What herbicide is effective for controlling resistant Chinese sprangletop?

During this period, many agrochemical dealers and growers have reported that Chinese sprangletop (Leptochloa chinensis) is very severe in rice fields, and many fields have failed to control it. Especially in fields where Chinese sprangletop control failed, later follow-up treatments also seem to be less than ideal. Below, based on some professional experience, I will discuss some management recommendations for resistant Chinese sprangletop.

Pre-emergence closed-canopy herbicides are still quite effective for controlling Chinese sprangletop, especially the herbicide variety pretilachlor, which achieves over 90% control of Chinese sprangletop. In dry direct-seeded rice, using closed-canopy herbicides such as pendimethalin and butachlor also provides very good control of Chinese sprangletop. More importantly, pre-emergence closed-canopy herbicides also control sedges very well; for example, pretilachlor achieves over 90% control of sedges. Reducing the population base of weeds such as sedges is very helpful for later weed control. In the later stage, we can then reduce the use of herbicides that are antagonistic to cyhalofop-butyl, thereby ensuring the efficacy of cyhalofop-butyl. At the 4-leaf stage of rice seedlings, you can use Weidaofu + cyhalofop-butyl for spray control, or Qianbai + cyhalofop-butyl for spray control.

Choose appropriate herbicides for mixing. When controlling Chinese sprangletop, avoid mixing with herbicides that are antagonistic to cyhalofop-butyl, such as pyrazosulfuron-ethyl, MCPA, and bentazone.

Avoid applying herbicides on hot sunny days. Cyhalofop-butyl needs to be absorbed systemically to work. If it is hot with strong sunlight, the weed stomata close, making it difficult for the plants to absorb the herbicide, and intense sunlight can also cause cyhalofop-butyl to photodegrade.