Investigating the Effect of Adjuvants on Nicosulfuron Efficacy in Controlling Redroot Pigweed (Amaranthus retroflexus)

In order to study the efficacy of nicosulfuron in the control of redroot pigweed (Amaranthus retroflexus L.) using adjuvants, a greenhouse experiment was conducted at the Research Greenhouse, Faculty of Agriculture, University of Ferdowsi, Mashhad, Iran. The experiment was carried out as a factorial based on a randomized complete block design with four replications. Treatments included adjuvant application in 11 levels (cotton oil, rapeseed oil, soybean oil, maize oils, Adigor®, Volck®, HydroMax™, Cytogate, Trend® 90, D-octil® and control (without the adjuvants), doses of nicosulfuron in six levels: 0 (control), 5, 10, 20, 40, and 80 g a.i ha-1 )0, 6.25, 1205, 25, 50, and 100% recommended herbicide dose). Dry weight, fresh weight, survival and control percent were measured. The results showed that herbicide rate, adjuvant use and their interaction had a significant effect on the examined attributes. Dry weight, fresh weight and pigweed survival were decreased, while the control percent was increased significantly, when herbicide dose was enhanced. Also, the results showed that by using the adjuvants, ED10¡ ED50 and ED90 values were decreased significantly, while nicosulfuron efficacy in the redroot pigweed control was raised significantly; further, the highest relative potential of hebricide was obtained by HydroMax™ and Trend®. In other words, when HydroMax™ and Trend® were combined with nicosulfuron, herbicide efficacy in controlling the dry weight and the fresh weight of redroot pigweed indicated a three-fold increase.