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Leopold Center
U.S. Department of Agriculture

 

 

Symptoms and Types of Fire Blight
(Photos courtesy of University of Illinois Extension)

 

Blossom Blight occurs when bacteria invade open flowers. The flower base and petiole will darken and ooze tiny droplets. Then the petiole will wilt.

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Canker Blight occurs when bacteria near last year's cankers renew their activity. First, the bark near an old canker will become infected. Then nearby vegetative shoots will begin to wilt, and their tips will look yellow or orange.

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Shoot Blight occurs when vegetative shoot tips are invaded. The tip of the shoot will wilt and curve downward like a sheperds crook, and then the shoot (and possibly the entire branch) will die.
 

Trauma Blight occurs when injuries caused by wind, hail, frost, or late pruning weaken the tissue and allow disease in. The infections can look like shoot or canker blight.

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Rootstock Blight occurs when bacteria from other infections on the tree move into the rootstock. A canker will form in the lower trunk that will girdle and kill the tree. Cankers will be visible on the scion trunk only, and infected trees may produce red leaves early in the fall.

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Email: mgleason@iastate.edu Telephone: (515) 294 0579 Address: 312 Bessey Hall, Iowa State University, Ames IA 50011