Yes it certainly could be. I've seen leaf damage from liquid insecticides. It may be the non active ingredients needed to make a good spray solution more so than the active ingredient.

I assume that's why proper dosage is very important.

Very true, ramble. More isn't always better.

I REALLY don't want to kill another apricot. They seem particularly susceptible.

I just sprayed my Harglow Apricot last week after 70% petal fall ( ( also mixed a bit of Immunox in the batch). All is well. I just followed the directions on the bottle. The only thing I see happening are the very fine cob webs on the tree (all trees). I thought triazicide killed insects 'upon contact'. Not all insects I guess. Mrs. G