Knowledgebase
cracket Plum Tree #577318
Asked July 06, 2019, 12:05 PM EDT
Oakland County Michigan
Expert Response
Hello,
Oozing sap is not a good sign. Sap on the trunk is usually either caused by borers or some type of canker disease in the inner bark tissues. Look for sawdust which is a symptom of borers. Take a knife to slice back behind the sap and dead outer bark to see if there is a tunnel behind it....another symptom of borers. If you see brown discolored interior bark, this is a symptom of a canker disease. There isn't a spray for canker diseases, all you can do is give the tree good care by watering when dry, and mulching around roots.
If you find borers there are insecticides to help. The one you used last year appears to have helped. Typically this has to be used each year until all symptoms of borers are gone. If you find a borer, try to get a clear picture of it and submit it here for identification. If you can take it from the tree undamaged, it can be sent to the MSU lab for I.D.
Other things I see in your picture- the tree is planted too deeply. At the base of the trunk, the tree should flare out as it meets the big roots. The bark damage doesn’t show any sign of callusing over. This would indicate the damage is either very recent, or the tree isn’t growing well enough to develop the callus it needs.
You may want to start over with a young healthy tree, showing no bark damage on the trunk. Get it planted correctly, protect the bark in winter with a guard or wrap, and follow the ‘Tree Owner’s Manual’ for care:
https://www.fs.usda.gov/naspf/sites/default/files/tree_owners_manual_print_res.pdf
See especially pages 9-11 and page 14 in the manual. Be careful not to nick or cut bark during planting, or with weed trimmers or mowers.
If you replace it, look for plum ‘Newport’ or ‘Mt. St. Helens’ as these are supposed to be more disease resistant.
You can hire a certified arborist, a professional who has taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a tree care plan. Find certified arborists by zip code here—-
