Efficacy Of Butralin On Weeds In Rice Paddy And Dryland And Its Safety

In order to research the application feasibility of butralin in rice and tomato field, the efficacy of butralin on weeds in rice paddy and dryland fields and its safety on rice and tomato growth were studied by indoor bioassay and field test in2011. The residue dynamics of butralin using gas chromatography (GC) was estimated. The results as follow:(1) Butralin48%EC applied at1080～3600g a.i./hm2at7days after transplanting rice by soil treatment had high efficacy on the annual gramineous weeds(Echinochloa crusgalli and Digitaria sanguinalis), and had obvious efficacy on broad-leaved weeds (Monochoria vaginalis and Rotala indica) and Cyperaceae weeds(Cyperus difformis and Eleocharis yokoscensis). Butralin48%EC applied at1080-3600g a.i./hm2by soil treatment before transplanting tomato had high efficacy on the annual gramineous weeds (Eleusine indica, Digitaria sanguinalis and Cynodon dactylon), and had obvious efficacy on broad-leaved weeds(Amaranthus retroflexus) and cyperaceae weeds(Cyperus difformis and Cyperus compressus), and had low efficacy on broad-leaved weeds (Alternanthera philoxeroides).(2) Butralin48%EC was safe at1080g a.i./hm2by soil-applied before seedlings after sowing seeds and had inhibitory at1800g a.i./hm2and was potential dangerous at3600～7200g a.i./hm2on rice seedling. Butralin48%EC was safe at1080～1800g a.i./hm2by foliar-applied after transplanting and had inhibitory at3600～7200g a.i./hm2but different rice varieties was different on rice growth. Butralin48%EC was safe at1080～3600g a.i./hm2by soil-applied after transplanting and had inhibitory on rice growth at7200g a.i./hm2. Butralin48%EC was safe on tomato seedling at1080～1800g a.i./hm2by soil treatment before seedlings after sowing seeds and was potential dangerous on tomato at3600～7200g a.i./hm2. The sensitivity of butralin at1080～1800g a.i./hm2to different tomato varieties was significantly different by foliar-applied after transplanting, and butralin at3600～7200g a.i./hm2had obvious inhibitory on tomato growth. Butralin was safe on tomato growth at1080～3600g a.i./hm2by soil-applied before transplanting and had the certain inhibitory on tomato growth at7200g a.i./hm2.(3) Samples of soil were extracted by acetone. The extract was cleaned-up with florisil cartridge. The residue of butralin was determined by GC method. The average recoveries ranged from90.71%to99.06%with relative standard deviation0.89%～3.34%. The lowest detectable concentration of butralin in soil was0.05mg/kg, and the detection limit was1.89×10-10g. The results showed that the half lives of butralin in soil were9.04d and11.17d at a recommended dosage (1800g a.i./hm2) and two recommended dosages (3600g a.i./hm2), respectively.