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Cherry leaf spot

Blumeriella jaapii

Overview

  • Can be a significant problem when inoculum builds on cherries grown in humid climates
  • Lack of control can cause premature leaf drop and declined winter hardiness
  • Sweet cherry generally less susceptible to cherry leaf spot than tart cherry, when it can become severe!

Symptoms

Disease cycle

  • Overwinters on leaves on orchard floor (think apple scab)
  • Spores discharged, ideal temperature 60 to 85 F., triggered by rain, beginning at bloom to 6 weeks after petal fall
  • Very similar to apple scab, varying hours of leaf wetness, depending on temperature, required for infection
  • Continued spread by conidia on infected leaves continues with wetting

Management

  • Sanitation by removal/chopping/decomposition of leaf litter should help, as well as good season-to-season control
  • Otherwise, fungicide applications beginning at petal fall (or first leaves) and continuing every 7 to 10 days until harvest, followed by 2 post-harvest applications
  • Tart cherries require more aggressive fungicide application schedule (including post-harvest) than sweet cherry, particularly during wet seasons