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Peach scab

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Cladosporium carpophilum
Written by: 
Jon Clements
Elizabeth Garofalo

Overview

  • caused by fungus Cladosporium carpophilum
  • also infects apricot and nectarine
  • typically of minor importance in New England
  • affects appearance and market value of fruit and can be entry point for brown rot

Symptoms

  • olive to black spots velvety spots on fruit, twigs, and leaves
  • on fruit has a tendence to be more severe on near stem end
  • lesions can combine to form larger areas of disease and can result in fruit cracking
  • shoot and twig infections are slightly raised and round to oval, brown in color with purple margins later in the season

Disease cycle

  • overwinters in the tree as twig infections
  • infection begins at shuck split and peaks in 2 to 6 weeks with high humidity
  • fungus is air- and water-borne
  • fruit is susceptible to infection from shuck split until harvest

Management

  • prune to maintain air movement in canopy
  • where a problem, fungicide sprays (Bravo at shuck split, Captan applied thereafter, sulfur) at 10 to 14 day intervals should begin at shuck split and continue until 40 days before harvest