What is wrong with my tter

Asked December 16, 2017, 5:29 PM EST

I have I believe they are choke cherry trees in my yard. They have these black things on the branches. Almost looks like the old time "snakes" you would light on July 4 Thank you for any help.

Brown County Minnesota black knot

4 Responses

Thank you for your answer. From what I'm reading, I should cut these branches off in late winter and dispose of the branches, correct?

Can this go to my maple trees also?

Is that all I should do?

Thank you for your help.


Yes remove the branches with the visible knots and dispose of them. No, your maple will not be affected only the prunus are affected by it. That should be all you need to do if you are able to remove the affected branches. You may need to watch and remove branches for a couple of years.

In addition to the information provided by the link to the fact sheet from the University of Minnesota, I would add that the black knot is attacking stone fruit species from genus Prunus. It is very common on plums, often found on cherries and only under very heavy infestation and optimal weather conditions for diseases development on peaches and apricots.

Effective black knot management requires both cultural and chemical approaches. The important first step is to cut out all knots, including those on nearby wild hosts, to reduce chances for future infections. Knot removal should be done in winter but it can also be done in the spring before bud break, before knots begin to release spores. Pruning cuts should be made to include the knots plus another 8-10” of growth closer to the trunk to remove infected tissue not yet showing symptoms. Black knot galls on main scaffolds or on trunks need to be removed by chisel. Some of the healthy tissue around the nuts must be removed as well (at least 1-2”). Pruned branches with the knots should be promptly removed from the site and burned to eliminate these as a source of infection. Managing black knot in an orchard showing symptoms is at least a two-year project as there are also infections that will not become invisible until the following year.

Chemical treatments should start early, approximately at bud break/opening in the spring as protectant sprays. Fungicides are applied at seven to ten-day intervals from green tip/tight cluster to about mid-June when the active shoot growth stops. These are the most important sprays. Of the spray materials listed in the fact sheet, in my experience, Chlorothalonil is the most effective.