Why a Mature Willow Drops Leaves Daily: Moisture Fluctuation and Root Damage

A large willow tree began shedding yellow leaves daily, some with brown dots, while a nearby willow showed dead branch tips. No aphids or bugs were visible. The expert advised checking for bark damage at the base and root injury from digging or mowers. If those are clear, the likely cause is soil moisture fluctuation.

Willows Need Consistent Moisture

Willows thrive in moist, even wet, soils. If the soil dries out—even temporarily—the tree responds by yellowing and dropping leaves. This is a survival mechanism. The key is to maintain evenly moist soil, especially during hot, dry periods. Deep watering with a soaker hose or slow trickle for several hours once or twice a week is better than frequent light watering.

Checklist for Diagnosis

1. Inspect trunk base for mechanical damage (mowers, string trimmers).
2. Check for recent root disturbance (construction, trenching).
3. Assess soil moisture at 12–18 inches depth.
4. Water deeply if soil is dry; mulch to retain moisture.

If the tree is otherwise healthy and the stress is corrected, it should re-leaf. The neighboring willow with dead tips may have a separate issue, such as borers or canker, warranting individual inspection.