Field research was conducted at Yuma and Goodyear, AZ on fallowed ground to measure the response of purple nutsedge (Cyperus rotundus) to butylate and EPTC (Goodyear only). At Yuma, the greatest reduction in number of live tubers resulted when two years of fallow were combined with annual a summer application of 3.3 lb/A of butylate. At Goodyear, butylate and EPTC were more effective at controlling purple nutsedge when applied in early July compared to an application in early September. In addition, timely one timely application of EPTC or butylate in July was more effective at reducing the number of live tubers than two applications (July, Sept.). Herbicide treatments applied in September were less effective with an irrigation compared to without an irrigation.