FireBlight - Bacterial Disease
Fireblight is a bacterial disease that is particularly destructive to apples andÂ crabapples. It also affects serviceberry, mountain ash, pears, cotoneasters, and,Â in some cases, cherries and plums. Fireblight is spread by wind, rain, splashingÂ water, birds and insects. It is highly contagious and is common in the valley hereÂ in Sheridan County. It is especially bad during cool, wet springs.
Symptoms of fireblight include: wilting leaves that can gradually, or fairlyÂ rapidly, turn brown. The leaf stems will turn black and the branch tips will alsoÂ turn black, as though they have been â€˜burnedâ€™ by a torch, hence the nameÂ fireblight. In some cases the branch tips will turn down, creating theÂ characteristic â€˜shepherdâ€™s crookâ€™ look. Sometimes clear or brownish/orangeÂ fluid can be seen near the site of infection, or running down the branch.
Plant disease resistant varieties. While this is a good defense, it is important toÂ realize that nothing is immune from disease. Even disease resistant varieties canÂ be infected if they are stressed, or are overwhelmed by exposure. Maintain theÂ health of your trees with adequate water, and protect them from damage orÂ other stress factors.
Prune out infected branches. This can be done at any time, and the sooner theÂ better to remove the source of infection from the environment. Before makingÂ the first pruning cut, and after each cut, disinfect pruning tools with a bleach orÂ rubbing alcohol solution made up of 1 part bleach/alcohol to 6 parts water.Â Prune 8-12â€ below the sign of infection. Destroy infected material by burning orÂ burial; do not compost the branches or stems. If the infection has entered theÂ main stem of the tree, there is little hope for recovery.
Spray the tree in the spring. In the spring as the new buds start to swell, sprayÂ the tree with an antibiotic containing streptomycin or erythromycin. Follow theÂ label mixing instructions. Spray at 5 to 7 day intervals until the flowers are doneÂ blooming. This treatment may need to be repeated for 2 to 3 years to bring theÂ disease under control.