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Plant Diseases/Identifying growth on tree


Tree 1
Tree 1  

We just moved to a new house and there is a tree in our yard that has an odd growth of black stuff on the limbs. A few of the limbs with the growth also have a sap type liquid hanging from it. Could you identify it and let us know if it is bad for the tree, and if so then how we could get rid of it.

Do you know what type of tree this is?  From your photo, it appears as some sort of fruit tree.  From the "Tree 2" photo. If this black stuff has a soft-like gummy consistency, it may be a condition called gummosis.  This is composed of sap that is exuded out through the bark.  It results from some sort of wound created in the bark.  These wounds can sometimes be caused by a boring insect.  The gummosis or sap flow happens in response to the wound made. Often it is insects.  Your tree would need to be examined "in person" to diagnose the issue accurately.

From "Tree #1" photo.  If these twig swellings are hard and crusty, this may be a disease that we see on plums called black knot.  It is caused by a fungus called Apiosporinia morbusa. Use your computer to "Google" some photos of black knot to compare with what you have. It can kill the tree if the knots are very widespread. Pruning the "Galls or knots" out can be effective at the right time of year and if there aren't too many in the tree.


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Dr Stephen Vann


Plant Diseases and Disorders of Lawn Grasses, Trees, Vegetables,and Ornamentals


Plant Diseases Identification and Management

B.S. Botany --- Miss. State Univ. M.S. Plant Pathology --- Miss. State Univ. Ph.D. Plant Pathology --- Texas A & M Univ.

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