The green menace

Emerald ash borer invades six Arkansas counties

The emerald ash borer is such a threat to the state’s ash trees that forest and agriculture authorities are urging campers and hunters not to carry wood from their homes to burn at camp, but instead to buy and use wood locally.
The emerald ash borer is such a threat to the state’s ash trees that forest and agriculture authorities are urging campers and hunters not to carry wood from their homes to burn at camp, but instead to buy and use wood locally.

Arkansas has always had a fair share of the planet's more than a million described species of insects. And now the emerald ash borer has found us, with confirmed sightings in six Arkansas counties. That could be only the tip of the iceberg.

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Special to the Democrat-Gazette

This healthy ash tree is loaded with seedpods. Ash trees in Arkansas are in danger from an invasive species of insect, the emerald ash borer.

As if we didn't have enough pests to contend with, invasive immigrants are attacking our plants. Last year it was the crape myrtle felt scale, and the Cooperative Extension Service gets weekly confirmations of this pest on crape myrtles in central and southern Arkansas.

The emerald ash borer is a small, metallic green beetle that kills ash trees.

It was first observed in dying ash trees in Canton, Mich., in 2002 but most likely had been active in that state for a few years. Michigan plant authorities have no confirmed explanation for how this imported pest from Asia arrived, but they suspect it came in on wooden shipping crates.

Once they landed, the insects multiplied and began to spread. What started in one county in Michigan has spread to almost a third of the United States, with new states added to the list each year.

The really bad news is that this is one borer that doesn't just attack weakened or stressed ash trees -- it will go after healthy ones, too. Death occurs within two or three years of an attack.

VULNERABLE

Ash trees are in the Fraxinus genus, part of the olive family. They account for less than 2 percent of the shade trees in Arkansas. In Michigan, ash trees were one of the main shade trees in home landscapes, having replaced the elm trees devastated by Dutch elm disease in the 1940s.

This situation really underlines the importance of planting a diverse mixture of tree species. Wherever landscapers plant the same species again and again -- creating a monoculture -- if a pest insect or disease occurs, the results can be devastating. It is always hard to lose even one tree, but there are neighborhoods in Michigan with almost no shade trees left, because they were all ash trees.

Millions of ash trees have died as a result of this small beetle during the 12 years or so since it immigrated. The spread of the pest was first thought to be through the movement of infested nursery stock of ash trees, but nursery inspections and quarantines have closed that avenue. Now the main culprit of spread is firewood and to a lesser extent, sawmill logs.

Many hunters and campers take their own firewood to burn at camp and unknowingly are spreading this devastating insect.

LIFE CYCLE

The "Green Menace," as it has been labeled, emerges from trees or wood in early summer to mate. Adults only live three weeks, but females lay a copious amount of eggs on ash trees. The eggs hatch, and the larvae tunnel into the trees where they feed all fall, then become dormant in the winter, before emerging in the summer to start the process over again.

The larvae feed in the cambium layer of the tree. They create so many S-shaped tunnels in this layer that they effectively girdle the tree inside, interrupting the flow of food and water and eventually killing the tree.

Normally, by the time you notice a tree is dying at the top, the damage is done and you can't do much about it.

BAD SIGNS

Evidence to look for includes:

• Many jagged holes on ash trees where woodpeckers are feeding on the larvae.

• D-shaped exit holes on the trunk in the summer where adults have emerged.

• S-shaped tunnels under the bark of dead or dying trees.

Dieback occurs typically at the top of the tree, and then sprouts emerge from the soil line or low on the trunk.

If you see any of these signs on ash trees, contact your local county extension office or call the Arkansas State Plant Board at (501) 225-1598.

QUARANTINE

The emerald ash borer was first seen in July in Clark, Hot Spring and Nevada counties in Arkansas and has since been found in three neighboring counties, Columbia, Dallas and Ouachita.

Firewood carried in by hunters and campers appears to be the way it arrived.

On Sept. 11, the Plant Board issued a 120-day quarantine for firewood in 25 southern counties. Firewood taken from any hardwood species must not be transported out of the area comprising Ashley, Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas, Drew, Garland, Grant, Hempstead, Hot Spring, Howard, Jefferson, Lafayette, Lincoln, Little River, Miller, Montgomery, Nevada, Ouachita, Pike, Saline, Sevier and Union counties.

The board also quarantined all forms of ash wood, living or dead, including nursery stock, green lumber with bark attached, logs, pulpwood, stumps, roots, branches, mulch and composted or uncomposted chips.

Anyone transporting wood across state lines or from areas where the insect has been found can be spreading any number of pest problems -- not just emerald ash borer, but thousand cankers disease, Asian long horned beetle, gypsy moth and red imported fire ant. Firewood should be bought and used locally to prevent the spread of pests in the state.

Some experts believe that the 10 billion ash trees in North America will be destroyed by this one pest. While inspections and quarantines help, the scope of global trade makes it impossible to catch every insect or disease that might enter the continent. Once these pests hit, the ripple factor spreads them exponentially from state to state.

Researchers are hard at work looking for control methods, including resistant species of tree, but that takes time and who knows what next pest is on the horizon? For now, Arkansans should monitor their ash trees and when planting new shade trees, select a diverse mix of species -- but don't add an ash.

Also, when hunting, fishing or camping, buy local firewood -- don't take your own from home.

More information about the emerald ash borer is in publication FSA-7066 from the Extension service, which can be found among the publications at uaex.edu.

HomeStyle on 09/20/2014

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