A Fatal Disease of Non-Native Pine Trees

Pine wilt is a fatal disease of pine caused by the pine wilt nematode (Bursaphelenchus xylophilus). Nematodes are microscopic, worm-like organisms that grow inside the tree’s water conducting tissue causing rapid death. As a native to North America, pine wilt nematode is primarily a pathogen of non-native, 2-3 needle pines. Pine wilt disease does not affect our native pine species, but can be devastating to popular landscape introductions such as Scots pine, Austrian pine, and others.

High-value Scotch and Austrian pine tree require treatment for Prevention
Once a tree is infected with the pine wilt nematode, the tree will die. There is no therapeutic control to treat an infected and dying tree. Only injections of Abamectin (nematicide) can prevent infection. This should be done to high value trees near other infected pines. Injections must be made in the early spring before July 1.

How is it spread?
Pine wilt disease is vectored from infected trees to healthy trees by native pine sawyer beetles (Monochamus spp.) as they feed on the bark and foliage of susceptible pines. The beetles rarely cause damage or kill the trees, they only vector the nematode. Additionally, their control is very difficult due to their life cycle and feeding patterns. Therefore, focusing on their control is not effective.

Risk to Community
Pine wilt spreads very quickly. It can kill hundreds of trees in dense areas within a year or two. Often times multiple trees in a grove or shelter-belt will die in one month and are at the highest risk of infection.

Treatment and Prevention
• The only treatment is a preventative injection required every other year.
• A direct Micro-injection of Aracinate (Abamectin) must be done professionally.
• Any size and age of non-native pines are susceptible.
• Removal and disposal of dead trees immediately can slow spread of disease.
• Do not store or keep infested firewood or branches.

• Keep trees as healthy as possible.
– water well in fall
– reduce competition from turf
– Consider Forest Floor Service with Activated Organic Matter program in addition to injection.

Pine wilt treatment
Cycle of pine wilt