Fireblight Is Appearing on Apple and Pear Trees

Mountain Home, Ark. –

            If the tips of your apple or pear trees are dying, you have fireblight. Fireblight is a bacterial disease that attacks both apple and pear trees.   It is the limiting factor as to what types and what varieties of these crops are suitable for growing in Arkansas.

            For the homeowner or hobby grower, the best thing to do is to use resistant varieties. Commercial growers and homeowners have the option of using Streptomycin, but anything other than proper rates and proper timing will result in fireblight developing resistance and making this control measure ineffective. Also, copper hydroxide may be used to control fireblight. Streptomycin or copper hydroxide should be applied just before blossoms open and continued every five days till all the flowers are gone.

            Fireblight gets its name from the appearance of trees following infection. The bacterium can infect both succulent new growth in the spring and flower buds. Shoot infections can be transmitted by insects, hail, freeze damage, and splattering rain. When a shoot is infected it will wilt at the tip and begin to die back along the shoot. The leaves will remain attached and have a “burned” look as if a blowtorch had been aimed at the tree.

            If a flower is infected, that flower will turn black and wilt. It will then move into the shoot and cause that shoot to wilt. Sometimes, the infection will get into only one or two shoots, but often it will damage the whole tree. The amount of damage depends upon the variety of fruit and the amount of disease spores in the tree.

            Removing the blighted wood is an important control measure, as it reduces the inoculum for further infections. Diseased wood should be pruned during an extended dry period or during the dormant season when the bacterium is not as active. Wood should be removed 10 inches below the last evidence of disease to insure elimination of the infection.

            It is advisable to disinfect pruning tools between each cut by using a 70% alcohol as a dip or swab. A 10% solution of laundry bleach can also be used, but is corrosive to most pruning tools. Tools should be cleaned, dried, and oiled at the end of the pruning season.

            The best cure is to plant resistant varieties, advises the Cooperative Extension Service, University of Arkansas. Pears such as ‘Bartlett’ should not be grown in Arkansas because of their fireblight susceptibility. For recommended pear and apple varieties, consult the University of Arkansas System Division of Agriculture Cooperative Extension office at 425-2335.

By Mark Keaton
County Extension Agent - Staff Chair
The Cooperative Extension Service
U of A System Division of Agriculture

Media Contact: Mark Keaton
County Extension Agent - Staff Chair
U of A Division of Agriculture
Cooperative Extension Service
3 East 9th St. Mountain Home AR 72653
(870) 425-2335
mkeaton@uada.edu

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