Disease May Affect MO’s Black Walnut Trees

Missouri is known for its black walnut trees—they’re a precious commodity, and Missouri has more black walnuts than any other state. Now, Missouri is starting to mount a defense against Thousand Cankers Disease.

By Lauren Hasler (Columbia, MO)

Thousand Cankers Disease is a potentially fatal fungus carried by a beetle that before this summer was only found in western states. But then it was discovered in Tennessee, which borders Missouri. Now Missouri landowners have to prepare for what many feel could be the worst.

It’s the calm before the storm in Missouri forests. Harlan Palm owns a black walnut tree farm in Callaway County, which is accessed by a locked gate.

Palm has managed this land for 37 years. These trees are his passion. He grew up on a farm and in 1970 read an article about the theft of walnut trees.

“I thought if they’re that valuable that someone wants to steal them, that’s something that I can raise. And when you’re born and raised on a farm you kinda have this feeling that you want to raise something in addition to kids.”

And for Palm, Thousand Cankers, a disease afflicting black walnut trees across several states, is terrifying. He guesses he has upwards of 1,000 walnut trees on his land.

“To put that in monetary value, when these trees are mature, this whole walnut property will be worth over half a million dollars. That’s why this threat of Thousand Cankers advancing into our native range, it’s a landowners worst nightmare.”

Thousand Cankers Disease is a newly identified fungus carried by a walnut twig beetle. Those beetles are about the size of half a grain of rice. Once the beetles find their way to a black walnut tree, the tree will die within 8 to 10 years.

Thousand Cankers is found only on walnut species. But before we go any further, let’s break down the name. Hank Stelzer is a professor of forestry at MU and works with MU Extension.

“This bug is ADHD. It literally just kind of drills and then it backs out, and then it drills again, and then it goes, nope, I’ll drill over here. And every time it does that it deposits the spores of the fungus. You get thousands of cankers underneath the bark.”

This bug was not expected to find its way to Missouri anytime soon. It originated out west and hadn’t been found any further east than Colorado. Then suddenly this summer it jumped to Tennessee. Stelzer thought Missouri had at least five years before it would be an issue. An estimated $850 million issue. That’s what the Missouri Department of Conservation says it could cost the state over a 20-year period.

“Here in Missouri though, the Thousand Cankers, that’s a potentially disastrous event. We have about 55 million walnut trees. If it gets out into the natural forest, it could be significant.”

Missouri has the most black walnut trees in the country. It was also the first of a handful of states to issue a quarantine of black walnut. It’s now illegal to bring any walnut products into Missouri from states where Thousand Cankers has been found. Currently, Missouri is focusing on educating as many people as possible while beginning to monitor forests for the disease.

But scientists now fear that the measures still may not stop Thousand Cankers Disease from creeping in. Harlan Palm attributes the beetle’s jump across the plains to an increasingly mobile population.

“As man is moving firewood and those kind of things more, we’re going to have more of these problems.”

The movement of firewood is not the only concern. Black walnut is a highly prized lumber tree. What’s called hobby wood is used to make picture frames, bowls, and furniture. It’s common to see these items sold on eBay and Craigslist and shipped across the country. If a twig beetle is hiding in the hobby wood or firewood, it would go along for the ride.

Tom McConnell has a 30-acre farm and does restorative forestry with mules in Ray County. He says that too many people treat forests as a row crop, harvesting the trees without properly managing the forests. This may contribute to Thousand Cankers.

“And in their efforts of trying to protect the row crop, they end up creating bigger and bigger problems. And I think some of this may have been a result of hat. I think it really comes down to individual stewardship. Land owners need to manage their forests properly.”

McConnell says they can do that by seeing more value in the forests than just the economic value of timber.

Around the state, Harlan Palm helps other forest owners manage about 3,000 trees each winter. That includes trimming off small, low branches in order to grow a tall, straight trunk.

That’s what you want when growing walnut trees as an investment because it’s best for veneer. He often has to decide to cut down a tree with potential in order to encourage growth in a nearby tree.

“Actually, these three trees are too close. I need to get rid of, and how do you make the decision of  which to get rid of? Ugh.”

In October, about 40 members of the Missouri chapter of the Walnut Council met for its fall meeting and tour in Polo, Missouri. It’s a tight-knit group of people.

The gathering began with a short business meeting and a presentation from MU’s Stelzer on Thousand Cankers. Each landowner was encouraged to voice their concerns and brainstorm solutions for the problem. Here’s Harlan Palm.

“We’re doomed, there’s no doubt about it.”

A previous president of the Missouri Walnut Council, Ellen Lebold has been planting walnut trees since 1980. By harvesting them she was able to put three kids through college. But she’s not worried about how Thousand Cankers will affect her.

“To me personally it probably will mean nothing, I’ll probably be dead and gone before it hits northwest Missouri. But it means that 30 years of labor will be down the drain, and any inheritance that I might have had, it’s gone down the drain.”

Brian Beckmann agrees. He traveled to the meeting with his father and brother from Lincoln County.

“If this isn’t controlled before it gets out of hand there won’t be any timber for the next generation, or the generation after. Being one of the younger members here, the old timers here have put in their time, it’s not for me, it’s for the next generation.”

It’s a lively bunch. Later in the afternoon the group takes a hayride and tours the James Ball tree farm.

“Bring your chain saw, Scott! Here he comes, he don’t know how to use it but he’ll try.”

Their enthusiasm may be short lived if Thousand Cankers is found in Missouri. But to many people it is no longer a question of whether Thousand Cankers will reach Missouri, but rather it’s a question of when? And whether Missouri will be up to the challenge.

(This story originally aired on Under the Microscope, November 11, 2010.)