I really am interested in the soil drench method, and soaking the vines in Actinovate. I will do this when I plant my new vines this spring.
One thing I noticed is that the gall started with one vine and seemed to spread to the vines next to it. I Have never had a spray program of any sort, as I have never had a mildew problem. I wonder now if spraying for mildew would help.
I guess the idea is that the Actinovate bacteria colonies in the soil will out compete the gall bacteria, at least that's what I read. And proper hygiene is a must as well. Once upon a time, I would use my dirty hands (after pulling weeds) to rub off sprouts. It dawned on me that I was carries contagion from the soil directly to the wound I was making. Not smart on my part, but wisdom doesn't come from a book, but from a strong desire to not repeat stupid things one has done.
I just had an revelation. While out cleaning around vines this morning, I noticed small snails around the base of several vines. So I wondered if there was a connection between them and crown gall. Some investigation shows that there may be. It seems to be a concern for blueberry growers so why not grape vines. I guess since they live in the soil, they could be carriers of the Agrobacterium that causes galling. Any knowledge to share or ideas on this?
I'm having trouble keeping my Cab Franc vines alive as well. As for the snails, I noticed 2 or 3 on the base of several vines this morning. I think they are working on the bark, which may be allowing the gall bacteria in. Of course the few I found today will no longer bother me, there are probably bunches more I don't see. I'm going to get some cheap beer and set some 'snail traps' out to see what I catch. I'm just not sure about using some of the snail baits on the market, unless someone here has tried it before.