Sooty Mold: Common Pests – Aphids, Scale & Whitefly

Aphids are common plant pests affecting all types of plants including trees and shrubs. Aphids feed on the plant sap produced by the plant leaves. They excrete a sugary, sticky, “honeydew” which covers leaves, tree limbs and trunks and anything under the infested tree or shrub.

Trees and shrubs with a high infestation of aphids or other sap feeding insects can have a black colored bark or leaves. The black coloring is due to sooty mold growth on the honeydew. The sooty mold will grow on concrete, rock, wood and anything under the plants. Ants love the honeydew so if you see lots of ants under or on the tree they are feeding on the honeydew, not on your tree. Smaller trees and shrubs can be severely weakened if the problem is not addressed.

Treat any of these bugs with either Horticultural Oil or Spinosad (see below) – both of which are insecticides. Plants need to be sprayed late in the day when the sun is going down and sprayed completely-top of leaves, bottom of leaves, stems -until dripping wet. Repeat the process once per week for at least three weeks and then monitor. The black sooty mold will wear off over time.

If you have any questions, feel free to stop by the Garden Center or Contact Us!