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Thursday, June 29, 2006 02:33 pm

Kiss your ash goodbye

A dreaded beetle makes its first appearance in Illinois

art3199
Adult emerald ash borer
Just two weeks ago, the Illinois Department of Agriculture announced that it had identified an emerald ash borer in Kane County, in the northeast corner of the state.

It was not good news.

This destructive nonnative pest (Agrilus planipennis) feeds on North American ash species (Fraxinus sp.), including white ash and green ash, both common species in Illinois (but not mountain ash, which is not a true ash). The small metallic-green beetle attacks both healthy and stressed trees.

Native to Asia, the beetle was first discovered in North America in southeastern Michigan in the summer of 2002. It seems that the pest arrived in infested wood packaging material. In the last five years, it has also been found in Ohio, Indiana, Maryland, and Ontario, Canada.

Signs of infestation include the presence of the adult metallic-green beetles on or around ash trees; thinning, yellowing leaves; eighth-inch-diameter D-shaped holes (about the size of a BB) in the bark; and shoots growing from the base of the tree (epicormic shoots). Other symptoms include die-back beginning in the upper third of the tree and progressing downward, serpentine tunnels just beneath the bark, vertical splits in the bark, and increased woodpecker activity. Infested trees may not show physical signs of damage for two years.

The adult emerald ash borer is about 3/8 to 5/8 inch long and 1/16 inch wide. The adult feeds on ash foliage but causes little damage to the leaves.

Emerald ash borer larvae feed on the inner bark of ash trees. These tunnels cut off the flow of nutrients and water between the tree’s roots and canopy, thus starving the tree. The larvae — legless, heavily segmented and creamy white — grow to about an inch long.

Several metallic-green insects are found in central Illinois. Bronze birch borer adults are similar but darker-colored beetles that leave D-shaped holes in stressed birch trees. Japanese beetles, which are now devouring plants in our area, are about a half-inch long. They are metallic green with coppery-brown wing covers.

The overall health of a tree is affected by planting techniques, care, and weather conditions. Trees should be watered during dry periods, mulched out to the drip line, properly fertilized, and protected from soil compaction. Before jumping to the conclusion that your ash tree is infested with emerald ash borer, remember that ash trees in Illinois are prone to several insect and disease problems, as well as environmental factors, that can cause similar symptoms.

Ash/lilac borer is a common native pest of ash trees. This wasp-mimicking moth leaves quarter-inch round holes on emerging from a tree. Sapsuckers also create holes in trees. The round holes are found in uniform rows up and down the affected tree’s trunk.
Common ash diseases include ash yellows, anthracnose, verticillium wilt, and cankers. “Ash decline” is a term used describe to the overall decline of an ash tree. Other causes of plant decline include stem-girdling roots, environmental stress such as drought, mechanical injury, and salt damage.

The emerald ash borer adult can fly, which slowly spreads the infestation, but human beings also contribute to the rapid spread of the beetle: Several infestations have been traced to the transport of firewood from an infested location. It is unsafe and in most locations illegal to transport ash firewood from a quarantined zone. Unseen but harmful tree pests may be present in the wood. To avoid accidental introduction of emerald ash borer and other pests, purchase only locally grown nursery stock and locally cut firewood.

For additional information, go to www.emeraldashborer.info. If you suspect the presence of emerald ash borer, call your local extension office. In Sangamon and Menard counties, that number is 217-782-4617.
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