I've recently moved into a new place in Saskatchewan and there is a row of choke cherries in the yard which is riddled with black knot. I pruned the first bush, but I have some questions that I would like to get answers for before I do the whole row (and potentially cause more harm than good!)
1. Should I prune now, or wait until fall when the plant is dormant?
2. I am trying to cut the branch so I get rid of all the rot, however there are occasions when I cut the branch right back to the crotch (I believe this is the correct term!) but the cut shows that there is still rot inside. Is it best to cut the healthy-looking main branch that the diseased one was attached to, to make sure there is no trace of rot remaining, even if I would cut off quite a large chunk of the bush in doing so?
3. Where is the best place to cut any branch?
a) as close as you can to the rot, without having any trace remaining, even if there is no offshoot branch near the cut
b) just above the nearest offshoot on the branch
c) the crotch where it meets the main branch
4. Should I sterilize the loppers between each bush, even though they all have black knot?
Really hope someone out there can help me - I want to do the best job I can!
I have successfully managed black knot in chokecherries by pruning out all diseased branches during the winter when the spores are not active. Doing it two years in a row really seemed to keep it in check and almost completely eliminate it. You should cut way behind the infected area, even if it means cutting the whole tree. They will sprout back fine if cut in the dormant season.
Twisted Tree Farm and Nursery
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