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Plant Pathology Infobytes

February 9, 1998

Hot Tip For Fire Blight Control

Continued wet weather could trigger another fire blight outbreak this spring. This bacterial disease was active in many home orchards last year and also caused extensive damage to Bradford pears in home landscapes.

Since fire blight tends to carry over from season-to-season and is most destructive in wet weather, this spring could be another of these times when fire blight causes widespread problems.

Fire blight is a descriptive name for the problem, since disease symptoms include black, scorched appearing branches, twigs, and foliage. The most common symptom of fire blight is a shoot blight, which occurs when the entire end of the branch is killed by the disease.

To reduce the incidence and severity of fire blight, a variety of disease managment measures have to be followed. One of the best ways to "turn down the heat" on fire blight is to apply an antibiotic spray during the bloom period for susceptible apples and pears in orchards and Bradford pears in the home landscape.

Fire blight spray is available under several trade names, so check with your local garden supply store. Look for a product which contain streptomycin sulfate (the antibiotic) as the active ingredient. This information is located on the product label.

To obtain best control of fire blight with fire blight spray, the first applications should be made at the start of the bloom period, and every five to seven days thereafter. Generally, one level tablespoon of this material should be mixed with two and one-half gallons of water for the spray mixture. Read and follow other label instructions for obtaining best fire blight control results.

A fire blight spraying program should be followed with a pruning program to remove cankers from infected twigs, branches, and shoots. But there's a "right way" and a "wrong way" to remove fire blight cankers. If you're not familiar with the pruning procedure, check with us at your county Extension office.

Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.