Polk City, Fl
|I have the problem with aphids and spider mites and know I need lady bugs to get rid of them. However, my crapes also have some kind of black dusty coating on the leaves and stems. This makes the leaves very brittle when I attempt to wipe it off. I have alot on 10 acres, not all are affected. Are the two problems related,or are they two separate issues. If so what can I do?
|Answer from NGA
June 21, 2010
|The black coating and the aphids are related. What you describe is sooty mold and while it won't hurt your crape myrtles, it doesn't look very attractive. When aphids feed they excrete a sticky substance called honeydew. As this sugary material ages it turns black. To get rid of the sooty mold you'll need to control the aphids. Insecticidal soaps work well against soft bodied aphids (and spider mites) but spraying may not be practical if you have 10 acres of trees! An option might be to use a systemic such as Bonide Systemic Insecticide Granules for the infected trees. Be sure to apply according to label directions. Best wishes with your crape myrtles.
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