Is there a tree dripping sap on your property – possibly staining sidewalks or other areas with sticky residue? Unfortunately, that is generally a sign of tree aphids. There are thousands of types of aphids who live in relatively temperate climates worldwide. They can cause severe stress to trees and other plants (roses are a prime target on the West Coast) and sometimes introduce fungal diseases.
Aphids are fairly small (smaller than most ants), somewhat pear-shaped, and come in a variety of colors. They are most commonly green, but some species are white, brown, black, and many other colors. Aphids feed on tree or other plant sap by, essentially, sucking it out with their straw-like mouths. They often bunch up in clusters, feeding together on the underside of leaves, around stem joints, or on new shoots and flower buds.
Aphid Tree Damage
Infestations of aphids pose a number of risks to trees and other plants. To start, their feeding weakens the tree, draining the sap the tree needs to remain vital and healthy. In plants affected by aphids, you may observe slowed growth rates, spotted or yellowed leaves, curled leaves, browning, wilting, lower yields of fruit or flowers and potentially the death of the plant.
Aphids also spread plant-based diseases. Weakened trees become more likely to succumb to the infections they spread. Fungal infections are common, as well as plant viruses. These diseases are usually much more harmful than the aphids themselves, the viruses in particular. Because of these risks, it is important to actively control aphid populations.
What is Honeydew?
As aphids feed on a plant’s sap, they secrete a sugary fluid called honeydew from their abdomen. When an aphid population grows large enough, the honeydew begins dripping down from the tree (and potentially making a mess of your sidewalk).
The honeydew that aphids produce is collected by certain birds, wasps, stingless bees, and honey bees. Honey bees process the honeydew into a darker, stronger honey which is highly sought after in Europe and Asia due to its purported medicinal value.
Biological Aphid Control
Other insects also harvest the honeydew. Some types of ants actually protect aphids from their natural predators because the ants essentially “farm” the aphids for the honeydew they produce. Deploying ant traps to reduce tree ant populations may help reduce aphid populations once their defenders are gone. Ladybird beetles (ladybugs) and their larvae feed on aphids, so encouraging the beetles can help balance out the aphids.
Chemical Aphid Control
Prevention, especially the biological variety, is best done in late winter or early spring. However, if you missed that window, treatment can still be effectively applied.
A number of pesticides, including surface sprays as well as systemic pesticides (chemicals that are absorbed into the system of a plant) may be used to treat aphid infestations. The systemic pesticides circulate through the plant, reaching the aphids as they feed and leaving other beneficial fauna undisturbed. Sprays like neem oil or insecticidal soap may also be effective, but they have to coat the tree thoroughly to insure that they actually make contact with the aphids and may impact beneficial residents.
If it’s too late and your biological measures were missed (or didn’t work effectively) Arbortek Trees regularly provides safe and effective pesticide treatments for trees and garden plants. Contact us for an assessment today.