Synergistic effect of imazapic plus prometryn on weeds in peanut (Arachis hypogaea L.) fields

Abstract

To clarify feasibility of using combinations of imazapic and prometryn to control weeds in peanut field, their interaction effect was evaluated in greenhouse and verified in field. The results of pot experiments showed that the interaction of imazapic at 32 g a.i. ha−1 and prometryn at 400–850 g a.i. ha−1 exhibited synergistic effects for the control of Chenopodium album L., Portulaca oleracea L. and Digitaria sanguinalis (L.) Scop., and that the observed response (E0) was significantly greater than that expected (E). The combination of imazapic at 52 g a.i. ha−1 and prometryn at 400–850 g a.i. ha−1 also had synergistic effects on the control of Echinochloa crus-galli (L.) Beauv., and the E0 value was significantly greater than the E value. Field experiment demonstrated that imazapic plus prometryn at 32 + 850 g a.i. ha-1 or 52 + 400 g a.i. ha-1 exhibited better weed density suppression (93.2% or 95.1%), which was significantly higher than imazapic (85.0%) and prometryn (71.8%) applied at 90 g a.i. ha−1 and 950 g a.i. ha−1, respectively. The combinations showed superior weed fresh weight control than when they were applied alone. Comparing with s-metolachlor, the mixtures also provided significantly higher control of weed density and fresh weight under field condition. The mixtures were safe for peanut. These findings indicate that PRE application of combinations of imazapic and prometryn has great potential for weed control in peanut fields in China and that recommended field doses of imazapic plus prometryn are 32 + 850 or 52 + 400 g a.i. ha−1.