Pine wilt is a fatal disease of pine (Pinus sp.) caused by the nematode Bursaphelenchus xylophilus.

As a native organism to North America it is a primary pathogen of non-native, 2-3 needle pines. This includes Scots pine (P. sylvestris), Austrian pine (P. nigra) and many others. The disease is vectored by pine sawyer beetles (Monochamus sp.) as they feed on the bark and foliage of susceptible pine trees.

This disease is a major concern for arborists as well as Christmas tree growers in the Midwest states, including IA, IL, MO, KS, NE, KY.

Field diagnosis is difficult due to the rapid death of infected trees. Early symptoms may be reduced vigor, fading green color, and yellowing throughout the entire tree.

Symptoms often begin from the top of the tree progressing down. Trees begin to die in midsummer and can die within weeks of the initial infection, leaving brown, dead needles still attached to the branches. It can be helpful to scout for infection centers formed by previous infections.

Susceptible Hosts

All 2-3 needle Pinus sp. are susceptible, non-native pines are most vulnerable. Susceptible tree species (listed most to least susceptible) include:

Scots, Austrian/Black, Aleppo, Japanese black, Japanese red, Mugo, Pitch, Swiss stone, Shortleaf, Virginia, Lodgepole, Jack, Red, Loblolly, and Monterey

Pathogen Bursaphelenchus xylophilus

Symptoms

• Rapid death

• Yellow needles turning brown in a few weeks

• Random distribution in the landscape ( common to insect vectors)

Signs

• None visible

Distinguish from Look-alikes

• Rapid death – herbicides or mechanical injuries are other agents that could kill as quickly

• Salt damage will cause needles to die from the tip back, but the pinewood nematode kills whole needles quickly

• Blight diseases will show spots (signs) on older needles and cause needle loss and decline over several years. The pinewood nematode usually kills in one season.

Pinetect is a tree injection product that is used to preventively treat pines that are susceptible to pine wilt disease. Optimal results occur when Pinetect is applied in the spring of the year prior to adult flight of the pine sawyer beetle, which vectors the nematode.

Any refillable injection device that is capable of injecting pine can be used to apply the product. Rainbow distributes the Pine Infuser system that can be used to apply Pinetect. Pinetect is the only labeled product that follows the application procedures and dosage rates developed by a leading authority, Kansas State University.

USDA Forest Service

Kansas State University

James, R., et. al. 2006. Prevention of pine wilt of Scots pine with systemic abamectin injections. Vol. 32, No. 5. September. James, R. 2005. Prevention of pine wilt of Scots pine with systemic abamectin injections. M.S. Thesis, Kansas State University, Manhattan, KS. American Phytopathological Society

Forestry Images

University of Illinois