A survey of rice-field weeds in Ratnapura and Kurunegala districts of Sri Lanka.
A total of 147 weed species were recorded in this survey of rice in 1989, of which 44 occurred in at least 20% of the fields. Echinochloa crus-galli, E. colonum and Ischaemum rugosum were the most prevalent, while Fimbristylis miliacea, Cyperus pilosus and C. iria were also widespread. Broadleaved weeds, though common, generally did not present major problems to farmers, except Ludwigia hyssopifolia in the Ratnapura district. No major differences in the weed flora of the two districts were evident, despite the climate in Kurunegala being drier than in Ratnapura.