杂草种类、叶龄及药后降水时间对烟嘧磺隆药效的影响

温室盆栽条件下研究了反枝苋Amaranthus retroflexus、马唐Digitaria sanguinalis、稗草Echinochloa crus-galli、牛筋草Eleusine indica和苘麻Abutilon theophrasti 5种杂草对烟嘧磺隆的敏感性。结果表明:反枝苋和稗草对该药剂最敏感,而苘麻对烟嘧磺隆的耐药性最高。药液中添加2.5 mL/L的有机硅助剂Silwet L-77提高了对除马唐以外的所有草种的防除效果,表明在作用于马唐时Silwet L-77与烟嘧磺隆之间存在拮抗作用。杂草叶龄对烟嘧磺隆的药效有明显的影响,3~5叶期施药,防效高达89.9%以上,而7叶期的防效只有75%。药后1.5 h和3.0 h降水3 mm降低了烟嘧磺隆的防效,但药后6.0 h降雨对药效无显著影响。烟嘧磺隆与Silwet L-77混用,可提高药剂对反枝苋的抗雨水冲刷能力,但对马唐的效果没有提高。

The Influence of Weed Species, Leaf Stage and Rainfastness on the Performance of Nicosulfuron

Pot experiments were conducted to determine the response of Amaranthus retrofluxes , Digitaria sangunalis , Echinochloa crus galli, Eleusine indica, Abutilon theophrasti to nicosulfuron. A. retrofluxes and E. crus galli were more susceptible than other species, while A. theophrasti was the most tolerant species. Addition of Silwet L 77 increased the efficacy of nicosulfuron on all weed species except D. sangunalis . The influence of leaf stage on the performance of nicosulfuron was examined on D. sangunalis . Results showed that application to D. sangunalis at 3 to 5 leaf stage achieved 82% control even under the application rate 10 g ai/hm 2. Control efficacy was significantly decreased with increasing growth stage from 5 leaf to 7 leaf. The rainfastness of nicosulfuron was examined on A. retrofluxes and D. sangunalis . A rainfall of 3 mm was applied 1.5, 3.0 and 6.0 h after spray using a rain simulator. The activity of nicosulfuron was reduced significantly by rainfall 1.5 and 3.0 h after spraying, but not reduced 6.0 h after application. Addition of Silwet L 77 improved the rainfastness of nicosulfuron on A. retrofluxes , not on D. sangunalis .