Strategies to manage weedy rice in Asia

Weedy rice, an emerging problem in Asia, increases production costs and reduces farmers' income through yield reduction and through lowered rice value at harvest. Rice farmers in many Asian countries are shifting from transplanting to direct seeding; however, due to physical and physiological similarities of weedy rice to cultivated rice and the absence of standing water at the time of crop emergence, adoption of direct-seeded rice systems makes weedy rice infestation one of the most serious problems. Selective herbicides to control weedy rice in conventional rice cultivars are not available and therefore managing weedy rice is a challenging and increasing problem for farmers in Asia. In the absence of selective herbicides, various cultural weed management strategies may help reduce the problem of weedy rice. These strategies may include the use of clean seeds and machinery, use of stale seedbed practice, thorough land preparation, rotation of different rice establishment methods, use of high seeding rate and row-seeded crop, use of purple-coloured cultivars, use of flooding, and adoption of crop rotation.

► Weedy rice is an emerging problem in Asia, especially in direct seeding.
► Various cultural weed management strategies may help reduce weedy rice problem.
► Use clean seeds, machinery, stale seedbed practice, and thorough land preparation.
► Strategies also include establishment methods, row-seeded crop, and crop rotation.