Pine Wilt

Image of pine wilt on a Scotch Pine
Pine wilt on a Scotch Pine

Overview of pine wilt 

Pine wilt causes rapid wilting and dying of pine trees, particularly Scots (Scotch) pines. Pine wilt is particularly common in scotch pines but is capable of infecting other non-native pines as well.

Signs and symptoms of of pine wilt 

Symptoms of the disease include wilting, browning needles and eventually tree death.

Disease cycle of pine wilt 

The pine wood nematode is spread by pine sawyer beetles, which bore under the trees bark. Nematodes and their eggs that have attached to the beetles are then transported to other trees that the beetles colonize. 

Type of Sample Needed for Diagnosis and Confirmation

To test for Pine wilt the diagnostic lab requires a branch 2-3 branch samples that are at least 2 inches in diameter. 

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if you plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents.  If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us

Management of pine wilt 

Keeping other trees stress free and avoiding wounding can help to reduce this spread, as the beetles are attracted to such trees.
Inspecting your other nearby pines is critical to controlling this disease. Dead and dying trees can be sources of bark beetles. Removal and destruction of these trees is the only effective line of defense in controlling pine wilt. The optimal time to remove such trees is during the winter months when the beetle is inactive. Infected trees should then be promptly burned, chipped or buried to reduce the risk of bark beetles spreading to healthy trees.

Unfortunately, chemical treatments have proven ineffective and impractical for pine wood nematode. For this reason, prompt action needs to be taken with infected trees to reduce spread

Pine wilt causes rapid wilting and dying of pine trees, particularly Scots (Scotch) pines.

See this link for more information about pine wilt.

Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on September 1, 2016. The information contained within may not be the most current and accurate depending on when it is accessed.