Alfalfa (Medicago sativa) growth responses to aphids and insecticides in the low desert

Tuesday, November 12, 2024

2:00 PM - 2:12 PM MST

Location: Phoenix Convention Center, 127 C

Presenting Author(s)

Michael D. Rethwisch

Crop Production and Entomology Advisor
University of California
Blythe, California

Co-Author(s)

KA

Kassandra Allan

Former Student Assistant
University of California
Lincoln, Nebraska
NT

Nathan Tribby

Former Student Assistant
University of California
Pomona, California
CP

Carla Pryor

Laboratory Assistant
University of California
Blythe, California

Eleven treatments were applied to new alfalfa (Medicago sativa) that was infested with blue alfalfa aphids (Acyrthosiphon kondoi) near Ripley, CA. Data were collected on insecticide efficacy and resulting alfalfa yields and quality. In addition, detailed data were collected on alfalfa responses to the various insecticides and aphid pressures. Some treatments, such as Transform, resulted in both longer and wider internodes of alfalfa stems, while others, such as Beleaf resulting multiple wide internodes, but not expanded internode lengths. Pyrethroid insecticides resulted in quick knockdown of aphids, but also greatly reduced number of ladybird beetles. This allowed aphids to proliferate and did not increase yields. High alfalfa yields were off-set by lower quality, while low yielding alfalfa had much higher relative feed values.