Bacterial Leaf Spot
BACTERIAL LEAF SPOT CONTROLAll shade trees are attacked by one or more fungi that cause scattered, rather definite, round to oval, angular, or irregularly shaped spots on the leaves. These spots usually become conspicuous from late June through August. Leaf spots are the most common diseases of shade and ornamental trees. Please take note that this disease is incurable, but not uncontrollable.
HOST PLANTS: Common in tomatoes, peppers, and members of the cabbage family. Cherries, plums, apricots, almonds, and peaches are especially susceptible.
SYMPTOMS: Powdery mildew starts on young leaves as raised blister-like areas that cause leaves to curl, exposing the lower leaf surface. Infected leaves become covered with a white to gray powdery growth, usually on the upper surface; unopened flower buds may be white with mildew and may never open. Leaves of severely infected plants turn brown and drop. The disease prefers young, succulent growth; mature leaves are usually not affected.
FAVORED ENVIRONMENT: Bacterial leaf spot favors an environment where plenty of moisture and warm temperatures are present. During the summer months, especially if plants are watered by overhead sprinklers, sufficient moisture may be present for infection when the bacteria are splashed or blown on to leaves. Wind and rain spread the bacteria to plants.
This infection overwinters in the soil around infected plants as well as on garden debris and seeds. The disease will also remain in the twig cankers, leaves, stems and fruit of infected trees.
BACTERIAL LEAF SPOT CONTROL:Choose resistant varieties if possible. Keep the dirt under the tree clean and rake up fallen fruit. Prune or stake plants to improve air flow. Make sure to disinfect your pruning equipment (one part bleach to 4 parts water) after each cutting. Use a thick layer of wood chips or mulch to cover the soil after a thorough cleaning. The mulch will prevent the fungus spores from splashing back up onto the leaves. Water in the early morning hours (avoiding overhead watering if possible) to give the plants time to dry out during the day. Avoid over-watering.
There is no cure for plants infected with bacterial leaf spot. Apply copper-based fungicides weekly at first sign of disease to prevent its spread. This organic fungicide will not kill leaf spot, but prevents the fungus spores from germinating. Applications of Fire Blight Spray will also control the disease. Use as a preventive treatment or apply at first sign of water soaked leaves.
Products for Bacterial Leaf Spot Control