After getting out of the car, my shoes were stuck to the asphalt! I looked up and sure enough, I was parked under a tree. Has this happened to you, especially in the fall? You have aphids in your tree!
Aphids are small, soft-bodied insects with long slender mouthparts that they use to pierce stems, leaves, and other tender plant parts and suck out fluids. Although they may be found singly, aphids often feed in dense groups on leaves or stems.
Management
Low to moderate numbers of leaf-feeding aphids aren’t usually damaging on trees. However, large populations of aphids can produce large quantities of a stick substance known as honeydew.
Although aphids seldom kill a mature plant, the damage they do and unsightly honeydew they generate sometimes warrant control. Check your trees and shrubs regularly for aphids to catch infestations early, so you can knock or hose them off.
Ants are often associated with aphid populations, especially on trees and shrubs. This is one clue that you have aphids. Another clue to aphid infestation is the sticky honeydew on the ground and on your car.
Biological Control
Natural enemies can be very important for controlling aphids, especially in gardens not sprayed with pesticides. Usually, natural enemy populations don’t appear in significant numbers until aphids begin to be numerous.
Applying commercially available lady beetles (lady bugs) may give some temporary control when properly handled. Although, most of them will disappear from your yard within a few days.
Cultural Control
Another way to reduce aphid populations on trees and shrubs is to knock off the insects with a strong spray of water. Most dislodged aphids won’t be able to return to the plant, and their honeydew will be washed off as well.
Chemical Control
If insecticides are needed, insecticidal soaps and oils are the best choices for most situations. Soaps, neem oil, and horticultural oil kill only aphids present on the day they are sprayed. Additional applications may be needed.
Systemic insecticides are also available for aphid control, primarily for trees and shrubs. Home-use soil applied products are often diluted with water in a bucket and poured around the base of the tree. Applications are usually made in spring when aphids first become apparent.
When using any pesticide, ALWAYS follow the label.
For more gardening information go to cecolusa.ucanr.edu.
Source: University of California Agricultural and Natural Resources.
