The need for improved weed management in rice - R. Labrada

Weeds are the cause of serious yield reduction problems in rice production worldwide. Losses caused by weeds vary from one country to another, depending on the predominant weed flora and on the control methods practised by farmers. Two examples give an idea of the dimensions of the problem. In China, 10 million tonnes (Mt) of rice are lost annually due to weed competition (Ze Pu Zhang, 2001); such a quantity of rice is sufficient to feed at least 56 million people for 1 year. In Sri Lanka, a country considered self-sufficient in rice, weeds are the major biotic stress in rice production and account for 30 to 40 percent of yield losses (Abeysekera, 2001).