Issue link: http://read.dmtmag.com/i/675334
44 MAY 15, 2016 Good Fruit Grower www.goodfruit.com G iven the prevalence of powdery mildew in cher- ries, Washington State University researchers have spent two years — and will continue for a third — examining the effectiveness of spray applications for the disease. The intent of the study is to see if there is a critical spray period during which the application of Quintec (quinoxyfen), a widely used fungicide in Washington, is most beneficial, said Dr. Claudia Probst, research associate at WSU's Irrigated Agriculture Research and Extension Center in Prosser, Washington. Specifically, is the fungicide more effective early in the season, at midseason or late season? Fungicide review The study is being conducted at WSU's Irrigated Agriculture Research and Extension Center in Prosser, Washington, in a one-acre research orchard using a completely randomized experimental setup with four, single-tree replicates per treatment. In addition to Quintec, the study exam- ined the use of Fontelis (penthiopyrad) and Pristine (boscalid, pyraclostrobin) — as well as Fontelis in combination with Quintec, varying which fungicide was sprayed at different times — to determine the best treatment when compared with untreated trees. In all, eight treatments were tested. Usually, growers would never apply a single fungicide, and in theory, all of these fungicides work to treat powdery mildew, Probst said. But a statistical analysis helps to determine if one works better than another, or in combination, when compared to the untreated control block of trees. Overall, researchers found there was no critical spray period. None of the treat- ments showed significant improvement controlling incidence of mildew on leaves in either year, except for one combination of Fontelis and Quintec in 2014. However, several treatments showed promise for controlling the severity of the disease on leaves and fruit, even though the effect was only observed in one year. For fruit, Pristine was the only fungi- cide that controlled both incidence and severity of the disease on fruit in both years, the research showed. "That was a little unexpected. I would have thought the other fungicides would do really well," she said. "Some fungi- cides just seem to do better at controlling foliar infection, and others are better at controlling fruit infection. Overall, the incidence of disease on leaves is not a good indicator on how much disease to expect on fruit." Quintec alone also did not control incidence or severity of the disease on leaves or fruit either year, the study showed. The Quintec-Fontelis spray Study aims to find best time to apply fungicide. by Shannon Dininny Spraying for A WSU study into powdery mildew looked at the effectiveness of applying fungicide early in the season, at midseason and late in the season. Courtesy Claudia Probst ® Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow Always read and follow label directions. www.dowagro.com Delegate ® Insecticide. Insecticide applications may target a single pest, but other pests are likely residing in your orchard. With Delegate, you can control multiple pests at once, including: n Codling moth n Thrips n Leafroller n Leafminer n Spotted wing Drosophila n Cherry fruit fly n Pear psylla Pests are controlled by contact and ingestion. And the translaminar movement (into the leaf) of Delegate helps reach pests out of the direct line of spray. To learn more, visit www.DelegateInsecticide.com. MULTIPLE PESTS LURK. COINCIDENTALLY, DELEGATE ® CONTROLS MULTIPLE PESTS.