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Posted 10 April 2009. PMN Crop News.

Several Steps Can Help Keep Pine Wilt Contained

Kansas State University.

Manhattan, Kansas (April 2, 2009)--Even if their owners remove and destroy every pine wilt-killed tree before the disease can spread (typically, before May 1), residents in the central United States will have to remain on guard, to protect the Scots pines that remain.


The deadly disease is both quick and efficient. It already has cut a swath through states where the Scots pine has long been a popular, non-native or “exotic” evergreen. Thus far, the heaviest losses have been in Iowa, Illinois, eastern Kansas, Kentucky, Missouri and southeastern Nebraska.

“Fortunately, careful scouting and good sanitation can eliminate most sporadic outbreaks before they get out of control,” said Megan Kennelly, plant pathologist with Kansas State University Research and Extension. “Plus, we now have two preventive injections. Either has to be applied by a professional every two years, but can provide 80 to 90 percent protection for trees that seem worth that kind of investment.”

To date, nothing is available to cure pine wilt.

Kennelly listed the following, however, as ways to prevent new Kansas infestations:

• Don't import pine firewood from contaminated areas. The pinewood nematodes that cause the fatal wilt can remain alive in cut wood.

• Work to prevent any tree stress caused by insects, other diseases or drought. The beetles that carry the pinewood nematodes from tree to tree appear to prefer stressed trees.

• Be wary of pine nursery stock from infested areas. Monitor all newly-planted pines for wilt symptoms.

• Keep a close eye on Scots pines that are more than 10 years old. So far, they have accounted for about 90 percent of the losses. (The other victims have included Austrian, jack, mugo, red and black pines.)

• If you suspect a tree may have pine wilt, contact your local K-State Research and Extension office, the Kansas Forest Service, or K-State’s Plant Disease Diagnostic Lab for assistance.

• If a tree tests positive for the disease, cut it down -- preferable by April 1, but no later than May 1. Don’t even leave a stump. Immediately burn, chip or bury the wood, to destroy the nematodes and beetles involved in pine wilt’s rather complicated disease cycle.

For more information about the preventive injections – which can be costly -- pine owners can contact their county or district K-State Research and Extension office, Kennelly said.

Kathleen Ward