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This study was conducted to evaluate the efficacy of weed control and phytotoxicity of oxyfluorfen using a transgenic rice line (CPPO06 event) resistant to protoporphyrinogen oxidase (Protox) inhibiting herbicides in the direct-seeding flooded rice. Five annual weeds including Echinochloa oryzoides and two perennial weeds were occurred in the test field. Oxyfluorfen at 120 g a.i. ha -1 in the application timing of two days before sowing and 0 and five days after sowing showed more than 90% weed control value except for Juglans mandshurica. Total weed control value was more than 95% in any application timing indicating a highly effective herbicide in the direct-seeding flooded rice. When compared with untreated control, no visual injuries were detected at single and double dosage of oxyfluorfen. The agronomic characteristics and yield components of CPPO06 event was reasonable in any time of application in this study. Based on these data, oxyfluorfen application before and after sowing can be applied to provide effective weed management in the direct-seeding flooded field.

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 efficacy and phytotoxicity of glufosinate-ammonium in controlling annual and perennial weeds on paddy ridges. Glufosinate-ammonium SL (900 g a. i./ha) and glufosinate-ammonium ME (600 g a. i./ha) mixed with fluthiacet-methyl (10 g a. i./ha) were tested in the field experiments. Five annual weed species, Glycine soja, Erigeron canadensis, Disitaria ciliaris, Poa annua and Echinochloa utilis, and four perennial weed species Elymus tsukushensis, Taraxacum platycarpum, Equisetum arvense and Artemisia princeps were identified on the paddy ridges. The results of this experiment indicated that these annual and perennial weeds could be effectively controlled by both the herbicides. Application of these herbicides did not negatively affect the number of tillers and plant height of rice grown near the treated paddy ridges. Therefore, it can be concluded that the non-selective glufosinate-ammonium can provide an effective control of weeds on the paddy ridges if application is properly made.