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Sticky Trees

Landscapers and gardeners are noticing a sticky material raining out of certain shade trees, predominately tulip poplar (also known locally as yellow poplar or tuliptree).  This is caused by a soft-bodied scale insect called the Tulip Poplar Scale.  Mature scales grow as large as 6-7 mm in diameter. They are covered by an oval, convex, waxy cover that varies from light grayish green to pinkish orange mottled with black.

Scale feed by sucking the sap out of the twigs and stems of the tree.  Soft scale will secrete excess (waste) sap in the form of “honeydew,” a sticky, sugar-rich material.  The honeydew will coat the leaves and trunks of the tree, plus anything underneath it (including cars, patio furniture, and decks).  Ants and wasps are often attracted to the honeydew.  A black, sooty mold will sometimes grow on the honeydew, covering the foliage and objects on the ground.

Large numbers of scale can weaken the tree, and make it more susceptible to other problems, including drought and borers. 

The best recommendation to protect your cars and picnic table is to move them away from the tulip tree.  Minor to moderate infestations won’t hurt the tree, especially if you keep the entire yard watered throughout the summer.

For heavy infestations, insecticides will be required. The easiest way to control this pest is with a soil drench of imidacloprid (Bayer Tree and Shrub Insect Control).  This should ideally be applied in the spring, but treatment now will still be of some benefit.  Various other insecticides can be sprayed onto the young crawler stage starting in mid-August, but it is practically impossible for homeowners to reach the tops of tall trees.  Dormant oil can also be used, but again, it’s nearly impossible to get coverage into a large tree.

Pictures of these white fuzzy insects can be found here: 

http://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/pdf/KPN1303.pdf

http://www.ipm.msu.edu/woodylandscape/ladybeetles.htm