University of Maryland Extension

Cherry Shot Hole on Flowering Cherries

Photo: Yoshino cherry blossoms
Back to Common Problems - Trees and Shrubs

Flowering cherries are among the most popular ornamental trees grown in Maryland.  When in bloom we know that springtime is here and we marvel at their beauty.

Then later in the season the problems start..... Sometimes during the growing season cherry trees (these diseases are worse during wet years) begin to develop severe leaf spots, yellowing leaves and early defoliation. These very common foliar diseases are collectively called “shot hole diseases” because of the “holes” left behind after the infected leaf tissue falls out. This is a "catch-all" symptomatic phrase and the two pathogens that commonly cause these symptoms are bacterial leaf spot caused by the bacterium, Xanthomonas pruni, and cherry leaf spot caused by the fungus, Blumeriella jaapii.

Symptoms:

Foliar symptoms begin as brown or reddish-brown leaf spots (see photo below). Both diseases are favored by wet weather (we tend to have wet springs) and infected leaves will turn yellow and drop from the trees in mid-summer if infection is severe. These diseases will also continue to infect leaves throughout the growing season if rainy weather persists.

Cherry leaves infected with cherry shot hole disease (click on photo to enlarge)

Management:

  • Remove older heavily damaged or poorly growing trees.
  • Try to adjust tree spacing and use proper pruning to allow better air circulation to promote faster leaf drying.
  • Remove and dispose of fallen leaves in the fall to reduce overwintering pathogens.
  • On high value trees or trees with a history of severe fungal leaf spot disease the use of fungicides may help. But, fungicides will not work if the leaf spot is caused by the bacterium, Xanthomonas pruni.  Be aware however, that these treatments will only provide preventative disease management or slow down the rate of disease development and will not cure already infected leaves. In most cases trees recover from these diseases and no treatment is necessary. If you decide you want to treat the tree contact a licensed arborist.
  • Spraying has to start as the new leaves are expanding and continue while rainy periods persist. A practical approach might be to apply two sprays, just as leaves are expanding and again when new leaves have reached full size. This approach will reduce the amount of disease and could give extended control in typical years.

Author: Dave Clement, Ph.D., Extension Specialist, Plant Pathology

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