Issue link: http://read.dmtmag.com/i/366055
12 SEPTEMBER 2014 GOOD FRUIT GROWER www.goodfruit.com "Willamette spider mite should be a minor issue," he said. But he cautions that if Willamette mite is found to be more wide- spread throughout the state, management guidelines may need to be developed. Treatment Growers are advised to avoid using pyrethroid insecticides for any spider mite infestations because pyrethroids can cause mite populations to flare, creating a worse problem than before treatment, the WSU researcher emphasized. He is also concerned about another class of insecticides that could flare spider mite populations—neonicotinoids. Of the vineyards in last year's sur- vey, only one had an economic spider mite problem, which appeared to be linked to repeated use of imi- d a c l o p r i d , a b r o a d - spectrum neonicotinoid. The grower had been using the neonicotinoid to control grape mealybug, a vector of grapevine leafroll associated disease. In previous research, James found that imida- cloprid acted as a "fer- tility drug" on two-spotted spider mite, significantly boosting egg production. Females fed leaves that had been sprayed with imidacloprid produced about 50 per- cent more progeny in their lifetime than two-spotted females fed leaves sprayed with water. "That can be pretty significant when you consider that most of the spider mite population is female," he said. Females kept on the systemically treated leaves also lived longer than those in the water treatment group. The boost in reproduction was particularly evident in hops, a crop that James has studied extensively. Further study of other neonicotinoids and their effect on spider mites is warranted, he added. Survey When James arrived from Australia in 1999 to join WSU, he found that grape growers were routinely using broad-spec- trum insecticides like Lorsban (chlorpy- rifos) and Sevin (carbaryl). Many of the pest issues then were chemically induced, he said. "Today, grape growers have made great strides in integrated pest man- agement and have dra- matically reduced their chemical use." Though he conducted a similar spider mite survey more than a decade ago, he says a new survey was warranted because of the change in pest management practices. Predatory mites were found in 60 percent of the samples in last year's survey. By using a free, volunteer workforce at the Washington State Penitentiary in Walla Walla to count the mites on leaf samples, James was able stretch research dollars and minimize costs to the grape industry. He is using the inmates again this season as part of his expanded mite survey. • Inmates help with GRAPE RESEARCH M ost spider mite research projects involve the tedious work of counting spider mites—peering down a microscope to count tiny specks on leaves. Some would even call it cruel and unusual punishment. But a Washington State University researcher has found a workforce that enjoys the monotonous work, and he's even saving money for the state's grape industry. One of the biggest expenses in spider mite research is the cost of counting and recording mites in the laboratory from collected leaf samples. It's a task usually assigned to research or lab technicians, and one that WSU's Dr. David James did early in his career. "Technicians don't want to do it," he said of the boring work that involves sitting hunched over a microscope for hours. But James found a creative way to count the spider mites in his project. He's using a workforce that not only has unlimited hours for work but also volunteers to work for free. The workers are a select group of inmates at the Washington State Penitentiary in Walla Walla. The mite counting worked so well last summer that he's using the prisoners at Walla Walla again this season in the second year of his grape spider mite project. A one-day workshop is held at the beginning of the season to train the prisoners how to recognize and identify spider mite species. Throughout the counting process, the inmates' work is checked to ensure mites are being properly counted. The prisoner spider mite work is part of the Sustainability in Prisons Project, a partnership between Washington's Evergreen State College and the Washington State Department of Corrections that started more than ten years ago. The sustain- ability project brings science and nature into prisons to involve inmates in a host of conservation and science programs, from beekeeping to raising rare and endan- gered species like the Oregon spotted frog, Taylor's checkerspot butterfly, and Oregon white oak trees. It's a rehabilitation of both people and the environment. James got involved with the Sustainability in Prisons Project several years ago when prison officials contacted him about his "Beauty with Benefits" research on using native flowering plants to increase butterflies and beneficial insects in vineyards (see "Beauty with Benefits," May 1, 2011, Good Fruit Grower). As a result, Walla Walla prisoners now rear and tag butterflies for James, who then releases them and follows their migration. The inmates' work with butterflies led to collaboration on James's mite research. He says the prisoners seem to enjoy the work. "I've been told that it has improved behavior and has been very positive from a mental health aspect. Some of these guys are in here for life. This gives them something to look forward to and a sense of achievement and purpose. It's a win for research, inmates, and the grape industry." —M. Hansen "I'd put it in the same category as bud and rust mites." —Dr. David James