Control of invasive plant mile-a-minute (Mikania micrantha) with the local crop sweet potato (Ipomoea batatas) and applications of the herbicide bentazon.
Preventing the reinvasion and spread of invasive alien plants after chemical herbicide applications is a common challenge. A set of field experiments to examine the combined effect of competition with a local crop, sweet potato and the herbicide bentazon were conducted in Longchuan County of Yunnan Province, China. The results showed that the preferred plant ratio of sweet potato to mile-a-minute for effective control of mile-a-minute was at 2.5:1. The control rates were ranged from 77.35-90.59% when bentazon applied at 720-1080 g ai hm-2 and the selectivity index was 1.39. Compared to the application of bentazon alone at 1080 g ai hm-2, inhibition rates for sweet potato and bentazon combined were higher, for a ratio of sweet potato to mile-a-minute of 2.5:1 with bentazon applied at 720 g ai hm-2, beyond 30 days after the herbicide treatment. Compared with either sweet potato competition or bentazon application alone, the combined impact of sweet potato competition and bentazon application was significantly higher. The suppression rates of the two methods combined were higher than 90% for a ratio of sweet potato to mile-a-minute of 2.5:1 plus bentazon applied at 1080 g ai hm-2 from 30-120 days. All results suggested that sweet potato competition and bentazon combined could achieve more secure, sustainable and long term control of mile-a-minute.