 |
Symptoms: Wilting and browning of leaves begins on branches in the upper canopy and progresses downward. Photo by Department of Plant Pathology |
Oak wilt is a fungal vascular wilt disease which is transmitted to healthy trees through below-ground root to root contact or Nitidulid (picnic) beetle feeding. Northern pin and red oaks are less resistant to oak wilt than bur and white oak. |
Symptoms: Wilting and browning of leaves begins on branches in the upper canopy and progresses downward. Photo by Department of Plant Pathology |
 |
Symptoms: Wilting starts at the leaf margin and progresses inward. Leaves often turn yellow before browning. Photo by Plant Disease Clinic |
 |
Symptoms: The fungus produces spores on fungal mats beneath the outer bark. Spores carried by picnic beetles start new infections as the beetle interacts with fresh wounds on uninfected trees. Unlike red oaks, white oaks rarely (if ever) produce spore mats. Photo by Department of Plant Pathology |
 |
Symptoms: Brown staining or streaking of the inner sapwood can occur in the branches or trunk. Photo by Robert Blanchette |
| Causal organism: | Ceratocystis fagacearum |
| Over wintering: | In plant material |
| Months of infection: | April-October (most susceptible April-June) |
| Method of dispersal: | Insect vectors and plant to plant contact (through root grafts) |
| Infection point: | Branches and roots |
| Control: | Avoid wounding trees in April, May, and June. Properly water, fertilize, and mulch trees. Contact city or county forester if oak wilt is suspected. Root grafts need to be severed with vibratory plows to prevent further infections. Properly dispose of infected red oaks by March before spore mats form in the spring. |
| Labelled fungicides (First application) |
Alamo *Alamo may be used as a curative treatment for WHITE OAKS only in the early stages of decline (June 15 - mid October) - preventative treatment |
| Comments: | HIGH RISK PERIOD: April - June No pruning, cover wounds within minutes with water-based paint or shellac. LOW RISK PERIOD: July-October Infections can occur on rare occasions. Covering wounds is optional. SAFE PERIOD: November-March Trees may be safely pruned. |
| For additional info | For additional info | Back to Oak Diseases |