Book excerpt: Weed infestations are a concern for every farmer . Depending on the type of rice production system, farmers across Asia often contend with the same or similar weed species. This group of species is relatively small, but of great importance, and includes many of the "world's worst weeds." In this guide, we have tried to collect practical information about some of the most common weeds of rice in Asia. The guide contains information about the botany, ecology, herbicide resistance, and cultural control of these species in a short text that should be easy to use in the field. In addition, it includes pictures to aid in early and accurate species identification.