Beware of black knot disease on cherry, chokecherry and plum trees -- pictures
73Black Knot Disease
(Apiosporina morbosa)
The problem with Black Knot disease is that the tree is infected with this fungus two years before you see any sign of the problem. The fungus grows under the bark and is invisible until the branches begin to swell.
Check your tree each spring to make sure there are no swollen branches. If you find rough swollen branches cut them off. If you find black gulls growing on your branches you are in big trouble. These branches with the black gulls must be cut back at least six inches beyond the healthy part of the branch.. Every single branch with these gulls must be cut. The cut branches must be removed and disposed. You can show no mercy.
These are beautiful trees and if they bear fruit it is even more important to keep a close eye on them.
Leaves riddled by beetles -- I thought they were the problem, I was wrong -- it was Black Knot Desease.
Look for branches that are rough and swollen
This was taken last spring -- the damage was not so obvious
Black gulls need to be cut out -- I did not realize the importance of removing all the gulls
Swollen stems are hard to see look closely
You can see the swollen stems if you look closely
These pictures were taken the next spring
The whole entire tree was over taken by the black gulls
The only thing to be done is to cut these branches away and disgard them
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
New hope after cutting the tree branches back really hard, I hope the tree recovers.
Lots of new branches -- looks like it will make it -- not as graceful but it will survive.
Still growing and looking healthy
September the single branches are developing branches
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Thank you lisadpreston.
While I was looking after my seriously ill husband, the black knot on our damson plum went unattended for a couple of years. Today, I cut off most of the infected branches, very similar to the photo that you show above. Hoping to find some more information about possibly being able to save the tree, I went back on the internet and found this site. Your article and the wonderful and very informative photos have given me hope. Thank you very much for sharing.
You are so welcome edith. I was so upset by my tree that I hoped I could help others not make the same mistake I did. I should have cut off all the branches not just the worst. Good luck with your tree.
Does this problem occur only on certain select species or can this effect any and every tree if left unattended?
Thanks!
Tommaso
It my understanding that it only affects the trees mentioned above. None of my other trees were affected.
My tree has the same problem - it's a much bigger tree though, probably 25+ years old with a lot of character. I want to try to save it. Has your tree had fruit since you've cut it back? How long did it take to see the new growth? (One or more seasons?)
Before my tree got infected the trunk and branches were so graceful and beautiful, but it has never had fruit. I am amazed how much it has grown this year. It isn't so beautiful but it did recover.
The sad thing is that no-matter-what you have to remove each and every infected branch and then remove the waste and rake up all leaves stems.
My tree recovered in one season but if it bore fruit it would not bare fruit until the next season because I cut all the branches off, but if you have some branches left I really don't know.
Also I would think it would depend on how many branches you have to remove. It is sad, a beautiful old and graceful tree cannot be replaced, and neither can the fruit.
It is worth a try -- the pictures above of the recovery are from just this year and it has grown really well. I am adding a new picture today to show how much it has grown this summer. Today is September 1, 2010 -- I cut it back in March 2010.
I am not an expert -- but this is what I have experienced.
Good luck with your tree. Let me know how it goes.
This happened to both my plum and cherry tree-I did the same-it looks much better now.It is really important to clean-wipe your pruning tools so you do not spread disease,fungus ect
That is a very good point IN2Deep. I never thought of cleaning the tools -- probably because I only had on cheery tree.
Thank you for writing about this problem, because after reading and seeing pictures of your plum tree, I am going out today to cut back all the branches cause the whole tree is infected with this disease.
Good luck Dorothy -- show no mercy on infected branches. They must go. I hope your tree recovers as did mine, but you must cut them all off -- all of them.
My plum tree looks bald, like the newly recruited marine! But at least, I got rid of those ugly black knots. Thank you. Will keep you abreast of developments, if any. Cheers!
Thank you -- I look forward to seeing your tree recover.
Thank you sooo much for posting your article! We noticed the black knots this year and had no idea what was going on. We hate that we have to cut so many branches because they are beautiful trees. Do you know what causes this disease or how we can prevent it from happening again?
Sadly my tree is infected BAD...Its June 12..Should I prune the heck out it now ? ..Will the summer heat kill the tree ? My wife is very upset.
The sooner the better, the gulls will only get worse. I know it is painful. When I cut my tree back I was afraid I had killed it. Good luck. I don't know about summer heat -- just the gulls, gulls are probably worse than heat.
I live in Alberta. Is it too late in the season to cut off all the black knot? My tree is 20 years old?
In the spring as early as possible you must cut it back and it will be worse in the spring than it is now. Good luck!
I started cutting mine back now in October. Is that okay? I won't hurt the tree, will I?
I am not a tree expert, but I think it will be alright. I cut mine back in the autumn, and it was fine -- the problem is that I didn't cut it back enough so in the spring the infected branches spread. It is important to get every single branch that is affected. Good luck with your tree.
I also have a plum tree that I have been pruning regularly so I don't have a lot of knots. There has to be some kind of fungicide that will help control it. I used a powder form some years back and it kept the knots away for several years. Can't remember what I used. Does anyone have any idea?
My plum had the beetles so bad last year, we were litterly taking them off by the handfulls to dump in soay water. The tree was covered in young fruit, but by the end of the season, not one was salvagable. Everything was shriveled and moldy. It was heartbreaking to watch it all slowly rot and die. I was going to give in and spray this year, but before the bud it was so cold and wet that there wasn't really any day to do it . Now the flowers are out. Is there still time to help it for this year? What can I do? It is terrible to have to watch the slow torcher of a tree trying so hard to survive.
When disposing of the cut branches, do we burn them? It seems that putting them to the curb for pick up or burying would just spred the disease. How do people who are not allowed to burn, deal with it?
Hi Julie, that is a really good question. I would put it them in bags and lable them or bury them far away from the trees, or call the local yard waste pick up, and ask them. You could lable the bags so the yard waste company knew this needed to be dealt with in a safe manner. The desease spreads by water splashing on the infected branches so I would think burying them would be a good option. As for buring I don't know enough to say that would destroy the spores. Burying them would keep the spores from getting into the air. These spores only affect certain trees. Let me know what you decided.
Hi Julie, I know how awful that is. My tree was eaten alive by beetles that is why I did not see the real danger. If your tree has black knot desease you must cut every single branch that is affected. As for the beetles I don't know. After pruning my tree recovered and was not attacked by beetles. Wet weather does not help -- try calling a tree surgeon or a local university that is involved in agriculture.
lisadpreston Level 4 Commenter 2 years ago
Beautiful pics. My favorite tree.