Pine Wood Nematode
Ornamental Disease Information Note 6
R.K. Jones, Extension Plant Pathologist
J.R. Baker, Extension Entomologist

The pine wood nematode or pine wilt nematode (Bursaphelenchus xylophilis) has been causing widespread losses to pines in Japan since the early 1900's. This nematode was first identified in the United States in Missouri in 1979. It has now been found in numerous mid-western and eastern states including North Carolina. A survey has shown this nematode to be widely distributed over much, if not all, of North Carolina.

Older trees appear to be more susceptible than young trees. The nematode generally does not attack pines less than 5 or 6 years old. Scots pine Christmas trees, 7-10 years old are being severely damaged in the mid-western states by this nematode.

Recent surveys have found the nematode in Pinus serotina (pond pine), two species of larch, one species of spruce (Picea glauca) and two species of cedar (Cedrus deodara and C. atlantica). More research must be done to determine how damaging the nematode will be to these plants. The most serious damage due to the pine wood nematode North Carolina at this time is to Japanese black pine planted along the Atlantic coast.

Susceptibility of Trees to the Pine Wood Nematode

The first symptom of the pine wood nematode disease is a general wilt of the needles. As the disease progresses, a yellowing of needles appears, followed by browning and death of the entire tree. Susceptible pine species may die within 30-90 days after the first visible symptoms (longer for more resistant species). The disease can also kill individual branches in a tree. These symptoms may be easily confused with those of several bark beetles, Fomes annosus root rot, etc.

Spread

Longhorned beetles in the genus Monochamus have been shown to transmit pine wood nematodes. These beetles are known as sawyers. The southern pine sawyer, Monochamus titillator, is one of our most common sawyer. It has been observed that sawyers generally infest trees which have been recently killed or trees that are under stress. These beetles are called sawyers because the larvae make a loud chewing noise as they feed. The larvae bore into the wood and degrade the value of the wood for lumber. The larvae are long, white grubs with no noticeable legs. Adult sawyers emerge mostly in April and May, but they are active throughout the summer and even in warm spells during winter.

Diagnosis

To confirm the involvement of pine wood nematode as the cause of dying pines, it is necessary to recover them from diseased wood. This can be done in the laboratory from symptomatic branches or increment borings from the trunk. Do not allow the branches or borings to dry out or get too hot. Submit them as quickly as possible for examination. Check with your local county Extension agent for more information.

Control

The control of pine wood nematodes involves quickly removing diseased trees. The wood should be burned, buried, or debarked. Grow pine species well adapted to your area. In the long term, resistant pines should be selected. Christmas trees and nursery stock which cannot be irrigated during prolonged droughts can be protected from borers such as sawyers by spraying them with lindane.

Since this pest is thought to have been present in the United States for a very long time, and the insects that spread it do not aggressively attack healthy trees, one should not become overly alarmed about pine wood nematode on healthy pines.

Other Resources

For assistance with a specific problem, contact your local North Carolina Cooperative Extension Service personnel.

Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application by growers may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data.

Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact your county North Carolina Cooperative Extension Service agent.

Published by North Carolina Cooperative Extension Service Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Last update to information: March 1996
Last checked by author: May 1996
Web page last updated Dec. 2000 by A.V. Lemay.