Beware of Black Knot Disease on Cherry, Chokecherry, and Plum Trees
Black Knot Disease
The problem with black knot disease is that it's hard to detect. My tree was infected with this fungus two years before I saw any sign of the problem. The fungus grows under the bark and is invisible until the branches begin to swell. Rain spreads the spores.
I thought beetles were the problem, but I was wrong. | Source
What to Do to Treat Black Knot Disease
- Check your tree each spring.
- If you find rough swollen branches, cut them off.
- If you find black gulls growing, you are in big trouble. These must be cut back at least six inches beyond the healthy part of the branch.
- Every single branch with these gulls must be cut—you can show no mercy.
- The cut branches must be removed and disposed of in such a way the spores cannot escape into the air or be exposed to rain. If you leave them for curb pick up, you might want to label the bag. It is probably not a good idea to burn them, but you could cut them up and bury them.
Look for branches that are rough and swollen. | Source
This was taken last spring when the damage was not so obvious. Had I known what it was and what to do, I could have avoided the worst stage.
Black gulls need to be cut out -- I did not realize the importance of removing ALL the gulls. | Source
Swollen stems are hard to see: look closely. | Source
You can see the swollen stems if you look closely. | Source
This and the following pictures were taken the next spring. | Source
The whole entire tree was over taken by black gulls. | Source
The only thing to be done is to cut these branches away and discard them very carefully. | Source
In the end, a white mold grows on this fungus and sadly your tree is disfigured and weakened.
I had to cut the tree back really hard as the damage was so bad. | Source
New hope after cutting the tree branches back really hard, I hope the tree recovers. | Source
Lots of new branches -- looks like it will make it -- not as graceful, but it will survive.
I will post updated pictures as the tree grows.
The tree is still growing and looking healthy. | Source
September -- the single branches are developing branches. | Source
June 2013: the tree was fully restored and much bigger than when I first trimmed it. | Source