Apple trees are susceptible to black rot, which is a fungal disease.
Home apple growers often find their trees affected by many diseases that affect fruit production and quality. Black rot is a disease that commonly affects both apple and crabapple trees. All apple varieties are susceptible to black rot. The disease causes apples to turn black and shrivel, which is where the disease got its name. Does this Spark an idea?
Identification
Black rot is caused by the fungus Physalospora obtusa, which affects the tree in two phases. When fruit is infected, the disease caused by this fungus is known as black rot. If the leaves of the tree are infected, the disease is called frogeye leaf spot. Both diseases are caused by the same fungus. Black rot is responsible for fruit rotting prematurely and weakening the apple tree. Frogeye leaf spot affects the leaves of the apple tree and causes canker to develop on its trunk.
Fruit Symptoms
Black rot begins when the fungus enters the fruit. This is most often caused by injury from weather or insects. Early symptoms of black rot include one light brown spot on apples, which enlarge and run in concentric rings around the apple. Black bands join the brown spots, and eventually the entire apple is black and rotted. Rotted apples remain intact and mummify. This mummified fruit can remain on the apple tree for a long time.
Leaf Symptoms
Frogeye leaf spot symptoms occur primarily on the leaves of the apple tree. This disease causes leaves to develop purple specks, which form lesions that can measure an 1/8 to a 1/4 inch in diameter. Lesions begin to take on a "frogeye" appearance, and black fruiting bodies develop on infected leaves. As the disease progresses, cankers develop on apple tree trunks. Cankers often extend down the tree trunk and are sunken. Older cankers develop black fruiting bodies that are fungal spores, and the wood around the cankers cracks and falls away.
Control
Black rot overwinters in infected leaf tissue, making cultural control methods extremely important. Pruned branches should not remain on the ground, but should be removed or burned. Rotted apples should be removed from the tree and the dead wood pruned out. Keeping your apple trees healthy and vigorous is important to avoid the development of cankers, as they most commonly affect trees under stress. Apply fungicides recommended for the treatment of black rot in the fruit stage of the disease. Fungicides are not helpful in controlling the leaf phase of the disease.
Tags: apple tree, leaf spot, black fruiting, black fruiting bodies, cankers develop, disease causes, Frogeye leaf
