treatment for black soot or blight found on oak leaf hydrangea and crepe myrtle
Both plants are about 8 years old, located on western side of house. Leaves were decimated by Japanese beetles about 2 mo ago. Since then leaves and some bark have a black film covering. I can't tell if there are mites. ( There are mites on my Cardinale vines on the n. side of the garden. ) Some of leaves on Oak Leaf Hydrangea are curling.
Sooty mold is a fungus that grows on the honeydew produced by plants that have been attacked by scale, aphids or other insects. It does not hurt the tree or shrub. Sometimes the sooty mold grows on a plant that is beneath a tree that has honeydew dripping from it. At this point in time of the year, there is little point in worrying about it. If you want to get rid of it, you could try spraying with horticultural oil to get rid of the insect that is causing the damage. http://www.ces.ncsu.edu/depts/ent/notes/Ornamentals_and_Turf/houseplants/note41/note41.html Your oak leaf hydrangea could be curling because it is so dry. vw