Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Cherry Leaf Spot

Problem
Purple spots appear on the upper surfaces of the leaves. The centers of the spots may fall out, leaving holes in the leaves. Many of the spotted leaves are yellow and dying. The undersides of the leaves may be dotted with cream-colored masses of spores. In severe cases, the fruit is also spotted. The tree defoliates prematurely, and the cherry yield is reduced and of poor quality. The fruit is often soft and watery.

Analysis
This plant disease, also known as yellow leaf spot, is caused by a fungus (Cocco myces hiemalis). The fungus spends the winter in fallen leaves. About the time the cherry trees are finished blooming, large numbers of spores are splashed and blown from leaves on the ground to the emerging leaves. The infection and premature death of the leaves greatly reduces the amount of food the tree can make and store. This results in weakened trees and reduced, poor-quality fruit yields. Such trees are much more susceptible to cold injury during the following winter. Cherry leaf spot is most severe during mild (60° to 70°F), wet weather.

Solution
Spray with a fungicide containing chlorothalonil or captan. In the fall, remove and destroy all leaf debris around the trees. Next spring, spray when the petals fall from the tree; repeat the spray at least 2 more times at intervals of 10 to 14 days. If the problem is severe, continue spraying until 7 days before harvest. 'Meteor' and 'Northstar' cherries are resistant to cherry leaf spot.

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