Which tree species are affected by Heterobasidion annosum root disease?

Which tree species are affected by Heterobasidion annosum root disease?

• A. Hemlock
• B. Firs
• C. Ponderosa pine
• D. All of the above

Answer: (D)

Heterobasidion annosum root disease has a broad host range among conifers, so it can infect several commonly planted species in Oregon. Western hemlock, true firs, and ponderosa pine all serve as hosts, making the disease a concern across these different tree groups. The fungus resides in infected roots or stumps and can spread to neighboring trees through root connections or via spores that come from infected stumps and slash. Because these three groups are susceptible, all of the above best explains why the disease can affect them. In practice, managing this disease focuses on preventing new infections by reducing root contact between infected and healthy trees and by treating or removing infected stumps and slash.

Heterobasidion annosum root disease has a broad host range among conifers, so it can infect several commonly planted species in Oregon. Western hemlock, true firs, and ponderosa pine all serve as hosts, making the disease a concern across these different tree groups. The fungus resides in infected roots or stumps and can spread to neighboring trees through root connections or via spores that come from infected stumps and slash. Because these three groups are susceptible, all of the above best explains why the disease can affect them. In practice, managing this disease focuses on preventing new infections by reducing root contact between infected and healthy trees and by treating or removing infected stumps and slash.