Botanic Garden >> Gardening > >> Question and Answer >> Plant Diseases

Black Canker on Weeping Willow: Pruning Over Costly Treatments

Black canker on weeping willows causes branch tips to blacken and die. While tree companies may propose expensive spray programs, chemical treatments are largely ineffective against canker diseases once established.

Effective Management

Prune out all infected branches 6-12 inches below visible cankers during dry weather. Disinfect tools between cuts.
Remove and destroy all pruned material; do not compost.
Improve tree vigor: water deeply during drought, fertilize based on soil test, avoid root disturbance.
Monitor for recurrence; willows often compartmentalize cankers if kept healthy.

Get a confirmed diagnosis from your Extension office before investing in treatments. Many "canker" diagnoses are actually stress-related dieback.

Plant Diseases: Weeping Willow with Bark Loss and Deformity: Internal Decay, Removal Advised; Weeping Willow Red Spiky Patches: Adventitious (Air) Roots, Not Borers—Harmless, Dry Up; Red Spikes on Willow Trunk? It’s Borer Frass—Here’s What to Do; Grapefruit Tree Greasy Spot Fungus: Organic Treatment Option; Woodpecker Damage and Borer Infestation in Willow Trees; Frothy Flux on Weeping Willow: Manage, Don't Panic; Lion's Mane Fungus on Willow: Decay Fungus in Hollow Trunk; Weeping Willow Oozing Smelly Sap — Bacterial Wetwood, Not Curable; Scale on Weeping Willow: Baking Soda Won’t Work—Use Proper Insecticide; Red Spiky Growth on Weeping Willow: Lichen or Decay Fungus?

Garden Articles

Weeping Cherry (Not Willow) Waterlogging: Prune Dead, No Fungicide

Weeping Pussy Willow Half-Crown Dieback: Soil Test Needed

Weeping Willow Unknown Insects: Photo Request for Identification

Weeping Willow Borer Damage: Treatment and Prevention

Greenish-White Scale on Oak: Lichens, Not a Disease

Yellow Jackets in Weeping Willow: After Honeydew, Not Tree

Weeping Willow Decline: Roundup Drift vs. Borer Damage

Plants

Weeping Willow with Wingless Yellowjacket-Like Insects: Likely Lady Beetles

Weeping Willow Decline: Black Trunk, Holes, and Yellowing Leaves

Weeping Cherry Orange Spots: Possible Virus, Need Photos

Basal Fungal Cankers on Weeping Willow from Poor Drainage

Weeping Willow Borer Infestation: Identification and Treatment

Weeping Willow Near House & Drain: Root Concerns & Growth Regulators

Bacterial Gummosis in Weeping Cherry