Clean-up from Black Rot

Asked April 14, 2018, 10:21 AM EDT

We have just cut down and burned a tree infected with extensive black rot nodules. It was a dark-leaved ornamental Prunus. We cut the tree, burned branches and and the bole and have now pulled the stump. I am fairly sure we did not burn every bit of the fungus nodules. And, I don’t know if the fungus lives in the soil or will be a problem for future or nearby plantings. Should we treat the soil where the root ball and remaining roots are with something like fungicide? Should we rake up stray nodules? I’m not sure we will get all of them. We plan to plant a flowering dogwood in the spot. Do you have any advice to be sure that tree thrives? Thanks.

Washtenaw County Michigan forestry

1 Response

Hello!
Thank you for your question.
The fungus that causes the black nodules on species of prunus is called black knot. It is not known to affect flowering dogwood trees, which are in the Cornaceae family. This link has a list of species affected:
https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/black-knot/
You are correct in assuming that you did not likely rid the yard of the fungus spores, as they are ever present in the environment. Because black knot is not likely to affect the planned Cornaceae shrub, it should not become infected. I would however, avoid planting species at high risk according to the list found in the link.
If you do have other Prunus species, I would consider treating those with a fungicide as the buds break, just to be sure.
I hope this helped! If you have any further questions, please feel free to respond to this thread or contact me using the information below.
Take care - and good luck!
-Julie