Dutch Elm Disease: Stump Removal and Root Graft Prevention

If your elm was diagnosed with Dutch elm disease (DED) and removed, stump removal alone does not prevent spread. The fungus (Ophiostoma novo-ulmi) spreads via root grafts between adjacent elms.

Root Graft Transmission

• Elms within 50 feet often share root grafts.
• If the diseased tree died before removal, the fungus likely reached the roots and can move to neighbors.
• Immediate removal upon diagnosis reduces but doesn't eliminate this risk.

Preventing Spread to Nearby Elms

Sever root grafts between the diseased tree and healthy neighbors:

1. Mechanical trenching: 24–30 inch deep trench (36–48 inches ideal) between trees. Use a trencher or vibrating plow. Refill immediately.
2. Chemical barrier: Sodium methyldithiocarbamate (Vapam/VPM) fumigant applied by licensed applicator only.

Critical Warnings

• Call 811 before digging—trenching near utilities is dangerous.
• Trenching is best done before or immediately after tree removal.
• If the tree was dead for months before removal, grafts may already have transmitted the fungus.

Stump Handling

Grind or remove the stump to eliminate beetle breeding sites (elm bark beetles vector DED), but root graft disruption is the key to protecting neighbors.

Consult a certified arborist or city forester for site-specific guidance.