Posted 15 April 2008. PMN Crop News.
K-State Plant Pathologist: Remove, Chip Dead Pines NOW
Kansas State University. www.ag.ksu.edu
Manhattan, Kansas (April 3, 2008)-A pine thatīs died since late last summer in the Midwest may very well be harboring the pine-wilt carriers that will spread the fatal disease further this spring.
"The most important step in saving the pines we have left is sanitation. Infected trees need to be cut to the ground - no stump - and chipped, burned or buried ASAP. We used to use May 1 as the deadline for chipping or burning but now consider April 1 safer," said Megan Kennelly, plant pathologist with Kansas State University.
Help in testing for the disease in Kansas is available through county and district K-State Research and Extension offices, the Kansas Forest Service, Kansas Department of Agriculture, and K-Stateīs Plant Disease Diagnostic Lab.
Pine wilt symptoms generally appear between August and December, Kennelly said. Affected trees can wilt and die within a few weeks to several months. The needles turn gray, then yellow and finally brown. This may occur branch by branch or all at one. The needles stay attached for up to a year.
"Another key symptom is reduced resin," she said. "Healthy pines `bleedī sticky resin from wounds. Trees with pine wilt often have little to no resin, and their branches become dry or brittle."
The early spring deadline for removing newly killed pines is vital, Kennelly said. A microscopic worm called the pinewood nematode causes pine wilt. It and the pine sawyer beetle both overwinter in infected pines. The beetle hatches around May 1 and flies to look for another pine on which to feed. Nematodes by the thousands hitch a ride.
"Youīve got to get rid of both of them before this yearīs beetles emerge," she warned. "You canīt even save the wood for your fireplace."
Scientists first identified pine wilt in the United States in 1979. So far, the heaviest losses have been in Iowa, Illinois, eastern Kansas, Kentucky, Missouri and southeastern Nebraska.
"Scots pines over 10 years old have accounted for about 90 percent of the losses," Kennelly said. "But, the disease has occasionally appeared in Austrian, jack, mugo, red, black and white pines."More information is available online at www.oznet.ksu.edu.