By Jeff Floyd
Certified horticulturist and arborist
The sticky shiny coating so widespread on the leaves of your pecans, oaks, elms, and other trees and shrubs this year is called honeydew.
It’s a nice conversational word used as a stand-in for insect poop. Plant-feeding insects are constantly sipping out the sugary carbs produced during photosynthesis through a sharp mouthpart resembling a straw. Then almost as quickly, they expel it out the other end of their bodies.
The gooey excretion rains out of trees onto objects below, leaving sidewalks, driveways, and windshields a sticky mess. If nothing interferes, aphids, scale, and even tiny spiders called mites become beneficiaries of the tree’s hard work. Insects at the top of the tree release honeydew onto lower leaves. The lowest leaves can become so heavily loaded with honeydew that they appear wet.
Rain will keep most of the honeydew from building up, and it will wash away some of the insects as well. But stressed trees are more susceptible to heavy infestations since they lack the natural defenses to deter them. Healthy trees can tolerate these juice-sucking pests for years with little to no harm. But the inconvenience of cleaning a film of bug poop off a car window every morning is too much for some folks to tolerate.
Arborists can treat infested trees with insecticides that target these pests and quickly eliminate them. Soil drenches with a class of chemicals called neonicotinoids can be taken up within a day-and-a-half on fully leafed trees. This treatment will begin to alleviate the problem within three days. Sprays work even faster by coating the pest and killing it within minutes.
Some systemic insecticides used in soil drenches can have a strange disadvantage in that they cause an explosion in the population of plant-feeding mites. If you’re dealing with this problem and are looking for relief, contact a certified arborist. These tree care experts will know how to adjust the treatment based on your situation.
