Could a flea-size beetle bring down a $1 billion industry?

A tiny insect has killed black walnut trees in several states and is headed for Missouri, which has the most in the US

Harlan Palm of Kingdom City, Mo., measures one of the roughly 700 black walnut trees he’s grown.
Ryan Schuessler

KINGDOM CITY, Mo. — Harlan Palm bought 30 acres of opportunity outside Kingdom City 40 years ago: black walnut trees.

“Trees are a product for the next generation,” he said. “It takes between 60 and 80 years before a (black walnut) tree has reached maturity.”

Raising a black walnut to that age can bring a decent return when the timber is sold — more than $1,000 for a high-quality tree. But a tiny beetle could stop many black walnuts from making it to that point, potentially crippling the industry to the tune of nearly $1 billion in Missouri alone.

A walnut twig beetle.
Steven A. Valley/Oregon Department of Agriculture

The walnut twig beetle is native to the Southwest and is about the size of a flea, but it packs a powerful punch. The beetle carries a fungus that causes thousand cankers disease, which has already decimated the black walnut population in Western states. And it’s moving east.

The first case of thousand cankers in the tree’s native range was confirmed in Tennessee in 2010. The disease has since been found in Pennsylvania, Virginia, North Carolina and most recently in Ohio.

However, the stakes are higher in Missouri, which has more black walnut trees than any other state in the nation. Simeon Wright, a forest pathologist at the Missouri Department of Conservation, said that there are at least 42 million black walnut trees in Missouri. In second place is Ohio, with less than half that number.

The Missouri Department of Conservation estimates that, should thousand cankers disease arrive in the state, Missouri could suffer more than $850 million in direct costs and industry losses over two decades, threatening more than 700 jobs.

“That’s what thousand cankers disease means to us walnut growers,” Palm said. “(Decades) of work, gone.”

The dream at risk

Palm has spent the past four decades meticulously caring for his trees. He knows the story of each one, as if they have their own personalities.

“This one,” he said, pointing to a tree that has grown a little crooked, “trembles every time I walk by with a chainsaw.”

There were only a handful of black walnut trees the day Palm first set foot on the land. Today he estimates there are more than 700 he cares for, and he hopes to eventually sell the timber as lumber or veneer logs. A conservative estimate of his land’s potential return hovers above $300,000, which he hopes will one day go to his two children.

“That was the dream,” he said.

But that money could remain a dream should the walnut twig beetle arrive in Missouri.

Keeping it out of Missouri as long as we can is pretty important. That’s probably the most important thing.

“Because it is a tiny insect, it takes a while to have a buildup,” Wright said. “The cankers are under the bark, and you can’t see them until there are thousands of them and the branches start to die. It will take several years for the insects and cankers to build up, but by that point, you’ve just got lots and lots of these insects.”

Symptoms include dead limbs at the top of the tree, sprouts growing below the dead limbs or on the trunk and dark brown cankers under the bark of dead limbs. After these symptoms are visible, a tree will usually die within three years.

“It’s very hard to get rid of at that point,” Wright said.

He added that the general consensus is that the walnut twig beetle is spreading through transportation of untreated wood across state lines. Years ago, the tree was introduced into Western states, where it came in contact with the walnut twig beetle in the insect’s native range. As wood from those trees was shipped east, the beetle traveled with it.

Slow spread

Missouri is one of many states that have established a quarantine on black walnut wood, barring the transportation of untreated wood across its borders. Wright and Palm said it is very important that individuals refrain from moving firewood between states and out of infected areas.

“Keeping it out of Missouri as long as we can is pretty important. That’s probably the most important thing,” Wright said. “We’re trying to do everything we can to raise awareness and make people aware that wood movement is probably how it’s going to get to Missouri.”

Still, he added, it seems the disease spreads slowly in this part of the country and it probably would not spread quickly across Missouri. The spread of thousand cankers disease in other states has been isolated and slow.

While those in the timber sector of the black walnut industry are bracing for the disease, the country’s largest seller of nuts from those trees, David Hammons of Hammons Black Walnuts in Stockton, Mo., is not as concerned.

Tree grower Harlan Palm shows a black walnut.
Ryan Schuessler

“We’re very much aware of thousand cankers and what it implies,” he said. “But we have found that it would not affect the nuts themselves.”

Hammons is a family-owned business four generations deep that buys black walnuts from 16 states. It can process up to 100,000 pounds of nuts a day, with annual production of 20 to 30 million pounds.

Hammons said the nut sector of the black walnut industry would be affected only if thousand cankers spread on a massive scale, killing an immense number of trees, and he believes that is unlikely, given how slowly the disease is spreading in the Midwest.

“We realize that it’s much less a serious of a threat. I won’t diminish the possibility of a threat, but I won’t say that it’s as big of a threat as it looks,” he said. “The fire and brimstone worry is past. Now it’s observe, report and contain.”

But the black walnut lumber producers aren’t taking any chances, since even one infected tree can spell trouble for an industry largely based on high-quality timber sales. Black walnut is a dark hardwood commonly used for veneer, furniture and cabinetry.

Bucky Pescaglia, president of Missouri Pacific Lumber in Fayette, Mo., recognizes what even a small area of infected trees in Missouri could do to his business. If his supply were quarantined, even temporarily, it would be difficult to produce and sell his product.

“What regulators would do to us if it was discovered in our state — that’s the short-term scary part,” he said.

Pescaglia said black walnut makes up approximately 95 percent of his company’s products, 90 percent of which comes from Missouri.

“The potential there, obviously, could be devastating — if a disease were to come through and wipe out the black walnut,” he said. “Black walnut is the cornerstone of our industry, our business.”

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