Posted: Oct 16, 2013 7:06 PM by Ashley Arp, KOMU 8 Reporter
Updated: Oct 17, 2013 3:57 PM
CALLAWAY COUNTY - When Thousand Cankers Disease (TCD) reaches Missouri, it could cost the state more than 850 million dollars and more than 700 jobs, according to the Missouri Department of Conservation. But that could take at least two decades.
People have identified TCD in walnut trees in nine Western states and it recently spread to Tennessee, Pennsylvania, North Carolina, Virginia, and Ohio.
Harlan Palm grew up on a farm in Minnesota and purchased land in Callaway County about forty years ago. He said he bought land specifically to raise walnut trees because the United States Forest Service saw potential in the walnut industry.
He said the Forest Service believed the number of young walnut trees was not enough to meet expected global demand for valuable walnut logs. He said if all the trees on his land reach maturity and are not affected by TCD, the next generation in his family could expect about half a million dollars. "And I'm a small land owner," he said.
Palm said nearly all Missouri farms grow black walnut timber. Palm said it's inevitable for TCD to eventually come to Missouri, if it's not already here. That's unfortunate, said Palm, because Missouri has twice the number of black walnut trees than any other state, at 42 million. Missouri also leads the world in production of nutmeats from the Black Walnuts.
So the potential devastating effect of TCD on black walnut trees could be similar to the chaos that Mad Cow Disease or Hoof and Mouth Disease brought to the cattle industry.
Palm said walnut nut producers, nut harvesters, and loggers and millers are just some of those who will be affected because the beetle only feeds on black walnut trees. He said about every city and urban residential community in Missouri have black walnut trees growing along streets and backyards.
The trees will eventually die from TCD, similar to American Chestnut trees that died from blight a generation ago.
Simeon Wright, a Missouri Department of Conservation Forest Pathologist, said TCD is a disease Walnut Twig Beetles carry. He said the disease could kill a tree within seven years after its initial infection.
He said when the beetle bites into thin bark in small branch, it introduces spores that grow into the fungal organism that causes cankers. Cankers constrict nutrients to twigs and leaves. The leaflets turn brown and die when they are too deprived of sap flow or nutrients. The disease appears first in the upper crown of a tree.
The disease is hard to recognize because many Missouri trees are now suffering similar looking damage from drought. He said if several trees in one area show similar symptoms, people should contact a forester to sample the branches. Infected trees could have discolored wood, wilted, brown leaves, and tiny insect tunnels. Another indication of problems is when sprouts begin growing from the trunk.
The beetle, about one-sixteenth of an inch long, spreads a disease-causing fungus, Geosmithia. Fungal infections kill the branches and trunk tissue as beetles carry the fungus into new bark tissue.
Officials have not found a cure for the disease, but Wright said identifying and removing infected trees can help manage it. He advised people not to move walnut wood from states with infected trees because transporting materials around the country significantly speeds the spread of the disease.
He also suggested home and landowners be on the lookout for potentially infected trees. Tree removal services charge about 50 to 100 percent more after trees die because workers face more dangers climbing and cutting down dead trees, according to Palm.
He said he and other Forest Pathologists conduct surveys each year to see if it has reached Missouri, but it's hard to know for sure.
It could take about seven years to identify the disease because most trees don't show enough damage early on.
Palm expects St. Louis and Kansas City walnut trees to become infected first because densely populated areas have the most wood workers per square mile. He said they purchase walnut slabs with "natural edge" with fresh bark attached which could be infected if it was growing in a diseased area.
Palm spoke to the Missouri House Representatives of Agriculture Policies Committee in April. He said the committee had not heard of the disease. He told the committee more funding is needed to help prevent the disease from spreading, but committee members said it's tough to set aside money because of current budget constraints.
Wright said the disease does not affect the walnut itself and it's still safe to eat and safe to process.