Cyhalofop-butyl

Cyhalofop-butyl is a white crystalline solid with a specific gravity of 1.2375 (20°C), boiling point of 363°C, melting point of 48-49°C, and vapor pressure of 8.8×10(-9)mmHg (20°C). It is soluble in most organic solvents, such as acetonitrile (57.3%), methanol (37.3%), acetone (60.7%), and chloroform (59.4%), but insoluble in water. The choice of formulation has a significant impact on the efficacy. With the same amount of active ingredient, the effectiveness of different formulations is as follows: emulsifiable concentrate > oil suspension concentrate > water emulsion > wettable powder.

The formulation processing usually involves the combination of active ingredient, adjuvant, solvent, and filler. Due to the different solubility of Cyhalofop-butyl in different solvents and the need for necessary adjuvant usage, a certain amount of adjuvant needs to be added to enhance the efficacy. In general, with the same amount of active ingredient, the effectiveness of different concentrations is as follows: 10% > 15% > 20% > 25% > 30% > 40%, excluding special adjuvants.

Different leaf ages of weeds have varying sensitivity to Cyhalofop-butyl. As the leaf age increases, the sensitivity decreases, and the application rate needs to be increased. Generally, for younger leaf ages, a smaller amount is required, while for older leaf ages, a larger amount is needed. The recommended application rate for barnyard grass is 1.5-2 leaves (experts can distinguish). The application rates for different concentrations are as follows: 10% - 60-70ml, 15% - 30-50ml, 20% - 25-35ml, 25% - 24-30ml, 30% - 20-25ml, 40% - 15-20ml. Due to the high safety of Cyhalofop-butyl on rice, it can be used to control barnyard grass in direct-seeded rice fields after 2-3 leaves have emerged. If the barnyard grass is identified later, it will be at the 3-5 leaf stage of rice. The best time to control barnyard grass with Cyhalofop-butyl is when the rice is at the 3-4 leaf stage.

Cyhalofop-butyl has been widely used in China for more than 10 years, and barnyard grass has developed some resistance to it. Increasing the application rate is necessary to achieve the desired effect. In areas with strong resistance, the application rate of Cyhalofop-butyl per mu ranges from 30-50 grams of active ingredient. In areas with less resistance, the minimum application rate is above 20 grams of active ingredient. Cyhalofop-butyl is currently popular for controlling mature sprangletop and resistant sprangletop. Higher application rates are required in fields with mature direct-seeded rice, while lower application rates are suitable for fields with newly direct-seeded rice. The normal application rate ranges from 20-30 grams of active ingredient.

Cyhalofop-butyl is a systemic herbicide that needs to be absorbed by the stems and leaves of weeds and translocated within the weed plants to exert its effect on the growth points. During application, it is important to ensure that the weed plants come into full contact with the herbicide solution. When using Cyhalofop-butyl on rice, the field should be drained first to expose more than 2/3 of the weed plants, and then a high-concentration and uniform fine spray should be applied. After 24 hours, the field should be flooded again to allow the herbicide solution to be fully absorbed and translocated.