No abstract

The survey of weed occurrence was conducted to identify problematic weed species on the paddy field. Total 524 sites of the 17 regions in Chungnam Province in Korea were investigated from June to August, 2013. In the whole region, 23 weed species were identified including 19 annuals and 4 perennials. The most dominant weed species in Chungnam paddy fields were Echinochloa crus-galli (25.3%), followed by Monochoria vaginalis (11.9%), Eleocharis kuroguwai (10.3%), Bidens tripartite (9.3%) and Aneilema japonicum (8.5%). The 95.2% of the investigation sites was determined under dominance value 1 (range of cover <10: numerous individuals) by Braun-Branquet indicating proper weed control in the paddy fields. This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in Chungnam Province in Korea.

: This study was conducted to evaluate the herbicidal efficacy of carfentrazone-ethyl mixtures in direct-seeding flooded rice. The efficacy of three different carfentrazone-ethly mixtures was greater than pyrazosulfuron-ethyl ·pyriminobac-methyl GR (PP GR). Weeding efficacy of three different carfentrazone-ethly mixtures was more than 96.9%. No phytotoxic effect was observed in the rice based on the plant height and the number of tillers. Yield of rice un three different carfentrazone-ethly mixtures application was more than both in the PP GR and in the hand weeding. Based on these data, three different carfentrazone-ethly mixtures can be applied to provide an effective weed management in direct-seeding flooded rice.

:This study was conducted in order to utilize the basic data for weed control by surveying the occurrence of weed species. Total 63 sites of upland Chinese cabbage fields in Chungnam Provinces were investigated. The result of survey, 71 weed species in 25 families were identified and classified to 39 annuals, 16 biennials and 16 perennials. Based on the occurrence ratio, the most weed species belonged to Compositae (20 species). 8, 6 and 5 weed species belonged to Poaceae, Cruciferae and Polygonaceae, respectively, and these 10 weed species in the most six families accounted for 50% of total weed occurrence. The most dominant weed species in upland Chinese cabbage fields were Portulaca oleracea (8.07%), followed by Digitaria ciliaris (7.54%), Rorippa palustris (6.44%), Chenopodium album (5.73%), Echinochloa crus-galli (5.02%) and Cyperus amuricus (3.95).

: This study was conducted to evaluate the efficacy of two different formulations and application timings of benzobicyclon+penoxsulam+pyrzaosulfuron-ethyl (BPP) in rice field. BPP granule (GR) and tablet (TB) controlled more than 90% of four weed species 10 and 15 days after sowing in direct seeding when compared with untreated control. BPP TB was highly effective to control herbicide resistant Scirpus juncoides and Monochoria vaginalis both 10 and 15 days after transplanting (DAT). BPP GR controlled 94.0 and 96.5% of S. juncoides and M. vaginalis, respectively 10 DAT, but its efficacy decreased to 88.5 and 49.8% respectively 15 DAT. When compared with untreated control, no visual injuries were detected at 255 and 510 g a.i./ha of BPP. The yield of rice increased in both BPP GR and TB in transplanting and direct seeding rice cultivation when compared with untreated control. Based on these data, early application (10 DAT) of BPP GR and TB can be applied to provide effective weed control, especially in the field infested with herbicide resistant weed species.