I have what looks like crown gall on an important 3 year old seedling I’ve been watching 
I know the bacterial dna can enter the distant tissues of the plant but does it always? I have many cuttings that have rooted and I’m wondering if I watch these for some time period, and they don’t develop any galls, can I assume the new plants are clean? Has anyone used Actinovate? Gallex, Bacticin? It would be very easy to treat the small cuttings if that would help. All opinions and ideas welcomed!
Hot water treatment of grape vine cuttings has been fairly successful for eliminating crown gall from the cuttings, see, for example,
“After one season’s growth, less than 2% of the hot-water-treated, grafted vines showed crown gall symptoms. In contrast, up to 60% of untreated control vines were galled.”
This treatment has also been somewhat successful for cherry and plum seedlings. Cherries and plums are members of the rose family. I don’t know whether anyone has tried it with roses, but I’d try it, if I had an important seedling that was infected. Good luck!
Judith - In my case, the gall was above ground. I cut off the affected cane and hoped for the best. That was over five years ago and it hasn’t reappeared. The plant is as healthy as ever. Everyone’s experience seems to be different.
I have just tried the heat method and we’ll see how it works. There’s so much confusing information about crown gall, it’s hard to determine what is actually going on.
My seedlings get put up in the desert and it gets up to 140 degrees up there - I wonder if that would work too? Maybe put the cuttings in a plastic bag for 1/2 hour-1 hour. If they don’t get fried, it might work. Heat treatment is supposed to work for rose mosaic virus as well.
Update on the gall heat treatment - I treated the 6 sample cuttings (which had already calloused) with hot water for 1/2 hour. I didn’t have a thermometer yet, so I heated the water to ‘hot’ but not so hot I couldn’t keep my hand in it. I would imagine it was at least 50 C or 122 F. After treatment, I put the cuttings back in the damp newspaper. The next day, I opened the paper to find the callous’ had turned brown but the rest of the cuttings looked fine. Of the 6 samples, I re-cut 2 of them to the next bud node. This morning I checked the cuttings and 2 from the brown calloused ones have sent out roots just above the callous! I am thrilled!
You guys have saved my seedling! I will watch it for a few years to make sure there are no galls forming, but I’m very excited to hear about this treatment method! I have now received the thermometer, and will heat up some water to estimate how hot the test water was. Will let you know.
Judith
Well, this is an unexpected consequence of this hot-water experiment. ALL of the cuttings rooted, both the ones whose callous turned brown from the treatment, and the ones I re-cut to the next node after the hot-water tx. That doesn’t usually happen for me. Could it be that the heat treatment stimulated root formation? Interesting. I measured the temperature of the water and I would estimate it to be around 122-124, so we’re good!
I think another experiment is in order.
Judith
Good catch, Judith! This may be a remarkable discovery! I can’t wait to hear your findings!
Fascinating! I look forward to hearing the results of your experiment.