ink ash (Fraxinus americana or F. spp.) is a pretty decent choice for a shade tree.
I grew up with two of them in our backyard. With tall, straight trunks and this very symmetrical, netted bark, they were difficult to climb. And they had those samara-seeds that helicoptered down in late spring. Unlike maple seeds, ash seeds are very pointy. We gave doctor “shots” to each other’s arms with them.
But a few years back the emerald ash borer (EAB) hitched a ride to the US most likely aboard a ship from Asia, probably in a packing crate. Exactly where it came ashore isn’t exactly known, of course, but possibly Canada. Apparently, the borer found lower Canada and the US hospitable to begin reproducing and eating the heck out of ash trees in the NE US south to West Virginia and Virginia, and as far west now as Missouri and Wisconsin.
Since 2002, EAB has killed more than 30 million ash trees in SW Michigan alone, according to the Michigan Department of Ag & Rural Development (MDARD). The borer has proved unstoppable.
The way the insect works is that the adults lay eggs on the foliage. The voracious larvae tunnel around under the bark, eating the food- and water-carrying vessels. This starves and dehydrates the tree to death, often in one season.
When fully sated, the larvae pupate, and emerge through D-shaped hopes they make in the bark. Lots of woodpeckers are attracted to EAB-infested trees, as the birds can hear the delicious and fat larvae eating away beneath the bark surface.
One could spray the ash foliage repeatedly during the time adult EAB are active, but it’s not practical on 50-foot-tall trees in your yard – let alone all the native ones growing in the wild.
Tree specialists in the Lansing area say TREE-age, registered in 2010, is 99 percent effective against ash borers. But again, who will spray the ones in the wild or in city parks – thereby breaking the chain of infestation?
These same specialists also said that if you live in the EAB zone and haven’t sprayed an ash tree yet, it is infested and will soon be dead. Michigan State University entomologist Dr. Deborah McCullough indicates that we are in year 3 of four years of anticipated devastation of ash trees by the borer. Then it will taper off, primarily because most of the ashes will have been killed.
To my way of thinking, borers are about the worst insects a tree can get. Think of how the bronze birch borer devastated the beautiful paper birches we used to have in the Upper Midwest! They again tunnelled down through the trunk, eating the valuable food and water channels.
Once the insects get inside the tree it’s virtually impossible to kill them. Trees don’t have a human-style circulatory system, so you can’t just give an injection and have it work.
Folks are working on control measures. Another insect, fungus or disease organism that likes to eat the borer larvae or adults is the best hope for a cure. MDARD is working with the US Department of Agriculture to introduce a parasitic wasp (small and benign to humans) that will feast on the EAB.
This is the most likely way to control the emerald ash borer, and is the same way control has been achieved with gypsy moths in Michigan.
Meantime, the advice has shifted to planting ash alternatives. You should buy your firewood locally wherever you’re camping, to avoid transporting the EAB – or any other insect – to uninfested geography.
More information may be found at www.michigan.gov/mdard/0,4610,7_125_1568_2390_18298___,00.html