Black Rot Canker in Apple Tree

(Question)

I have a 4-5 year old Vista Bella Apple tree that seems to be infected with black rot canker. I did not get any flowers this year (even though an apple tree that was right next to it was covered with blossoms – I have since removed it as I had given it to my daughter.) All the branches (5-6) about 1-1 1/2 inch diameter are infected at their bases (cracking and rough bark). If I cut them all off, as is suggested on line, it will kill the tree. I have attempted to gouge out 2 areas on the trunk – 2 x 3 inch, to remove any of the brown canker running up and down in the wood of the tree and painted it with gesso.

Is it worth saving? Is there any treatment for it? Can I replant in the same spot if I cut it out (I have limited space in my back yard)? How does one prevent canker, for future reference.

I would appreciate whatever advice you can offer me.

(Answer)

I’m afraid you are describing a very unfortunate situation.

Canker is a bacterial fungus commonly found on fruit trees. In fact, as you have already learned through online searches, this is a very difficult disease to manage. It is possible to cut away diseased tissue, especially if found on the trunk. Small branches that are infected can be pruned out where possible.  This is usually done in the dormant season, and where infection is less than 50% of branch circumference.  Removed branches and wood should be burned or chopped in to small pieces to avoid spreading. Cutting tools need to be clean & sharp.

All that said, since you have the disease in all branches and on the trunk and if they are approaching the point of girdling the tree, it is very likely that the tree is beyond saving. It is also true that the disease can spread to other fruit trees., especially if the infected fruit is left on the ground.

Further, as North Carolina State University explains, “There is no satisfactory control for black root rot. If possible, orchard sites with a history of the disease should not be replanted. If replanting is attempted, the site should be deep plowed and subsoiled, old roots removed, and the site allowed to remain fallow as long as possible. All rootstocks are susceptible.”

Here is a good reference.

 

https://extension.psu.edu/plants/gardening/fphg/pome/diseases/black-rot