The City has announced a program to protect street trees from the Emerald Ash Borer,  starting with the us here in the SouthWest quadrant.  You may be seeing flags in the tree lawns where the insecticide has been applied.  

Two methods are currently approved:

• injection of Tree-äge (emamectin benzoate) into the tree trunk, which protects the tree for 2-3 years, and can save otherwise healthy trees after they have lost up to 50 per cent of their canopy to the borer,
• application of a soil drench containing imidacloprid at the base of trees near the trunk; best results are with two applications per year on trees that are not already infested.

The City is using Tree-äge;  see News Release - Forestry Division Aims to Protect City’s Ash Trees for details.

Here also is a fact sheet from the Cornell Cooperative Extension:

The emeral ash borer.doc

Call the Cornell Cooperative Extension at 461-1000, or visit www.aphis.usda.gov,  if you would like more advice about treating trees on your private property.