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Plant Diseases/Chinese Pistache


QUESTION: I live in Sacramento, CA and I have a Chinese Pistache Keith Davey that was planted three years ago and appears to have a problem. I noticed that at the start of spring one year ago there was a large black area on one side of the trunk at the base of the tree.  As spring progressed the black spread to the other side of the trunk and also to a few of the branches that had been pruned in January, but had no growth last year.  The tree appeared to be growing healthy except for those couple branches and the black at base of trunk.  As Summer progressed I noticed that the black on one side of the tree trunk had gone away and the pruned branches also appeared to be back to a normal color, but still no growth.  At the start of spring this year the tree appears to be sprouting normally, but that large black area is still at the base of the tree.  What could have caused this to occur?  What if anything can be done to prevent this from worsening or to promote healing?  Will the lifespan of this tree be affected and do I need to consider replacing this tree while it is still young and easy to remove.


I am somewhat unclear as to this "black" area near the base.  Can you send along a photo of the base of your tree that clearly shows this black area?  Does this area look like the bark has been damaged/removed ie a physical abnormality or is the bark just discolored?  If there is an apparent physical damage, the lifespan can indeed be compromised since insects and disease organisms can enter through this wound.  Stringtrimmers and lawnmowers are often the culprits, unfortunately.

If possible, sending a photo may reveal some clues.


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Base of Trunk
Base of Trunk  
QUESTION: Here is a photograph of the bsse of the tree it looks as though it is healing, but this area was dark black in color at this time a year ago.

Thank you for the image.  This elongnated "slit" area at the base of the tree is probably an old wound that occurred to the tree.  The tree has healed to some extent by the rolling of the bark along the edges of this "slit".  This opened area will compromise the overall strength of the tree, making it more likely to break over during high winds or an accumulation of winter precipitation on the branches.  With good care (fertilization, water etc)the tree may live for many years, however this weakened area will always be present.  By promoting vigorous growth, the tree will seal off the dead portions within.  Mulching can be helpful, however keep in mind NOT pile it up around the trunk like a volcano that is often too common.  The mulch should be no more than 3" deep.  Pull it away from the trunk since it will provide a good hiding place for critters and insects.  Mulch conserves moisture and keeps the string trimmers and lawnmowers away.

Check out this free publication (PDF)on tree care.  See at:


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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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