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Marssonina Leaf Spot / Blight - Marssonina populi   HOSTS: Aspen, cottonwoods, and poplars. DESCRIPTION:
Dark
brown flecks with yellow margins scattered over leaf surfaces. Spots
later merge to form blotches. Mature spots have a white center. Often
confused with leaf scorch due to drought stress. LIFE
CYCLE: The
fungus overwinters in infected leaf debris on the ground. Infection
occurs when spores are released and carried by the wind and rain
to developing newly expanded, spring leaves. Secondary infection occurs
later in the summer when fruiting from infected leaves produce spores
that are blown to adjacent leaves. CONTROLS:Cultural: Rake up and destroy infected leaves. Keep irrigation water off leaves. Mineral: Spray a protectant lime sulfur (without oil) as buds begin to break. If weather is wet and warm, protect developing leaves with sulfur. |
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