Apple tree diagnosis -- canker?

This image is of a 13 or 14-year-old Liberty apple tree. I fear it's a canker that has caused this large split of the bark running most of the way down the trunk.

Can anyone confirm this?

And if it is a canker, is there any hope for this tree, given the magnitude of the split relative to the size of this semi-dwarf tree?

Is there any realistic option other than cutting it down?

Thanks.

Brian

 

It's tough to see from the photo whether tissue inside of the curls is live or not. The formation resembles early development of a target canker which I haven't seen often on Apples (unlike Euro/Nectria canker). It could be rapid cellular expansion causing bark ridging, or it could be a large previous wounding that is not compartmentalizing well.

Whatever the case (have an area arborist come by to diagnose in person), don't throw the baby out with the bath water. If it continues to have a reasonable flush of leaves in the spring and produces fruit, I'd say you have something worth maintaining. Take a walk through a production orchard and you can see some of the most hideous, downtrodden woody plants in existence. A little management can take an Apple a long way depending on what your objectives are. Aesthetics -- not so much.

 

If the damaged area is on the south side of the trunk, there is a good possibility that what you have is sunscald, or sunburn of the bark. This is especially likely if anything has been done, like pruning on this side of the tree, to introduce more sunlight here.

 

I am not too familiar with Victoria's climate, but if you have there late winter frosts I would second vitog in his opinion that it is sunscald rather than canker. Only the small area above the big split resembles canker. Cankers are caused by living organisms like fungi, bacteria etc. Sunscald is caused by rapid and drastic fluctuation in the air temperature.

Young trees are most susceptible to sunscald during dormancy, late in winter and early in spring, when sun already operates very strongly, but nights are below the freezing point. During the day the sun heats excessively the south or south-west facing side of the trunk. The warm temperature can break dormancy in the cork cadmium layer just beneath the still thin outer bark. Immediately after the sunset, the temperature falls quickly and drastically below freezing. Awoken, active cadmium cells are not able to survive the low temperature and die. The rapid change in temperature can also cause the outer bark to contract faster than the inner layers of the wood resulting in cracks and splitting. This in turn exposes cambium to further damage. When the tree wakes up from dormancy in spring and resumes growing there are no living cadmium cells to supply cork for the outer layer of the bark. So the cracks grow.

Is your tree exposed to full direct sunlight? Is the split on the side of the tree facing S or S-W?

Despite of the size of the split, if I were you, I would not be too quick with cutting the tree down. I would wait and see how it is doing first.

If it is sunscald, to prevent further damage paint the trunk with whitewash made by dissolving hydrate lime in water with some salt added, or with white latex, also thinned with water. Keep the split clean to prevent invasion by insects and diseases.

 

Interestingly, the split on the side of the tree does indeed face south. Given Victoria's extremely mild climate, I would not have thought sunscald was a likely problem here, but these suggestions are certainly thought-provoking, as even a place with a moderate climate does experience times when daytime warmth is followed by nighttime cold temperatures.

Thanks for the thoughts. If anyone else has ideas - and especially if anyone has opinions about the likelihood of sunscald in the most mild of southwest B.C. climates - I'd be most interested in reading what you have to say.

 

I had problems with sunscald on a large sweet cherry tree in Burnaby, BC. This happened after I pruned out the center of the tree to open it up to more sunlight. I'm not convinced that the problem was sunscald as it is normally described. I think it was simple sunburn on bark that had not been exposed previously to much sunlight. I can't remember what time of year I pruned that tree, but I usually prune during the summer because I'm trying to shrink the tree, not encourage more growth.