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.
|Essential Organic 1-0-1||1 qt||166003GR|
|Plant Biotik||5 lbs||67-0071|
|Plant Probiotic||5 lbs||67-0070|
|Regalia PTO||1 gal||70-2850|
|RootShield Plus||10 lbs||71-27911|
|SiTKO 0-7-17||2.5 gal||16GP30053|
|Triathlon BA||1 gal||71-3040|
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.
|Affirm WDG||0.5 lb||71-1129|
|Banrot 40 WP||2 lb||71-1210|
|Cleary's 3336 EG||5 lb||71-2550|
|Concert II||2.5 gal||71-1365|
|Medallion WDG||8 oz||71-16502|
|Mural WDG||1 lb||71-1690|
|Orkestra Intrinsic||16 oz||71-2200|
|Pageant Intrinsic WG||1 lb||71-26801|
|Palladium WDG||2 lb||71-2685|
|Segway O||16 oz||71-31101|
|Terrazole WP||2 lb||3183862|
|Truban 30 WP||2 lb||71-3065|
|Winter protection fabric||6 oz, 12' x 150'||81-730200|
|Winter protection fabric||6 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.
|Orkestra Intrinsic||16 oz||71-2200|
|BotaniGard MAXX||1 pt||70-1253|
|BotaniGard MAXX||1 gal||70-1254|
|BotaniGard MAXX||2.5 gal||70-1255|
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.
|2.5 gal |
|Banrot WP||2 lb||X||X||71-1210|
|1 gal |
|Rootshield Plus G |
Rootshield Plus WP
|1 lb |
|Segway O||16 oz||X||X||71-31101|
|Subdue MAXX||1 qt||X||X||71-2979|
|Terrazole L |
|1 qt |
|ZeroTol 2.0||2.5 gal||X||X||X||71-35501|
Maintenance Essentials: How to Keep Your Fertilizer Injector in Top ConditionHow 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
- Purchase a ‘Do It Yourself’ Mini-Maintenance Kit that includes the components and Dosa-Klean for your size Dosatron.
- Dissolve one packet of Dosa-Klean into one gallon of water. Larger injector units may require two packets per two gallons of water.
- 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.
- Next, it’s important to install all of the new components included in the maintenance kit.
- Put the injector back together. If needed, Dosatron includes instructions with pictures to assist you.
- Finish by conducting another calibration test, to ensure everything is injecting properly.
|Dosatron Mini-Maintenance Kit|
Image courtesy of Dosatron
|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 DiseasesAs 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.
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|
Always read and follow the pesticide label. Products other than those mentioned may also be safe and effective.
|Product||Description||Mode of Action||Botrytis||Anthracnose||Item no.|
|Affirm WDG||0.5 lb.||19||X||X||71-1129|
|Camelot O*||1 gal.||M1||X||70-21202|
|Daconil Ultrex*||5 lbs.||M5||X||X||71-1420|
|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|
** Residue may be noticeable
Managing the 3 Ms of Poinsettias: Manganese, Molybdenum and MagnesiumThe 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.
- 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).
- 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).
- With intermediate mobility, early deficiency symptoms can occur anywhere on the plant. Somewhat mobile nutrients include molybdenum (Mo) and sulfur (S).
Manganese (Mn) Deficiency
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 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
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.
|Chelated manganese||1 lb.||91-2193|
|Ammonium molybdate||1 lb.||91-2198|
|Magnesium sulfate/Epsom salts||55 lbs.||14MGSUL55|
Tech Tip Articles
The Plants Strike Back: A SAR Wars Story
A Perennial Cover Story: How to Manage Temperature in Outdoor Production
New Options for the New Year: New Pesticides Bring Improved Control for Growers
Rooting Out Root Rots: How to Defeat Pythium and Phytophthora
Maintenance Essentials: How to Keep Your Fertilizer Injector in Top Condition
In Defense of Cyclamen: How to Fight Off Foliar Diseases
Managing the 3 Ms of Poinsettias: Manganese, Molybdenum and Magnesium
Tech Tip PDF Archive
From Worrier to Warrior: How to Conquer the Black Vine Weevil
The Very Hungry Caterpillars: Tips to Control These Prolific Pests
Stopping a Crossover Pest: How to Defeat Two-Spotted Spider Mites
Singing the Botrytis Blues: Tips to Help Growers Change Their Tune
A Grower's Guide to PGRs: Tips for Ornamentals and Vegetables
Aphids, Mites and Thrips: Tips to Stay Ahead of the Terrible Trio
Introducing In-Vivo Nematodes: A New BCA Option for Organic Production
Managing Diseases in Propagation: Four Practical Steps to Minimize Risk
When Clean isn't Clean Enough: Getting Serious About Sanitation
Cooking Up a Masterpiece: The Recipe to Keep Botrytis at Bay
Your Fourth Quarter Game Plan: Successful Late-Season Whitefly Control
The ABCs of PGRs on Poinsettia: Smart Strategies to Enhance Crop Quality
In with Beneficial Predators: Out with Whiteflies on Poinsettia
They Mite Be Giants: Stopping the Summer Spider Mite Surge
It Does a Plant Good: The Importance of Calcium in Plant Growth
Root Rot on Your Radar: Preventing Pythium in Fall Garden Mums
Get a Leg Up: Staying Ahead of the Merciless Thrips
Feast or Famine: Managing Iron Deficiency and Toxicity
Stop Trouble in Its Tracks: Preventing Disease in Propagation
Tools to Keep Resistance in Check: New Insecticides and Miticides for 2015