Use care to prevent emerald ash borer
STARKVILLE, Miss. -- Mississippi is one of just two states east of the Mississippi River not infested with emerald ash borers, and landscapes need everyone’s help to keep it that way.
Blake Layton, Mississippi State University Extension Service entomologist, said the emerald ash borer -- or EAB -- is an invasive, nonnative pest that has killed hundreds of millions of ash trees in the eastern U.S. Fairly expensive, annual treatments can protect high-value landscape trees, but they have to be applied preventatively.
“Emerald ash borers can spread under their own power, but most adult beetles fly fewer than 2-3 miles from the tree from which they emerged,” Layton said. “The rapid spread of emerald ash borer is largely the result of human-assisted movement.”
Emerald ash borers were first detected in the U.S. near Detroit in 2002. They are thought to have arrived from Asia in wooden shipping containers and pallets made from infested ash lumber. The pests are now established in every state east of the Mississippi River except Mississippi and Florida.
“Transporting firewood from an infested area to a noninfested area is a primary culprit,” Layton said. “These insects primarily attack ash trees. Individual trees can be preventatively protected at a cost of $50 to $100 each annually, but there is no realistic control method for forests.”
Dr. Blake Layton, Mississippi State University Extension Service entomologist, discusses emerald ash borers and their threat to the state.
Adult emerald ash borers are small, peg-shaped, metallic-green beetles usually 1/3- to 1/2-inch long. Larvae have slender, white, segmented bodies and live beneath the outer bark of infested trees. Although adults feed on leaves, they do not cause significant damage.
Layton urged homeowners and landowners to inspect their ash trees and contact the local county Extension office if they suspect EAB infestation. Signs or symptoms include yellow, thin or wilted foliage; unusual woodpecker presence and pecking holes; D-shaped beetle exit holes; or shoots growing from roots or a tree’s trunk, often with larger-than-normal leaves.
“The serious damage is caused by the larvae, which bore in the inner bark, girdling tree limbs and trunks. Damage usually progresses down from the crown,” Layton said. “Mortality of untreated trees is 99%, and trees usually die within three to five years of infestation.”
Layton said experience in other states has shown that trees that have lost more than half of their canopy because of EAB usually cannot be saved.
“That is why it is important to begin preventatively treating trees you really want to protect when EAB is detected within 15 to 30 miles of your location,” Layton said. “Although some treatments, such as the trunk injection treatments, may only be applied by licensed commercial applicators, there are some effective treatments that can be applied by homeowners.”
According to the U.S. Department of Agriculture Animal and Health Inspection Service, all 16 species of ash trees and White Fringe trees are at risk from this pest. The insects can be transported in firewood, ash wood products, infested ash plantings and trees, ash wood packing material, and ash wood debris and trimmings, including chips.
“These materials can spread the infestation even if no beetles are visible,” USDA states online in their materials about EAB.
Quarantines are in place to prevent the transportation of ash wood from infected areas to other areas. The single biggest measure any person can take to prevent the spread of the emerald ash borer is to not transport firewood.
“EAB larvae can survive hidden in the bark of firewood,” USDA states. “Remember: buy local, burn local.”
“Experiences in other states have shown that once EAB arrives in an area, trees that are not properly protected will be killed,” Layton said.
Preventative insecticide treatments include those that are soil applied, injected in trunks or sprayed on trunks.
“The objective is to have the insecticide in the tree by the time adults emerge and begin feeding on leaves and laying eggs,” he said.
A variety of information is available online from USDA and other reputable sources.
The MSU Extension Service offers the publication “Protect Landscape Ash Trees from Emerald Ash Borers” at http://extension.msstate.edu/publications. It provides detailed information on how and when to treat trees for emerald ash borers.