Industry News: Tree Health

Q: Pear tree has hard, dark clusters on the branches. What are they?

Tuesday, May 17, 2016  

Q: We have an ornamental pear tree in our backyard that is approximately 20-25 years old. Two years ago in the fall I noticed a few branches that had hard, dark clusters that wouldn't come off, even when hit with a rake. They don't fall off in the winter, and now they are on nearly every branch. The tree still leafs out, but it is unsightly, and we are concerned about this spreading. We planned to plant another ornamental pear tree in the front, but now I am leery.  Also, if we have to take our tree down, is it safe to plant another tree?  It provides wonderful shade and privacy.  Thank you.

A: Take a look at this Clemson University video. If your malady resembles the one in the video, then you have black knot--a fungal disease. Read this article, Fixes for Black Knot Tree Diseases: What to do When Black Knot Keeps Coming Back, for more information about the treatment of black knot. It points to the 2-pronged approach of pruning off infected areas PLUS application of a fungicide. The only thing I might add to the linked information is that when you prune off infected areas, you should consider sanitizing your pruning tools after each cut so that you aren't to blame for spreading the disease further on the same tree. I think you will find all the information easy to understand and use. Good luck.

Responder: David Jahn, RCA # 425, Des Moines, IA