The Role of Cercospora Summer Black Stem and Leaf Spot in the Alfalfa Decline Problem in La Paz County

Abstract

An alfalfa decline problem has appeared recently in fields between Poston and Parker in La Paz County. Cercospora summer black stem and leaf spot, a fungal disease of alfalfa, has been associated with the decline problem. The efficacy of three fungicides were tested for control of the disease and the decline problem. Bravo, Kocide, and Spotless significantly reduced the severity of Cercospora summer black stem and leaf spot; however, significant increases in yield were not realized. Alfalfa decline in La Paz County may involve other factors in addition to plant disease.