Weedy rice (Oryza spp.)

Abstract Weedy rice (Oryza spp.) has emerged as a global threat to rice production in direct-seeded rice (DSR) systems. It is a difficult-to-control weed in DSR because of its close similarity to cultivated rice and lack of in-crop selective herbicide options for its control. Therefore integration of multiple tactics at multiple times (prior to and after rice sowing) would be needed for its effective and sustainable management in conventional (nonherbicide tolerant) rice cultivars. These multiple tactics include the use of clean seed machinery, tillage manipulation, stale seedbed technique, a combination of preemergence herbicides (e.g., pretilachor or oxadiazon) and flooding before rice sowing, manipulating crop–weed competition in favor of rice by using high seeding rate, rotation of rice establishment methods, line sowing, hand/mechanical weeding/roguing, early flooding, and crop rotation. Herbicide-tolerant rice technology enables the use of selective herbicides (in-crop) for controlling weedy rice effectively in DSR.