Canker on Apple Tree

Hi everyone,
This is my first ever post so I am not posting this in the right place or posting in the right way please let me know.
I am visiting my grandmother who has several apple trees on her arm in Idaho (Zone 5A). One of her older trees has some damage that appears to be caused by canker (black bark with exposed sapwood - some with weeping sap and some that is already dead). The reading I have done suggests cutting off the offending limbs, burning them to prevent spread, and treating the wound with wound seal. My question is this, is it OK to cut it now in July or should she wait until it goes dormant? I might normally wait, but I live states away and I don't think I will be back during the dormant season.
Thanks in advance!

Blake Parkinson
Heritage Orchard
Columbia Missouri

It's hard to advise without knowing the scale of branch structure (and foliage) involved. If the affected limbs are still full of relatively healthy leaves, and make up a signifiant percentage of the tree's photosynthesizing limbs, I would probably wait until dormant season (perhaps you could mark the limbs in question so that your grandmother could have someone else come and take them off?). If the limbs are quite sickly with yellow leaves and wrinkled bark, in addition to the areas affected by canker, I probably would not hesitate to take them off. If it makes sense, you also might consider leaving a "stub" like you might if pruning off larger fireblight-affected limbs in the summer. This way, you get rid of as much affected tissue as possible asap, but can do the definitive pruning on a later visit.

Kordick Family Farm
Westfield, NC
Zone 7a

Follow what Brittany suggested Blake, leaving that "ugly stub" for later cleanup in the dormant season. What I would add is to apply a fungicide/bactericide if you are not already, in order to protect adjacent tissue, particularly for fireblight (you mention "weeping sap"). Consider whether a more active management plan could have prevented this, and what you may do in the future to help her out.

Thank you for the response Brittany and Todd!
I did end up cutting the infected wood back to wood that looked healthy (waiting might have indeed been better, but it seemed the "right" thing to do given other factors). The Ag Extension office confirmed it was canker and we are talking through management plans.

I really appreciate the help!


Blake Parkinson
Heritage Orchard
Columbia Missouri



Edited 1 time(s). Last edit at 07/28/2022 05:20PM by Blake Parkinson.