'A bad time for Eastern forests:'

the ash tree beetle approaches

By Charlene Polk

A tiny, metallic green beetle, smaller than a penny, could spell the end of the leafy ash trees that are found in forests that cover more than 126,000 acres of Shenandoah National Park.

The beetle, the emerald ash borer (EAB), a native of Asia, has been making its way across the United States since it was discovered in Michigan in 2002.

The insect, which has no native predators in this country, can kill an ash tree in as little as a year.
“The spread of the beetle is very difficult to control,” Shenandoah biologist Rolf Gubler said. “They cause tree mortality in about one to three years, so they can take out an entire ash community very rapidly.”

Gubler fears that the beetle, which has already infested trees in Prince George’s County in neighboring Maryland, after it came in on infected nursery stock, will make its way into the park.

Rose Buckner, of the Maryland Department of Agriculture, said that workers there have quarantined the county but are still in the early stages of EAB eradication.

“We think we’ve probably not found the outer barriers of our quarantine area yet,” she said. “We keep finding trees further and further out of that area that are infested.”

The county quarantine dictates that no firewood leaves the county, because one of the easiest ways for the EAB to spread is through firewood, Buckner said. “Once firewood’s cut it’s all pretty indistinguishable,” she added.

Because of this, Shenandoah National Park has issued a voluntary firewood compliance code, which warns visitors not to bring any firewood into the park that is not local, Gubler said.

Park personnel are intermittently monitoring campers to be sure that no out-of-state firewood is brought into the park, he said. They are especially on the lookout for firewood from the Great Lakes states, since that is where the EAB has been established the longest.

“If we do find firewood from out of the area, we ask them to burn the firewood on site or seal it in plastic bags and take it back with them,” Gubler said.

So far, the EAB has been found in Michigan, Ohio, Illinois, Indiana and Maryland, while a similar pest, the Asian long-horned beetle, has been identified in New York and New Jersey.

The EAB has caused the most damage in Michigan, where, as of 2005, it was responsible for the death or decline of 15 million ash trees in just the Detroit area, not to mention the trees it has killed throughout the Midwest.

It could cause similar damage in Shenandoah, a park that has already lost an enormous number of trees to invasive insects. In the late 1980s and early 1990s, gypsy moths killed a significant number of oak trees, and more recently, the hemlock woolly A

adelgid was responsible for the death of thousands of hemlock trees in the park.

Wayne Millington, a regional pest management coordinator for national parks, said that problems with invasive species will only continue to increase.

“It’s a big wheel rolling downhill very fast,” he said. “We don’t know at what point the forest just can’t take it anymore. It’s a bad time for the Eastern forest.”

The EAB has the ability to impact ash trees in the same way the woolly adelgid impacted hemlocks, Gubler said. The park would not have as much trouble, though, with the EAB as it did with the woolly adelgid, he said.

“It came in fast,” he said. “Shenandoah was one of the first parks to get it. We were the index case. Other parks learned from us. They tried other things and those controls weren’t available when we had the problem.” Gubler said that unlike the case of the adelgid, if the EAB entered Shenandoah biologists would know how best to deal with it because it has already entered other areas and they have watched what has been done to eradicate it in those places.

But James Akerson, a forest ecologist at Shenandoah, thinks that an EAB infestation would be even more devastating than that of the woolly adelgid, because hemlocks only made up 1 percent of the park’s trees while ash trees are found in nearly half of the park’s vegetation communities.

According to Wendy Cass, a botanist at Shenandoah, “Ash trees are a component of 16 of the park's 34 vegetation communities,” and these 16 communities make up 65 percent of the park’s area.

Akerson, an exotic plant specialist, pointed out that if the EAB enters the park, the ash trees that it kills will likely be replaced by invasive plants, which already account for 23 percent of Shenandoah’s plant species. The invasive plants would then go on to spread rapidly, disrupting native ecological communities, as mile-a-minute vine, kudzu and Japanese stilt grass have already done.

“We’re losing natives and non-natives are replacing them,” Millington said. “It’s like a gigantic set of dominoes and they’re all falling.”

Millington, like Akerson, thinks that the EAB will be even more effective at killing than the woolly adelgid. The woolly adelgid doesn’t kill a tree immediately, but the EAB starts to kill a tree as soon as it burrows into it, Millington said. Furthermore, while the woolly adelgid targets already stressed trees, the EAB will kill any tree, he said.

Millington also pointed out that while there are only two species of hemlock trees in Shenandoah, there are numerous species of ash trees that would be affected by an infestation.

Yet another problem with the possibility of an EAB infestation is that it would be hard to detect and nearly impossible to stop once it was detected. The EAB hides inside the tree during its developmental stage and then the apparently healthy tree suddenly loses its leaves and dies, Millington explained. “From what I’ve heard you don’t know until it’s too late,” he said.

“The state put a lot of money into removing ash trees that were near infected nursery stock, but they still weren’t able to stop the infestation,” he said.

Millington said he did not know how the park would be able to successfully eradicate the insect if it entered Shenandoah.

Akerson thinks the park can’t effectively deal with any of its invasive species problems because there is not enough funding.

“The park service is under-funded,” he said. “Twenty three percent of known documented [plant] species are non-native. The mile-a-minute vine is quickly becoming the worst invasive plant we have in Shenandoah and I think it’ll become as bad as kudzu is in the South.”

Nevertheless, Shenandoah is not any worse off than other parks, Akerson said.

Gubler agreed that in the last 20 years invasive species have become a huge problem everywhere, because of the rapid movement of goods from place to place.

“I think the situation continues to worsen,” he said. “Every federal agency, the BLM, the NPS, is dealing with invasive species. A lot are even aquatic, like the snakehead. You can’t just think insects, you have to think mammals and fish too.”

Millington said that Eastern forests in particular were already under a lot of stress because of poor air quality and past insect attacks, such as that of the gypsy moth and woolly adelgid, and that the EAB would have an even greater impact because of this.

(photos courtesy of Maryland Department of Agriculture and Megan Wilson)