Plum Canker and Blossom Blast

Plum Canker and Blossom Blast

Trees need a lot of care.  Had I known then what I know now about fruit trees, I would never have been so negligent in the care that I gave them, and I would have put a lot more research and planning into where I was planting the trees and what kind of trees grow best in the Willamette Valley.  When you learn by trial and error, you just waste a lot of time, money and effort.   An ounce of prevention is worth a pound of cure.   And in this day and age with the internet there is no lack of information about how to do it right in your garden.   Or at least how to do it better.

In the last few years I’ve lost two arborvitae and three fruit trees to disease or other factors.  I will surely lose more if I don’t commit to a better care program, and that is what I am currently focused on.  The most recent disaster that I have had to deal with is the canker problem that devastated my Toka plum tree.  The photos provide a very ugly and clear example of what canker on a plum tree can look like.   In this case, it probably doesn’t get much worse than this, and the tree was so diseased with these cankers everywhere, that it didn’t bear any fruit last year, and once again after blossoming this year everything just dried up and only a few new limbs were able to produce a glimmer of hopeful green shoots.   I believe this is referred to as “blossom blast” which is described well in the first link below. Once the canker spreads to the degree it did with the Toka plum, there was nothing I could do to save it.  I could have possibly cut it back to almost nothing, sprayed intensively, cut out some of the remaining canker and then hoped for the best, but why bother?  It would have mutilated the tree and made it look awful.   Since it was only three years old, I figured it was best and safest to cut it down to prevent any spreading of the disease to my other fruit trees.   Hopefully it’s not too late.

Strangely enough, the fungus that caused the canker on the Toka plum didn’t spread to my other plum that is barely 10 feet away.   It is a dwarf Satsuma plum and doesn’t have a speck of disease on it.  What does this tell me?  That it is a much more disease resistant variety to this particular type of canker, possibly a good choice for the Willamette Valley, and that I was lucky to have chosen it?  Sometimes it’s just the luck of the draw.  This year the Satsuma is producing prodigious amount of plums too.  Probably because I sprayed, pruned appropriately, and I fertilized with 16-16-16 fertilizer and topped it all off with compost around the base.  Well, the warm weather probably helped a lot too.   Most likely it’s just a resistant variety for this type of canker.  Fortunately, I do not see any canker on my apple or pear trees either, thank goodness!  A preventative care program that maintains a tree’s good health is the best guard against canker, and when cankers do appear despite good care, you must cut them out and treat the wounds as soon as possible in June or July.   A good You Tube video of the surgery process is here:

I have another canker problem on all my cherry trees, but I may have time to save them if I put in the effort to cut out the canker, dress the wounds, and spray and prune appropriately in the future.   One dormant spray each year is just not enough.

There are different strains of fungi that cause different kinds of bacterial cankers, and from what I understand the disease changes names depending on the spores and the stage of the disease.   Below are some good links that explain it all very well.

Most interesting information on Bacterial Canker in Prunus Species that cause blossom blast and canker. This description seems the most relevant to my problem:,311,311

Perennial Canker Fact Sheet:

How to Cure Canker in Apple Trees:

Extensive PDF on tree diseases with great photos:

Interesting forum comments on using a blowtorch to cauterize canker on cherry trees.   Sounds like it might help, but may not stop it completely:



I will attempt to cut out and dress the wounds on the cherry tree canker this summer.  I think it’s too late for my big cherry tree, even though it doesn’t seem to be that bothered by its canker, but I will try to do some work on my three younger cherry trees.  I may also experiment with a blow torch to cauterize the wounds.  If I do, then I will take photos and try to get a post up.  Wish me luck!

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