Greenhouse Update -
March 7, 2008
Leanne Pundt, Extension Educator, University of Connecticut
Inspect incoming plants for key insects, diseases, weeds and cultural problems. Inspect the entire plant – leaves, stems and roots for signs of pest activity and for general health. Roots should be white with vigorous growth – brown, decayed roots are evidence of root rot disease or root death. If plugs have poorly developed roots, you may want to delay planting until they have a more developed root system.
Gently tap the foliage on incoming plugs, (especially those with softer lush growth or known trouble makers) to detect thrips or aphids. For example, I have been seeing aphids & thrips on Ipomoea “Marguerite” in my travels.
However, tapping often does not dislodge two spotted spider mites. Turn over and look on the underside of the leaves, along the midrib, for all stages of the spider mites (eggs, nymphs, larvae and adults). Sometimes, you will see white empty egg cases. For example, I have been seeing spider mites on Ipomoea “Tricolor” and “Blackie”.
If at all possible, do not accept plant shipments with serious insects or diseases with wide host ranges, and are difficult to treat. It is also much easier to treat a few flats of plugs than your entire greenhouse. So, take the time to inspect those plug trays!
Aphids
Three of the most common aphids in spring crops include foxglove, green peach and melon aphids. If growers are considering releasing parasitic wasps against aphids, the parasitic wasps are very host specific. You need to know what species of aphid you have in order to release the right parasite.
Here is a link to a chart telling the difference between green peach aphids, melon aphids and foxglove aphids. You should be able to see these characteristics with a hand lens. Look under aphids.
http://nysipm.cornell.edu/publications/bpguide99/files/arthropod2.pdf
The parasitic wasp, Aphidius matricariae, works against the green peach or tobacco aphid. For larger aphids, like the foxglove aphids, the parasitic wasp Aphidius ervi can be used. Aphelenus abdominalis can also be used against the foxglove aphid. For the melon or cotton aphid, Aphidius colemani can be used. Some companies also sell a mix of different species.
If aphids are already numerous, use a selective material such as Endeavor, (pymetrozine) that is compatible with aphid & whitefly parasites and with predatory mites used to control thrips or spider mites. Avoid high nitrogen fertilization that promotes lush growth favorable to aphids.
If
not using biological control agents, systemic insecticides such as
Tristar, Flagship (spray), Safari (drench) and Marathon seem to be
performing well against many different types of aphids. Ultra Fine
Oil or Safe T Side Spray Oil can also be used, especially on certain
edible crops. (Follow label precautions to prevent possible plant
damage). Thorough coverage is needed when using contact materials
such as oils or soaps.
Leanne Pundt, Extension Educator
University of Connecticut
| January 8, 2008 |
| New England Greenhouse Update now online. University Extension Specialists in New England, in conjunction with USDA's Northeast Sustainable Agriculture Research and Education, contribute information to this new website. Timely updates are provided for commercial growers of greenhouse crops and flowers in Massachusetts, Connecticut and Rhode Island. You can use this additional resource for more information about current observations and recommendations on environmentally safe production practices. |
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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.