Maple Anthracnose: Black Leaves and Summer Defoliation

Your large maple's blackening, wilting leaves and August leaf drop over several years point to maple anthracnose (Aureobasidium apocryptum / Kabatiella apocrypta), a fungal disease favored by cool, wet springs.

Symptoms

• Brown/black irregular blotches along veins.
• Leaves curl, blacken, drop prematurely.
• May cause twig dieback in severe years.
• Tree often refushes in summer (second flush).

Management

1. Sanitation (critical): Rake and destroy ALL fallen leaves—primary inoculum source.
2. Fungicide (preventive only): Apply at bud break, repeat 2–3 times at 10–14 day intervals.
   • Chlorothalonil (Daconil)
   • Copper fungicide
   • Mancozeb
3. Cultural: Improve air flow, avoid overhead water.

Outlook

Anthracnose rarely kills mature maples. It's a chronic aesthetic issue. The small backyard maple with wilted leaves may have the same disease or Verticillium wilt—get a diagnosis if it declines further.

Focus on spring sanitation and protection; accept some summer leaf drop as normal for susceptible maples in wet springs.