Managing weedy rice (Oryza sativa L.) in Malaysia: challenges and ways forward

Rice industry in Malaysia faces serious challenges in managing weedy rice (Oryza sativa L.) since it was first observed in 1988. Unfortunately, there is no simple control method for weedy rice. Recommended practices in Malaysia adopted various integrated weedy rice management strategies mainly on land preparation and pre-harvest period controls. Multiple tillage, chemical applications via pre-emergence and pre-sowing herbicide, and manual weeding are the usual weedy rice control practices by majority of Malaysian farmers. The conspecific nature of weedy rice with cultivated rice increased the difficulty to control the weed with several weedy rice biotypes have already mimic the local varieties. Introduction of Clearfield® Rice Production System (CPS) in 2010 has shifted the current weedy rice management strategies to an herbicide-tolerant crop approach. Some concerns of the technology including potential resistant to weedy rice and environmental issues were discussed. Additional weedy rice management strategies as alternative approaches for Malaysia rice agro-ecosystems were proposed in this review to fill the gaps on current weedy rice controls including reducing cross contamination between farms, managing weedy rice seedbank, empowering alternative culture methods in rice farming, strengthening current Clearfield® system, and exploring ‘omics' research for other potential herbicide tolerant rice. Improvement in communication is proposed to ensure any information on weedy rice management is effectively transferred between farmers and authorities.