Pine Wilt Disease Diagnostic Guide

Bursaphelenchus xylophilus

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.

Trees at Risk

Non-native pine species including Scots, Austrian and Mugo are most susceptible, although other pine species can be attacked on occasion.

Mugo Pine

Scots Pine

Austrian Pine

Symptoms of Damage

As a native to North America the pine wilt nematode is primarily a pathogen of non-native, 2-3 needle pines. This lethal disease is caused by a nematode that is vectored from tree to tree by pine sawyer beetles.

  • 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.

Pine Wilt SignsPine Wilt Signs

Pine Wilt SignsPine Wilt Nematode


The disease is transferred from infected trees to healthy trees by pine sawyer beetles (Monochamus spp.) as they feed on the bark and foliage of susceptible pines. Incidence and severity of pine wilt disease symptoms may increase during times of drought and high temperatures during summer months.

Treatment Strategy

Aracinate™ is a tree injection product that is used to preventively treat pines that are susceptible to pine wilt nematode. Optimal results occur when Aracinate™ is applied in the spring of the year prior to adult flight of the pine sawyer beetle, which vectors the nematode. Aracinate™ is the only labeled product that follows the application procedures and dosage rates developed by Kansas State University. Applications should be made in early to mid-Spring (March through May).

PLEASE NOTE: The product Pinetect™, previously recommended by Rainbow has been discontinued and is no longer available. Aracinate™, which is an identical formulation to Pinetect™, is its replacement. Aracinate™ is labeled for pine wilt nematode and is also commonly used for many different spider mites and eriophyid mites.

Other Treatment Practices:

  • Preventive trunk and limb sprays with Tengard® to control the pine sawyer beetle and other pine bark beetles.
  • Preventive applications of Xytect™ for control of sawfly and other insects.
  • Promptly remove and burn infected trees.
  • DO NOT transport woodchips from infected trees.
  • Cover firewood from infected trees for at least a year to prevent emergence of beetles.
  • Plant resistant native pines and 5-needle pines.
  • Tree Injection using Aracinate

    Dosage: 5 mL/in DBH for the first 6 in DBH and 15 mlL for each additional inch DBH
    Timing: Treat only on a preventive basis. Optimal results are obtained when injections are made in the spring of the year.
    Re-Treatment: Every two years
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Treatment Expectations

Aracinate™ will provide two years of protection from pine wilt nematode.

A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy Use of the images does not imply endorsement of treatments by

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