ABSTRACT
Weeds are the most important biological constraint to rice production worldwide (106). Perhaps the most difficult to control weed (actually a weed complex) in rice is weedy rice (Oryza spp.). This chapter describes general characteristics and the negative agronomic importance of weedy rice. The variability of weedy rice and the genetic relationships between weedy and cultivated rice are discussed in terms of the difficulty to identify weedy rice and the likelihood that it will remain undetected until infestations are sufficiently high to cause major losses in crop productivity. Practical approaches to field management of weedy rice, including chemical control and use of herbicideresistant rice varieties, are also discussed. Finally, consideration is given to the spread of weedy rice and farmer attitudes that affect management of this weed complex.
