Evaluation Of The Phytotoxicity Of Glufosinate, The Interaction Of Glufosinate With Several Agro-chemicals

Glufosinate has been used widely as a non-selective herbicide in the world. Glufosinate-resistant crops were successfully bred in China. However, there was nothing done about the phytotoxicity of this herbicide. During 2001~2002, field and greenhouse experiments were conducted to evaluate the efficacy of glufosinate in controlling summer weeds in Beijing, to determine the interaction of the chemical with quizalofop-methyl and MCPA, and the effect of adjuvants ammonium sulfate, laurocapram Azone, and vegetative oil Hasten on its bioactivity.The results of the repeated field experiments showed that the herbicidal activity of glufosinate was faster than that of glyphosate and slower than that of paraquat. Glufosinate at 400 g a.i./ha was effective on Portulaca oleracea, Amaranthus retrqflexus, Eclipta prostrata, and Potentilla chinensis, at 800 g a.i./ha on Echinochloa crus-galli, Digitaria sanguinalis, and Abutilon theophrasti, but not on Chenopodium album and Sedges.According to the Additive Dosage Model, glufosinate plus quizalofop-methyl over a range of 53.3~3.3:1 ratios was significantly synergic to E. crus-galli. The best ratio was 9.99:1. The phytotoxicity at this ratio was as 1.45 times as the expected. The mixtures of the two herbicides over a range of 26.6~3.3:1 was synergic to A. retrqflexus. The interaction of the mixture of glufosinate plus MCPA on E. crus-galli depended on the ratios of the two herbicides. It gave synergic effect on the weed at the ratios of 2:1 and 1:1 and antagonistic effect at the ratios of 1:2,1:4 and 1:8. These two herbicides trended to provide additive effect on A. retrqflexus.Added ammonium sulfate, laurocapram and the vegetative oil could enhance the phytotoxicity of glufosinate to E. crus-galli and A. retrqflexus. However, the extent of the increase in the toxicity depended on the kind of adjuvant and the amount added. Glufosinate had the highest phytotoxicity when ammonium sulfate was added at the rate of 0.2% among three added rates of 0.15%, 0.2%, and 0.3%. Toxicities to E. crus-galli and A. retrqflexus increased by 0.73 and 1.57 times, respectively. The amount of added laurocapram was negatively correlated with the phytotoxicity of glufosinate over a range of 0.5-2.0%. Added laurocapram of 0.5% increased in the toxicity to both weed species by 0.95 times. The amount of added the vegetative oil, however, was positively correlated with phytotoxicity of glufosinate over a range of 0.5~2.0%. Added the vegetative oil of 2.0% increased in toxicities to E. crus-galli and A. retrqflexus by 0.28 and 1.52 times, respectively. The order of enhancing toxicity ofglufosinate to E. crus-galli was laurocapram > ammonium sulfate > the vegetative oil, to A. retroflexus, ammonium sulfate>the vegetative oil > laurocapram.