Fruit trees come in many variations but can be generalized as pomes, stone fruits, berries and citrus. While each fruit tree has its own characteristics and growth rates, these deciduous trees have one thing in common: Fruit trees are all susceptible to disease. Though some diseases are more harmful to certain trees than others, all fruit tree diseases can result in reduced fruit production if they are left untreated.
Anthracnose is a common leaf spot disease that is spread through fungal spores. These spores infect newly developing foliage, causing the appearance of wilted and spotted leaves. The infected leaves experience necrosis and the severely infected trees experience premature defoliation and fruit drop. All fruit trees can be affected by anthracnose.
Black rot is a damaging fungal disease that develops on mummified fruit and infected cankers. Spread by fungal spores, black rot causes the unsightly rotting and decay of the developing fruit. Infected trees will drop rotted fruit prematurely and suffer from dieback and blight. The apple tree is especially susceptible to this disease. Black rot does not kill the fruit tree. However, the continuous defoliation and blight will weaken the tree and can result in the tree's fatal decline.
Crown gall is a disease that infects the woody areas of the fruit tree. This weak bacterial disease is unable to penetrate the surfaces of the tree and must infect the fruit tree through open wounds. Infected fruit trees develop small, oval galls near the points of infection. The initial gall is soft and spongy but hardens and enlarges as the disease progresses. Chemical controls are available for this disease. However, chemical treatments are not effective on all fruit variations.
Powdery mildew is a fairly harmless disease that results in mostly cosmetic infections. The fungus develops across the foliage and fruit of the tree. It leaves a powdery, white mildew of fungus that feeds on the epidermal surface of the host. This common disease is easily treated, controlled and prevented with regular fungicidal treatments, which can include an organic sulphur-based spray.