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Worse in wet years. Leaves become blotched with brown; may yellow and fall. New shoots may be blighted or distorted. Branches may develop cankers and die. If infection is severe for several years, the tree may begin to decline.
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(Refer to the PDC Fact Sheet "Leaf Spot Diseases of Shade Trees and Ornamentals" for more information.) Clean fallen leaves and prune dead branches. Resistant varieties are available. To be effective, fungicides must be applied before symptoms are seen. Sprays should begin at bud break and continue on a 10 to 14 day interval through the period of spring rains. Use azoxystrobin, chlorothalonil, chlorothalonil + fenarimol, copper products, mancozeb, maneb, myclobutanil, propiconazole, sulfur, thiophanate-methyl or triadimefon. Injection with benzimidazole (Arbotech) in fall has controlled infection for two years. |
