Peach trees are susceptible to several fungal diseases. While these diseases may not destroy the whole tree, they can devastate the foliage and the crop. Proper maintenance and quick action at the first sign of the disease will go a long way toward minimizing the effect.
Brown rot attacks the peaches and causes them to rot while still on the tree. The first sign is a brown spot that spreads until the whole peach is brown. This fungal disease spreads on the wind from one tree to another. It can also attack the flowers and twigs and cause them to fall off. It likes moist and wet conditions. To prevent brown rot, plant your tree so it gets good air circulation.
Peach scab is another fungal infection. It strikes most in, but is not limited to, the southern states because of the warm wet conditions. It can strike all types of peach trees. It causes small green spots that turn brown and eventually black, but it does not rot out the peach like brown rot does. It can cause the fruit to crack open, but it does not affect the taste of the fruit. It will appear just when the flowers fall off and the fruit starts to develop.
Peach scab can be prevented, or the impact minimized, by pruning to make sure the tree gets proper air circulation and by not planting your trees too close together.
Powdery mildew is a fungus that affects many types of plants, including peach trees. It appears as spots of white fuzz on the tree that eventually come together and cover the leaf. It can destroy the whole crop. Signs include stunted or distorted leaves and leaves that fall off. It can be removed in part by rubbing the leaves. As with all fungus infections, proper spacing of the trees and good pruning will improve the air circulation and take away the moist environment that fungi love.
Peach Leaf Curl
Peach leaf curl attacks almost all varieties of peaches and causes most of the leaves to drop off early in the season and leads to crop loss. Temperature is the factor that causes this disease to develop. Infections occur at early season temperatures of 50 to 70 F (10-21 C). Little infection occurs below 45 F (7 C). Peach tree leaves will be severely deformed and have abnormal coloration ranging from light green to yellow to red or purple. As they age, the leaves develop a dusty look, turn brown, shrivel up and drop. Infected fruit can drop off. Fruit that remains on the tree can become crooked at the stem or develop red or purple lesions with a wart-like appearance.