There seems to be more interest in greenhouse-grown specialty food crops, such as mescaline (salad) mix, raspberries and heirloom cherry tomatoes. Greenhouse-grown herbs have been a common specialty crop for awhile. Growers are looking at “preharvest” vegetable plants, such as fruiting tomatoes, lettuce and other greens in containers. They consider these niche markets worth trying because of their potential high return.
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is extension entomologist, Cornell University Cooperative Extension, Long Island Horticultural Research and Extension Center.
Treating edible plants
These specialty crops can be a challenge to produce and market. The trouble with some of these crops can occur when trying to control insect and disease pests on food crops in the same greenhouses where nonedible ornamental plants were or are grown. To use a pesticide on an edible plant, the material must have an established residue tolerance (except for a few pesticides with certain active ingredients exempt from tolerance).
The first solution is to consider biological controls, cultural techniques and other non-pesticide tools where possible to prevent or manage insects and diseases at a tolerable level. Biological controls, including banker plants, are used successfully in greenhouse vegetable production for spider mites and whiteflies. For more information on banker plants, check out www.bugwood.org/arthropod/day2/matteoni.pdf and http://mrec.ifas.ufl.edu/lso/banker/banker.htm.
I am familiar with one grower who used only Encarsia
formosa
wasps to successfully control greenhouse whitefly on cherry and standard tomatoes. He never applied an insecticide.
A crop grown without pesticides can have great marketing potential to some buyers, including consumers at farmer’s markets and restaurants looking to buy locally grown produce. The switch to biologicals should not be undertaken without careful consideration and a monitoring program in place.
Need for reinforcements
Although biologicals can provide effective pest control, it is necessary to have a backup plan when intervention is needed. Some pest-control products for ornamental plants, including Enstar, Mavrik, Citation, Ovation and DuraGuard, must never be applied to edible greenhouse plants. Which products are specifically labeled for greenhouse vegetables can be confusing. Some products have lost their label for greenhouse vegetables, but other new products have received registration.
If compatibility with biological control is an issue, consult with suppliers or the Koppert Side Effects list for specifics. Some products are even approved for organic production.
Remember that product and label uses must be approved for your state or region. Trial new materials on a small scale before treating an entire crop to be sure no plants are injured. Consult your local extension specialist and talk with experienced growers for additional support.
Products labeled for control of insect and mite pests on greenhouse food crops*
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