Please advise on Bacterial Canker on Interspecifics


A couple questions about canker:

From what I’ve read the recommended treatment is to cut out any canker. I’ve done this where necessary which has resulted in a lopsided tree. Unfortunately, now my flavour grenade has developed a small canker low on the trunk ~8" above the graft. I think probably it is due to rapid growth which causes the bark to split.

Ideally I’d like to save this tree. Last year I experimented with smearing an anti-bacterial (equate or neosporin) on the canker which caused the discoloration in the second photo. It wasn’t effective.

I’ve seen a couple videos where people cut out infected tissue and burn the wound with a torch and then seal it / paint it. Something such as in

It seems drastic. Also, trees are supposed to try to seal off infections and cutting it open would seem to make it worse. Right now the canker is small but so is the tree - maybe 1.5" - 1.75" caliper. Has anyone tried this? How do you treat canker?

I’ve attached a few photos to illustrate.

I am also considering cutting the tree down to below the infection (but above the graft) and letting it grow back. This is the disappointing option because it means not getting fruit for a couple years.

Also, I have a peacotum nearby. One of the branches on the peacotum has something - I’m not sure if it is bacterial canker. I’ve noticed the same growth on other trees and I always just cut it out. Is this also canker?

Above, the canker in April 2015 before anti-bacterial experiment.

Above, the canker in February 2016 after anti-bacterial experiment.

Above, bark splitting close to the graft.

Above, bark splitting close to the graft.

Above, not sure if this is canker? Anyone know?

Above, annotated.

Above, the whole tree, unbalanced due to losing some branches to canker.


DuPont Kocide 3000. Follow the directions for both soil drench and foliar application.


I don’t know if that is canker. I’ve had canker on a plout and I see it on wild cherries and it looks different. On the pluot I pruned the branch 3 inches beyond the damage.
I have had similar damage as yours on a peach tree last year. As Richard suggested I used copper. I scraped the areas first to clean them up then I sprayed the damaged areas with copper 3 or 4 times over a two week period. After that I sprayed the damaged area daily for a few days with peroxide. Probably 4 or 5 times. The tree looks much better this year.


I’d send a piece to a pathologist before doing any serious surgical damage. There are many reasons trees can experience canker and plums are not all that susceptible here to bacterial canker. In my Z6 S. NY location J. plums often suffer some cambium damage, probably due to issues of cold. These kinds of bark burn are not really treatable but as long as the injury doesn’t cut off the entire vascular system (encircle the trunk), trees remain productive and reasonably vigorous.

For all practical purposes, pluots are actually J. plums (with firm fruit).


I would agree with this. Even if canker MSU reports that copper is ineffective (once infected). I spray mine anyway. And all suggestions sound reasonable. I just keep the tree going as long as possible.
A couple things to do in the future. Note rootstock. I have found some seem to become infected quicker than others depending on rootstock. Also do not plant trees deep. You want root flares. Deeply planted trees suffer, and that can weaken the immune system and secondary infections occur. You want the tree to have a huge root flare. Better to plant shallow than deep, you can always throw soil on it.


Copper is useful to put down after cutting out the damage, but its not going to help on its own. I would probably cut that out if it was my tree, but I agree with Alan that its cherries that you need to worry about canker on, not so much plums or peaches.


I would take a Grill lighter and burn it out. It only takes a few seconds over the affected area. The tree, will look pretty sorry at first, but then it will seal off the wound and get better.


And what it if has nothing to do with disease?


The splitting area will heal with new tissue underneath. Sometimes it takes a while longer than we would like. I would get rid of the canker.


I don’t have a ton of experience with canker, but enough to know this works well. Nothing else really does. I have had canker on three cherry trees and two peach trees. Different organisms, and yes peaches do fine with it, cherries not so much. I do have a 7 year old cherry tree that has had canker for 4 years. It’s still here. So I have had some luck removing infection. If the lesion is not canker, lesions still attract disease and are a weak spot and should be removed (repaired!).


I’ve enjoyed reading this thread.


The discolored bark around the wound is what makes me concerned. Its not definitely canker but thats a strong sign. Cutting into a tiny bit of that darkened bark will make it clear, if there is any dead cambium (brown but wet) underneath its a canker. If not, its all fine.


My plums have what i took to be canker. They look exactly the same way. Are there plum verietys that are resistent?


Interesting Scott. I never treat anything that hasn’t shown itself to be a big threat and I’ve never lost a plum to canker. It may be a different deal in my region.

I always assumed the wounds were simply freeze damage because it never happens to E. plums and the damage shows up after winter. But what I get may have nothing to do with what’s in the picture, although, as you know, I manage hundreds of J. plums in numerous sites.


I decided to try cutting out the area affected. There was a lot of dead cambium - it wasn’t brown and wet though. It was a rust red color and dry. The affected tissue extended upward about an inch above the visible lesion and was deeper than I expected. You can see in the attached pictures.

I painted over the wound with a light color interior latex paint and the tree is staked. The paint should help retain moisture and prevent borers and infection.

Here’s hoping the tree survives. I’m also going to pick off fruit this year so it can focus on healing.

My Hatchet Job:

Paint to seal:

The extent of the cut depth-wise:


The cambium was definitely dead. It was a rust red color and very dry and extended beyond the visible lesion. I’m not sure it was canker but it’s gone now.

This is the reason I decided to go the surgical route. I’d rather have 1 dead tree than a sick tree that is a source of infection for all nearby trees.

I have a 2nd Flavour Grenade, the peacotum, santa rosa, and elberta peach all within about 20 feet of this tree. So I figure it’s better to try cutting it out. If the tree dies then it was weak and deserved to die, and I have the santa rosa and backup FG as pollinators still for the peacotum. If it lives great! and the orchard as a whole is more healthy.


My Italian Plum had canker (small wounds) on two branches. I treated them with diluted copper and they healed. Worked well.


It’s about all you can do and that wound will not hurt the tree. It should produce.
If you left that dry rot, it would be soaked with water and be a perfect medium for further infections, good job. I usually spray the wound with copper afterward, I was thinking about copper with hydrogen peroxide, maybe 2 cups in one gallon of water. Although it may not work as the copper may react with the peroxide. You could just pour some peroxide on, then spray with copper. Not sure this does anything at all?? I know in Veterinary medicine when a cow’s foot is infected, it is cleaned out and wrapped with copper sulfate. Sounds like a reasonable coarse of action with trees too, at least to spray some form of copper to prevent any possible further infection. I too paint them, but usually just when it’s time to touch up the paint on all my trees. Still it is not going to hurt the tree to paint it right afterward. Heck it may protect it better than copper! It’s sealed now, that is a good thing.


I don’t believe paint helps a wound to heal in any way (this is a highly studied issue) but I doubt it will hurt either. We always want to treat wounds, but the tree really does the work and not at all in the manner of animals.

Trees create their own barriers between a wound and the rest of the tree- if the wound is infected the barrier prevents it from spreading into healthy wood. Animals attack the infection and kill it. This is why paint and pruning compounds don’t really work- the trees compounds are more effective.

Cutting out an infection should only be useful if it is spreading and the tree is unable to wall it off. Once you’ve cut out such and infection there is nothing else you can do.


Band aids keep out infection and dirt, so does a layer of paint. By painting you put a band aid on. Wound healers don’t work because they leave the area wet, paint will not, it will dry.
If that was a canker, by cutting it out you spread cells and/or spores all over that wound. Nothing can really be done to avoid that. Spreading cancer by scalpel is extremely common, and why robotic laser surgery is far superior at malignant tumor removal.
I could not in good faith leave the wound unsterilized. Maybe the tree will dry and the spore won’t reinfect area, I would not take that chance. I spent my life working with fungi and bacteria and that wound is teeming with fungal life as most likely that canker is fungal, not bacterial. The bacterial cankers are mostly on cherries, although both are possible on both trees. I love microbiology! i just read all I can, and now no longer working with human pathogens, plant pathogens are my new love. I love learning about the anatomy, physiology and biochemistry of this new (to me) class of pathogens.
I have been wanting this book for a long time

This one looks even better.