Safety and weed control efficiency of bromoxynil mixed with quizalofop-p-ethyl on flax

In order to screen safe and efficient of herbicides for the control of weeds in flax field, the safety and control efficiency of bromoxynil mixed with quizalofop-p-ethyl against weed in flax field were determined by indoor bioassay and field experiments, and the yields was also studied. The results showed that the mixture of bromoxynil and quizalofop-p-ethyl had no toxic effect on flax at 375-450 g a.i./hm², 21 days after the application under laboratory conditions. When the dosage increased to 675 g a.i./hm², the phytotoxicity on the seedlings was observed. The selectivity index of mixture to Echinochloa crusgalli and Amaranthus retroflexus were both 1.42, which was higher than the value of MCPA-Na (0.53, 0.85). This result indicated that there was potential hazard risk for the application in flax field, and the dosage of the mixture should be strictly controlled. In the field application, the average increase of flax height, 35 days after treatment, was 42.33 cm, which was higher than that of the control (bromoxynil: 40.93 cm; quizalofop-p-ethyl: 41.80 cm) and the blank control (39.07 cm). Compared to the application of bromoxynil or quizalofop-p-ethyl alone, the average fresh weight of flax treated by the mixture was increased by 2.7% and 4.6% respectively, which was 8.3% higher than that of the blank control. Therefore, the mixture of bromoxynil and quizalofop-p-ethyl can be used to control Gramineae and broad-leaved weeds in flax fields. In order to prevent the occurrence of phytotoxicity, the dosage should be strictly controlled. Besides, the directional spray should be carried out with the protective cover sprinkler.