Sweet alyssum is paired with lettuce in field plots demonstrating the 'companion cropping' concept.
This post is part of the Science Tuesday feature series on the USDA blog. Check back each week as we showcase stories and news from USDA’s rich science and research portfolio.
People generally don’t go out of their way to attract insects. But on a few small farms outside Tallahassee, Florida, that’s precisely what some growers are doing—with guidance from scientists from USDA’s Agricultural Research Service (ARS) and Florida A&M University (FAMU).
Through the scientists’ field demonstrations and technical presentations, the growers are learning how to pair their crops with “companion plants.” Some of these, like sweet alyssum, a flowering annual, attract and bolster populations of beneficial insects that prey on costly crop pests. Other plants, like giant red mustard, repel the pests and “push” them away from the main crop. Then, there are so-called “trap crops.”
“These are companion crops you can plant next to the main crop to lure pests away to where it can be controlled with pesticides, biocontrol agents, or other means,” explains ARS entomologist Susie Legaspi in Gainesville, FL. Legaspi co-directs FAMU’s Center for Biological Control (CBC) in Tallahassee.
Companion cropping and biocontrol are complementary facets of an integrated pest management (IPM) approach that’s become increasingly popular among the Tallahassee region’s community of organic growers and sustainable farmers, many of whom market their produce directly to local chefs and farmers markets.
Legaspi and her colleagues have been demonstrating IPM principles to growers, home and urban gardeners, students, and other interested parties since 2008. Among such groups is the Red Hills Small Farm Alliance. Some Alliance members have begun using flowering plants like sweet alyssum and buckwheat to bolster hoverfly numbers following their release to biologically control whiteflies and aphids in vulnerable crops like collards, tomato, salad greens, melon, and cantaloupe.
Companion plants are especially attractive to adult hoverflies, which feed on nectar. More adults, in turn, mean more larvae, which are the predators that feed on pests in the main crop.
Besides the Red Hills group, similar projects involving spined soldier bug releases have also begun at Turkey Hill Farm in Tallahassee and Crescent Moon Farm in Sopchoppy, FL. Data resulting from growers’ trials of companion cropping will also be used to assess cost-effectiveness and impact on pest populations.
Pest control isn’t the only potential gain, though. Companion plants can shelter shade-loving crops from direct sunlight, provide structural support (think beans on corn stalks), suppress weeds, and share nutrients in the form of nitrogen-fixing root bacteria and organic matter.
At the end of the day, it’s a buddy system worth encouraging.
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