Black Spot Fungus on Mature Maple: Why Fall Cleanup Beats Spring Spraying

Diagnosis

Huge maple, black round spots on leaves, premature leaf drop, thinner canopy last summer. = Leaf spot fungus.

Primary Control: Sanitation

Rake and destroy ALL fallen leaves this fall. This drastically reduces overwintering spores. Most effective single action.

Supporting Cultural Practices

• Proper watering, fertilizing, pruning to maintain vigor.
• Stressed/newly transplanted trees more vulnerable to repeated defoliation.

Chemical Control (If Warranted)

• Fungicides for homeowner use (CT): thiophanate-methyl, chlorothalonil, mancozeb.
• First spray at budbreak; 2–3 more at 7–14 day intervals.
• Additional sprays in unusually wet springs.
• Once symptoms visible, too late for chemical control.