While the cool conditions slow down pest development, the wet conditions foster a number of foliage diseases. Continue applications of fungicides for control of this fungal disease. Treatment is rarely necessary and may actually be too late already this season as trees have fully leafed out in most areas. Typical symptoms include small brown dots on infected foliage and leaf drop , often followed by larger irregular dark blotches on leaves . W ASH RUSTis beginning to show up on ash in some areas of the state.
Symptoms are yellow to yellow orange spots on the upper surface of the leaves.
Within several weeks, these affected leaves will become distorted and develop a sharp bend at the petiole. Ash rust can be treated with Bordeaux mix applied when the leaves are developing. Again, once the symptoms are observed, it is too late for effective control. Prune out new swellings on the branches to reduce the spread of this disease. Affected plants are sometimes completely covered with orange, gelatinous round masses on the tips of branches.