Question
I have a large holly tree. It has red berries and bloomed this spring, however, it now is dropping leaves and the leaves are yellow.  The remaining leaves have a sticky, blackish substance adhering to them.  What should I do?

Thank you.

Answer
John:
If the black stuff will rub off the leaf with a wet finger or paper towel, this is called sooty mold.  It is not a disease, but rather the result of an insect infestation.  The black stuff grows on the insect "poop" that is shiny and sticky- called honey dew.  You will need an insecticide. The dropping leaves may be due to another issue. If the tree is well established, such things like a sudden cold snap or other stress can cause this.  Scrape the twigs with a fingernail. Look for green beneath. This may indicate that the drop is just a temporary thing.

Regards

Steve