I've got 12 hemlock trees infested with woolly adelgids. The local garden
store recommended Bayer Tree & Shrub insecticide and recommended that I
drench them. After measuring the circumference of the trees, also as they
suggested, it looks like mixing one ounce of the insecticide per inch of
circumference for all those trees in a 2-gallon watering can means that I'll
need 6 gallons of this stuff @ $90 per gallon!

My question: is drenching really necessary or can I just use the alternate
method of spraying them at a much lower concentration and expect decent
results? I thought I might drench the ones that are too tall to reach with
the sprayer and just spray the ones I can reach.

John,
Maryland