WEED EMERGENCE AND CONTROL IN SOME DIFFERENT TYPES OF RICE (ORYZA SATIVA) CULTIVATION WITH CONTINUOUSLY REPLICATED CULTURE IN KOREA

摘要

This study was conducted to investigate the ecology of weed occurrence and to establish its economical weed control system under different cultivation methods in the paddy field. Herbicides, sulfonylurea compounds, were continuously applied at the rice field for four years. The main problem weed among annual and perennial weeds was Eleocharis kuroguwai that increased with number of cultivated year and the amount of its tuber was high at direct seeding on dry paddy field. Most of annual weeds including Echinochloa crus-galli were controlled in machine transplanting, water and dry direct seeding within 2 years. The tuber formation of Eleocharis kuroguwai was highly inhibited at the middle and latter period, and the sulfonylurea compound herbicide treatment by two times inhibited about 75～84%, and the additional treatment of bentazone showed 84～98%. This trend of control effect was similar in machine transplanting, water and dry direct seeding. The tuber formation of E. kuroguwai was highly inhibited by bentazone SL application at the middle stage of rice cultivation. The control of E. kuroguwai could be effective by the application of sulfonylurea system herbicides at the early stage of rice and the additional application on 20 days after the first treatment or bentazone SL application on 40～50 days after the first treatment.