Leaf disease on apple tree
My Jonathan apple tree has developed leaf disease (perhaps leaf blight) and is dropping many leaves. I noticed the leaf disease 2 weeks ago and sprayed with BONIDE Fruit Tree & Plant Guard (Lambda-cyhalothrin 0,5%, Pyraclostrobin 3.06%, Boscalid 5.6%) but more and more leaves continue to drop. Please let me know what is causing this problem and what I should do to save the tree. THANKS!!!
We viewed your photo. This looks like some apple scab as well as leaf burn. It is possible that some of the leaf burn may be due to the spray. You may see some defoliation. Rake all leaves and dispose. https://extension.umd.edu/hgic/plants/diseases-apples-and-pears
In general apples are susceptible to insect and disease issues and eventually will require a spray schedule for control. The best recommendation is to select resistant varieties and provide good care, training, and pruning. Take a look at the spray schedule from Va Tech