Verticillium Wilt vs Dutch Elm Disease

Verticillium wilt affects more than 350 plant species — including elm — and produces wilting symptoms easily confused with Dutch Elm Disease. The fungal pathogens are different, the host range is different, and the management strategy is different.

What Verticillium wilt is

Verticillium wilt in trees is caused mostly by Verticillium dahliae and to a lesser extent Verticillium albo-atrum. These soil-borne fungi enter trees through wounded roots, colonize the xylem, and cause wilting symptoms much like DED. Unlike Ophiostoma novo-ulmi, Verticillium has an extraordinarily broad host range — maple, ash, catalpa, magnolia, smoke tree, and dozens of other species are affected.

Where they overlap

Both conditions:

Cause flagging — wilting confined to individual branches

Show vascular discoloration when bark is peeled back

Block xylem water transport, causing leaves to wilt

Can be either acute or chronic

How to tell them apart

Feature | Dutch Elm Disease | Verticillium wilt
Vascular streak color | Chocolate brown to black | Olive green to greenish brown
Host range | Elm only (Ulmus spp.) | 350+ species including maple, ash, catalpa
Vector | Elm bark beetles | None — soil-borne via root wounds
Spread between trees | Beetle or root graft | Through soil; rarely tree-to-tree directly
Common with site disturbance | No | Yes — strongly associated with construction or root injury
Best diagnostic feature | Brown streaks + beetle galleries | Olive-green wood + presence on non-elm hosts nearby

The streak color test

This is the single most useful field check. Peel back bark from a wilting branch about 1/2 inch in diameter and look at the wood:

Dark chocolate brown to black streaks: Dutch Elm Disease

Olive green to dull greenish-brown streaks: Verticillium wilt

The Verticillium discoloration looks distinctly green-tinted when viewed in good light, especially when contrasted against healthy wood.

When to suspect Verticillium

Verticillium becomes likely when:

The site has had recent excavation, root damage, or compaction

Other tree species nearby (especially maple) show similar symptoms

The elm is younger or has been recently transplanted

Symptoms appeared without any beetle activity in the area

The streaks look greenish rather than brown

Confirmation

State diagnostic labs can identify Verticillium through wood culture. PCR assays distinguish V. dahliae from V. albo-atrum and from Ophiostoma species.

Why misdiagnosis matters

Verticillium wilt does not respond to systemic fungicide injections. Worse, the fungus persists in the soil for years (forming microsclerotia that survive 10+ years), so removing the tree doesn't eliminate the pathogen. Replanting elm — or any of 350 other susceptible species — into a Verticillium-infected site usually leads to repeat infections.

Management focuses on:

Watering and nutrition support to help the tree compartmentalize infection

Pruning out severely affected branches

Avoiding replanting susceptible species in known infected sites

Choosing Verticillium-resistant species for replacement (oak, beech, sycamore, ginkgo)

Related pages

Differential Diagnosis Guide

What Are the Symptoms of Dutch Elm Disease?

How Does Dutch Elm Disease Spread in a Tree?

Dutch Elm Disease Symptom Checker

References

Goud, J. C., Termorshuizen, A. J., et al. (2004). "Long survival of Verticillium dahliae in soil." European Journal of Plant Pathology, 110(2), 195–204.

Sinclair, W. A., & Lyon, H. H. (2005). Diseases of Trees and Shrubs (2nd ed.). Cornell University Press.

Bhat, R. G., & Subbarao, K. V. (1999). "Host range specificity in Verticillium dahliae." Phytopathology, 89(12), 1218–1225.