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.
Dennis, I am wondering about your Cab Franc. I am 6a also. Most of my cab franc are back to sprouting from the ground at the beginning of year three. I had canes horizontally on the trellis and was expecting a good year. I am about ready to pull mine up. Where are you with yours?
Out of the original 11 planted, only 4 have survived. Plus one cane that came up from the 101-14 root stock that I plan on grafting to. None of the surviving vines have done well. I believe the 101-14 root stock is resistant to galling, so I want to graft America to it as a trial. Here is what the current (sad) group of Cab Franc vines look like.
101-14 stock to be grafted.
Only one cane this year.
This one budded up this spring, then died. This happened to many of the 11 that I planted, which makes me wonder if they are really suited for this area (Southern Ohio). We get warm days in the spring which can have a few cold nights all the way to the middle of May.
SO, bottom line, I don't think the Cab Franc variety is a good fit for my area. If the root stock (101-14) survives, then I'll graft something else onto it and keep the established root system.
The dead vine shown had some signs of galling. But, the others that died were killed (IMO) in a late spring freeze. These vines seemed to be ready for the season and was ready for bud break, after a May freeze (2 years in a row), all activity ceased, leading me to my conclusion. These vines where planted in 2019, and did well the first year. But then it got cold and I lost a few in 2020, and even more this year.