By PAUL HETZLER

The emerald city isn’t what it used to be, and it’s not because Dorothy and the Wizard of Oz have left. By emerald city I mean Fort Wayne, Ind. Or Naperville, Ill., or Dayton, Ohio. Since its discovery in 2002, the emerald ash borer (EAB) has drastically altered the face of these and many other “emerald cities.”

Formerly tree-lined streets are now barren, entire neighborhoods stripped of trees because of the emerald invader.

For such a destructive pest, the emerald ash borer is actually beautiful. It’s a small (3/8” to ½”) bullet-shaped beetle that would be easy to overlook if not for its bright, metallic, emerald-green color with shiny copper highlights. The beetles themselves do little harm, but their immature stage (larvae) feed on cambium tissue of ash trees, girdling and thus killing them.

Since the EAB kills only true ash (anything in the genus Fraxinus), mountain ash isn’t targeted. But aside from the relatively few ash that will be treated with insecticides (at considerable expense) through the estimated 15-year duration of EAB infestation, most of the 900 million ash trees in New York will disappear.

With EAB closing in from the west, south and north, there’s no way to stop it from reaching the North Country. In fact, given that it’s been found in southern Ontario just across the St. Lawrence River, including in Cornwall, its arrival may be sooner rather than later. In lab studies, the emerald ash borer has flown 20 miles non-stop. In the real world it’s unlikely they’d fly that far, but EAB is quite capable of flying over the St. Lawrence, and you can bet they won’t be checking in with the Border Patrol.

The fourth annual Emerald Ash Borer Awareness Week is May 18-24, 2014, and there are many things one can do to prepare for the inevitable appearance of this insect. Towns and villages need to identify how many ash trees they have in order to calculate removal costs and plan accordingly, and also to locate ash trees of good health and form that they may want to preserve. While some towns have tree inventories, most do not, and some of those may welcome volunteer help to survey ash trees.

Learning the signs of EAB infestation and scouting for possible cases is also important. When adult EAB first emerge from an infested tree they make a distinctive D-shaped exit hole, with the straight part of the D on the bottom. While it has a distinctive shape, the hole is tiny—1/8” across—and hard to see.

A more conspicuous sign is the sprouting of branches directly out of the trunk. This is called epicormic sprouting, and is a response to severe stress. Bark splitting, and heavy woodpecker feeding in late winter are other signs. Report all suspected cases of EAB infestation to the NYSDEC or your Cooperative Extension office.

Some companies are preying on homeowner fears, pushing insecticide treatments in areas with no EAB. It’s recommended that homeowners treat their ash trees when EAB is confirmed within 10 miles. Even ash trees with early infestations can be saved through treatment. Insecticide options can be found at www.emeraldashborer.info as well as at your DEC office or Cornell Cooperative Extension office.

Planning, cooperation and community involvement are the keys to weathering the EAB storm with as many ash trees as possible, and without breaking the bank. Devastated areas are already replacing trees (with far greater diversity of species), turning their communities green again. Dorothy would have approved.

Paul Hetzler is a forester and Cornell Cooperative Extension of St. Lawrence County horticulture and natural resources educator.