Emerald Ash Borer found at Wappapello Lake: Drawing the battle lines in Southeast Missouri  

X marks the spot. James Gracey, a forester with the Corps at Wappapello Lake, points out the evidence that this tree in the Old Greenville Historic Area is infested with the emerald ash borer. The invasive species leaves its tracks below the bark in the cambium layer of the tree. (Photo by Nicole Dalrymple)

D-shaped exit holes mark the spot where the emerald ash borer has emerged in the spring. The beetles only live a few days and die after laying eggs on the bark of ash trees. (Photo by Nicole Dalrymple)

Dec. 22, 2008

By Nicole Dalrymple
St. Louis District

Battle lines are being drawn in Southeast Missouri after the discovery of an emerald ash borer infestation at Wappapello Lake.  A multi-agency effort between local, state and federal agencies is in full swing to contain the spread of this invasive species, which has been found in nine other states and is threatening the ash tree population.
 
The Emerald Ash Borer (EAB) is an emerald-colored exotic beetle, native to Asia that was first confirmed in southeastern Michigan in 2002 but believed to have been there several years before.

Experts believe the bug arrived in crate or pallet material on a vessel that crossed the Pacific Ocean with commodities and wares for the American market.  The introduction of non-native species is one of the potential hazards associated with globalization and increased international trade. 

The EAB, not much larger than a thumbtack, deposits its eggs in the bark of ash trees.  Its larvae hatch and burrow through the bark, feeding on the underlying cambium, or living layer of the tree.  The larvae pupate over the winter, emerge as adult beetles in the spring, breed, fly to other ash trees, and start the cycle over again.  The life expectancy of an adult beetle is less than one month.

The beetles seek and attack trees already distressed by injury and drought.  The presence of the beetle is often revealed by the occurrence of D-shaped exit holes, the spot from which the adults have emerged in the spring and early summer. 

Another sign is S-shaped galleries revealed when bark with exit holes is peeled back.  These galleries are the aftermath of the larvae feasting on the cambium layer during the previous summer and fall.  The larvaes feeding activities sever the vessels that transport nutrients and water from the tree's roots to its crown. 

Thanks to environmental factors and natural resistances, the EABs destructiveness on the Asian ash population is limited.  In contrast, North American ash trees, which make up about 25 percent of the nation's eastern deciduous forests, have no similar resistance and are being killed by the millions.  More than 20 million ash trees are known to have already been killed in Michigan and Indiana alone.

James Gracey, a forester with the Corps at Wappapello, explained that there are four species of ash at the lake: white, blue, green and pumpkin.  "All four are naturally occurring in Missouri and all four are vulnerable to the EAB," he said. 

The EAB will attack and kill all 17 species of ash native to North America.   

"Ash is a very valuable wood," Gracey added.  "It is used for lumber and furniture and is very common in the southeast portion of Missouri, as well as throughout the Mississippi River valley." 

The discovery of the EAB at Wappapello Lake is the first citing in the State of Missouri and the first on Corps land within the Mississippi Valley Division.  The Great Lakes and Ohio River Division has confirmed that the EAB has been found at Corps lakes along the Wabash River, on land managed by the State of Indiana, and at Delaware Lake near Columbus, Ohio.  The EAB has also been found in Illinois, Maryland, Pennsylvania, Virginia, West Virginia and Wisconsin. 
   
"It was certainly upsetting news to learn that the EAB was here," said Gary Stilts, Wappapello Lake operations manager.  "We like to be first in things but not something like this.  But it happened and we have it, and we'll do everything possible to stop it here." 

Based on a tree-ring study done by the U.S. Department of Agriculture, it appears that the EAB has been present at the Old Greenville location for 4-5 years, within a year of the confirmed finding in Michigan. 

Despite the length of infestation, the EAB appears to have remained relatively confined.  Infested trees have been found within a one-mile radius, approximately 120 acres, in and near the lake's Old Greenville historic area and campground.  Searches continue  for infested trees outside of this area. 

The lake is taking on an aggressive strategy of tree removal to hopefully stop the spread of the EAB and contain this infestation.  This has required permitting, special certifications and coordination with the U.S. Fish and Wildlife Service and the State of Missouri Historic Preservation Office.  
  
"We are attacking the problem on different levels and with several different strategies," Gracey explained.  "We will remove as many trees as possible before next spring and then continue efforts in the summer.  We won't be done in one year."

Because the EAB will attack ash trees ranging in size from 1-inch diameter to the largest in the forest, and the dense concentration of ash in the infected area, the impact could be the removal of hundreds of thousands of trees.

Unfortunately, tree removal is the only way to eradicate the EAB, Gracey explained, but the staff will work responsibly.  "Only ash trees are being targeted for removal," Gracey said.  "We will leave the other trees alone.  We don't want to remove trees that aren't vulnerable to the EAB."  

Containment and eradication is a team effort, drawing on the resources of the  Corps, the U.S. Fish and Wildlife Service, the U.S. Forest Service, the Department of Agriculture and many state agencies, including the Missouri Department of Natural Resources and the Department of Conservation. 

Gracey, who has been a forester for 26 years and leads the natural resources team at Wappapello, said he and his team are embracing a 'refuse to lose' moniker and are actively seeking ways to remove the trees at a low cost to the government and big benefit to the natural resource and those who enjoy it.

Gracey likened the infestation to having cancer.  "If you have cancer and go into remission, you always monitor and keep up with your check-ups," he said.  "When we think the EAB is gone and that we have been successful, we will continue to monitor, because it could always be reintroduced."

Additional steps being taken to help stop the spread and prevent additional infestation, include a federal and state quarantine on moving firewood out of Wayne County, Mo. 

Visitors to Wappapello Lake and to Missouri are also being urged to avoid bringing firewood in from outside of the state.  Transporting firewood is most likely the way EAB got to Wappapello Lake.  The suspected area of initial infestation is right next to a campsite. 

"The discovery of this highly destructive pest at a campground is a strong indication that it probably arrived in firewood," said Rob Lawrence, Missouri Department of Conservation forest entomologist.  "If people knew how devastating this insect can be, they would never consider bringing firewood from out of state."

Ongoing efforts in Missouri are being closely watched by neighboring states.  Gracey said that the ash tree population of northeast Arkansas forests is about 50 percent, much higher than that in Missouri.  "If the EAB is found in Arkansas it could have a devastating impact on the state's forests," he said.

"In reality, containing the EAB is going to be very difficult," Gracey conceded, "but we aren't going to give up without a fight.  I don't want to look back 10 to 15 years from now and wonder if we could have done more.  We are going to do everything possible, using all the resources we have available, to keep the infestation contained.   We are going to give 110 percent."

Visitors to Corps facilities are urged to refrain from bringing in firewood from other states, but to buy local wood and burn all firewood while on site.

For additional information visit:
http://www.emeraldashborer.info/
http://mdc.mo.gov/forest/features/firewood.htm