Effects of adjuvants on the effectiveness and rainfastness of rimsulfuron in potato (Solanum tuberosum L.)

Abstract

The use of adjuvants is an effective way to improve weed control. We evaluated the effect of a non-ionic surfactant (NIS, Contact) and a crop oil concentrate (COC, Renol) on the efficacy and rainfastness of the rimsulfuron on redroot pigweed (Amaranthus retroflexus L.) and common lambsquarters (Chenopodium album L.) in pot studies as well as NIS surfactant in a potato under field conditions. In outdoor pot studies, NIS (0.15 L ha− 1) and COC (0.5 L ha− 1) did not improve the efficacy of rimsulfuron on A. retroflexus while they enhanced the performance and rainfastness of rimsulfuron 14 and two-fold on Chenopodium album at those rates, respectively. However, increasing the NIS concentration to 1 L ha− 1 increased rimsulfuron efficacy by 11-fold for A. retroflexus compared to around 3-fold for C. album. The same treatment also reduced the rainfastness of rimsulfuron on A. retroflexus while improving the rainfastness of rimsulfuron on Chenopodium album compared to 0.04 L ha− 1. The ED50 and ED90 values indicated that the addition of the 0.2 L ha− 1 of NIS improved the efficacy of both recommended (60 g ai. ha− 1) and the reduced (30 g ai. ha− 1) doses of rimsulfuron in field conditions. The highest potato yield (60 t ha− 1) was recorded when rimsulfuron was applied at recommended dose at three different crop growth stages including the development of leaves (S1), harvestable vegetative plants (S4), and tubers (S7), without using a NIS. Overall, the NIS improved rimsulfuron efficacy, especially when the herbicide was applied at a lower dose.