WSU Tree Fruit Research & Extension Center

Little Cherry Disease

Saturday, January 19, 2019

WSU Ongoing Projects

In the spring of 2014, researchers at WSU received a grant from the Washington Tree Fruit Research Commission to begin development of a comprehensive management plan for controlling LCD in Washington sweet cherry orchards.This is a multi-disciplinary grant addressing objectives from virology (K. Eastwell,, entomology (E. Beers,, & A. Bixby-Brosi, and economics (K. Gallardo,

The four objectives of the project are to:

  1. Determine mechanisms of LCD-virus transmission via insect vectors via apple and grape mealybugs (Beers and Bixby-Brosi).
  2. Determine control methods for apple and grape mealybug in cherries (Beers and Bixby-Brosi see above section Recommendations for mealybug control.
  3. Develop an inexpensive diagnostic kit for fieldmen, growers and extension personnel to detect LCD infected trees (Eastwell).
  4. Assess the economic impact of LCD given its effects on crop yield, crop quality, and tree death (Gallardo).

A second grant was received from the Washington State Department of Agriculture as part of the Specialty Crop Block Grant Program. This project will address the efficacy of pesticides, including systemic compounds. It also aims to determine the probability of non-symptomatic trees being infected in large blocks of untested trees adjacent to a known LCD infection. Visual diagnosis of LCD is unreliable, and molecular assays are currently the only tools available. However, they are too expensive to be cost effective for large-scale testing. Management of LCD in whole orchards is typically determined on the basis of few tested trees.  The decision to remove only symptomatic trees leaves potentially infected non-symptomatic trees to serve as a reservoir; while entire orchard removal risks removal of healthy trees resulting in a replant/economic setback. This project aims to correlate infection with measurable factors (i.e., mealybug presence, LCD visual symptoms), in order to develop a whole-orchard comprehensive management plan.

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