When needed, benomyl should give control. Sooty mold makes a black coating on leaves and stems. The fungus grows on the honeydew left by insects. Control sooty mold preventing the build up of insects populations. Verticillium wilt causes wilting and death of leaves on infected branches.
Severe infections kill trees.
Fertilize with high nitrogen fertilizers. During hot, dry weather leaves turn yellow and fall off. This conditions is due to the weather and is not a disease. The problem is most common on newly transplanted trees. Yellowing may be preceded small, angular, brown spots on the leaves.