How to control Echinochloa (sawan / swank grass) in paddy?

Echinochloa (sawan, swank, jungle rice, barnyard grass) is the most damaging grassy weed in rice and is hard to spot early because the young plant mimics paddy seedlings, so by the time you notice, it is often too big to control well. The keys are early action and rotating modes of action, because Echinochloa has developed resistance to some common rice herbicides. In transplanted rice, a pre-emergence herbicide such as pretilachlor applied a few days after transplanting, followed if needed by an early post-emergence product like bispyribac-sodium or a recommended grass killer at the small-weed stage, gives good control. In DSR the pressure is higher, so pre-emergence within 1 to 3 days of sowing is essential, plus a timely post-emergence spray. Keeping a shallow layer of water on transplanted rice suppresses Echinochloa, while letting the field dry lets it flush. Use the stale seedbed method, a dense crop stand, and clean seed (it spreads through weedy seed lots). Rotate herbicide modes year to year to slow resistance. Use only herbicides recommended for rice, follow the label dose and timing, and confirm with your KVK, since timing is strict and resistance varies by area.