Nov 17, 2010
Aphid ID in Leafy Vegetables 2010
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 appearing on desert lettuce and cole crops. Most of the important aphid species we find on local crops do not over-summer here because of high temperatures. Thus they typically begin migrating onto desert crops beginning in November, often being blown in with the 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 into the area from the north and north/west. Consequently, once the aphids reach our desert valleys, they typically move from crop to crop until they find a suitable host to feed and colonize on. 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). Because these aphid species will not colonize lettuce, it is important to be able to distinguish them from the key aphid pests commonly found on lettuce that do colonize and require management to prevent problems at harvest (green peach aphid, foxglove aphid, lettuce aphid). The bottom line: proper aphid identification can save a PCA time and money, and prevent unnecessary insecticide applications. A simple pictorial key provides information that can assist PCAs with identifying winged aphids important in lettuce and other leafy vegetables (to see the aphid ID tool, click here).
To contact John Palumbo go to: jpalumbo@ag.Arizona.edu