When is the appropriate time to prune a young plum or other stone fruit for shape?
When is the appropriate time to prune diseased areas?
It is my understanding that pruning for shape should be done in late winter. However, with stone fruits, this can leave them susceptible to disease, and therefore pruning should be done during summer when it is hot and dry and pathogens, such as canker, are not active. If this is accurate, should existing diseased areas be left, and therefore allowed to spread, until the proper time during Summer, or can they be pruned at any time?
Hi I lived in 7a now 9 a-b and I still prune all of my trees in Feb. the same schedule seems to be working, for pruning as well as spraying. Check in with Mamuang who is closer to your zone.
Primarily plums, but also cherry, peach, and nectarines.
The severity varies. Some is newly developed, and I am hoping that I can remove the areas of bark before it increases in size. Others are large compared to the branch circumference, and very exploded. I am surprised these branches still seem to be thriving. In most cases, removing the branches below the infection point would mean removing a significant amount of the tree, as there are small infections are spread throughout, or located close to the trunk.
I would try and remove it all. It might cost you a few branches. But that is a better option then to leave a source of disease to spread further.
Disinfect pruning tools. Burn the pruning wood. (or keep it in plastic bags and trow it away in the trash (not compost bin))
You could also try and post a picture of the diseased area’s.
Im from the EU. so diease pressure here might be different. I think you have black knott in the US. If never seen that. But you could have that ?
a picture will probably help us determine what might plague your tree’s and how best to handle.
All trees had dead or diseased wood pruned off at some point in time. Below are current examples.
1
Cherry. Over ten years old. 1-1 1/2" diameter branches. First tree to become infected. Result of cicada damage. It hasn’t appeared to impact the trees ability to grow beyond the points of infection.
2
Cherry. 1 1/4" diameter trunk. This tree suffered significant loss of leaves, and dying of upper branches within two months of planting. The upper portion developed significant amount of disease, which was pruned off. It appears new areas of disease are occurring.
3
Cherry. Over 10 years old.
1-1 1/2" diameter branches
5
Plum. 1 3/4" trunk. The charred coloration on the larger branches of the upper portion, and possibly the extent of the damage, may be attributed to the use of a blow torch, per recommendations I found. I later found additional information that stated using a blow torch does not help. I did not bother the base of the trunk. Despite this damage, the tree currently appears to be growing well.
I have used a blowtorch on cankers, so far it has been helping. So based on my experience it is not a bad thing to do.
The only thing looking bad to me is your cherry. I’m not sure what those things on your plums are but they are not oozing and do not look like cankers to me.
For my pruning I am mostly concerned about canker on cherries as my plums usually don’t get it. But it depends how much canker is present in your orchard; I had a massive wild cherry get canker and for a few years my plums were also getting canker. For my plums I prune around now (I finished them a few days ago). The cherries I will also prune now if I have not had a lot of canker issues recently, but I often paint or blowtorch fresh pruning wounds. Once the wound sets it is hard for canker to enter, so you only need to get it at the start.
If you have lots of canker problems though it is a good idea to wait until a long dry spell in the summer. For any open oozing cankers you see now I would definitely prune them out immediately to avoid spread, and paint or torch the wounds.
I recall seeing some mild gumming in the areas that the blow torch was used on - # 5 (two top left images). I was under the impression that the non-gumming wounds are early stage of canker.
