The Study On Phytotoxicity Of Acetochlor Against Maize

The study was focus on the relationship between the phytotoxicity against maize of acetochlor and temperature, application timing and maize varieties etc. And it was also studied that the relationship between the efficacy of acetochlor and weeds stage. The results provided a scientific guidance for safe application of acetochlor with high efficacy in maize field.The results of study on the phytotoxicity of acetochlor against maize when acetochlor applied in maize pre-emergence period showed that: The different varieties of maize had different sensitivities to acetochlor. In the seeding stage, the earlier acetochlor was applied the more maize growth was reduced, and the bud of maize was more sensibility than the root. The phytotoxicity of acetochlor to maize was strong influenced by temperature. Under low temperature, the serious phytotoxicity could be found in all acetochlor treatments, and under high temperature, the degree of phytotoxicity was increased accompanied the increase of use doses of acetochlor.The results of study on the phytotoxicity of acetochlor applied in maize post-emergence period showed that: The seedling was restrained and the root was stimulated, the injury of acetochlor applied in maize pre-emergence period was less than the post-emergence period. The different varieties of maize had different sensitivity to acetochlor,. The sensitivity of maize to acetochlor was different with different maize stage, the sequence was: pre-emergence stage> 2 leaves stage> 3 leaves stage. The injury was not significant impacted by low or high temperature.The result of efficacy of acetochlor against different stage weed showed that acetochlor had good efficacy to control the younger weed. Acetochlor could provide enough efficacy against 1.5 leaves Digitaria Sanguinalis and 1 leaf Amaranthus restroflexus L. in net-covered experimental field, it also could provide good efficacy against 3.5 leaves Digitaria sanguinalis and 3.5 leaves Amaranthus restroflexus L. in field.The study showed that acetochlor was safer to maize when it applied in maize post-emergence period than that in per-emergence period. The efficacy against younger weed is acceptable when acetochlor is applied in the early post-emergence period of maize.