Fruit trees are susceptible to a wide variety of disease. These types of trees generally grow in warm, moist climates, which can encourage disease. These diseases can damage the healthiest of trees and spread quickly among the crop. Most diseases can be detected and treated early to help save the trees.
Apple scab is a fungus that is caused from heavy rainfalls and high humidity. This disease can make the fruit very blemished so that it can not be sold. Apple scab begins as a small, fuzzy, green spot on the leaves and fruit of the tree. The spots will eventually turn brown and have a raised appearance much like that of a scab. The best way to control apple scab is by spraying a fungicide when the apples are still very young. The application should be made when the fruit is still a bud and up to 1/2 inch in diameter.
Black rot is a fungal disease that can cause complete loss of a fruit crop in warm and humid climates. The first symptoms of the disease appear on the new leaves in the spring. Small purple dots eventually turn into circular brown lesions. The lesions on the fruit begin as red spots, then turn from black to brown and have a leathery texture. The tree will develop fissures or cracks in the surface of the bark, which can eventually rot away the tree. The best method to control black rot is to prune away all dead and diseased limbs and treat the healthy part of the tree with fungicide early in the spring.
Powdery mildew is a fungus that appears as a dusty gray mildew on the leaves of the fruit tree. This is caused by high levels of rain and humidity. At first the spots are small and can be removed by rubbing the leaves. Eventually the disease will appear as mildew and can disfigure the leaves. The fungus can survive the winter cold so the tree must be treated to get rid of the disease. Rake up any diseased leaves and remove them from the area. Spray fungicide in early fall to get rid of the mildew.
Southern blight is a disease that is caused by heavy amounts of moisture. The first symptoms are the yellowing of the lower-level leaves. The leaves of the tree will begin to die and new stems will fall over. White mold will appear on the branches of the trees. The best method of control is to spray the trees and surrounding soil with fungicide in early spring.