grown much cooler, doing so comes with some risk: The lower temperatures significantly increase crop time and raise the risk for Botrytis.



Fertilizer

Geraniums are moderate feeders. Maintain 200 ppm CLF, reducing that to 125-150 ppm as the crop approaches marketable size. This practice improves shelf life and eases the transition to be planted outdoors. Fine-tuning your geranium fertilizer program through water testing is recommended.


Height control via PGRs

Florel on geranium
While smaller pots (e.g., 4.5”) can be grown without it, geraniums often benefit from a soft hand pinch to improve branching. For 6” and larger pots, a soft pinch should be made 2-3 weeks after transplant. In the interest of efficiency, a Florel application can be used in place of a pinch. Zonal geraniums require foliar sprays of Florel at 500ppm, while 350ppn is more common among ivy geraniums and ivy/zonal hybrids such as Calliope and Caliente. Florel can be re-applied two weeks later, as long as the crop is six or more weeks until full bloom is needed.

Cycocel has long been used to control height and leaf size on geraniums. Zonals generally receive 1500 ppm, while Calliope and most ivy geraniums are treated at 1000 ppm. To avoid yellowing or distorted foliage, spray Cycocel only to glisten. This approach can be used on a bi-weekly basis. Cycocel metabolizes quickly in the warmer temperatures that we often experience in late spring and summer. More frequent sprays, up to once a week, may be required.


This trial compares the effects of Bonzi and Cycocel on geranium
Bonzi is another PGR option for zonal and ivy geraniums. Bonzi can be applied as a foliar spray at 1-5 ppm on compact or ivy varieties, and up to 10 ppm on more vigorous varieties when the plants are 75% of finished size. Bonzi is only absorbed through the stems and roots, rather than the foliage. For tightly spaced plants, drenching Bonzi might be a better option. Rates vary based on plant vigor, ranging from 0.25-0.5 ppm in most cases.


Height control without PGRs

To control geranium height without PGRs, the Morning Temperature Dip technique can be quite effective. Most plant stretch occurs during the first three hours of daylight. Beginning at first light in the greenhouse and continuing for the first three hours of the day, drop the air temperature to 5° F below the night set point. After three hours, return temperatures to their normal setting. This simple practice can greatly reduce the need for PGRs, limiting stem elongation without significantly decreasing the average daily temperature.



Product NameDescriptionItem Number
Bonzi
1 qt
2.5 gal
70-1260
70-1270
Cycocel
1 qt
1 gal
73-1380
73-1381
Florel
1 qt
1 gal
608-395
55-100161
Printable version

A Greenhouse Game Changer: Introducing the Bluelab 3-in-1 Pulse Meter

Pulse meter with depth gauge
Photo credit: Bluelab Corporation


Technology is coming to the aid of growers once again, this time in the form of a versatile direct-stick meter. The Pulse multimedia meter from Bluelab measures EC (electrical conductivity, a.k.a. soluble salts), soil moisture and temperature in a wide variety of growing media.

Peat, coir, composted pine bark, rockwool and mineral soils can all be tested with nearly instant results. For the greatest amount of precision, the Pulse meter offers different settings for each type of soil mix. Settings can be quickly and easily changed to efficiently test multiple media mixes.

The Pulse meter can also be used to test solutions, saving the need for an additional meter. Test results can be transferred to a Bluetooth-enabled smartphone with the help of the free Pulse mobile app. Test data is stored by the app, so growers can easily review and analyze data. The Pulse app is currently available for Android devices; support for iPhones is expected to follow sometime in 2019.

The Pulse mobile app is currently
available for Android devices.
Photo credit: Bluelab Corporation

Compared to making slurries and performing the 2:1 test, the Pulse meter is a bona fide timesaver. Testing is so fast that a large number of samples can be taken in order to get the most representative picture of what’s going on in the crop.

Calibration and cleanup are fast and easy, too. The probes are 8 inches long and come with a built-in depth gauge to ensure consistent measurements. (Note: The Pulse meter can accurately test pots 4 inches deep or deeper.) Just like the other meters from Bluelab, the Pulse meter is reliable and is backed by excellent technical support.

Bluelab Pulse Multimedia Meter

Item number: 83-2778

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