![]() Resistant apple cultivars include Black Oxford, Enterprise, and William’s Pride. The fungus is carried on the wind, quickly making it spread. Photo Credit: Mike Lewinski / Flickr / CC BY 2.0Ĭedar-apple rust is easy to spot with tell-tale yellow or orange spots that develop on the leaves in early stages, then galls that form on branch tips. Risk: These two diseases do not cause rots in the fruit. Season: Warm, humid weather conditions lead to disease development. Prune and thin the apple trees to increase air circulation and dryness. Treatment: The UMaine Cooperative Extension recommends applying a fungicide application in mid to late July, with a second application in August. The spores may also become airborne and affect nearby fruits this way. Spores of the sooty blotch and flyspeck fungus splash onto fruits during rainfall. Sooty blotch and flyspeck prefer conditions with high humidity in unpruned, large trees or trees with lots of morning dew.Ĭauses: The fungi causing these two diseases overwinter in the twigs of apple, pear, and woody plants. Visible symptoms take a month or more to appear after infection. Sooty blotch forms irregular, olive-green blemishes around the apple’s surface. Symptoms: Flyspeck is a fungus that appears as circular clusters of tiny, defined black dots. There are no known apple cultivars resistant to sooty blotch and flyspeck. They often appear together and develop in the late summer. They cause blemishes on the apple’s surface but do not harm it. Photo Credit: Jerzy Opioła / Wikimedia Commons / CC BY-SA 4.0įlyspeck and sooty blotch are fungi that grow on the surface of apples. Repeated infections will weaken the tree, making it susceptible to other diseases. Severe cases may cause complete defoliation by early summer. The disease continues to spread all season with each rainfall. Season: According to the UMaine Cooperative Extension, infections can occur as soon as early May when green tissue emerges from the bud. ![]() The University of Maine (UMaine) Cooperative Extension recommends applying preventive sprays such as captan, sulfur, or other fungicides. Remove abandoned apple trees within 100 yards of your orchard. ![]() Treatment: Rake up leaves and remove them from the orchard before May. Frequent rains and prolonged leaf wetness enable severe scab infection conditions. Apple scab can also spread from nearby trees already infected. These spores then infect nearby apple trees. Infected fruit will usually drop, and infections may limit flower formation.Ĭauses: Spores released from infected apple leaves that have remained on the ground through winter. On the fruit, dark green spots appear on its surface (later becoming darker, flaky, and even cracked). Symptoms: Brown or olive green spots develop on apple tree leaves, which may curl and fall off. Some popular cultivars that are susceptible to apple scab are McIntosh, Cortland, and Macoun. There are many apple tree species that are resistant to apple scab, including Honeycrisp, Freedom, and William’s Pride. The good news? By planting resistant varieties or using fungicides, you can avoid this bitter fate and save your apples and your tree. Photo Credit: Fructibus / Wikimedia Commons / CC0 1.0Īpple scab is a fungal disease that can weaken a tree and spoil the fruits.
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