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Fireblight

Erwinia amylovora

Authors:  Esther McGinnis and Kasia Kinzer

Symptoms

  • Young shoots wilt and droop, forming a distinctive “shepherd’s crook.” 
  • Leaves on infected shoots turn brown as if scorched by fire.
  • Fruit may turn dark and shriveled and persist on the branch.
  • Slightly sunken bark cankers may appear on branches and stems.

Fireblight 2

Figure 1. Distinctive “shepherd’s crook on apple (Penn State Department of Plant Pathology & Environmental Microbiology Archives, Penn State University, Bugwood.org) 

Fireblight 1

Figure 2. Fireblight symptom on fruit (Bruce Watt, University of Maine, Bugwood.org

Management and other important facts

  • Plant less susceptible apple and crabapple cultivars.
  • Mark infected twigs with ribbon or paint during the growing season.
  • Prune all marked twigs and cankered branches in late winter at least 8-12 inches below the infection.
  • May also use “ugly stub” method of pruning.
  • Avoid excessive application of fertilizer that may promote overly lush growth.
  • If fireblight is a yearly problem on a high value apple tree, apply a copper spray just as the leaf buds are starting to swell in spring; do not apply after ½-inch of green, leafy tissue is visible because the copper spray may burn the leaf tissue

This website was supported by the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through grant 14-SCBGP-ND-0038.
Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA.

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