Midwest ash trees at risk
By James D. Ritchie

The emerald ash borer is moving west

It’s one of the less desired results of globalization. The emerald ash borer, a native of Asia, has invaded North America and is steadily munching its way through ash trees in 10 U.S. states and two Canadian provinces.

“We believe the borer came here as a stowaway in wooden packing materials such as crates and pallets, probably from China,” said Hank Stelzer, University of Missouri extension forester and a member of a federal-state EAB task force. “It invaded eastern states first, but we knew it was only a matter of time until EAB showed up in Missouri. We’ve been looking for it statewide and last July we trapped the first borers at a Corps of Engineers campsite near Greenville, in Wayne County, Mo.

“It was carried in to the Wayne County campground on firewood from another state. We’re sure of that,” he added.

The EAB’s arrival in the U.S. was first noticed in 2002 in Michigan. To date, EAB has killed an estimated 40 million ash trees in that state. Since, it has been discovered in Illinois, Indiana, Ohio, Pennsylvania, Virginia, West Virginia and Maryland. The Wayne County discovery marks EAB’s western most appearance and the first time the pest has been detected west of the Mississippi River. Shortly afterward, Wayne County was placed under federal and state quarantines, prohibiting the removal of any unprocessed hardwood, including nursery stock, from the county.

“So far, we believe we have the pest confined to Corps of Engineers land near Lake Wappapello,” said Doug LeDoux, pest survey coordinator with the Missouri Department of Agriculture, who is helping conduct EAB “de-limiting” surveys all over Missouri.

Hank Stelzer is less optimistic. “EAB will probably be spotty coming into the state,” he said. “But I’m afraid it will eventually be like Dutch elm disease and pretty well take out the ash trees.”

Adult emerald ash borers are metallic-green beetles about a half-inch long. They are not strong fliers. On their own, they move only a half-mile or so per year. But their ability to hitchhike on wood—especially firewood—spreads their range quickly. Once they emerge, adult EAB live only a short time. They may feed lightly on ash tree leaves, but their main goal is to mate, lay 25 to 50 eggs in bark crevices and die shortly afterward.

When EAB larvae hatch out, they burrow through the tree bark and feed on the inner bark (phloem), leaving tunnels that interrupt the transmission of water and nutrients. Trees literally starve.

“Infected mature trees usually die within 2 to 4 years,” said LeDoux. “It takes less time for EAB to do in smaller trees.”

The borer attacks ash trees from the top down, which is one reason damage is not noticeable for a while.

“By the time you see cracking bark and the V-shaped splits EAB makes in the bark, it’s too late,” said Stelzer. Few insecticide treatments are labeled; some of them must be applied by licensed arborists.

“Treatments can cost $300 or more per tree and only last for a relatively short time,” Stelzer added. “Trees will need re-treatment every other year. It’s too expensive in most cases.”

Longer term, biological controls hold some promise. In China, scientists are studying parasitic wasps that attack the eggs and larvae of EAB.

“Efforts are underway here now to see if these wasps could be safe and effective controls of EAB in North America,” said Stelzer.

As a timber tree, ash makes up less than 5 percent of Missouri’s hardwood forests, although it’s an important wood for makers of tool handles and baseball bats. In towns and cities, though, white and green ash can comprise 15 percent or more of the trees. For example, more than 90 percent of the trees at the Jefferson Expansion Memorial (site of the Gateway Arch) in St. Louis are green ash.

“EAB could have a devastating impact in communities across Missouri,” said Stelzer. “Standing dead trees are a safety hazard; cities and towns could end up spending millions of dollars removing afflicted ash trees.”

Ironically, white and green ash trees became popular shade and landscape trees because they are resistant to another aggressive pest—the gypsy moth.

While there’s no immediate antidote to EAB, once the pest infects your ash trees, a task force of state and federal pest control specialists is stepping up efforts to keep track of the pest and try to keep it contained.

“We’re monitoring traps all over the state and getting daily updates on the borer,” said Hank Stelzer. “And we publish an EAB risk map on the extension forestry Web site.”

To report possible emerald ash borer sightings
• Call (866) 716-9974 or,
• Contact your local office of the Missouri Department of Conservation or,
• Contact your county extension office.

Ozark oaks are dying Ozarks red oaks are dying by the thousands. A series of circumstances let the red-oak borer and several other pests get a toehold in aging oak forests and the impact has become noticeable on a million acres of Missouri forest and 1.2-million in Arkansas. “Actually, there are three or four borers that damage red oaks,” said Hank Stelzer, University of Missouri extension forester. “Once the borer has weakened a tree, a fungus infests the roots and finishes the tree off. “Older, mature trees are most susceptible and we have a lot of older red oak trees,” Stelzer added. “After the turn of the 20th Century, trees all over the Ozarks were logged off. The second-growth red oaks now are 90 to 100 years old and that’s about the life expectancy of the species. “Drought aggravates the problem, too,” Stelzer went on. “We began to notice a lot of oaks dying after the 1980 drought. Trees couldn’t suck water and nutrients from the rocky clay soil and that set trees up for attack by the borers and eventually the root-choking fungus.” Sawmills, especially hardwood flooring mills that depend on high-quality oak, are beginning to feel an impact. “The borer damage does seem to be tied to droughty years; the borer seems to come and go with different seasons,” said a Howell County logger, who doesn’t want his name printed. “But we’re noticing damage on younger trees now, not just older trees.” The logger sells wood to flooring mills and, so far, the damage hasn’t impacted those companies who are his customers. “But, thanks to the downturn in housing, demand for hardwood floor—for all construction lumber—is down right now,” he said. “When demand picks up again, the problem will be more noticeable.” At some point, the die-off of mature red oaks will affect more than commercial lumbering. Oak acorns are a principal food source for whitetail deer, wild turkey, squirrels and the restored black bear population depends on carbohydrate-rich acorns to get fattened up for a long winter’s nap. “There isn’t a lot that can be done about it,” said Stelzer. “Better timber stand management could have helped keep oak stands healthy, but only about one in 10 landowners does a good job of managing their trees. The aging red oaks are at about their life expectancy.”

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