Indoor Toxicity and Field Control Effect of Different Herbicides to Major Weeds in Tobacco Fields

To screen efficient and safe herbicides against major harmful weeds in tobacco fields, indoor toxicity and field effect of 16 common pre-/post-seedling herbicides were detected on the gramineous weeds, broad-leaved species and sedge family by the tests of seed germination, indoor toxicity, and field control. The results showed that the inhibition rates of oxyfluorfen-metolachlor-pendimethalin and S-metolachlor ranged 45.7%-73.5% on seed germination of the tested weeds, yet with serious phytotoxicity to tobacco. S-metolachlor, napropamide, metolachlor, and clomazone-metolachlor were recommended to use before seedling emergence, with high toxicity to grass weeds while no harm to tobacco, and the field fresh mass control effect reaching 83.20%-92.57%. The post-seedling herbicides rimsulfuron-quizalofop-P-ethyl, rimsulfuron-haloxyfop-P-methyl, and rimsulfuron-clethodim, ranged their ED₅₀ for gramineous weeds as 56.0-264.6, 65.6-143.1, and 105.8-241.6 g/hm², respectively, while for broad-leaved as 172.7-303.8, 22.5-209.1, and 143.9-267.8 g/hm², respectively. They also exhibited field fresh mass control effects of 86.73%-92.82%, indicating better weed control effect and no harm, thus were recommended for the control of grass and broad-leaved weeds in tobacco fields. The research might lay a foundation for the precise control of weeds and rational use of herbicides in tobacco fields.