Contact Joanie the mod at BT. She has been using the Bayer for a couple of years, with success. She sent me a PM with info (below) and I had asked her for an update in the early winter, but I got no response. I did apply some Bayer 12 Month Tree & Shrub Control (liquid so my dog wouldn't eat it off the surface) to about 6 trees in about November - all different species as a test - and none have rolled over dead yet. If you find out more, please let us know.
Hi Rich! I am currently using a Bayer product, it's the systemic for trees and shrubs. I'll look at the label today and let you know exactly which one. I have used it on all of the trees in Ted's collection, including elms, apricots, junipers, pines, maples, tropicals like ficus... he has a large variety of trees. Application is by mixing into a gallon of water, I think that we use 3 tablespoons per gallon but I'll check my notes. Apply to the soil around the active root zone. We apply about every three months. It washed out of the soil pretty quickly in a bonsai situation. We started applying as soon as I started working for him, in fact that was one of my first jobs, so it's been about eight or nine months and several applications so far. He has used the product in the past, but he is almost blind so can't do it himself any more.
It has worked as far as I can tell. I go again today, and will be checking for aphids and thrips in particular. I wasn't happy with the thrips, they developed on the ficus when the tree should have been protected, but they got another dose a couple of weeks ago.
It does take a while to get into the tree's system, so you do have to spray as well if you have a problem. Collected trees may not have enough active roots to uptake it? It does have a mild, low number fertilizer. Ted also uses Osmocote on his trees (which I don't like, but it's easy and that's his choice) and the mild fert in the Bayer isn't a problem combined with the Osmocote.
I had some initial misgivings about applying it to the elms, since I had read that they don't like systemics, but Ted said that he had used it before and told me to go ahead. So far, no adverse effects. Everything looks very good.
Hope this helps! I'm no expert, and haven't had long-term experience, but from what I have seen it is good and effective. We haven't had any problems except the thrips, in nine months. And the grapes and mumes haven't yet developed spotty leaves. Here's hoping....
Joanie
