INDIANAPOLIS (AP) — A deadly tree fungus that’s been
detected for the first time in Indiana poses a real threat to the black
walnut trees that are the state’s most valuable tree, the state
entomologist said Friday.
Small insects called weevils that
emerged from two stressed trees at a black walnut plantation in southern
Indiana’s Brown County were found to be carrying the fungus that causes
thousand cankers disease. That plantation, in the Yellowwood State
Forest, has been quarantined by state officials.
The fungus
affects many types of walnut trees, but it is lethal within a few years
to black walnut trees, a valued tree that in addition to producing
richly flavored nuts is used for flooring, millwork and veneer for
furniture.
Although the two trees where the weevils were found
aren’t infected with the disease, State Entomologist Phil Marshall said
officials are keeping a close eye on that plantation and surrounding
black walnut trees for signs of infection.
He said the discovery
of the fungus on the weevil marks the first time that pathogen has been
detected on an insect other than the walnut twig beetle, which transmits
the disease.
"It’s not a serious situation, but it’s a matter of
very important concern. We’ve found it and we’ve found something unusual
and different from what is known about this disease complex right now,"
said Marshall, director of the state Department of Natural Resources’
division of entomology and plant pathology.
He said the DNR, the
U.S. Forest Service and Purdue University are conducting additional
studies at the plantation to better understand the disease and the
insects there. The fungus was discovered during a survey for insect
pests and fungi in Indiana and Missouri led by the U.S. Forest Service.
Indiana
now joins Maryland, North Carolina, Ohio, Pennsylvania, Tennessee and
Virginia among the eastern and central states where the disease has been
found. It has also been found in eight western states — Arizona,
California, Colorado, Idaho, New Mexico, Oregon, Utah and Washington.
The
DNR said Indiana has an estimated 31.5 million black walnut trees,
which are often grown in plantations, but are also common in the state’s
urban and rural forests.
About 17.7 million board feet of black
walnut valued at about $21.4 million is harvested annually in Indiana,
the agency said. Losing the state’s black walnut trees to the fungus
would deliver a $1.7 billion economic blow to the state, the DNR said.
Indiana
ranked fourth in the nation in the volume of cubic feet of black walnut
lumber it produced in 2004, said Elizabeth Jackson at Purdue
University’s Hardwood Tree Improvement & Regeneration Center.
Jackson,
who’s also executive director of the National Walnut Council, said the
wood from black walnut trees is highly prized for its grain pattern and
its rich color.
"It has a deep chocolate color that’s been valued
by consumers for many decades," she said. "The trees’ value to the wood
industry is phenomenal."
The trees also produce the protein-rich nuts that are an important food source for wildlife and are
savored by humans.
Indiana
residents can help prevent the spread of forest pests and disease such
as thousand cankers disease by avoiding moving firewood or other wood
products with bark, Jackson said.