THE USE OF HERBICIDES FOR WEED-CONTROL IN FLOODED RICE IN NORTH ITALY

The use of chemicals to control weeds in flooded rice in the Po Valley , Italy is restricted by limited knowledge of potentially useful herbi cides. Different strategies of chemical weed control, including differ ent application timings of several types of herbicides are compared ba sed on effectiveness and selectivity. Echinochloa spp., the most commo n weed was, in the experimental conditions, better controlled with ear ly applications (pre-sowing and preemergence) of new herbicides which were effective substitutes for molinate, the use of which is no longer allowed in some Italian areas. Alisma plantago-aquatica, Bolboschoenu s maritimus and Schoenoplectus macronatus were controlled by different types of herbicides applied post-emergence. Cinosulfuron (sulfonylure a) showed the highest effectiveness and selectivity in controlling the more common Hetherantera spp., even when applied in very low amounts.