Why River Birch Trees Drop Leaves All Summer and How to Fix It

Diagnosing Excessive Summer Leaf Drop in River Birch

A homeowner in Potomac, Maryland, reports that their 23-year-old river birch trees shed leaves continuously from early June through fall, requiring daily cleanup. This is not normal behavior for river birch, which typically drops some leaves in summer but not constantly.

Common Causes

• Water stress – Both drought and waterlogged soil can trigger leaf abscission.
• Leaf blight diseases – Fungal pathogens like Septoria cause premature leaf drop.
• Aphid infestations – Heavy feeding leads to honeydew, sooty mold, and leaf loss.

Action Plan

1. Check soil moisture: The root zone should be moist but not soggy. Adjust irrigation accordingly.
2. Inspect leaves for spots, yellowing, or sticky residue (honeydew).
3. Contact the Maryland DNR Forest Service for a free on-site evaluation by a forester or pest management specialist. They can identify the specific issue and recommend treatment.

Resource: Maryland Forest Service Contact List

Long-Term Management

Once the cause is identified, proper watering, sanitation (raking fallen leaves), and targeted treatments can restore normal leaf retention and reduce cleanup burden.