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Fire Blight

 

Contributed by :Mallory Kelley

Fire blight affects many plant species each year, and once you know the symptoms you will start noticing it everywhere.  This spring it seems to be more prevalent and a warmer winter along with the drought stress we had in the fall is what I attribute it to. Fire Blight, caused by the bacterium Erwinia amylovora, is a common and destructive disease of pear, apple, quince, hawthorn, many other members of the rose plant family as well as several stone fruit trees. The host range of the fire blight pathogen includes nearly 130 plant species in 40 genera. Badly diseased trees and shrubs are usually disfigured and may even be killed by fire blight.

Peach tree with a shriveled rotten peach

The term fire blight describes the blackened, burned appearance of damaged flowers, twigs, and foliage. Symptoms appear in early spring. Blossoms first become water-soaked, then wilt, and finally turn brown. Fruit may be infected by the bacterium directly through the skin or through the stem. Immature fruit are initially water-soaked, turning brownish black and becoming mummified as the disease progresses. These mummies often cling to the trees for several months.

Shortly after the blossoms die, leaves on the same spur or shoot turn brown and black. As the twig and leaf blight phase progresses, leaves die and curl downward, but do not drop from the tree which produces a “shepherd’s crook” appearance. This is usually the time when this disease is noticed on a tree or shrub. Spraying at this time is pointless, sanitization is the only cure.  This means cutting back at least 12 inches behind the scorched area and sanitizing pruners between every cut.  Choosing tolerant plant varieties is an easy way to reduce the likelihood of getting fire blight. Another option is to apply antibiotics (bactericides) very early in the spring, but timing can be very tricky for complete control.  Remember, Antibiotics are protectants and not cures so they must be present to prevent the infection. The best way for a homeowner to avoid fireblight is to choose resistant varieties.

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March through August,the Alabama Cooperative Extension System offers a Gardening Helpline for the general public each Monday through Thursday from 9:00 a.m. until 1:00 p.m.  This helpline is operated by Master Gardener Volunteers who use research based information to best answer all of your gardening questions.

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