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Vegetable IPM Updates Archive
Cooperative Extension
Aphid ID in Leafy Vegetables (Nov. 16, 2011)

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). Also, you are likely to find cowpea aphid in lettuce as it is common in alfalfa at this time. However, experience has shown us that although small colonies may be found on lettuce, the populations rarely increase in lettuce crops. 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. Please click on the following link to view the Aphid ID tool.

Lettuce Aphid
Lettuce Aphid

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For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.

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