Good Fruit Grower

May 15

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30 MAY 15, 2016 Good Fruit Grower Research underway to study leafhopper vectors of Western X. by Holly Ferguson S ince 2010, sweet cherry growers in Washington have found an increased incidence of trees showing undersized and unmarketable fruit at ripening time. Widespread infection of cherry trees with the agent or agents causing this con- dition known as little cherry disease (LCD) has growers concerned about the extent of economic damage to their orchards and how long this outbreak will last. How the infection spreads among trees has not been fully investigated although insect vectors, i.e., leafhop- pers and mealybugs, have been implicated. While more information is sought on this disease, growers are advised to remove infected trees and manage insect populations with broad-spectrum insecticides. Unfortunately, these treatments often kill non-target insects and beneficial organisms. Little cherry disease can be caused by little cherry virus 1 (LChV1) and/or little cherry virus 2 (LChV2). Western X disease, caused by a specialized bacteria named Western X phytoplasma (WX), is a related disease. LChV2 is transmitted by mealybugs, and WX is known to be vectored by leafhoppers. A 2014 study conducted by Washington State University's Clean Plant Center Northwest (CPCNW) showed that LChV2 was the most prevalent pathogen detected in cherry samples showing symptoms of LCD, followed by WX. LChV1 was rarely found and was always in co-infection with LChV2 or WX. With Western X phytoplasma infection, symptoms include fruit that is undersized, light pink or strawlike in color, and bitter in taste. Red and light pink cherries may be seen in the same bunch. Symptoms develop slowly; a tree infected in late summer may not show symptoms until the next summer or fall. Cherry trees on Mahaleb rootstocks are particularly sensitive to WX infection and will typically decline rapidly within one to two seasons of the initial infection. Some notably different symptoms seen with infection by LChV1 and LChV2 include prema- ture fall coloration in certain cultivars (Canindex 1), and late-ripening and flavorless fruit. In Washington, Western X disease was first reported in peaches at the 1940 Washington State Horticultural Association meeting and in cherries at the 1946 meet- ing. Work done in the early 1950s at what was then called the Tree Fruit Experiment Station in Wenatchee, Washington, determined that only certain leafhoppers were capable of transmitting the pathogen from fruit tree to fruit tree. Studies conducted by Washington and Idaho scientists showed that the geminate leafhopper Renewed focus on little cherry disease Good to Know Targeting all leafhoppers with insecticide sprays when only one or two species are culprits is not economically justified. A new standard in spotted wing drosophila detection • Early detection in low population density • Superior attraction in wide range of crops and locations • Extended field life • Scentry SWD Lure performed better than competing lure systems in recent field trials SWD LURE & TRAP SOLUTION Source: Dr. Elizabeth H. Beers, 2014 WSU-TFREC Trece™ is a trademark owned by Trece, Inc. Contact your local distributor or call 1-800-735-5323 Visit our website, THE SPIDER POLETM THE SPIDER POLETM THE SPIDER POLETM Cherr y Thinner Cherr y Thinner 1811 Thompson Road • Cowiche, WA 509 678-4951 • Fax 509 678-4952 NOW - NO MORE LADDERS ! • Substantial labor cost reduction • Faster and easier thinning of all varieties of cherries • Easy to learn how to use • Light weight for all day use • Able to add on extension to handle • Self Cleaning • Thin Clumps and reduce mildew • Always wear eye protection Call Foothills Today !

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