GGSPro Tech Tips

Broad Mites: A Game of Hide and Seek

Broad mites on Shasta daisy
Curled leaves that lead to foliage looking hard and gnarled are symptoms that could indicate a broad-mite (Polyphagotarsonemus latus) infestation. Broad mites are typically found in the growing tips, causing stunting of that tender growing tissue. In severe cases, broad mites have also been found causing distortion on flowers and deformed fruit growth on certain edible crops.

These mites are microscopic and difficult to locate even with 20X or higher magnification. Microscopic mites may be small but they can cause big problems for the many crops that host them including: ageratum, azalea, begonia, dahlia, gerbera daisy, ivy, bedding impatiens, lantana, marigold, New Guinea impatiens, peppers, snapdragon, torenia, verbena and zinnia.

Broad mites on peppers
Broad mite egg with geometric pattern

Broad mites’ small size makes detection difficult and plant damage is often well underway before the source is discovered. Female broad mites are only 0.2 mm long and the males are even smaller. The females may pupate and wait in the soil until they find the appropriate host on which to feed.

The broad mites also have distinctive eggs, which aid in their diagnosis. Their eggs are translucent and oval-shaped with a geometric pattern on the surface. These eggs are usually found on the undersides of leaves, but are sometimes found on the upper leaf surface as well.

Broad mites on gerbera
The detection dilemma is intensified by the fact that the mites are reclusive, often tucked away deep in the folded growing tip tissue. The nearly colorless broad mite injects a toxin as they feed, which contributes to the color change, cupping and even death of plant tissue. Since high soluble salts or environmental factors can cause similar symptoms, a positive identification is essential in making the correct treatment.

Broad mites on ivy
Translaminar systemic miticides are the preferred methods of control. Options include: Avid, Kontos, Pylon, Savate and Sirocco as foliar sprays and Kontos when applied as a soil drench. Akari and Sanmite are not translaminar systemics, but with good spray coverage they, too, may be successful. It’s advised that you always read pesticide labels and make sure to follow all label recommendations and restrictions. Products other than those mentioned here may also be safe and effective.

ProductDescriptionItem Number
1 qt
8 oz
250 mL
1 pt
4 oz
8 oz
8 oz

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Shoreflies, Don't Bother Me! Prevention and Control Tips for Shoreflies and Fungus Gnats

Fungus gnats and shoreflies are major pests among greenhouse crops, but they often don’t get the attention they deserve. These mini menaces wreak havoc on three different fronts: First, they creep consumers out by leaving their calling cards (fecal matter) on the foliage of otherwise beautiful plant material. Second, below the canopy, feeding larvae do direct harm to roots, stems and, occasionally, foliage (especially leaves in contact with growing media). The damage can be fatal, especially to young seedlings and cuttings in propagation. Third, adult fungus gnats and shoreflies are known to spread root and crown rot diseases in their travels. 
Fungus gnat damage on dahlia leaf.

In order to control fungus gnats and shoreflies, you must be able to properly identify them; some differences in chemical and biological control options need to be accounted for. Adult fungus gnats are dark, delicate-looking flies, similar in appearance to mosquitoes, with slender legs and long segmented antennae. Their wings are clear with a distinctive “Y” shaped vein. Fungus gnat larvae have a shiny black head and an elongated, whitish-to-clear, legless body. 
Fungus gnat larvae with distinctive
black head capsule.
Photo credit: Bioline Agrisciences

Shorefly adults more closely resemble miniature houseflies. Compared to fungus gnats, shoreflies are stronger fliers, with shorter legs and antennae. Shoreflies have five distinctive clear-to-white spots on their wings. Shorefly larvae are also clear to white, but lack a distinct head capsule. The pupal stage is dark brown with an interesting “fork” structure on one end[i]. While shorefly adults can spread plant pathogens, the larvae are not directly damaging to plants.

Habitat Management

Shorefly pupae. 
Photo credit: Bioline Agrisciences
Shorefly adult displaying spots on the wings.
Habitat modification and sanitation are the first lines of defense against fungus gnats and shoreflies. Fungus gnats lay their eggs in cracks and crevices in the growing media. In greenhouses, this usually occurs on the surface of the soil but can happen in drain holes in the sides and bottom of pots, too. Constantly moist media, and the algae it encourages, make a suitable habitat for fungus gnat larvae. Shoreflies live in consistently damp areas with abundant algae. The larval stage feeds on algae and the pupal stage is semi-aquatic, partially submerged in water. Moisture management, including improved drainage and taking steps to limit algae, can pay dividends by creating a less favorable habitat for pest development.
Power washing and approved cleaners such as Strip-it Pro can be used to remove organic matter from surfaces between crops. After a thorough cleaning, sanitation products such as: Greenshield II, Kleengrow, SaniDate 5.0 and Zerotol 2.0 can be used to finish the job and ensure a clean start.

Control Options

Chemical control of fungus gnats and shoreflies should target the larval stage because control of adults isn’t very effective with the available pesticides. The table below lists products recommended by GGSPro. All treatments are made to the soil.

Active Ingredient
Fungus gnats
Item Number
1 lb
IGR, sprench, 21 days of control
1 lb
IGR, sprench, vegetable transplants
1 qt
IGR, sprench, soil surface spray, 21 days, Distance- fruiting vegetables
1 qt
IGR, sprench, soil surface spray, 21 days, Distance- fruiting vegetables
Gnatrol WDG
16 lbs
BT- israelensis
Make 3 applications 1 wk apart
1 pt
Soil surface spray only, 7-14 days
3 lbs
Soil drench, vegetable transplants

Biological control often begins with soil treatments of nematodes, which are highly successful in controlling the larval stages of fungus gnats and shoreflies. Choose Steinernema feltiae for fungus gnats and S. carpocapsae for shoreflies. Nematode treatments are generally effective for about 3 weeks and can be applied to all types of crops and most types of growing media. Following treatment, the number of adults will decline gradually, as the adults die off and fewer emerge from the soil to replace them.

Dalotia coriaria, (aka Atheta or rove beetle), is a small beetle with a huge appetite for many soil-dwelling pests including fungus gnat and shorefly larvae, with thrips pupae control as an added bonus. Once established in a cool, moist location, they’ll often establish themselves in the crops. 
Dalotia adult feeding on fungus gnat larvae.
Photo credit: Bioline Agrisciences

Stratiolaelaps scimitus (formerly known as Hypoaspis mites), is a tiny predator mite that patrols the soil surface and feeds on many of the same soil-dwelling pests as Dalotia.

In greenhouses where pesticides are seldom used, the aptly named Hunter fly (Coenosia attenuate) will sometimes appear as a welcome ally. Hunter flies consume adult fungus gnats and shoreflies along with some other flying insects. They aren’t commercially available at this time, but they have been introducing themselves to commercial greenhouses in the northeastern U.S. 

Hunter fly (Coenosia attenuata).
Photo credit: Leanne Pundt, UConn

 Use yellow sticky cards to monitor for adult fungus gnats and shoreflies, and deploy the BCAs at the first sign of pest pressure. Certain compatible pesticides can be safely used in conjunction with biological control agents; contact GGSPro for assistance.

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.

Steinernema feltiae

Item Number
NEMAforce SF
Beneficial Insectary
50M - 1 tray x 50M
NEMAforce SF
Beneficial Insectary
250M -1 tray 250M
NEMAforce SF
Beneficial Insectary
1.25B -5 tray 250M
Exhibitline Sf
250M - 5 trays x 50M
Exhibitline Sf
1.25B - 5 trays x 250M
250M - 5 trays x 50M
1.25B - 5 trays X 250M
100 M -1 cup
500M -2 cups X 250 M
2B- 8 cups X 250M
25M / sponge*
35M / sponge*
50M / sponge*
* Order by Monday for following week ship

[i] Shore Fly Biology and Control, J. Sanderson, Cornell -

Printable version

BCAs for Beginners: How to Get Started with Biological Controls

The use of biological control agents (BCAs) to fight insect and mite pests continues to expand in the horticulture industry. Contributing factors include the desires to grow with eco-friendly techniques and to reduce chemical usage. Growers recognize the opportunity to appeal to customers with ‘natural’ products.

As a chemical-free product, BCAs can add value to crops in several ways. First, many consumers are drawn to the notion of reduced risk from chemical exposure. Second, the knowledge gained by BCA usage over the years is making it easier for new users to succeed.
Eretmocerus ememicus parasitic wasp

If you’re considering biological controls, think of it as growing a new crop for the first time: Investing the time to understand the best cultural conditions of the BCA you want to use will very likely increase the initial level of success. Like plants, beneficial insects or mites work best in specific ranges of temperature, light and humidity. Most BCAs won’t establish easily in a population in your greenhouse, and will need to be released on a schedule in order to maintain control. Similar to growing a crop, the experience gained each year will lead to refinements and, hopefully, better results the next time around.

Monitoring the BCA populations and the pest populations throughout the crop cycle is key. Doing so allows for adjustments to be made as needed in order to finish a high-quality crop. Scouting the plants for insect presence, counting and tracking insect trends on sticky cards and leaves, and recording the data definitely requires a commitment of time, energy and resources.

GGSPro BCA compatibility chart. Click to enlarge.

The scouting and monitoring process should measure the status of the battle in the canopy between BCAs and the pest target. This allows decisions to be made about quantities for continued releases of BCAs or whether a chemical intervention is called for. Yes, an insecticide or miticide may sometimes still be needed, but proper choice of a product will allow continued use of biological control with no or limited interruption. GGSPro has compiled compatibility data from suppliers and from researchers to assist with product selection. We assist our BCA customers with compatible pesticide choices by utilizing our searchable database.

In reality, monitoring begins before the BCAs are released into the crop canopy. A quality assurance test should be done for each biological control after shipments are received and before each release to assess the vigor. Dr. Rose Buitenhuis, of Vineland Research and Innovation Centre in Lincoln, Ontario, has written the industry standard, Grower Guide: Quality Assurance of Biocontrol Products (available online), or ask GGSPro for guidance.

Before diving into biological controls, plan ahead with a switch to softer chemistry or biological insecticides, such as Ancora, BotaniGard, SuffOil-X and M-Pede. Review pesticide application records from the previous four months, especially if broad-spectrum insecticides have been used. Note that drenches applied only to the soil may be completely compatible with the use of most beneficial insects, while a foliar spray of the same product may be harmful and require a waiting period before release.

Speaking of drenches, nematodes are among the easiest entries into biological control, as they’re compatible with most foliar applications of chemicals and with many drench products. In the soil, the nematode Steinernema feltiae controls fungus gnat larvae and thrips pupae. Other species are available for control of Black Vine Weevil larvae and various grubs.

Plan to start small with BCAs, as you would with any new crop. Try beneficials in a single house or just with an herb crop, for example. Plan for control of the pests normally expected in a certain crop, be it thrips in gerbera daisy or aphids on bellis or calibrachoa.

Control of insect pests is most effective when biologicals are released before pest populations build. That is, before damage is readily visible, when pests are only detected through scouting activities, or when history leads to an expectation of a pest’s seasonal arrival. Many BCA species will feed on pollen or alternative insects in the absence of the target prey.

Spider mite control is somewhat of an exception. In most crops, the predatory mite Phytoseiulus persimilis can overtake a moderate population of two-spotted spider mite and can clean up the crop. However, P. persimilis is only applied after spider mites have been detected, as it won’t feed on any other food source. In all other cases, the BCA is applied preventatively or proactively before pest populations build.

If you’re considering biological control, plan ahead, plan to learn and plan to maintain realistic expectations. BCAs can be very effective, but they’re not a simple solution. Biocontrol is a dynamic process with many variables than cannot always be anticipated in advance. A commitment and dedication to monitoring populations is necessary to allow for early detection of expanding pest numbers. If needed, spray treatments can be used to reset the balance in favor of the biological control and provide a fresh start. A chemical ‘reset’ leads to analysis of timing and conditions in the biological strategy and becomes the experience that we build upon in the next cycle or the next crop.

BCA products available from Griffin. Click to enlarge.

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Primula Particulars: How to Produce a Picture-Perfect Crop

Primula has a delightful way of ushering in the spring season with an extraordinary blast of color and fragrance. This cool-weather crop has gone through extensive breeding over the years, resulting in a wide array of intense colors. The dull grays and browns of winter can be replaced with clusters of vivid flowers over a compact rosette of green foliage. Primula is a crop that just makes people happy.

Primula is typically grown one plant per 4” to 4½" pot, and requires a well-drained soilless mix with an ideal pH of 5.3 to 5.8. Primula is a long-term crop from seed. Growing from plugs or cell pack liners saves time and sidesteps germination problems during the summer heat.

Primula Crop Timing and Temperature Requirements

When using the following tables, bear in mind that a primula crop flowers over a fairly long period of time. Primula are classified as early, mid-season or late. The crop times outlined below will be affected by your growing conditions.

Plug Size


Early Season12-14 weeks10-12 weeks8-10 weeks
Mid Season14-16 weeks12-14 weeks10-12 weeks
Late Season16-18 weeks14-16 weeks12-14 weeks

From Plug



Planting to 5 Weeks

70°F or less (Encourages adequate foliage to develop before bud set.)


Early Season
5 Weeks to Visible Bud



Early Season

45-60°F (Temperature depends on forcing requirements.)

50°F (If there is a need to force bloom 60-62°)


Primula leaf curl caused by calcium deficiency
Primula fertilizer requirements change during the crop cycle. Higher ppm are used during the warm period (first 4-5 weeks) and then reduced during the cool period. Fertilizers should provide most of the nitrogen in the nitrate form and should be acid-forming to help hold pH down (5.3-5.8). A standard fertilizer program that works well for primula is 20-10-20 rotated with 15-0-15. The exact rotation is dictated by the water quality.

Primula requires ample amounts of iron and magnesium to maintain rich green foliage. If media or tissue analyses indicate a deficiency, prompt treatment is needed. Iron can be provided by applications of iron chelate (Sprint 138 or 330) as a drench at 4 oz/100 gal. Be sure to rinse the excess off of the foliage to avoid any phytotoxicity.

Magnesium can be supplied as Epsom salts by applying 8 oz/100 gal as a pulse treatment or 2 oz/100 gal on a constant feed basis. Epsom salts cannot be tank-mixed with calcium fertilizers, such as the 15-0-15.

The short, overcast days of winter will make it harder for the plants to take up calcium, as their transpiration rates are much lower in these conditions. Curling leaves are a symptom of calcium deficiency on primula. Additional calcium can be applied with foliar sprays of calcium chloride dihydrate at 0.5 oz/3 gal of water (1 lb/100 gal), along with 0.25 tsp/gal (4 oz/100 gal) of CapSil as a spreading agent.

Crop StageFertilizer Rates
Planting to 5 Weeks200 ppm CLF
5 Weeks to First Color150 ppm CLF
First Color to SaleClear water

Plant Growth Regulators

Primula growth is controlled with cool temperatures; PGRs are seldom needed. If necessary, the following growth regulators are effective:

  • B-Nine 2500 ppm (2 Tbls/gal)
  • Bonzi at 10 ppm (2 tsp/gal)

  • Bonzi 0.5-1 ppm (1.66-3.33 ozs/gal thru the injector at 1:100)
*Do not use Florel on primula

Melting Down or Scorching

Tip scorch on primula
The first step in preventing primula foliage from melting down or scorching is to check crown and root zones to rule out diseases such as Pythium, Phytophthora or Rhizoctonia. Keeping soil too wet during low light levels can lead to root rot.

If we’re able to rule out diseases, we then need to dig deeper. Primula is a cool crop that’s grown during the time of year when we experience our shortest days and lowest light levels – December through February.

Physiological disorders sometimes are behind the symptoms. Daylength and light intensity increase toward the end of the primula crop cycle; this created water stress when combined with cold soil temperatures that slow root activity. Bright days of late winter can create enough of a water deficit that the margins of the leaves scorch. This is particularly true on the first sunny day after a spell of cloudy weather! Consider syringing overhead a few times during the brightest part of the day to reduce water stress, allowing enough time for foliage to dry before nightfall.

Diseases and Insects

Botrytis on primula Thrips damage on primula flowers
Botrytis is the most common disease found in primula. This crop requires cool conditions and high humidity to produce good quality plants, both of which favor the development of Botrytis. Good sanitation, watering early in the day and good air movement all help control and prevent disease.

Even with the best cultural controls, fungicides sprays are often still necessary. Products that have shown good efficacy on Botrytis either as a preventative or curative spray include Affirm, Astun, Botrystop, Cease, Mural, Pageant, Palladium and Triathlon BA.

Insects that target primula are aphid, fungus gnat, shorefly, thrips and caterpillars. Consult the GGSPro team for detailed pest control options and rates.

ProductDescriptionItem Number
Jack's WSF 15-0-15
25 lb
Jack's WSF 20-10-20
25 lb
.5 lb
1 qt
12 lb
Calcium chloride dihydrate
1 lb
1 gal
1 gal
Epsom salts
50 lb
1 lb
1 lb
2 lb
Sprint 138
5 lb
Sprint 330
5 lb
Triathlon BA
1 gal
Printable version

Mind Those Mites: Scouting and Control Tips for Poinsettia

Most growers would agree that summer conditions favor spider mites. Warm temperatures shorten life cycles, causing explosive mite populations. As weather shifts from hot and dry to cooler conditions with long nights during poinsettia season, mite pressure is reduced.

Lewis mite damage on poinsettia
Lewis mites and, occasionally, spider mites can be problematic for poinsettias. Growers are often challenged to tell the difference between the two species. Both prefer to feed on the undersides of leaves, laying eggs closest to the midrib. Both mites will produce webbing, though Lewis mites only do this when the infestation is heavy.

Mites won’t be found on sticky cards, so scouting for early detection of eggs or mites is especially crucial. Concentrate scouting in areas of the greenhouse where air movement is highest. This is where you’ll find the lower humidity that mites prefer.

Mature foliage may begin to reveal symptoms that mimic nutritional deficiencies. Observe foliage for faint light green to yellow speckling. Mites can be easily identified with the use of a hand lens while examining the undersides of leaves. A useful tool is the beating tray to tap foliage for mite presence. Against white paper, mites may appear like moving speckles of black pepper. The chart below provides key characteristics of both mite species.

Life stages of the two-spotted spider mite and Lewis mite.
Photos credit: Dr. Surendra Dara, University of California

Two-Spotted Spider Mite Lewis Mite
Host range Multiple hosts. Pest of field crops and greenhouse plants. Multiple hosts. Mainly greenhouse pest. AKA poinsettia spider mite.
Male Wedge-shaped, 0.3 mm Wedge-shaped, mustard-colored, 0.25 mm
Female Oval, 0.4-0.5 mm. Single dark spot on either side of the body Oval, 0.36 mm. Multiple small spots
Life stages Egg, larva, protonymph, deutonymph and adult Egg, larva, protonymph, deutonymph and adult, though males have only one nymphal stage
Egg Round, clear initially and turns whitish as it matures Round, pale-greenish and turns light orange with maturity
Egg laying About 100 eggs in 10 days About 60-90 eggs in a month
Life cycle 5-20 days depending on temperature 12-14 days at 70°F
Diapause Ceases reproduction during cold winters Continuously reproduces without diapause
Damage Feeds undersurface of leaves. Causes yellow mottling, scarring, bronzing and leaf fall-off Similar, in general, but needs to be determined on strawberries
Webbing Prominent At high infestation levels
Predatory mites Phytoseiulus persimilis, Neoseiulus californicus, N. fallacis, Amblyseius andersoni, etc. N. californicus, N. fallacis, A. andersoni, etc.
Chart credit: Dr. Surendra Dara, University of California

Unless growers are certain which mite is present, GGSPro recommends miticides that control both species, making two applications one week apart.

CapSil is a high-quality surfactant that improves spray coverage. During poinsettia bract formation, CapSil rates are reduced to 4 oz per 100 gal. Not more than one application of CapSil per week is made to ensure plant safety.

Pesticide 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 also be safe, legal and effective.

MOASpider mitesLewis MitesItem Number
Akari 5SC
1 qt
Avid 0.15 EC
Minx 2
1 qt
Beethoven TR
12-2 oz cans
Floramite SC
1 qt
250 ml (8.45 oz)
Sanmite 75 WSP
4-1 oz packages
8 oz
Shuttle O
1 pt
Sirocco SC
8 oz
16 oz
Tetrasan 5 WDG
1 lb
*Drench only, applied early in crop
Note: Pylon cannot be used on poinsettia.

Under Pressure: How to Defend Against Fall Pansy Diseases

Few crops can compete with the performance of pansies and violas during this time of year! 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 color and can overwinter to provide an early burst of color in the spring. 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 earn mention for being particularly challenging for fall pansy production: Thielaviopsis and Phytophthora.

Thielaviopsis causing uneven growth in flats of pansies
Thielaviopsis, also known as Black Root Rot, is a devigorating 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 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 a positive identification.

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

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 disease. The zoospores (swimming stage) of Phytophthora 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 prevention of Thielaviopsis. Chemical control options appear in the table below.

Pansy infected with Anthracnose
Foliar diseases become more prevalent as the crop progresses and the weather cools. Anthracnose (Colletotrichum), Botrytis and Cercospora are among the troublemakers.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 4th Edition Reference Guide, which includes cultural and chemical controls, as well as helpful diagnostic pictures. The tables below also contain fungicide suggestions.

Products for Root and Crown Diseases

Apply as soil drenches except as noted. The Affirm label forbids chemigation; bulk tank application is needed.

Disease FungicideMode
CommentsItem number
Chemigation label expected fall 201771-1129
Cleary’s 3336 EG
Max label rate, re-apply in 3 weeks71-2550
Cleary’s 3336 F
Max label rate, re-apply in 3 weeks71-2575
Name will change to Spirato GHN71-1570
2 oz per 100 gal rate71-16502
OHP 6672 F
Max label rate, re-apply in 3 weeks71-2670
OHP 6672 WSP
Max label rate, re-apply in 3 weeks71-2672
Orkestra Intrinsic
7 & 11
New product, trial for plant safety71-2200
Rootshield Plus G
Pre-incorporation 71-27911
Rootshield Plus WP
Best applied at time of transplant71-27951
Foliar spray, avoid open bloom71-1180
Foliar spray, avoid open bloom71-11352
Foliar spray or drench71-27601
1 & 14
Soil drench, use max label rate71-1210
Foliar spray or drench71-1520
Foliar spray or drench, preventative71-1400
Foliar spray or drench71-1655
Orkestra Intrinsic
7 & 11
New product, trial for plant safety71-2200
40 & 45
Foliar spray or drench71-2300
Rootshield Plus G
Pre-incorporation 71-27911
Rootshield Plus WP
Best applied at time of transplant71-27951
Foliar spray or drench71-3100
Foliar spray or drench71-31101
Stature SC
Foliar spray or drench71-14652
Subdue MAXX
Some resistance reported71-2978

Products for Common Foliar Diseases of Pansies

FungicideMOAAnthracnoseBotrytisCercosporaItem Number
Camelot O
Daconil Ultrex
Daconil Weatherstik
Emblem / Spirato GHN
7 & 11
Orkestra Intrinsic
7 & 11
9 & 12
Pageant Intrinsic
7 & 11
Phyton 35
Protect DF
Strike Plus / Trigo
3 & 11
Triathlon BA
Zerotol 2.0

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.

When Less is More: Using Bonzi Micro-Drenches on Poinsettia

Controlling poinsettia height throughout the growing cycle is key to avoiding problems at the time of sale. Research has shown that most plant stretch occurs in the first three hours of the day, beginning at first light. One method that greatly reduces stretch is to drop the temperature during this time frame, by 5o F below the night temperature. Discontinue this technique when the cyathia become visible.

When it comes to maximizing bract expansion, poinsettias benefit from as little plant growth regulators (PGRs) as possible. The less applied, the better. Foliar sprays of PGR are more likely to reduce bract size than drenching. Bonzi drenches can be utilized to encourage uniform poinsettias of ideal height without significant reductions in bract size.

Dramm CD-2 Chemdose
Bonzi “micro-drenches” were developed and named by Dr. Jim Barrett from the University of Florida. This technique utilizes drenches of low rates of Bonzi, usually in the range of 1/10th to 1/8th ppm that can be made as often as weekly if required throughout the production cycle. (After October 25, higher rates can be used if needed with a reduced impact on bract size. Read on for details.) Bonzi micro-drenches may be applied through an injector or Dramm Chemdose. The CD-2 Chemdose from Dramm precisely doses PGRs or soil-applied pesticides, and is ideally suited for applying micro-drenches. Doses as low as 2.5 mL can be delivered accurately. The CD-2 connects to your injector or hydraulic sprayer at pressures lower than 100 psi. Weighing less than 10 lbs., the CD-2 can be worn on the chest or mounted on a small cart.

Graphical tracking is very helpful in managing plant height among varieties of varying vigor. Such tracking ensures that data-based decision making is employed. Graphical tracking is available at

Bonzi "Micro-Drench" Strategy

Medium-Vigor Verieties High-Vigor Varieties
South 1/10th - 1/7th ppm 1/10th - 1/5th ppm
North 1/10th ppm 1/8th ppm

Bonzi "Micro-Drench" Rates

ppm tsp/100 gal oz/100 gal Ml/100 gal
1/5th 4 0.64 20
1/7th ~3 0.46 14.3
1/8th ~2.5 0.4 12.5
1/10th 2 0.32 10

Bonzi PPM Drench Volumes

Pots Baskets Other
Container Size oz per pot Container Size oz per pot Container Size oz per pot
4" 2 8" 10 14" coco 37
4.5" 2.5 10" 15 16" coco 46
5" 3 12" 28 10" Dillen color 25
6", 6.5", or 7" azalea 4 14" 56 12" Dillen color 43
7.5" azalea 9 15" Dillen color 58
8" azalea 10
8.5" azalea 13
10" azalea 25
12" 43

Starting after October 25, higher drench rates (0.25-1.0 ppm) can be used to provide stronger hold if needed with a slight reduction in bract size. Very vigorous varieties, for example, would apply a Bonzi drench at a rate of 1.0 ppm. Consult with GGSPro or your Griffin sales representative for varietal response information to determine if a Bonzi drench rate would be beneficial or necessary to avoid late-season stretch.

Product Description Item Number
Bonzi 1 qt 70-1260
Bonzi 2.5 gal 70-1270
Paclo Pro 1 gal 73-1830
Dramm CD-2 ChemdosePrecision flow meter, battery operated41-1196

The Way to a Plant’s Heart is Through its Roots: Building Strong Plants with Organic and Natural Nutrition Options

Organic, natural, all-natural and chemical-free are all terms deemed to add value to our food and flower crops. Even if you never intend to grow organically or chemical-free, there is an undeniable trend toward more natural products, sustainable methods and limited chemical exposure.

Growers have been struck with a need for more choices in plant nutrition and pest control to produce chemical-free crops economically and without losses. Insect- and disease-control options can be very limited for specific crops, most notably, herbal crops. Nutrition and building a strong plant, of course, are the first lines of defense against pests and disease.

Growers have been struck with a need for more choices in plant nutrition and pest control to produce chemical-free crops economically and without losses. Nutrition and building a strong plant, of course, are the first lines of defense against pests and disease.

At Griffin, we’ve expanded our selections of organic (OMRI-listed or WSDA) and organic-based nutritional products and supplements to fill this need. Nature’s Source 10-4-5 Nursery & Landscape Special Plant Food is an organic-based product, but not organic certified. Like Nature’s Source OMRI-listed 3-1-1, the Nursery and Landscape formulation is a liquid product derived from an oilseed extract. However, the Nursery and Landscape product contains higher levels of the essential micronutrients. Organic granular fertilizers with slow-release profiles are available in EcoVita 7-5-10 (100-day) by Verdanta and in Sustane’s 8-4-4 All Natural (45-day). Both are OMRI-listed.

Vegetables and other crops with high potassium demand can be easily supplemented with Verdanta’s granular K-Vita (OMRI), Verdanta’s liquid PL-2 (OMRI) or JH Biotech’s Biomin Potassium liquid non-organic formulation. Additionally, nitrogen content can be easily boosted as needed with the new Biomin N, 5% nitrogen in a liquid mix of amino acids derived from hydrolyzed plant protein (OMRI-listed), without increasing phosphate or potassium.

Organic, liquid formulations of micronutrients are now available. Biomin Booster 126 is a mix of micros, providing copper, iron, magnesium, manganese, boron and zinc. Biomin Calcium provides 5% calcium in a formulation that aides in calcium uptake through foliage or roots. Biomin Magnesium contains 3% chelated magnesium and can be applied as a drench or to the foliage. Other elements are also available.

Beyond the nutrition basics, we offer several products designed to provide artificial growing media with more of the components found in natural soils. Silica has been shown to reduce pest and disease infestation of a number of crops. SiTKO 0-7-17 (5% silica) or Sil-Guard 0-2-5 (7% silica), by Growth Products, can be used to add silica to growing media or to mineral soils. Silica has been shown to increase the strength of cell walls, making at least some plants resistant to invasion by pathogens or insects. Drought resistance/recovery and reduced shock during propagation and transplanting are additional benefits. Silica also competes with sodium, and can mitigate damage due to high salt content. Contact GGSPro to determine if a silica supplement may be appropriate for your production.

Beyond the nutrition basics, we offer several products designed to provide artificial growing media with more of the components found in natural soils.

Some of the most complex components of natural soils, humic and fulvic acids, are now available in a jug from JH Biotech, Inc. These complex materials originate from the breakdown of organic matter. They’re known benefactors of plant growth, increasing the cation exchange of soils and facilitating the uptake of micronutrient metals. Humax is 12% humic acid and is OMRI-listed; Fulmax is WSDA organic. Even natural mineral soils can benefit from replenishing or boosting the silicate, humate and fulvate content in poor or depleted soils.

Essential Organic 1-0-1 combines 7% humic acid with a long list of other natural ingredients, including cellulose, lignin, amino acids, sugars, plant hormones and micronutrients calcium, magnesium, sulfur and iron, all in a non-settling, non-clogging formulation. The natural rooting hormones in Essentials Organic promote rooting in propagation and in production.

No matter which crops you grow, from organic produce to perennials, these products may have a place in your production and provide your plants with everything they need to grow strong.

ProductCommentsDescriptionItem Number
Nature’s Source 10-4-5 Nursery & Landscape SpecialOrganic-based4.7 gal67-0086
Nature's Source 3-1-1OMRI4.7 gal67-0065
Verdanta EcoVita 7-5-10OMRI, 100-day40 lbs67-9215
Sustane 8-4-4 All-NaturalOMRI, 45-day50 lbs67-30570
Verdanta K-Vita 2-0-20OMRI40 lbs67-9205
Verdanta's PL-2 2-0-6OMRI1 gal67-9220
Biomin Potassium1 gal16-03481
Biomin NOMRI1 gal16-03421
Biomin Booster 126OMRI, WSDA1 gal16-03081
Biomin CalciumOMRI, WSDA1 gal16-03011
Biomin MagnesiumOMRI, WSDA1 gal16-03041
SiTKO 0-7-17Contains silica, phosphate, salicylic acid2.5 gal16GP30053
Sil-Guard 0-2-5Contains silica and phosphite2.5 gal16GP501821
HumaxOMRI, WSDA1 gal16-01111
FulmaxWSDA1 gal16-01181
Essential Organic 1-0-1OMRI1 qt166002GR

Beetle Mania: Let's Start a Revolution (in Japanese Beetle Control)

Did you know that, according to the Entomological Society of America, there are more than 30 million insect species in the world? At any one time, it’s been estimated that you could count 10 quintillion insects present on the earth!
The United States alone is home to more than 23,000 species of beetles. GGSPro has helped growers deal with infestations of ambrosia, Asiatic, box elder, cucumber, Colorado potato, flea, lily leaf, longhorn, pine bark, potato, tortoise and turpentine beetles, to name a few. One beetle generates more inquiries than any other: the Japanese beetle.
GGSPro has helped growers deal with many kinds of beetle infestation. One beetle generates more inquiries than any other: the Japanese beetle.
Adult Japanese beetles on rose
Adult Japanese beetles emerge from the soil and begin feeding in June. They are ½” long and have a hard metallic green shell with copper colored wings. The small white tuffs of hair that stick out from their abdomen help to distinguish Japanese beetles from other species.
The adults have a short life span, roughly 40 days. Female Japanese beetles feed, mate and lay eggs, repeating this process every 24-48 hours. At each egg laying, the female beetles deposit one to five eggs 2-4” deep in soil.
Japanese beetle larvae emerge in early August and feed on plant roots. They are whitish gray C-shaped grubs ¾” long with six legs. Japanese beetle grubs can be identified by the V-shaped pattern of hairs on their behinds.
Japanese beetle grub
Actively feeding Japanese beetles secrete a pheromone which attracts other adult beetles. This enables them to attack plants in groups, causing severe damage.
The following products are insecticides that are labeled for Japanese beetles and are available from Griffin. Most of these products represent some risk to bees. Refer to the bee safety codes and explanations below to make the best choices. 
Product Item # Comments
Acephate 97UP 70-1105 Residual control about 7 days.
Avalon Golf & Nursery
70-1210 Do not use in Nassau or Suffolk County, NY
Coretect 70-1380 Systemic product must apply prior to adult emergence.
Chlorpyrifos SPC 4 70-14852 Restricted-use pesticide
Decathlon 70-14201 Quick knockdown, short residual control
Discus N/G
Discus L
Duraguard 70-21261 RUP
Flagship WG 70-1700 RUP: NY, MA
Mainspring 70-2331 RUP: NY
Marathon II 70-23711 RUP: CT, MD, NY
Marathon WSP 70-23701 RUP: CT, MD, NY
Mallet 2F T & O 70-2340 RUP: CT, MD, NY
Mantra 60% WSP 70-2350 RUO: CT, MD, NY
Menace GC 7.9% 70-2389 RUP
Pyganic 5.0 Specialty 70-2687 RUP
Safari 20 SG 70-2995 RUP: CT, MA, MD, NY
Sevin SL 70-3002 Quick knockdown, short residual control
Talstar Pro 70-34121 Quick knockdown, short residual control
TriStar 30 SL 70-85221 Considered nontoxic to bees after 3 hours
Toxicity Key
Highly Toxic
EPA Describe as highly
toxic or very highly toxic to
Low Toxicity
EPA describe as a potential pathogen
or with low toxicity to bees
EPA describes as toxic to
Special Case
Special use notes per label; contact
GGSPro for more information

Exposure Key

  1. Toxicity risk through both direct exposure and residual exposure - avoid treatment when bees are visiting the treatment area.
    Visiting the treatment area refers to bees that may visit the plants after treatment. Bees are protected when bees are absent from the treetment area bot hduring and following treatment. Avoid use of these products when crops and/or weeds are in bloom.
  2. Toxicity risk through residual exposure only - avoid treatment when bees rae visiting the treatment area.
    Visiting the treatment area refers to bees that may visit the plants after treatment. Bees are protected when bees are absent from the area following treatment. Avoid use of these products when crops and/or weeds are in bloom.
  3. Toxicity risk through direct exposure only - avoid treatment when bees are actively visiting or actively foraging in the treatment area
    Actively visiting the treatment area referse to bees you see on the plants and pertains to the products that do not show residual effect. Bees are protected when bees are absent during treatment.

Garden Mums and Florel: New Research to Prevent Premature Budding

Ethephon is the active ingredient in several widely used plant growth regulators (PGRs), including Florel, Collate and Verve. Research conducted by Peter Konjoian in the 1980s laid the foundation for other researchers and growers to learn how to harness the power of ethephon. Some of Florel’s attributes include increasing lateral branching, improving plant architecture, maintaining plants in a vegetative state and reducing internode elongation.

Mystic Mums, photo courtesy of Dummen Orange
Konjoian also documented the “dark side” of ethephon: It’s a stress enhancer, leading to the recommendation that applications only be made to actively growing plants that are free from water, transplant or other stresses in order to avoid adverse plant reactions.

For many years, GGSPro has recommended Florel applications for garden mum crops. The benefits for this important crop include reducing the risk of pre-mature budding, optimized branching even under adverse conditions and the ability to influence the bloom date. We often refer to Florel applications as “cheap insurance” for garden mum growers.

Chrysanthemum crown buds

Our recommendation, historically, has been to apply a foliar spray of Florel at 500 ppm as soon as the rooted cuttings arrive and then make a second application 2 weeks later. This program has served growers very well, but the ability to overcome pre-mature budding under cool early-season conditions has been variable. In some cases, it worked like a charm; in other cases, it didn’t fully succeed.

Research shared in fall 2016 at the FRA Research Meetings by Jim Faust answers our questions about the lack of consistent success we saw in attempting to stop pre-mature budding. Thanks go to Jim Faust and Audrey Lecordier from Clemson University for allowing us to summarize their important garden mum research in this bulletin.

Faust and Lecordier set out to determine treatments needed to prevent pre-mature budding of natural-season garden mums produced under cool summer conditions. They demonstrated that extending the photoperiod, even up to 16.5 hours, did not stop pre-mature budding with a simulated cool summer temperature regime of 55° nights and 65° days.

The same held true for night interruption treatments. Next, they made 1, 2 or 3 Florel treatments beginning after 3 weeks of simulated cool temperatures. Concentrations ranged from 500-1000 ppm. They made several important observations that can significantly impact garden mum production:

  • Flower initiation may occur earlier than previously thought, leading to a recommendation to apply 500 ppm Florel in the rooting phase. This is deemed sufficient to keep the mums in a vegetative state coming out of propagation.
  • Three weekly applications of 750 ppm of Florel can re-set the flower clock during periods of cool summer weather that might otherwise lead to pre-mature budding.
  • Natural-season garden mum crops can be timed even with cool summer conditions by making weekly applications of 750 ppm Florel during the vegetative phase. Make the last Florel application one week ahead of the response time weeks to ship in the first color stage. As an example: For a variety with a 6-week response time, make the last Florel application 7 weeks before the desired first-color date. (While a useful tool, consider the timing approximate and subject to factors such as heat delay. Keep good records and refine your approach with experience.
  • Garden mums receiving 3 weekly Florel applications had significantly more buds and blooms per stem when compared to plants receiving 0, 1 or 2 Florel treatments. In this experiment, the control plants averaged 35 buds and blooms per stem while the mums receiving three applications of Florel at 750 ppm averaged 54 buds and blooms per stem.

Florel has the effect of reducing internode elongation in many treated plants, so it’s reasonable to expect that garden mums receiving the recommended amount of Florel treatments might finish shorter than untreated plants. In this experiment, however, the plants receiving three 750 ppm Florel applications were slightly taller than the control plants. This is probably due to the fact that they stayed vegetative longer than the control plants, outweighing the internode elongation reduction effects of Florel.

Special instructions regarding the use of Florel

Foliar spray applications of Florel should be applied evenly across all plant surfaces to the point of drip. It does not translocate from treated to untreated foliage. GGSPro does not recommend the use of surfactants with Florel.

Highly alkaline water may need to be treated in order for Florel to be effective. When Florel is added to the spray tank it must be able to drop the pH of the spray solution to 5.0 or lower to work properly. Distilled or acidified water may be needed in some cases. Indicate 5 can also be used to adjust the final pH of the spray solution. Do not apply Florel to plants under water stress. Slower drying conditions will maximize the effectiveness of Florel applications.

Typical Florel Program for Garden Mums

Floral ppm
During propagation500
Upon arrival rooted cuttings500
Two weeks later500

Florel Program For Garden Mums in Conditions with Medium-to-High Risk of Premature Budding

Florel ppm
During propagation500
Risk identified750
One week later750
One week later750

Florel rates: 500 ppm = 1.6 oz per gal, 750 ppm = 2.4 oz per gal

Note: Florel treatments made after July 5th will likely delay the natural-season bloom date.
Call GGSPro for questions regarding the use of Florel or Indicate 5.

ProductsDescriptionItem Number
Florel 3.9%1 qt608-395
Florel 3.9%1 gal55-100161
Indicate 51 gal31705

A New Option in Pest Control: A First Look at Altus Insecticide

Altus is a new insecticide product from Bayer, offering some unique benefits to growers of ornamentals and edibles. Although more data is needed to better understand the impact and performance of Altus over time, early indicators suggest it will be a useful tool in the growers’ arsenal.

Aphids on calibrachoa
Altus is a new soluble concentrate (SC) formulation of a broad-spectrum insecticide with a unique mode of action (MOA 4D). It’s labeled for use in greenhouses, field and container nurseries, shadehouses, interiorscapes and landscapes. Altus can be applied as a foliar spray for aphids, leafhoppers, plant bugs and whiteflies. Suppression of scale and Western flower thrips can also be expected.

One of the unique features is the edible crop uses on the label. Altus is labeled for use on a lengthy list of vegetable transplants. In addition, cucumbers, lettuce, peppers and tomatoes can be treated when grown to harvest with a 1-3 day pre-harvest interval (PHI), depending on the crop.

Altus is effective against all life stages, including eggs in some cases. It’s rain-fast in one hour, and has demonstrated good safety with bees and many BCAs (more data is still needed regarding BCA safety). Altus will not require an EPA bee safety box on the label. Growers that have chosen not to use neonicotinoid insecticides can effectively substitute Altus and control most of the same pests without the associated bee hazards.

Four-lined plant bug damage on coleus
Plant and bloom safety has been excellent. Altus has a 4-hour REI (California requires a 12-hour REI). Although no cross-resistance with other MOA 4 insecticides has been observed, Bayer recommends rotating with products outside of that MOA class. Sample rotations are found below.

Griffin item number #70-1161: Altus 17.09% SC 64oz. Not registered in DC, HI and NY as of 5/3/17.

Sample rotation for aphids (rotating with Altus MOA 4D)

ProductMOACommentsItem Number
Botanigard ESUNMany edible crops70-12501
Botanigard WPUNMany edible crops; best for tomato and BCAs70-12521
Botanigard MaxxUNMany edible crops; includes natural pyrethrin70-1253
Hachi-Hachi SC21A70-1795
Kontos23Spray or drench, some edible crops70-19601
Mainspring 28Drenches most effective for aphids70-2331

Sample rotation for whiteflies (rotating with Altus MOA 4D)

ProductMOACommentsItem Number
AzaGuardUNTank mix with Botanigard; many edible crops70-1224
Azatin OUNTank mix with Botanigard; many edible crops70-12301
Botanigard ESUNMany edible crops70-12501
Botanigard WPUNMany edible crops; best for tomato and BCAs70-12521
Botanigard MaxxUNMany edible crops; includes natural pyrethrin70-1253
Distance7CB Biotype only; some edible crops70-1465
Fulcrum7CB Biotype only70-1710
Kontos23Spray or drench; some edible crops70-19601
Mainspring 28Apply preventatively; Bemesia only70-2331
Molt-XUNTank mix with Botanigard; many edible crops70-2400
Savate 2370-2980
Suffoil-XUNMany edible crops70-4040
Ultra-Pure OilUNMany edible crops70-21401

This article is intended to help applicators plan pesticide programs, but it does not replace the need to read the entire pesticide label. Pesticide labels contain more essential information than can be included in this guide, including Personal Protection Equipment (PPE), special precautions, maximum yearly application rates and more. Information include 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 here may be safe, legal and effective. 

Catch-22 for Herbs and Pesticides: Best Practices to Minimize Pesticide Use

Herbs grown today can be used by consumers in several ways including ornamental plants, for medicinal and culinary purposes, and for homemade items like potpourri. The idea that herbs are pest-free is a common consumer perception but, regrettably, not true.

Very few pesticides on the market are registered for use on all herbs, so scouting is essential for early detection of pests. The best way to manage pests is to place emphasis on IPM practices. With proper planning and implementation, pest detection and establishing thresholds for action can be achieved.

Insect Control Implementation

Examining a sticky card with a hand lens
Yellow sticky cards, placed vertically with one-third in the plant canopy, will attract flying insects such as winged aphids, fungus gnats, shoreflies, thrips and whiteflies. The “beat test” can be used to dislodge pest from plants to provide an overview of pest presence. A hand lens or optivisor can be used to identify smaller insects not detectable on sticky cards such as spider mites, soft scales or mealybugs. Examine the undersides of the leaves and along leaf veins for presence of eggs or immature nymphs. Be observant of sticky substances on leaf surfaces, known as honeydew, that are secreted by aphids, mealybugs and soft-scale insects. Ants may also be present and will actually defend these colonies.

If you want to stay on top of pest problems, learn to recognize symptoms or signs of pest
activity as well as the presence of beneficial organisms. A symptom is evidence of activity such as holes in a leaf or a wilting leaf. A sign is evidence of an organism causing the damage such an aphid shed skin or mycelium growing on a leaf surface.
Brown marmorated eggs 
and hatching nymphs

If growing herbs outdoors, utilize the growing degree day (GDD) to determine insect emergence times. Grower degree days are a measure of accumulated heat. Growers and landscape technicians can use this measurement of heat to predict which insects will be active at which point, in order to improve pesticide application efficacy and reduce pesticide use.

Row covers placed over plants serve to protect them from harsh weather conditions as well as limit insect, disease and other pests. Trap plants are used in luring pests away from the main plant during critical times. Trap crops can be paced around the perimeter of the crop to be protected or within the crop, depending on the pest to be trapped. Examples of trap crops includes nasturtium to attract aphids, basil and marigold to attract thrips, or chervil to attract slugs.

Companion plants such as marigolds, sweet alyssum, cosmos and caraway can also attract beneficial predator insects to aid in controlling pests. Biocontrol of insects and mites is becoming an increasingly popular way to manage these pests. Contact the GGSPro team for assistance in implementing a biocontrol plan for herbs.

If chemical control is needed, choose soft or reduced-risk pesticides, referred to as biorational pesticides. Most herb growers look for products that are OMRI-certified and have zero-day or short pre-harvest intervals (PHI). Griffin offers products such as insecticidal soap, horticultural oil, neem/azadirachtin insect growth regulators and microbial products labeled for herbs. GGSPro has written a bulletin titled, “Pesticides Labeled for Herbs” that’s a useful guide for herb growers. The bulletin is free upon request. It is the grower’s responsibility to read and follow the entire pesticide label, including checking to be sure the herb you wish to treat appears on the label.

Insecticidal soap and horticultural oils rely on thorough coverage for success. These products provide a quick knockdown but have no residual control. Applications using soaps or oils should be made when conditions are good for drying (clear, sunny days) and air temperatures are between 40-80oF.

Insect growth regulators are often tank-mixed with other pesticides to help inhibit or interfere with part of an insect’s life cycle. A common example allowed for greenhouse herbs would be azadirachtin, found in Molt-X, AzaGuard or Azatin O for use on aphids, thrips and whitefly control. Specifically in aphid control, it works by preventing the molting process of the aphid, where the old skin is shed to allow a new one as the insect grows. These products do not control adult pests.

Microbial products can be a bacterium, such as in DiPel, which specifically targets worm (lepidopteran) larvae. Grandevo PTO is another bacteria-based product, with broad activity against insects and mites. Fungal microbial insecticides that target many soft-body insects include Botanigard/Mycotrol/BioCeres and Preferal. Repeated applications are recommended along with a high humidity requirement to aid in these fungal spores surviving while they germinate and penetrate into the insect’s exoskeleton to cause insect mortality. Broader chemical control options include Conserve (outside herbs only), Entrust SC, and Pyganic 5.0.

Disease Control Implementation

Preventing diseases should be proactive rather than reactive. Knowledge of the disease pathogens most prevalent in herb production is a good place to start. The most common disease issues include Botrytis, powdery and downy mildew, Alternaria leaf spot and damping-off diseases caused by Pythiumor Rhizoctonia. Good cultural practices include avoiding high-density planting and extended leaf wetness while providing good air movement. Taken together, these steps reduce humidity and therefore foliar disease occurrence.

Botrytis spores and stem canker on basil
Scouting is just as important for diseases as it is for insects and mites. It’s important to examine the root system for evidence of healthy, white roots. Biofungicides such as Rootshield, Cease, Companion and Triathlon BA applied as soil drenches aid in protecting roots against root pathogens and may also reduce the need for foliar fungicides. Damping off can cause seeds to fail to germinate, or it may cause them to succumb to a stem canker that girdles the stem.

Visible spores may or not be present on leaf or stem surfaces. Botrytis will appear as fuzzy gray-colored spores. Botrytissporulation increases significantly during humid, overcast weather conditions. Biofungicides such as Cease, Companion or Triathlon BA as well as traditional fungicides such as ZeroTol or Heritage can be applied if symptoms are observed.
Selecting herb varieties with disease resistance, especially to powdery and downy mildews, offers reliable protection while not compromising flavor or appearance.

Bacterial infections appear as water-soaked brown or black greasy looking spots which may be surrounded by a yellow halo when they occur on the foliage. In some cases, bacteria may be carried in the seed coat, especially on vegetables. Purchasing treated seeds where available may help eradicate infections. Bacterial infections require the pathogen inoculum, a susceptible host plant and wet conditions. Bactericides required to treat bacterial infections are limited and labels must list the herb being treated. Camelot O and Phyton 35 are labeled for several herbs, but not all.
Bacterial leaf spot on cilantro

Increase plant defenses against foliar pathogens by using the microbial biofungicides Regalia PTO, Fosphite and Alude. Essential Organic 1-0-1 is a root and plant stimulator that contains multiple beneficial active ingredients including kelp. Sil-Guard (0-2-5) contains potassium silicate to aid in strengthening plant cell walls and stem strength to aid in reducing stress to environmental conditions. 
Fungicide ProductsDescriptionItem Number
Alude2.5 Gal71-27601
Camelot1 gal70-21201
Cease1 gal71-13301
Companion1 gal71-1375
Fosphite EC1 gal71-1520
Heritage4 oz71-1404
Regalia PTO1 gal70-2850
Rootshield WP10 lb71-2789
Triathlon BA1 gal71-3040
Insecticide ProductsDescriptionItem Number
AzaGuard EC1 qt70-1224
Azatin O1 qt70-12301
BioCeres WP1 lb70-1245
BotaniGard ES1 qt70-12501
BotaniGard Maxx1 qt70-1253
BotaniGard WP1 lb70-12521
DiPel Pro1 lb70-1450
Entrust SC1 qt70-1538
Grandevo PTO5 lb70-1760
M-Pede2.5 gal75-10262
Mycotrol WPO1 lb70-2420
Preferal1 lb70-2650
Pyganic 5.0 Speciality1 qt70-2687
Ultra-Pure Oil2.5 gal70-21401
Plant StimulatorsDescriptionItem Number
Essential Organic 1-0-11 qt166003GR
Sil-Guard2.5 gal16GP501821
Row CoversDescriptionItem Number
15' x 300'DuPont 1.25 oz78-2045
50'-500'DuPont 15' width78-2005
50'-500'DuPont 30' width78-2010
50'-500'DuPont 45' width78-2015
50'-500'DuPont 60' width78-2020

The Plants Strike Back: A SAR Wars Story

Plants have defense systems that are activated when a plant is infected by a pathogen or suffers insect damage. The attack on the plant sets off a signal, which is carried through the plant in the form of a small molecule such as salicylic acid, jasmonic acid or ethylene, for example.

The exact chemical signal is dependent upon the plant type and the nature of the attack. Is it an insect or a pathogen? Is it a pathogen which kills plant tissue such as Pythium or Fusarium, or a foliar infection like rust or powdery mildew? The answer determines which chemical signal is sent, and initiates a cascade of biochemical reactions within the plant, which can be quite wide-ranging. For example, the plant may produce an elevated level of antifungal proteins, or reinforce its cell walls with cellulose, lignin and proteins.

Systemic Acquired Resistance (SAR) is like the immune system of a plant. A number of plant-protection and fertilizer products can trigger the signals of the SAR pathways in plants.
The observable effect of this chemical signal is termed Systemic Acquired Resistance (SAR). Think of SAR as the immune system of a plant; it’s comparable to our own immune systems in that the immunity or resistance generated may be long- or short-lived, and the degree of resistance will vary by organism being presented.

A number of plant-protection and fertilizer products can trigger the signals of the SAR pathways in plants. These products range from small molecules to living organisms. The defense signal(s) can be elicited by small molecules such as potassium phosphite, thiamine or potassium silicate.

Potassium phosphite fungicides such as Fosphite and Alude have undergone the rigorous testing required of registered fungicides (as well as the test of time). They’re well-known for their efficacy in preventing Pythiumand Phytophthora, and for stimulating root growth. In part, the activity is due to induced resistance by the phosphite.
Geranium (shown above) is among several crops that
can be sensitive to excess silicate. Others include
begonia, gerbera, pansy, petunia and tomato.

Thiamine, or vitamin B1, is also capable of inducing a SAR signal. Thiamine is just one of many plant-boosting ingredients in the nutritional supplement Essential Organic 1-0-1 (formerly called Essential Plus). Potassium silicate and potassium phosphite are supplied in SilGuard (0-2-5). Silicate, phosphite and salicylic acid – all three – are provided in the supplement SiTKO SA 0-7-17. Some common bedding plants can be sensitive to excess silicate including begonia, geranium, gerbera, pansy, petunia and tomato, so it’s important to observe label rates and precautions.

More complex natural products such as extracts of kelp, algae or certain terrestrial plants, as well as biochar (created by pyrolysis of wood or other plant material) have been shown to improve crop performance. The improvement seen is, in part, due to the ability of the materials to induce resistance signaling in the plants, along with any nutritional benefit, of course. Kelp extracts can be found in Growth Products’ Essential Organic 1-0-1, a root and plant stimulator product. Essential Organic is a complex product combining many beneficial ingredients for plant health, in addition to those that may elicit resistance.

Another professional product based on plant extracts is Regalia PTO fungicide. Regalia is derived from extracts of the giant knot weed, Reynoutria sachalinensis. Regalia PTO has been shown to protect plants through induced resistance. It’s effective against a large number of fungal and bacterial pathogens, and can be used as a spray or a drench.

Even more complex interactions occur between plants and the living bacteria and fungi we use as plant protectants including Bacillus species, Trichoderma species, mycorrhizae mixes and others. Companion, Cease, Triathlon BA, RootShield and RootShield Plus are all registered fungicides which utilize microbe-to-plant interactions to protect the plant from infection. Products based on Bacillus bacterial strains provide root and foliar protections due to multiple mechanisms, at least one of which is induction of the plants’ own resistance pathways. Bacillus fungicidal products include Companion, Cease and Triathlon BA. Similarly, the RootShield products, based on a Trichodermafungus, are used for protection against root rots, and they’ve also been shown to reduce the need for foliar fungicide applications.

Griffin has recently added biological soil supplements by Nature’s Source to our product offering. Plant Probiotic and Biotik products both combine Bacillus, Trichoderma and other organisms in a soil amendment aimed at growth stimulation. These multi-microbial formulations aid in nutrient uptake and reduce plant stress, in part at least, by inducing the resistance system within the plant.

Multi-microbial formulations, as found in Plant Probiotic and Biotik, aid in nutrient uptake and reduce plant stress. This happens, at least in part, by inducing the resistance system within the plant.

This is similar to the beneficial effects of mycorrhizae, which colonize the root systems of up to 80% of all plant species in nature. Endomycorrhizae colonize inside of the root cells and are most prevalent, while ectomycorrhizae are associated with the root surface and are most prevalent in interaction with hardwood and conifer trees. The organisms form threadlike chains that function as extensions of the root, delivering water and mineral nutrients to the plant. In the symbiotic relationship that occurs, the plant feeds the mycorrhizae with sugars and more complex nutrients. Observed benefits include improved plant health and more efficient nutrient usage, both of which may lower the costs for fertilizer and fungicides.

Mycorrhizae organisms won’t colonize all plant species equally and mycorrhizae products should be an appropriate mix for the plants being inoculated. A new line of mycorrhizae products, called MycoApply, is set to come to market – and to the Griffin product portfolio – soon. MycoApply products are based primarily on members of the Glomus genus, and multiple formulations will be available for growers to choose from.

Analogous to vaccines and human immunity, products which utilize induced resistance should be thought of as preventative, reducing the overall need for curative actions and improving plant health. Many of these products work by multiple mechanisms, and in ways researchers are still striving to understand. However, taking advantage of the current knowledge and tapping into the plants’ ability to launch a defense can benefit your growing operation with healthier plants and reduced usage, and therefore longer lifetimes, of chemical fungicides.
ProductsDescriptionItem Number
Alude2.5 gal71-27601
Cease1 gal71-13301
Companion1 gal71-1375
Essential Organic 1-0-11 qt166003GR
Fosphate1 gal71-1520
MycoApplyNAComing Soon
Plant Biotik5 lbs67-0071
Plant Probiotic5 lbs67-0070
Regalia PTO1 gal70-2850
RootShield10 lbs71-2780
RootShield Plus10 lbs71-27911
SilGuard2.5 gal16GP501821
SiTKO 0-7-172.5 gal16GP30053
Triathlon BA1 gal71-3040

A Perennial Cover Story: How to Manage Temperature in Outdoor Production

What to do… cover or uncover?

Outdoor perennial production is subject to all of the natural elements and, just like the weather itself, doesn’t follow a specific set of rules. The main goal is to avoid extreme temperature fluctuations. Perennials that are warmed too much become more sensitive to cold nighttime temperatures, and more susceptible to cold damage. Keep temperature swings in check by preventing daytime temperatures from heating up your perennial crops. Let the weather report be your guide; closely monitor the forecast to help you determine when to remove or reapply coverings to your crop.

Perennials that are warmed too much become more sensitive to cold nighttime temperatures, and more susceptible to cold damage.

When outside temperatures begin to rise above 40°F and new plant growth starts to develop, ventilate the hoop house or uncover the beds to promote air circulation. Doing so ensures that new growth doesn’t stretch or become soft. Avoiding heat build-up on sunny winter days is very important!

Greenhouses with roll-up sides are ideal to maintain cool temperatures if outside temperatures rise above freezing. White poly and/or positive ventilation can also be used to keep daytime air temperatures cool. The “winter protection fabric” from Griffin comes in 12’ and 15’ widths; it’s a convenient way to cover and uncover your perennials. Once warm weather arrives in the spring and remains above freezing for a period of time, removal of the thermal blanket coverings and white hoop house poly can be permanent. When you’re done with them for the season, let them dry, fold them up and store them for next season. 

Experience teaches: “When in doubt, keep them covered.”

Alyssum Summit Golden Yellow
Photo courtesy of Syngenta Flowers, Inc.
After uncovering, it’s important to address any decayed or damaged plant material that resulted from overwintering. Thorough cleanup is key to preventing problematic foliar diseases including Botrytis, powdery mildew, rust and downy mildew. Broad-spectrum fungicide sprays such as Affirm, Mural, Orkestra Intrinsic, Pageant Intrinsic or Palladium are helpful in preventing these foliage diseases, too. Specifically for outdoor use, Concert II is another good broad-spectrum option.

A preventative broad-spectrum fungicide drench can also be applied to add extra protection from root, stem and crown diseases. Banrot, Segway, Terrazole or Truban are recommended options to keep Pythium at bay. To prevent Rhizoctonia, consider Cleary’s 3336, Emblem or Medallion.

ProductsDescriptionitem Number
Affirm WDG0.5 lb71-1129
Banrot 40 WP2 lb71-1210
Cleary's 3336 EG5 lb71-2550
Concert II2.5 gal71-1365
Emblem1 pt71-1570
Medallion WDG8 oz71-16502
Mural WDG1 lb71-1690
Orkestra Intrinsic16 oz71-2200
Pageant Intrinsic WG1 lb71-26801
Palladium WDG2 lb71-2685
Segway O16 oz71-31101
Terrazole WP2 lb3183862
Truban 30 WP2 lb71-3065
Winter protection fabric6 oz, 12' x 150'81-730200
Winter protection fabric6 oz, 15' x 150'81-730400

New Options for the New Year: New Pesticides Bring Improved Control for Growers

Several new pesticides came to market in late 2016, including two fungicides and one insecticide that bring improved attributes to the table. For growers who are considering the addition of these products to their toolbox for spring 2017, let’s take a closer look at each:

Orkestra Intrinsic, from BASF, combines two active ingredients (AIs) representing modes of action 7 and 11. One active ingredient, pyraclostrobin, has been available to growers in the product Pageant Intrinsic. In addition to being a broad-spectrum preventative strobiluron fungicide, pyraclostrobin has been shown to have many plant health benefits. Tolerance to cold and drought have been documented, as well as faster and better rooting on a wide variety of plant material.

Fluxapyroxad is the other active ingredient; it’s a new AI for greenhouse and nursery growers. It expands the number of diseases controlled, as well as providing knockdown activity for common foliar diseases such as Botrytis and powdery mildew. When applied as a soil drench, fluxapyroxad also adds Thielaviopsis control.

Orkestra Intrinsic is formulated as a liquid suspension concentrate. Foliar sprays control Botrytis, downy mildew and powdery mildew, as well as many leaf spot diseases, crown rots and stem blights.  Soil drenches provide preventative control of Fusarium, Rhizoctonia and Sclerotinia, and suppression of Phytophthora, Pythium and Thielaviopsis.

Impatiens downy mildew
It is labeled for use on ornamental plants in greenhouses, shade houses, lathhouses, outdoor nurseries, retail nurseries and landscapes. Orkestra has a 12-hour REI, making it suitable for inclusion in many disease programs. Registered in all states except California.    

Segovis is a unique new fungicide from Syngenta. Its active ingredient is oxathiapiprolin, designated as mode of action group U15. Segovis brings with it the longest length of residual control of downy mildew on the market when applied as a soil drench—up to 6 weeks depending on the drench rate applied. This is very welcome news to growers producing Impatiens walleriana that are defending their crops from impatiens downy mildew.

Segovis brings the longest length of residual control of downy mildew on the market when applied as a soil drench—up to 6 weeks depending on the drench rate applied.

Segovis is also highly effective against Phytophthora when applied by spray or drench. Aerial Phytophthora has been an in increasing problem for spring petunia growers, especially in the propagation of vegetative cuttings. Best applied preventatively or at the first sign of disease, Segovis is labeled for ornamentals in greenhouses, shade houses, lathhouses, outdoor nurseries and commercial landscapes. Segovis is a good tank-mix partner, has just a 4-hour REI and no signal words on the label. Not registered in New York.
Aerial Phytophthora on vegetative petunia

BotaniGard MAXX from Bioworks is a dual active-ingredient insecticide with the mode of action group 3A. Many growers are familiar with BotaniGard; it utilizes the microbial insecticide Beauveria bassianastrain GHA, which works by germinating on several soft-bodied insects and making penetration, causing death over a period of a few to several days. BotaniGard MAXX adds a second active ingredient, a natural pyrethrin, to add a quick knockdown of several insects. Used as a foliar spray it provides control of aphids, thrips, whitefly, mealybugs, leafhoppers, plants bugs and many more.

Many growers are familiar with BotaniGard. BotaniGard MAXX adds a second active ingredient to add a quick knockdown of several insects.

BotaniGard MAXX is labeled for ornamentals, herbs, vegetables, fruits and nuts in greenhouses, shade houses, nursery, field, landscape, turf and interiorscapes. It has a 4-hour REI, 0-day PHI, excellent plant safety and can be used through a variety of low-volume applicators. Bioworks publishes a compatibility guide to assist with tank mixing. Registered in all states except California.    

ProductDescriptionItem Number
Orkestra Intrinsic16 oz71-2200
Segovis1 pt71-3100
BotaniGard MAXX1 pt70-1253
BotaniGard MAXX1 gal70-1254
BotaniGard MAXX2.5 gal70-1255

Rooting Out Root Rots: How to Defeat Pythium and Phytophthora

Soilborne pathogens cause significant losses to ornamental and vegetable crops in greenhouses and nurseries worldwide. Pythium and Phytophthora are among the most common of these pathogens. Such pathogens are commonly referred to as “water mold” pathogens rather than true fungi because they’re associated with wet conditions, wherein they produce swimming zoospores. These pathogens lead to root and crown rots, and can cause disease if splashed onto plant foliage.

Both Pythium and Phytophthora are natural soil inhabitants and gain access into production areas via irrigation water, soil, airborne spores, insects, weeds, equipment and footwear. They can also carryover in crops harboring the pathogen. 

Pythium root rot on petunia
Pythium is characterized by brown patches on roots. A diagnostic tool for Pythium is the ability to gently slide the outer root tissue off the root, leaving only the inner cortex. Infected plants will generally show mild-to-severe yellowing prior to collapse. Optimum soil temperatures for Pythium vary with the pathogen species: P. aphanidermatum is 95oF, P. irregulare is 86oF and P. ultimum is 76-86oF.

Pythium is an opportunistic disease. It easily spreads through water, and tends to infect plants that are already subject to stress. Fungus gnats are also known to spread Pythium in the greenhouse environment.

Cultural management is key in reducing Pythium risk: Produce crops within their ideal temperature range. Avoid strong wet/dry media moisture cycles. Avoiding excessive fertilization that can contribute to high media-soluble salts (EC). Practice strong sanitation prior to and during crop production. Be sure to filter or treat recirculated water.

Phytophthora root rot and aerial blight on fuchsia

Phytophthora is a fast-moving pathogen. It’s characterized by decline symptoms including leaf yellowing, stunting, wilting and blighting of petioles. This pathogen often leads to plant death in a short period of time. Root symptoms are similar to Pythium except for root sloughing. Examination by cutting into the crown area may reveal a reddish brown discoloration and dark streaks moving up the vascular system.

Phytophthora onset is favored by high soil moisture and warm soil temperatures. Like Pythium, optimum soil temperatures will vary with the Phytophthora species. Phytophthora overwinters in soil/media mainly as dormant resting spores (oospores or chlamydospores).

We're fortunate to have a range of choices, both chemical and biofungicides, labeled to prevent and control Pythium and Phytophthora pathogens.

We’re fortunate to have a range of choices, both chemical and biofungicides, labeled to prevent and control Pythium and Phytophthora pathogens when applied as drenches. Biological fungicides must be applied preventatively as they have no curative properties. These fungicides fit nicely into a traditional IPM program as being compatible with most chemical fungicides if needed. Traditional chemical fungicides may be applied preventatively as well as curatively. All labels must be examined carefully for crops being treated, and for application intervals.

The GGSPro Technical Reference Guide contains important mode of action (MOA) information to help growers make good fungicide rota­tion choices. The GGSPro team is available to answer your inquiries as well. Pesticides other than those mentioned here may also be legal, safe and effective.

Product Description Biological Chemical Ornamental Edible Item no.
Actinovate 18 oz X X X 31007318
2.5 gal
1 gal
X X X 71-27601
Banrot WP 2 lb X X 71-1210
Triathlon BA
1 gal
1 gal
1 gal
X X X 71-13301
Rootshield Plus G
Rootshield Plus WP
1 lb
1 lb
X 71-27911
Segway O 16 oz X X 71-31101
Subdue MAXX 1 qt X X 71-2979
Terrazole L
Terrazole WP
Truban EC
Truban WP
1 qt
2 lb
1 qt
2 lb
X X 71-3025
ZeroTol 2.0 2.5 gal X X X 71-35501

Maintenance Essentials: How to Keep Your Fertilizer Injector in Top Condition

How many times have you heard the statement, “If you take care of your equipment, it’ll last longer?” We can all agree that, eventually, your car will need an oil change, your air conditioner will need refrigerant and your lawnmower blades will need sharpening. Where does your fertilizer injector rank when it comes to maintenance?

Most greenhouse operations deliver the majority of their fertilizer through the irrigation system, making fertilizer injectors essential. An injector that’s not working properly can result in increased crop times and poor plant quality. Lela Kelly from Dosatron says some growers believe that, because the injector is sucking liquid and the stock tank isn’t as full, it must be functioning properly. This isn’t always true! It’s best to check your injector for accuracy and put it on a yearly maintenance program.

Just because your injector is sucking liquid and the stock tank isn’t as full, doesn't mean it's functioning properly.

To check the calibration of your fertilizer injector, start with a calibrated conductivity/EC meter and measure the conductivity of a clear water sample. Next, mix up a fertilizer stock solution to yield a 200-ppm nitrogen solution through the injector at 1:100. Turn the injector on and allow the fertilizer to flow through the hose for several minutes. Collect at least a quart of fertilizer solution to ensure a uniform sample,and use the conductivity/EC meter to measure the conductivity of that fertilizer solution.

Take this conductivity reading from the fertilizer and subtract the conductivity reading of the clear water to yield the true conductivity of the fertilizer solution. Compare the reading with the EC or conductivity reading for 200-ppm nitrogen on the fertilizer bag. If the conductivity reading is within 5-10% of the target EC or conductivity, your fertilizer injector is working properly. If this conductivity reading significantly deviates from the target, the injector isn’t working properly and should be repaired, re-built or replaced.

A physical calibration test can also be conducted by setting your Dosatron to 1:128, (1:128 = 1 ounce to 1 gallon of water). Fill a container with 5 ounces of fertilizer solution and place the Dosatron suction hose inside. Turn your Dosatron on so that it sucks up the 5 ounces. When the 5 ounces of fertilizer solution is gone, it should have yielded a 5-gallon bucket of fertilizer solution. This indicates that the injector is calibrated. If the injector doesn’t deliver enough fertilize, it’s an immediate indication that it’s time for a seal kit/component kit replacement.

Dosatron fertilizer injectors are powered by water pressure, using the flow of water in your irrigation system to drive a piston pump and using patented technology to deliver a precise dose of fertilizer or chemicals through the irrigation lines. It’s important to set up your injector system properly, using both a filter and a check valve. Dosatron recommends a 200-micron filter to keep all debris from effecting the action of the unit. A check valve is also important. “Back Flow” water can impact the unit with as much as four times the initial water pressure, and can cause severe damage to the injector.

Quick Steps to Maintain Your Dosatron Injector

    Dosatron Mini-Maintenance Kit
    Image courtesy of Dosatron
  1. Purchase a ‘Do It Yourself’ Mini-Maintenance Kit that includes the components and Dosa-Klean for your size Dosatron.
  2. Before and after Dosa-Klean
    Image courtesy of Dosatron
    The night prior to changing the maintenance kit, take apart your Dosatron and thoroughly rinse all parts in clean water to remove any chemicals.
  3. Dissolve one packet of Dosa-Klean into one gallon of water. Larger injector units may require two packets per two gallons of water.
  4. Soak overnight or up to 48 hours in the Dosa-Klean solution, then rinse thoroughly. Dosa-Klean will remove rust, mineral deposits and calcifications without scrubbing.
  5. Next, it’s important to install all of the new components included in the maintenance kit.
  6. Put the injector back together. If needed, Dosatron includes instructions with pictures to assist you.
  7. Finish by conducting another calibration test, to ensure everything is injecting properly.
Note: If your Dosatron is not clicking, this is not an issue that a seal kit/component kit will fix. It’s indicative of a motor problem, and you should call Dosatron’s Customer Service for assistance at 800-523-8499.
Product Description Item no.
Dosatron Mini-Maintenance Kit D14MZ2 14-GPM Unit 219-000
Dosatron Mini-Maintenance Kit D45RE15 20-GPM Unit 219-001
Dosatron Mini-Maintenance Kit D8R 40-GPM Unit 219-003
Dosatron Mini-Maintenance Kit D8RE2 40-GPM Unit 219-005
Dosatron Mini-Maintenance Kit D20S 100-GPM Unit 219-004
Dosatron Dosa-Klean Single-Use Packet -- 85 gms. 33-2633
Dosatron Dosa-Klean Economy Pail -- 3 lbs. 33-2636

In Defense of Cyclamen: How to Fight Off Foliar Diseases

As the weather begins the slow slide into the darker and more humid conditions of fall and winter, cyclamen crops require extra attention. Cyclamen benefit from the cooler temperatures after a summer of high temperature stress but, as the crop canopy fills in, the increase in humidity poses challenges. Specifically, foliar diseases can become more common at this stage of the crop.

Sierra Synchro cyclamen on the bench.
Photo courtesy of Syngenta Flowers.
Botrytis can gain a foothold during the fall and winter due to the dense plant canopy. Look for gray, fuzzy growth under the canopy. Under high disease pressure, petioles and developing flower stalks can be girdled near the corm. Flower damage shows as darkly pigmented areas or dark spotting on the petals. To help keep Botrytis at bay, remove senesced leaves and flowers, increase airflow and, to the extent possible, keep the relative humidity in check.

Overfertilization can predispose plants to foliar diseases, as well as crown and root rots. Keep close tabs on soil EC levels and leach if needed to keep EC levels below 1.25 via the saturated paste method. Many cyclamen growers rely on calcium nitrate and potassium nitrate as the backbone of their cyclamen fertilizer program. GGSPro has a bulletin on cyclamen production that provides detailed nutritional information. Fungicides are often needed to augment even the best cultural practices. Resistance is a significant issue when it comes to Botrytis,so take advantage of the chart at the end of this table that sorts effective fungicides by mode of action.

Cyclamen benefit from the cooler temperatures of fall and winter but, as the crop canopy fills in, foliar diseases can become more common at this stage of the crop.

Unfortunately, Botrytis isn’t the only foliar disease cyclamen growers need to prepare for. Two anthracnose diseases also affect cyclamen. The less serious Colletotrichum causes small brown spots on leaves. The more serious Gleosporium(Cryptocline) attacks young petioles, with distinctive drying and malformation of the young tissue. Gleosporium can also attack older tissue and flower buds, resulting in drying and distortion. The cultural techniques discussed for Botrytis will also be helpful here. In some cases, fungicides that control Botrytis are also effective against anthracnose diseases. Consult the table below for assistance in sorting through the available options.

Cyclamen displaying INSV symptoms
Viruses can produce distinct foliar symptoms that can be confused with other foliar problems. The thrips-transmitted tospoviruses, INSV and TMSV, both occur in cyclamen. Watch for ring spots, mosaic patterns, atypical leaf coloration (yellow, bronze or brown) and distortion. Should you discover any of these symptoms during your scouting efforts, discard effected plants immediately and work to control thrips. GGSPro can advise regarding biocontrol options, as well as insecticides that have shown good plant safety on cyclamen.

Always read and follow the pesticide label. Products other than those mentioned may also be safe and effective.

ProductDescriptionMode of ActionBotrytisAnthracnoseItem no.
Affirm WDG 0.5 lb. 19 X X 71-1129
Camelot O* 1 gal. M1 X 70-21202
Cease 1 gal. 44 X X 71-13301
Daconil Ultrex* 5 lbs. M5 X X 71-1420
Emblem 1 pt. 12 X X 71-1570
Medallion WDG 8 oz. 12 X X 71-16502
Mural WDG 1 lb. 7&11 X X 71-1690
Nordox 75 WG** 12.5 lbs. M1 X 71-1700
Orkestra Intrinsic* 16 oz. 7&11 X X 71-2200
Pageant Intrinsic WG 1 lb. 7&11 X X 71-26801
Palladium WDG 2 lbs. 9&12 X X 71-2685
Phyton 35* 1 gal. M1 X 71-2737
Protect DF** 6 lbs. M3 X 71-2748
Trigo 1 lb. 3&11 X X Coming Soon
Triathlon BA 1 gal. 44 X X 71-3040
* Cyclamen bloom safety unknown
** Residue may be noticeable

Managing the 3 Ms of Poinsettias: Manganese, Molybdenum and Magnesium

The pH of soilless media plays a large role in the availability of nutrients to plants. Most micronutrients tend to be more available to plants at low media pH. For crops inefficient at uptake of micronutrients, pH above 6.0 may result in micronutrient deficiencies. For crops efficient at micronutrient uptake, such as poinsettias, pH below 5.8 can cause micronutrient toxicities.

Some crops and nutrients are more affected by media pH than others. Poinsettias and the nutrients Iron (Fe), manganese (Mn) and molybdenum (Mo) are good examples. Fe and Mn are more available to plants as the pH drops below 6.2. Molybdenum and poinsettias present an opposite situation. Molybdenum is more available at higher pH.

To avoid a combined problem of reduced availability and low uptake, it’s essential to maintain poinsettias at a soil pH in the range of 6.0-6.5.

Nutrients can be classified according to how mobile they are within the plant. The differences in nutrient mobility lead to differences in symptom expression, which can be recognized and used for diagnosis of nutrient deficiency or toxicity. Nutrients are classified as: mobile, immobile or intermediate.

  1. Mobile nutrients move easily within the plant. The lower leaves are able to give up these nutrients to supply the younger leaves. Therefore, deficiency symptoms first express on the lower leaves of the plant. Mobile nutrients include nitrogen (N), phosphorus (P), potassium (K) and magnesium (Mg). 
  2. Immobile nutrients don’t move easily through the plant. The lower leaves are unable to supply nutrients to the younger foliage. Deficiency symptoms first express on the youngest leaves. Immobile nutrients include boron (B), calcium (Ca), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn).
  3. With intermediate mobility, early deficiency symptoms can occur anywhere on the plant. Somewhat mobile nutrients include molybdenum (Mo) and sulfur (S). 

Manganese (Mn) Deficiency

Manganese deficiency
Poinsettias with manganese deficiency exhibit symptoms including interveinal chlorosis starting with the youngest growth. The veins will appear sunken while the tissue between the veins looks raised. Frequent media analysis should be conducted to treat before symptoms appear. Maintain media pH below 6.2 to improve manganese availability.

Mn symptoms can be easily confused with iron deficiency. To distinguish from an iron deficiency, look for the characteristic change in leaf texture to a corrugated look, sometimes similar to an orange peel in appearance—that’s typical of manganese. High levels of iron in the media inhibit the uptake of manganese. If media tests confirm a deficiency, apply a corrective drench of chelated manganese at 1.0-1.5 oz per 100 gal. Retest the media before making additional applications.

Molybdenum (Mo) Deficiency

Molybdenum deficiency
Poinsettias have a unique requirement for molybdenum and are produced at a higher media pH to accommodate this need. Molybdenum becomes more available as soil pH rises above 6.0. Growers incorporate poinsettia feeds with molybdenum as a part of the fertilizer regime, but they often have to supplement with additional ammonium molybdate. This is especially true when using standard peat-lite fertilizers. Some of the newer poinsettia cultivars appear to have higher Mo requirements. If you’re not using a fertilizer specifically for poinsettias with elevated Mo, or soil tests indicate Mo is lacking, you can make pulse treatments or opt for a constant injection plan, both of which are explained in a bulletin from GGSPro titled, “Molybdenum Applications for Poinsettias.”

Molybdenum deficiencies are slow to express and should be treated preventatively in the months of September and October. Marginal leaf yellowing and cupping with leaf scorch distorted symptoms usually occur in the mid-region of the foliage right below the bracts. Molybdenum applications made after the symptoms appear, unfortunately, won’t reverse these symptoms. Large, well-formed bracts will often hide those symptoms. Growers experiencing low soil pH may have to rely on a foliar spray instead of a soil drench, although correcting the soil pH is recommended.

Magnesium (Mg) Deficiency

Magnesium deficiency
Magnesium deficiency symptoms begin with an overall diminished green foliage color. Left untreated, symptoms progress to interveinal chlorosis first appearing on the lowest leaves. Downward cupping and a thicker texture may also occur with more severe deficiencies. Magnesium deficiency is often an indication that the overall fertility level of the crop is too low.

Apply magnesium as a one-time corrective drench application or as a part of a constant liquid feed program. Epsom salts are an inexpensive option to provide magnesium, and can be added to most fertilizers with the exception of those containing calcium (e.g., 15-0-15, 13-2-13). The one-time corrective rate for Epsom salts is 8 oz per 100 gal. Constant injection of Epsom salts can be done at lower rates, generally 2-3 oz per 100 gal based on the amount of magnesium in the irrigation water, including the fertilizer.

ProductDescriptionItem No
Chelated manganese1 lb.91-2193
Ammonium molybdate1 lb.91-2198
Magnesium sulfate/Epsom salts55 lbs.14MGSUL55

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