Cucurbits XXX–2

Aphids

Whitney S. Cranshaw & Michael J. Brewer

Green Peach Aphid

Note: Cucurbits may be easily injured by formulations of some insecticides. It is often a good precaution to not apply insecticides when foliage is wet. Be sure to check label before using to make sure insecticide will not cause plant injury and/or perform a small-scale test application to verify safety.

Identification (and Life Cycle/Seasonal History)

A few species of aphids may occur on cucumbers and melons in high numbers, particularly late in the growing season. They are less frequent on squashes, including zucchini, and pumpkin. They are green, winged or wingless, and in high densities a waxy coating on the body may be visible, given the infested plants a whitish appearance (this should not be confused with powdery mildew).

Plant Response and Damage

Aphids suck the sap from their host plants and in high densities may cause plant decline. More importantly, these aphids can transmit several mosaic-type virus diseases. These diseases are very rapidly transmitted to the plants by the aphids. Most of this transmission occurs from winged aphids that land briefly on plants and inoculate the plants with the virus during a very brief feeding probe. Although several insecticides are labeled for aphid control , these treatments will have little effect on virus spread because of the rapid transmission of disease.

Biological Control

Several species of parasitic wasps are numerous, and arguably are responsible for the often good natural regulation of these aphids. There are several predators, including lady bird beetles, lacewings (larvae are called aphidlions), and syrphid fly larvae, that can become abundant late in the growing season.

Host Plant Resistance

Virus resistant varieties are available.

Chemical Control

Note: Several insecticides are labeled for aphid control on cucurbits. Keep in mind that aphids transmit viruses quickly and other management approaches should be used in conjunction with or as alternatives to insecticides.

Categories: Insects, Cucurbits, Cucumber, Melons, Squash, Pumpkins, Aphids

Date: 09/15/2002