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Monday - August 23, 2010

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: What's that sticky stuff on plants under many trees?
Answered by: Jimmy Mills


Here in Austin, I've recently noticed a sticky film appearing on shrubs, flowers, grass, etc. under many trees. It appears to be coming from the trees under which they are planted. The sticky film seems to be attracting white flies and other pests to these plants. Is there currently some sort of tree insect infestation that is causing this or are the trees stressed due to the recent heat? It doesn't appear to be moisture due to transpiration.


What you are experiencing is the annual onslaught of honeydew here in Austin. Honeydew is a waste-product of aphids and other sap-sucking insects such as scale. As honeydew is excreted by sucking insects, it falls and coats any surface upon which it lands. Here is a previous answer from last Fall.

This article from University of Minnesota Extension , and another from the University of Kentucky College of Agriculture  give a rather thorough explanation of honey dew and aphids and their effects on plants.

You may also notice blackening of the plants under the trees because of an infestation of sooty mold that grows on the honeydew.



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