Until recently, aphid pressure has been relatively light in most areas throughout the desert southwest. There have been a few reports of alate (winged) green peach aphids showing up on a few plants, with minimal colonization. However, last week, a local PCA brought in some aphids for identification from a celery field in the Yuma Valley. The terminal area of the plant had several immature apterous (wingless) aphids colonized within the crown of the plant. The aphids were identified as foxglove aphids (FGA), Aulacorthum solani. In addition, FGA have been found on untreated lettuce at the Yuma Ag Center. The apterous forms are pear-shaped and the abdomen is green in color. The cornicles are moderately long, thin, and tapered, varying in color from almost colorless to dark, and with dark tips. The distinguishing characteristic of FGA is the dark green patches at the base of the cornicles. In lettuce, FGA are serious pests of all spring lettuce types (leaf, romaine and head) and typically begin showing up in January under mild weather condition, and are generally most active in Feb and March. They are more mobile than green peach aphid and tend to disperse more throughout the plant. However, they tend to colonize intensively in heads and hearts once plants begin to cup. They are a serious pest of celery where they primarily colonize the young growth protected within the plant and will contaminate celery hearts at harvest rendering them unmarketable. An application of Movento (spirotetramat) at 5 oz/ac is the recommended insecticide for FGA in celery and in lettuce once plants have begun to form heads. FGA do not colonize cole crops or spinach. For more information on FGA and other aphid species found on leafy vegetables go to Insect Management on Desert Produce Crops: Aphids. Remember: "when in doubt, scout".

Foxglove Aphid

To contact John Palumbo go to: jpalumbo@ag.arizona.edu

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.