Powdery mildew can be minimized by improving air circulation around the tree by pruning and thinning. Chemical control is usually not necessary. However, fungicide sprays can be applied as soon as symptoms are detected. Among the compounds registered for use in Connecticut are potassium bicarbonate, chlorothalonil, horticultural oil, thiophanate-methyl, and triadimefon. Consult the label for dosage rates and safety precautions.
Dogwoods are very susceptible to drought stress.
Symptoms include reduced leaf size, premature coloring of the leaves, and premature leaf drop. Severe, yearly defoliation will adversely affect the health of the tree. Dogwoods benefit from thorough watering during dry spells, and mulch will hold water for the tree. In addition, avoid planting other plants around the base of the tree that will compete for water. Insect Problems Cottony maple scale, Pulvinaria innumerabilis .