Efficacy of Norflurazon for Nutsedge Control in Parker Valley Alfalfa

Abstract

Summer weeds such as nutsedge are of economic concern to alfalfa growers in western Arizona. A two year replicated evaluation of the effectiveness of granular norflurazon herbicide for purple nutsedge control was conducted on an established alfalfa field in La Paz County. Zorial Rapid 80 WP and Evital 5G herbicides were tested for their effectiveness at controlling purple nutsedge when applied following hay harvest but prior to irrigation in early spring and late summer. Zorial 80 WP was applied at 2.0 lb a. i. /acre. Evital 5G was applied in spring 1996 at application rates of 1.0, 1.5, 2.0, and 3.0 lb a. i. /acre. Split applications were made the following summer to four plots for a total of 2.0, 3.0, and 4.0 lb a. i. /acre/year. In 1996, purple nutsedge control resulting from a single application of Evital 5G at 2.0 lb a. i. /acre was 41, 82, and 35% at 35, 63, and 99 DAT, respectively. However, Zorial 80 WP applied at 2.0 lb a. i. /acre provided poor purple nutsedge control due to poor soil incorporation since the liquid was unable to penetrate the dense nutsedge foliage. The treatments were reapplied in spring and summer of 1997.