The latest Arizona Vegetable Integrated Pest Management Update from the University of Arizona Cooperative Extension in Yuma, Ariz.

Aphid identification in leafy vegetables

By John Palumbo, UA Research Scientist and Extension Specialist

The proper identification of winged aphid species found on leafy vegetables in the desert is important for cost-effective pest management. This is the time of the growing season when we often observe winged (alate) aphids on desert lettuce and cole crops.

Most of the important aphid species found on local crops do not over-summer in the desert because of high temperatures. The aphids typically begin migrating to desert crops beginning in November; often blown in with gusting winds.

My experience over the past 20 years suggests this is due in part to cooler weather and changes in prevailing winds that now begin to blow in from the north and northwest.

Consequently, once the aphids reach the desert valleys, the insects typically move from crop to crop until they find a suitable host to feed and colonize. It is not uncommon to find winged aphids on lettuce or broccoli that are specific pests of small grains (i.e., corn leaf aphid) or alfalfa (i.e., pea aphid).

Since these aphid species will not colonize lettuce, it is important to distinguish them from the key aphid pests commonly found on lettuce that do colonize and require management to prevent problems at harvest (including the green peach aphid, foxglove aphid, and lettuce aphid).

The bottom line is proper aphid identification can save pest control advisers (PCAs) time and money, plus prevent unnecessary insecticide applications.

This pictorial key provides information that can assist PCAs with identifying winged aphids important in lettuce and other leafy vegetables –  for aphid ID tool click here.

Contact Palumbo: (928) 782-3836 or jpalumbo@ag.arizona.edu.