Question
We live in Idaho and have discovered borers in our Ash tree.  Is there anything that can be done to save the tree?  Is fall a good time to try and save it?  The tree hasn't shown signs of dyeing yet, just several bore holes.

Answer
Most borers attack only trees that are stressed due to drought, injury or disease. Consequently, any means of promoting vigorous tree growth should be considered the primary approach for borer management. Fertilize with 10-10-10 fertilizer at a rate of 1 lb per inch of trunk diameter. Scatter this around the tree and water in good.

Spray the trunk with an insecticide called Merit now and again in April. This should kill the borers in the trunk. And in the spring kill any adult borers laying eggs.