Dutch Elm Disease is a fungal vascular wilt which is transmitted to healthy trees through root to root contact or by bark beetle feeding in the canopy of the tree.  |
Symptoms: Dieback of individual branches in the upper canopy of the tree. Photo by Robert Blanchette |
 |
Symptoms: Early wilting and browning of leaves. Wilting leaves usually change color from green to yellow and then brown. Photo by Chad J. Behrendt |
 |
Symptoms: Infected branches appear discolored with brown streaking in the sapwood. The brown staining is an accumulation of host defense compounds. Photo by Chad J. Behrendt |
 |
Symptoms: Elm bark beetle galleries. These beetles are responsible for the overland transmission of the disease. Beetles colonize freshly killed trees for reproduction and winter survival. Photo by Department of Plant Pathology |
 |
Symptoms: Chemical injection of elm trees can occur as a preventative or curative treatment. Photo by Department of Plant Pathology |
| Causal organism: | Ophiostoma novo-ulmi |
| Over wintering: | In plant material and debris (cut logs) |
| Months of infection: | April-September |
| Method of dispersal: | Insect vectors and plant to plant contact (through root grafts) |
| Infection point: | Branches and roots |
| Control: | Plant resistant cultivars when possible (see DED Resistant Elm Cultivars). Inspect trees frequently. If Dutch Elm Disease is suspected, contact your city forester or county extension educator for diagnosis, treatment, removal and/or disposal of the tree. Chemical injection can help prevent infection and cure newly infected trees. Properly water, fertilize, and mulch trees to maintain vigor. Avoid pruning trees from April to October. |
| Labeled fungicides (First application) |
Arbortect 20-S (Preventative: late May-June) (Therapeutic: late June - mid October, as soon as detected) Alamo (experimental) (June - mid October, as soon as detected) |
| Comments: | Elm bark beetles feed in branch crotches, where they chew directly through the bark and introduce the fungus into the tree. Native elm bark beetles can also introduce the fungus into the tree. |
| For additional info | Back to Elm Diseases |