Issue link: http://read.dmtmag.com/i/56260
Reduced risk? A new study finds that reduced-risk pesticides are not less risky to beneficial insects. by Richard Lehnert A three-year study just completed in Michigan apple orchards showed that reduced-risk pesti- cides—which growers are now adopting—are more damaging to the functional ecology of the orchards than the products they are replacing. Orchards using these reduced-risk pes- ticides have fewer beneficial organisms to help control pests, so growers will likely orchards sprayed with organophosphate insecticides, such as Guthion (azinphos- methyl). "Green lacewings as larvae tend to feed on soft-bodied insects like aphids," Whalon wrote. "They look like little alligators as larvae and have beautiful, elaborate lace wings as adults. In fact, they can significantly impact pest populations." Mark Whalon incur higher costs to control secondary pests, and use more, not fewer, spray applications, the study concludes. The reduced-risk orchards had fewer species of beneficial organisms and lower populations. The study began in 2009 and involved 22 orchards. Dr. Mark Whalon's labora- tory, at Michigan State University, con- ducted the study, using funding from the Michigan Apple Committee. It showed that the practice of using more insecticidal modes of action low- ered the diversity of, as well as the num- ber of, beneficial organisms, including pollinators. Growers are being encour- aged to alternate among spray materials to reduce the development of resistant pests and also because the new reduced- risk materials are less broad spectrum. The shift in pesticides is coming about as a result of implementation of the Food Quality Protection Act of 1996. "Because insecticides post-FQPA tend to be narrower in the spectrum of arthro- pods impacted, growers have to use a broader range of new modes of action to control a typical apple pest complex," Whalon wrote in his final report. "There- fore, they are inadvertently reducing the diversity in their orchards." Some of the specific natural enemy changes they observed include: • Green lacewings declined signifi- cantly in orchards using those insecti- cides defined by the U.S. Environmental Protection Agency as "reduced risk." Numbers remained constant in the 22 MARCH 1, 2012 GOOD FRUIT GROWER www.goodfruit.com What's good for the orchard is bad for the family tree. Delegate® WG insecticide from Dow AgroSciences uses an innovative mode of action to deliver fast knockdown and long-lasting control of codling moths — along with leafrollers and a broad spectrum of other insects — before they damage pome fruit. With Delegate, there won't be any pest reunions in the orchard this season. Just high-quality apples. Science. Yield. Success.™