Issue link: http://read.dmtmag.com/i/675334
www.goodfruit.com Good Fruit Grower MAY 15, 2016 43 incubation period, she said, but "tem- perature and humidity alone are not enough to start infection on cherries." In future studies, Probst will study the sudden transition from resistance to susceptibility that appears to occur in the month of June in hopes of determining the trigger. Overall, fruit infection is a silent and highly unpredictable process, while infections of leaves is "loud and in your face," she said. "With fruit, you have to just wait and see what you get at harvest." Future research Powdery mildew spores can live for up to two months on sweet cherries — a situation that is unique to cherries. For that reason, the latest findings present new areas for research, such as examining the role of cherry fruits in the fungal life cycle, points of infection, and the impact of cherry volatiles on spore germination, Probst said. Skeena cher- ries, for example, produce three times more alcohol than Lapins, which could play a role. She also aims to discover what she calls the "ABC's" of powdery mildew with hopes of achieving sustainable disease management techniques. Prior to 1944, powdery mildew was only known to occur in leaves, but the fungus has affected cherries in the Pacific Northwest ever since. Other key cherry growing regions do not have powdery mildew issues: Chile and Turkey have no mildew. Spain doesn't even spray for it, and in Italy, a fellow researcher had to Google fruit symptoms on the Internet to tell her it's not an issue there, Probst said. Germany saw it on leaves in 2004 but not since, she said, and it appears on leaves in Iran once in a while but never on fruit. "What happened in Washington in 1944 to make that fungus decide to jump from the leaves to the fruit?" she asked. "That's where adaptation becomes of real interest to us." Growers have an opportunity to understand more about the disease, and controlling with spray is a short- term view, she said. "The goal is to keep pathogen populations under sustained disruptive pressure and provide an additional layer of protection against the disease." • Courtesy Claudia Probst Powdery mildew was once only known to occur in leaves, but since 1944, the fungus has affected cherries, too — but only in the Pacific Northwest. "What happened in Washington in 1944 to make that fungus decide to jump from the leaves to the fruit? That's where adaptation becomes of real interest to us." —Claudia Probst Spray study On the following pages, see how researchers are looking into the best time to spray for powdery mildew. Model M8540 4857 Contractors Dr. East Wenatchee (509) 886-1566 www.valleytractor.com (800) 461-5539 www.kubota.com ©Kubota Tractor Corporation, 2011 EQUIPMENT SALES Our Valley Tractor people ensure that promise is kept. At Valley Tractor – Our promise to you is to deliver outstanding customer service before, during, and after the sale. Bruce Haupt Sales Manager Kelly Hersel Sales Ernie Cazares Sales Bob Mardian Part Time Sales The proven Orchard Tractor leader in reliability and lower operating costs.