Greenhouse Update - April 25, 2005
Leanne Pundt, Extension Educator, UConn
Powdery Mildew -- has become more common this past week, on gerbera, vegetative petunias, phlox and other favorite hosts. Some varieties of verbena are also very susceptible to this disease. Warm days, followed by cool nights, encourage powdery mildew. Once powdery mildew is detected, begin a fungicide spray program. Some of the fungicides available include: Eagle, Milstop, Compass, Cygnus, Daconil Weather Stik, Heritage, Pipron, Rubigan, Spectro, Strike, Phyton, Kocide, Banner Maxx and Terraguard. (check labels for registrated crops and other information). Cleary's has broad crop clearance for ornamentals, but continued use may result in resistance. Rotate among chemical classes:
Also, Cleary's, Fungo Flo, Spectro and Zyban may leave a visible residue.
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Powdery Mildew on gerbera daisy. (L. Pundt photo)
click for a larger image |
Aphids continue to occur on many greenhouse crops. One concern is that aphids are moving from ornamental plants unto edible crops such as peppers (see photo below).
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Foxglove aphid damage to peppers. Note leaf distortion. Do not confuse with distortion from thrips feeding.
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Many of the insecticides labeled for ornamentals are not labeled for edible crops. See the updated tables under Pest Management for Vegetable Bedding Plants on this website for more information.
Spider Mites -- The warm temperatures last week also favored the development of two-spotted spider mites, especially in hot, dry areas of greenhouses. Early detection of mites is critical on edible crops such as herbs. Lemon balm, is a good indicator plant for spider mite activity on herbs. (See photo below). Under Pest Management for Herb Bedding Plants Grown in the Greenhouse, see the updated tables for insecticide and miticides labeled for use on herbs.
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| Spider mite feeding damage to Lemon Balm. Note chlorotic tippling on leaves. (click for a larger image) |
I find a 16x handlens (see photo below) helpful to detect spider mites and their eggs. Look on the underside of the lowermost leaves, along the midvein or on leaves where stippling occurs for the spider mites (See photo above).
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| 16 x handlens is useful to detect spider mites. (click for a larger image) |
Some suppliers of handlens and other IPM supplies include:
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Previous 2005 Greenhouse Updates
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| GREENHOUSE IPM COORDINATOR (commercial interests and growers) |
LEANNE PUNDT | 860-626-6240 |
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The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.