Issue link: https://read.dmtmag.com/i/466321
18 MARCH 1, 2015 GOOD FRUIT GROWER www.goodfruit.com SOURCE: BETSY BEERS, WASHINGTON STATE UNIVERSITY Seasonal average number of SWD captured by district First capture in Washington districts Winter temperatures affect timing of spotted wing drosophila emergence. 2013 (warm winter) 2014 (cold winter) 400 600 800 1,000 1,200 200 400 600 800 1,000 1,200 APRIL MAY JUNE JULY AUGUST SEPTEMBER 200 and Scentry, based on research from scientists at U.S. Department of Agriculture's research station in Yakima, Washington. (See "The lure of a better fl y trap," Good Fruit Grower, May 15, 2014.) "For the fi rst time, we have synthetic lures as opposed to homemade concoctions, which means we now have product with quality control and some degree of reliabil- ity," Beers said. In comparing Trécé and Scentry lures with apple cider vinegar, which has been the standard for fruit fl y baits, researchers found that although apple cider vinegar worked well late in the season, synthetic lures attracted more fl ies earlier. Beers noted that for cherries, early in the season—in June and July— is when detection is important, not in October when fruit are long gone. "So if someone tells you their bait catches more fl ies, be sure to ask when, because trapping more fl ies in October isn't very helpful if you're a cherry grower." Trials in 2013 and 2014 found that apple cider vinegar and synthetic lures worked well in combination and syn- thetic lures caught the fi rst fl y one to four weeks earlier than apple cider vinegar. Differences were not as clear in 2014, but synthetic lures never did worse than apple cider vinegar (and frequently did better). "I think synthetic lures will be where the industry goes in the future," she said. Control measures Initial screening of pesticides indicated which materi- als could kill spotted wing drosophila. The next phase of testing was to determine how long they lasted in the fi eld, a critical question to prevent damage. Recent trials mon- itoring residual life indicate that pesticides like Delegate (spinetoram), Entrust (spinosad), and Warrior (lamb- da-cyhalothrin) have long residual activity, while Sevin (carbaryl) and malathion have much shorter residual activity. In the latter cases, the shorter activity is paired with a shorter preharvest interval, giving these materials a different fi t in the overall control program. The organic formulation of spinosad is the most effective of organic sprays, but it lacks an effective rota- tion partner. (The label specifi es that a rotation material be used.) Beers said some members of the diamide insecticide class Exirel (whose active ingredient is cyantraniliprole, also known by the brand name Cyazypyr), shows potential for spotted wing drosophila control. Registration is pending for cyantraniliprole. Altacor (rynaxypyr), another insecticide in the diamide family, gave little control. •