Experts tackle readers’ garden questions.
Q: Can you please let me know what you think might be wrong with our fruitless plum tree. When you enlarge photos, you can see tiny holes and splitting bark. Also, less than half the tree bloomed this year. Normally we spray to prevent getting plums but we didn’t spray this tree. I’m not sure if we need to have tree dug up and removed. Please advise.
Judy Schulz, Citrus Heights
Sacramento’s “Bug Man” Baldo Villegas: I think that the tree should be replaced. It looks like the shothole beetles have gotten into the dead part of the tree. I can’t make out if the tree is partly alive as I see some blooms in the back of the tree.
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It is hard to figure out what killed the tree. It could be over-watering or the use of a “weed and feed” product on the lawn near the tree.
To diagnose the cause of death, one would have to do a site inspection and ask lots of questions – especially if weed and feed products were used on the lawn near the tree. It could also be due to too much water on one side of the tree. I am open to other guesses.
Regardless of what caused the tree’s decline, the shothole borers – little red-black beetles about 1/10th of an inch long – appear to have infested the trunk and branches. According to University of California integrated pest management notes, shothole borers (Scolytus rugulosus) attack stone fruits (such as plum trees) as well as pears, apples and almonds.
Shaped like little black bullets, these beetles tunnel into fruit tree bark and wood, weakening and damaging trunks and branches. These borers most often attack very young trees or trees weakened by disease or other factors (such as exposure to herbicides or prolonged drought).
Insecticides are not recommended. Infected wood should be removed and destroyed immediately. As what appears to be the case of your tree, severely infested trees should be removed.
Baldo Villegas is a retired state entomologist and master consulting rosarian. The Bee’s Debbie Arrington contributed to this report.
Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to email@example.com. Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:
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