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No. 6, May 2008
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Last scheduled offering of the Floriculture College of Knowledge in Ohio
Floriculture diagnostic updates
New plant growth regulator research website
Check out MSU’s Landscape Alert newsletter
Out-the-door treatments for insects on bedding plants
Michigan’s first MAEAP certified greenhouse
Downy and powdery mildews showing up now |
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Erik Runkle, Horticulture
The Floriculture College of Knowledge certificate program will be offered in Columbus, Ohio in coordination with the OFA Short Course, July 11-12. Classes in Track II will be presented, which include Bedding Plant Production, Growth Regulators, Environmental Management of Light, and Forcing Perennials in Greenhouses. This is the last planned offering of these Track II classes.
Each class is approximately four hours long and provides intensive, research-based information on each topic. You’ll learn from university faculty and staff how to improve your knowledge and skills in growing greenhouse crops. Participants that complete all 12 production courses and pass their exams receive a professional certificate that recognizes than as a certified greenhouse grower.
Registration includes the cost to participate in the classes, presentation notes, textbooks and handouts, as well as refreshments during breaks. For more information on the classes offered or on the program, please visit the College of Knowledge website at http://hrt.msu.edu/cok. Registration is through OFA; visit http://www.ofa.org/reg.aspx to register online. The last date to pre-register and receive discount pricing is June 27.
Courses in Track III will be offered in Lansing, Michigan in coordination with the Michigan Greenhouse Growers Expo on November 11-12. This is the last planned offering of the College of Knowledge program. Please contact Sandy Allen at (517) 355-5191 ext. 1339 or e-mail her at allens@msu.edu if you have any questions. |
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Matthew Blanchard and Erik Runkle
Horticulture
May 23, 2008 -- Controlling stem extension of greenhouse crops can be a challenge on naturally tall crops. To manage plant height, growers often apply various plant growth retarding chemicals as well as utilize nonchemical strategies such as infrequent irrigation or a temperature drop in the early morning. Over the past 15-plus years, researchers in the floriculture group at Michigan State University have performed dozens of experiments with chemical plant growth regulators (PGRs) to evaluate their effectiveness at suppressing stem extension on greenhouse crops. The results for many species have been published in trade magazines and refereed journals and presented at various conferences.
A new MSU floriculture web page, http://www.hrt.msu.edu/florAoE/PGRinfo, has been developed to provide a summary of research results from many of these PGR trials. The information presented is limited to research performed at MSU and includes PGR responses for both herbaceous perennials and annual bedding plants. Visitors to the web page can select a species from a drop-down menu and then one or more photographs are displayed that demonstrate the PGR responses.
The web page does not provide recommended products or application rates; rather, it is intended to serve as a guideline to help growers determine whether a PGR is effective on a particular species. A summary table is also provided that lists the commercially available PGRs commonly used on greenhouse crops and their active ingredients. In most cases, we would expect similar responses among products containing the same active ingredient.
We hope that this web page will be a valuable resource for greenhouse growers when making PGR application decisions. As with all growth regulators, we recommend that growers perform their own trials on a small scale to determine appropriate rates given the species and cultivar, desired response, and environmental conditions. As additional research is performed at MSU on PGRs, this web page will be updated to provide growers with the most recent research-based information. We welcome your feedback on this new grower tool. For more information, please visit the MSU PGR research web site at: http://www.hrt.msu.edu/florAoE/PGRinfo. |
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Andrea Buchholz, asst. editor
May 14, 2008 -- This is the end of season for the Greenhouse Alert newsletter. Throughout the next few months, we may send out additional articles as they become available. In the mean time, many readers will find items of interest in our Landscape Alert newsletter. To access past issues, visit: http://www.ipm.msu.edu/land-cat.htm
The Landscape Alert addresses pest management and plant care for a wide ranging audience that includes nurserymen, commercial landscapers, turf managers, master gardeners and Christmas tree growers. Here is a list of contents in the May 2, 2008.
Landscape and nursery
 Right tree, right place
 Scouting for weeds: corn speedwell
 Tar spot on maple fungicide timing is now
Turfgrass
 Lawn tips to save cash
Christmas trees and forestry
 Herbicide-resistant weeds in Michigan Christmas tree plantations
 Charcoal of Fraser and Canaan fir
 Christmas trees and forestry insect update for May 2
 Gypsy moth spray window update May 2
Around the home
 Ground nesting bees are scary but harmless
 Warm weather brought the ticks out
 Polyxenus millipedes
 Red squirrel injury to arborvitae
 Where did all those winter cutworms go?
Other news
 Weather news
You can sign up to get an email announcement for the Landscape Alert similar to the one you receive for the Greenhouse Alert at: http://www.ipm.msu.edu/email-landscape.htm |
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David Smitley, Entomology
May 14, 2008 -- Warmer temperatures and longer periods of daylight always give insects a big boost in April and May. Consequently, it is not unusual to discover yellow sticky cards covered with thrips or whiteflies, or outbreaks of spider mites and aphids in greenhouses full of flats scheduled to be shipped in the next week. If you discover an insect problem now, I suggest using a safe, effective contact spray that will knock down the infestation enough to provide good protection for two weeks. This will get your bedding plants through the shipping and retail phase. Once they have been planted outdoors, the aphids, mites, whiteflies and thrips will disappear naturally. Some good choices for out-the-doortreatments are:
- Thrips, aphids, whiteflies: Avid, Marathon II, Orthene 97, Safari, Sanmite, Tristar, Flagship, and Talstar.
- Mites: Avid, Floramite, Hexygon, Sanmite.
With everything in bloom, you want to use the safest products available. None of the products listed above are known to cause a phytotoxicity problem when used at the rate on the label. Usually wettable powder and flowable formulations are the least likely to be phytotoxic. With wettable powders, make sure the pesticide is completely dissolved in the spray tank and the tank is agitated. This will prevent sludge from forming at the bottom of the spray tank, which could be phytotoxic if sprayed on plants. The re-entry time-period following application of the products listed above is 12 hours with the exceptions of Floramite (4 hours), Orthene (24 hours) and Tristar (24 hours). |
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Jeanne Himmelein, MSUE educator
Congratulations Mark Elzinga of Elzinga and Hoeksema Millennium Greenhouse.
May 1, 2008 -- Michigan Agricultural Environmental Assessment Program (MAEAP) is an innovative, proactive program that helps farms of all sizes and commodities voluntarily prevent or minimize pollution risks. It teaches producers how to identify and prevent environmental risks and how to apply effective land stewardship practices that comply with the state and federal environmental regulations.
Mark has successfully satisfied the three-phase program by first participating in an educational program explaining the Greenhouse*A*Syst and MAEAP program, secondly by having an on-farm risk assessment and making changes to issues of concern. The final step, which occurred today, was having the facility verified by a third-party verifier. Michigan Department of Agriculture employee Josh Appleby verified the greenhouse operation and honored Mark with the MAEAP sign to showcase the greenhouse operation. |
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Tom Dudek, MSUE educator
May 1, 2008 -- Greenhouse growers need to pay attention to a couple of mildews that are occurring in area greenhouses. Downy mildew has shown up on Jamesbrittania cultivars. Look for the greyish/purplish fuzz on the undersides of the leaves. Plants in question may show a slight yellowing on the upper leaf surface.
Downy mildew can be explosive when the weather is wet and humid. The downy mildew pathogen requires free moisture from condensation or watering on the plant surface to germinate. Limit disease by venting, reducing the time that leaves are wet (fewer than six hours) and keeping relative humidity to a minimum (less than 85 percent). Downy mildew has a unique thick-walled survival structure that allows it to persist in soil, growing media or diseased plants for years. If downy mildew is found, dispose of all diseased plants immediately. Place the entire plant, including the growing media and pot, in a bag and promptly seal it. Do not carry diseased plants through the greenhouse for disposal because spores on the infected plants will be released and may infect nearby healthy plants of the same plant type. Disposing of diseased plants removes a source of spores that would otherwise allow the downy mildew to spread. |
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| Downy mildew. (Click image to enlarge.) |
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Powdery mildew is being observed on Torenia and Non-Stop Begonias at this time. Look for the whitish flour like dust on the leaves. Powdery mildew, unlike many foliar diseases, does not need free moisture on the leaf to thrive. Favorable environmental conditions include high relative humidity (greater than 95 percent), moderate temperatures of between 68oF to 86o F and relatively low light levels. Infections may be more common in the spring and fall when changes between the day and night temperatures encourage high relative humidity levels, especially at night. Spores (conidia) are produced in chains. Air currents and water splash in the greenhouse easily move these spores. The spores germinate and thread-like strands (hyphae) grow along the leaf tissue. Powdery mildews obtain plant nutrients by sending feeding organs (haustoria) into the epidermis. Once a spore lands on a plant, it may take as little as three days but more often five to seven days for infection to develop.
In both cases intensive fungicide programs are essential. The following recommendations are from Dr. Mary Hausbeck, MSU Plant Pathology.
Control by using a Subdue MAXX drench once followed by sprays of :
1. Heritage 50WDG plus mancozeb
2. Stature DM 50WP plus mancozeb
3. FenStop plus Mancozeb
Repeat foliar sprays beginning with 1.
Heavy disease pressure-treat with a rotation of: Eagle followed by Terraguard 50W.
Light disease pressure-treat with a rotation of: Heritage, Insignia, Strike and then Compass. |
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