Maple

Cool, wet weather in the spring is favorable for outbreaks of Maple anthracnose, caused by the fungus Gloeosporium apocryptum. Symptoms are brown to black lesions along the veins of newly opening leaves. The lesions expand and can cover large areas of the leaves. Buds, leaves, twigs, and branches up to an inch in diameter may be killed. The infected leaves fall from the tree, causing the tree to expend additional energy to re-foliate. 

Yearly infections can weaken maple trees, predisposing them to other diseases and insects. Good sanitation is critical in anthracnose control. All fallen leaves and twigs should be raked up and removed from the planting. If the tree is small enough to make pruning practical, infected twigs should be pruned out of the canopy. A product containing chlorothalonil or mancozeb or copper may be applied at bud swell in the spring, and twice afterward at 10–14-day intervals.

Take Aways:

• Clean up all fallen leaves now and in the fall.
• Apply fungicides at bud swell in the spring.
• Chlorothalonil, mancozeb, and copper are effective.

 

This work is supported by the Crop Protection and Pest Management Program [grant no. 2017-70006- 27279/project accession no. 1013890] from the USDA National Institute of Food and Agriculture.