Pine Wood Nematode
Ornamental Disease Information Note 6
R.K. Jones, Extension Plant Pathologist
J.R. Baker, Extension Entomologist
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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.
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.
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.
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.
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.
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.
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
For assistance with a specific problem, contact your local North Carolina Cooperative Extension Service personnel.
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.