Extension Educator, Horticulture
This has not been a good news year for ash trees. An exotic insect pest called the emerald ash borer has killed millions of ash trees in Michigan, Indiana, Ohio, Maryland and Ontario Canada. This year it was found in two locations in northern Illinois: Kane county and the Village of Wilmette, a north suburb of Chicago. It brings a whole new meaning to the phrase a "pile of ashes".
As a reminder, emerald ash borer adults are emerald green 3/8 to 5/8 inch long beetles. Adult beetles are more abundant in June and July but may be present into early September. The white larvae actually do the most damage by feeding under the bark of trees. Their feeding cuts off the tree's vascular system and therefore food and water. The beetles leave characteristic "D" shaped holes in the trunk or branches.
The ash story would be much worse if the insect had gone undetected and areas left without quarantine. The Illinois Department of Agriculture recently established a quarantine zone in Kane County, site of the first emerald ash borer (EAB) infestation in the state and is conducting a survey to determine additional quarantine areas because of the Wilmette infestation.Movement of ash trees, logs or firewood out of the quarantine area is prohibited to control the spread of the insect. Areas of Michigan, Indiana and Ohio are under quarantine for EAB as well.
The adult beetle flies short distances but can survive for long periods and long distances as a hitchhiker in wood products. It may have made it into the U.S. in wood packing crates from its native Asia. Researchers speculate the insect came into Illinois in firewood from infested emerald ash borer areas.
As people picnic and camp this time of year they may be tempted to bring firewood with them. A safer route is to use only locally acquired firewood. According to Illinois Department of Natural Resources Acting Director Sam Flood, "Our message to campers, picnickers and other visitors to our state parks is clear – do not bring firewood to our parks if you know the wood is from an area under quarantine due to emerald ash borer." Flood also states, "Whether you're coming to a state campground or having a family gathering at a park shelter, make sure you buy or bring only firewood that is well-seasoned and can be totally burned during your visit. With firewood, if you bring it, we want you to burn it before you leave the site. Consider using alternatives like charcoal and pre-fabricated logs that are available at retail outlets."
At present EAB only attacks ash trees. If you have an ailing tree and you suspect EAB make sure the tree is really an ash. Ashes have compound leaves. That means their leaves are composed of 5-9 (usually 7) leaflets along a main rib. The leaves are attached opposite each other on the stem. We have mainly green and white ash, but we also find European, black and blue ash. Mountain Ash is a completely different beast, so it doesn't enter into this discussion.
A sick ash tree may not necessarily be infested with emerald ash borer. Here in Illinois ash trees suffer from several other insect and disease problems including ash yellows, verticillium wilt, anthracnose and other insect borers such as lilac/ash borer and apple tree borer. Your best bet is to practice good tree maintenance by applying 3-4 inches of wood chip mulch, watering during drought periods, and keeping weed trimmers and lawn mowers away from tree trunks.
If you suspect a tree has EAB, contact your local county U of I Extension office.
For more information on EAB, check the web site at www.emeraldashborer.info.