Spotted, Yellowing Leaves on Crabapple
Each year my crabapple seems to lose its leaves earlier and earlier. They develop spots, turn yellow and soon drop. What can I do?
Apple scab is a fungal disease that causes the problem you describe. It is a common problem on crabapples. Fortunately many of the newer varieties have been developed to be resistant to this and the deadly fireblight disease. Applying a fungicide when the flower buds are starting to show color and every 10 to 14 days for a total of 4 or 5 applications usually provides good control for susceptible varieties. A long term solution that is less work and better for the environment is to replace this tree with one of the disease resistant crabapples.