Landscape: Garden

Reducing Honeydew from Trees

Pro-active dates: October to March

Rescue dates: Late spring to late summer

Commonly found on: Ash, crabapple, crape myrtle, elm, fruit trees, hackberry, hawthorn, locust, maple, oak, willow, and zelkova. Sometimes conifers and other shade trees.

Actions to take: Prevent with preseason treatments whenever possible. Prevention works best when tree are fertilized at the same time. Suppress the problem during the growing season as soon as possible, as populations build quickly when the weather is warm. Don’t over fertilize, especially early in the season. Where honeydew has dripped on sidewalks and other surfaces, wash with a soapy water mix. Washing the tree canopy is sometimes necessary as well.

More Information: When the heat of summer comes, we sometimes notice a sticky sap that drops from certain trees onto sidewalks, parking lots, cars and even us! This “sticky sap” not tree sap at all, but a secretion from the insects that are feeding on young leaves. These insects, including aphids, lace bugs, certain scale, mealybugs, thrips and a few other types, suck out the fluid in plants. Honeydew by itself may be annoying to deal will not typically hurt the tree. However, the pests that make the honeydew can become damaging to the tree if the populations build high enough. When the honeydew secretion stays on the tree leaves, a black mold (sooty mold) often starts to grow. This can further weaken the tree because it reduces the amount of sunlight the leaves absorb. Prevention in the off season typically maintains populations well below any kind of damaging level. It also eliminates the need to treat the canopy which can be hard to do in the summer when cars, people and objects are nearby.

Maintain good tree health. Identify the most problematic tree species on the site and treat in the off season. In season treatments should begin early if possible.

If you have a property that may present honeydew symptoms during the summer, please Jon Maystrik at Arborwell for more information and to provide recommendations.

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