Weed problems and their management in rice fields of Malaysia: An overview

Abstract

The available literature on weed problems and weed control in rice fields in Malaysia is reviewed and suggestions for future research are included. The problem of weed competition with rice is of great economic importance in the country because it causes a 10-35% reduction in grain yield. About US$4.10 million is spent annually on herbicides for rice alone, and this amounts to approximately 7% of the total expenditure on herbicides. The shift in methods of rice culture from transplanting to direct seeding has magnified the weed problem. The problem of weedy rice is particularly acute in the direct-seeding rice areas. Although a number of sulfonylurea herbicides (e.g. cinosulfuron, metsulfuron, bensulfuron and pyrazosulfuron) have been found to be suitable alternatives to the old herbicide 2,4-D, an integrated weed management program must be developed in order to reduce the problem of herbicide resistance in weeds. Weed control methods that are more friendly to the environment and affordable to farmers must be sought. Weed-competitive and allelopathic rice varieties must be produced. The problem of weeds in rice calls for systematic studies on biotechnological methods of control of weedy rice. Detailed studies on the biology and ecology of notorious rice weeds, particularly Oryza sativa L. (weedy rice), Echinochloa spp., Leptochloa chinensis (L.) Nees, Fimbristylis miliacea (L.) Vahl. and Limnocharis flava (L.) Buch. need to be done in order to formulate successful weed control measures.

E Efficacy and Economics of Herbicidal Weed Management in Monsoon Rice of Bangladesh

“…Moreover, mimic nature of grassy weeds like Echinochloa crusgalli to rice seedlings (Rao and Moody, 1988), increase difficulty of manual weeding. To overcome this problem, herbicidal weed control has been widely used to manage weeds in some Asian rice-growing countries for example, Philippines (Casimero et al, 1994;Johnson et al, 2010), Malaysia (Karim et al, 2004) and Vietnam (Luat, 2000). It has been widely accepted by researchers that herbicides have the potential to reduce labour inputs (Ahmed et al, 2001).…”

Allelopathic Effect of Echinochloa colona L. and Cyperus iria L. Weed Extracts on the Seed Germination and Seedling Growth of Rice and Soyabean

“…According to Karim et al [5], the annual rice yield loss due to weed infestation is about 15-21%. Weed management has been a challenge for the rice farmers as weed is one of the major problems in rice production [6].…”

Weed Dynamics of Aerobic Rice (Oryza sativa L.) under Chemical and Non-Chemical Weed Management Practices in Irrigated Ecosystem

“…High weed infestation is a major constraint for broader adoption of DSR (Rao et al, 2007). Yield reduction due to weeds is more critical in direct seeded rice than in transplanted rice (Karim et al, 2004). DSR approach demands a weed management strategy that is selective, efficient and cost effective with little or no adverse ecological effects.…”