Greenhouse Update -
March 24, 2008
Leanne Pundt, Extension Educator, University of Connecticut
Cooler Greenhouse Temperatures – Many growers may be growing crops cooler, due to the higher energy costs. In cooler greenhouses, plants & floors tend to stay wet longer, after watering, which can lead to outbreaks of foliar diseases such as Botrytis blight and downy mildew. Water only as needed, in the mid to later morning (10 am to noon) to help promote leaf dryness. Using HAF fans as well as heating & venting, will also help promote leaf drying.
Aphids can tolerate cooler temperatures (Green Peach Aphid has a developmental threshold of 39F). Fungus gnats will also favor a moister growing media. Thrips and spider mites may slow down development but will still be present (and may come in on incoming plants). During cooler temperatures, you may see the overwintering form of the two spotted spider mite, which is more orange in color without the two dark spots. (See photo).
Some growers have been implementing biological control of fungus gnats: (using beneficial nematodes (Steinernema feltiae) and the soil dwelling predatory mite (Hypoaspsis miles). In one greenhouse, we saw a naturally occurring parasite of fungus gnats, Synacra pauperi on their yellow sticky cards (See photo). The adults are approximately the same size as fungus gnats (1/8 of an inch long). You will see a noticeable constriction between the head and thorax and between the thorax and the abdomen. The abdomen tapers to a sharp tip. Antennae are beaded and elbowed.
Females inset their eggs into the fungus gnat larvae. However, only one parasitic wasp emerges from each pupae. Fungus gnat larvae live until they pupate, then die, after which the parasitic wasp pupates.
For more information see: http://www.entomology.wisc.edu/mbcn/kyf702.html
Leanne Pundt, Extension Educator
University of Connecticut
| January 8, 2008 |
| March 7, 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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GREENHOUSE IPM COORDINATOR (commercial interests and growers) |
LEANNE PUNDT | 860-626-6240 |
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