Management strategies for weedy rice in Asia
Rice is the principal source of food for more than half of the world population. In Asia, it is commonly grown by manual transplanting of seedlings after tillage in wet conditions. In recent years, however, growers in many Asian countries are slowly moving toward direct seeding of rice in response to the labor and water scarcity and increased production costs. Direct-seeded systems have several advantages; however, weeds, including weedy rice, are the major problem in these systems.
In Asia, the adoption of direct-seeded rice systems makes weedy rice infestation one of the most serious problems that growers encounter. This is mainly because of the morphological and physiological similarities of weedy rice to cultivated rice and the absence of standing water at the time of crop emergence. By infesting rice fields, weedy rice increases production costs and reduces farmers’ income by decreasing grain yield and grain quality. Chemical control measures to manage weedy rice in conventional rice cultivars are not an easy option, simply because of the similar physiological and morphological traits between weedy rice and cultivated rice. Therefore, managing weedy rice is a challenging and increasing problem for farmers in Asia. In the absence of selective herbicides, cultural weed management strategies may help reduce the problem of weedy rice.
This publication describes various cultural weed management strategies, both preventive and cultural, to reduce the problem of weedy rice in direct-seeded rice systems. This information will help researchers and extension specialists to develop programs to manage weedy rice in rice production systems.