Klebba wrote:
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

Most of the reasonably knowledgeable folks I have discussed this with
here (also Maryland) tell me they have had best luck with systemic
treatment. You need to get the Merit into the soil so the roots suck it
up. I had decent success using granular Merit & scratching into the soil
/ mulch area under my hemlocks, then watering it in thoroughly. It may
be too late in the season by now to control them this way.

There are tons of articles on the subject by various regional
Universities. One short concise one is he

http://www.uky.edu/Ag/Entomology/ent...rees/ef452.htm

I also used granular Merit in the soil at the base of my Purple Leaf
Plum trees to help with controlling Japanese beetles, both the grubs in
the soil as well as the adults munching on the leaves. The numbers of
dead adults under these treated trees was amazing.

David in Olney