Plum Tree Problem

Asked February 28, 2016, 9:08 PM EST

I have a plum tree which has some type of disease or infestation. The tree is about 5 years old and was bought at a local Lowes garden center already about 6 feet tall. The tree does flower and fruit but the fruit stays small and many fall off the tree. The year before last I notice some tent caterpillars on the tree and removed them by hand. I haven't seen them since then but starting last year many of the limbs have become diseased or infected. Pictures are attached. If you need additional information or pictures please let me know. Please advise what the issue is and whether the tree is salvageable or should just be cut down. If I plant another tree in its place is there anything I can do to prevent it from getting diseased or infested. Thank you,

Anne Arundel County Maryland

1 Response

Based on your photo this looks like black knot, a fungal disease on your plum tree. Prune out black knot (fungal disease) at least 4 inches below the gall-like black knots and remove the clippings from the landscape. Chemical control is not recommnded.
If there is a wild cherry growing nearby, and you are able to, you can remove and destroy it. This tree (and others that will be further away) serve as a host for the pathogen.
You will have to decide if you want to consider removal. Plums in general are not that long lived.

Tree fruits can be a challenge to grow for the average homeowner. (Stone fruits) and apples tend to have the most pest and disease problems and they need to be on a strict spray schedule. You will have to familiarize yourself with and manage or prevent problems. Fruit drop - it is possible that you may be dealing with several issues such as insects, spring frosts, etc.
See our website for Getting Started With Fruit Trees. Some trees are more prone to pests and diseases and you may want to start out with small fruits like blueberries and blackberries.