Expert Problem Solver

Sooty Mold

Sooty Mold
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Bonide Solutions:
"Sooty mold is caused by saprophytic fungi that grows on the excrement of sap sucking insects such as scale, aphids, and whiteflies. This excrement is called “honeydew” which can be sticky to the touch. Sooty mold does not infect the plant cells but can shade the leaf from sunlight which reduces the plants ability to do photosynthesis.

Most people find that sooty mold is not aesthetically pleasing, but just cleaning the sooty mold off the plant will not help solve the issue. The insects that create the honeydew must be killed. Products such as horticultural oil will suffocate not only the sooty mold but also kill the insects creating the honeydew which the mold grows on.