oak wilt
(Bretziella fagacearum)
This species is Introduced in the United States
Major Hosts:
The species in the red oak family are highly susceptible and may die within a few weeks of infection. The white oak group is more tolerant and those trees may live several years after infection.
Key Features:
Disease: Gray fungal mats and pads (fruiting bodies) develop under the bark of red oaks and are rarely seen. These pads create bark splits through which sap feeding (picnic) beetles are attracted to the fungal mats and pick up the spores. Oak bark beetles are also attracted to the stressed trees and therefore are capable of spreading the fungus to other trees. A major component in the spread of the disease is represented by root grafts.
Damage: In red oaks the leaves turn brown, typically starting at the top of the canopy. Cracks form in bark covering fungal pads, which are rarely seen. Staining of vascular tissue may occur but is not a reliable symptom. Trees under stress from adverse environmental conditions, disease, defoliation, advanced age or poor tree care practices are most susceptible. Positive identification requires lab culturing.
Control/Management:
First, get positive confirmation of the disease. If confirmed, management typically includes soil trenching to sever root grafts and protect adjoining oaks, as well as removal of infected trees. For high value trees, trunk injections with fungicides can be used as an effective preventative measure.
The species in the red oak family are highly susceptible and may die within a few weeks of infection. The white oak group is more tolerant and those trees may live several years after infection.
Key Features:
Disease: Gray fungal mats and pads (fruiting bodies) develop under the bark of red oaks and are rarely seen. These pads create bark splits through which sap feeding (picnic) beetles are attracted to the fungal mats and pick up the spores. Oak bark beetles are also attracted to the stressed trees and therefore are capable of spreading the fungus to other trees. A major component in the spread of the disease is represented by root grafts.
Damage: In red oaks the leaves turn brown, typically starting at the top of the canopy. Cracks form in bark covering fungal pads, which are rarely seen. Staining of vascular tissue may occur but is not a reliable symptom. Trees under stress from adverse environmental conditions, disease, defoliation, advanced age or poor tree care practices are most susceptible. Positive identification requires lab culturing.
Control/Management:
First, get positive confirmation of the disease. If confirmed, management typically includes soil trenching to sever root grafts and protect adjoining oaks, as well as removal of infected trees. For high value trees, trunk injections with fungicides can be used as an effective preventative measure.
Selected Images
Invasive Listing Sources
Taxonomic Rank
| Domain: Eukarya |
| Kingdom: Fungi |
| Phylum: Ascomycota |
| Subphylum: Pezizomycotina |
| Class: Sordariomycetes |
| Subclass: Hypocreomycetidae |
| Order: Microascales |
| Family: Ceratocystidaceae |
| Genus: Bretziella |
| Bretziella fagacearum |