Journal of Weed Science and Technology
Online ISSN : 1882-4757
Print ISSN : 0372-798X
ISSN-L : 0372-798X
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Volume 55, Issue 3
Displaying 1-9 of 9 articles from this issue
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Reports
  • Effects of cultivation practices on root development and weed tuber propagation in organic paddy rice field.
    Shinji Iwaishi, Takaaki Miki, Sigeru Kato, Yanrong Wang
    2010 Volume 55 Issue 3 Pages 149-157
    Published: 2010
    Released on J-STAGE: October 15, 2010
    DOIhttps://doi.org/10.3719/weed.55.149
    JOURNAL FREE ACCESS
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    To confirm the effects of tilling practices with organic material incorporation on weed flora, we conducted an experiment in the paddy field, where organic rice had been grown successively for more than 30 years, in Hatamachi, Nagano, and examined root system formation of weed and rice under tillage practices with organic matter as soil amendment from 2003 to 2005. A factorial experiment was carried out with split plot design of 1) fall tillage (done and none), 2) timing of spring tillage and fertilization (0 day and 40 days before water immersion) and 3) fertilization and tilling depth (5 cm and 15 cm), The fresh mass of Sagittaria trifolia L, Scirpus hotarui Roxb. var. ohwianus T. Koyama Ohwi, and other small broad leaved weeds decreased under the cultivation practices. Although the soil available nitrogen was decreased by the fall tillage, the rice yield in plots without weeding increased, along with the weeds root dry mass and tuber dry mass of Eleocharis kuroguwai Ohwi reduced. Available nitrogen emission from soil tilling at the time of water immersion increased in comparison with that 40 days before immersion, which then made new tuber enlargement if no plowing was done before water immersion. It was suggested that the plowing practice of fall tillage with straw incorporated, then spring shallow tillage with organic fertilized immediately before transplanting and early weeding after transplanting, could decrease nutrient supply quantity in addition to weeding effect, exert influences on the root system development of the paddy rice, and avoid the weed domination and rice yield decrease.
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  • Wheat seeding time, seeding rate and trifluralin application affect the control of wild oat (Avena fatua).
    Motoaki Asai, Yasuhiro Yogo
    2010 Volume 55 Issue 3 Pages 158-166
    Published: 2010
    Released on J-STAGE: October 15, 2010
    DOIhttps://doi.org/10.3719/weed.55.158
    JOURNAL FREE ACCESS
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    Field experiments were conducted in Tsukuba, Ibaraki, in 2000 and 2001, to determine the effects of seeding time and trifluralin application on suppression of wild oat (Avena fatua, which causes serious problems in winter cereal production) and winter wheat growth. Wild oat emerged mainly in late November to early December in both years. Delayed seeding reduced wild oat density; a seeding date past late November was estimated to suppress wild oat seed set lower than the initial density. Trifluralin emulsion applied at 1.34 kg/ha, highest recommended rate, reduced wild oat plants, panicles and spikelets to 70% and 30% of controls, with variation between years. The effect of trifluralin application on wild oat suppression was roughly equivalent to one week delayed seeding, indicating that late November seeding with trifluralin correspond to early December seeding without trifluralin. Seeding time affect wheat growth, delayed seeding time caused yield reduction in the 2000 experiment, when weather conditions were cold, even though seeding rates were increased. These data indicate that delayed seeding is effective for wild oat management in infested fields and can replace the need for trifluralin application.
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  • Effect of a diquat-paraquat herbicide mixture and straw cover on wild oat (Avena fatua) seedling emergence
    Motoaki Asai, Yasuhiro Yogo
    2010 Volume 55 Issue 3 Pages 167-173
    Published: 2010
    Released on J-STAGE: October 15, 2010
    DOIhttps://doi.org/10.3719/weed.55.167
    JOURNAL FREE ACCESS
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    Paraquat is an herbicide that inhibits germination and seedling growth of grasses, including wild oat (Avena fatua L.), a problematic weed in winter cereals. Outdoor pot experiments were conducted to determine the influence of paraquat on wild oat seedling emergence to evaluate the efficacy of this herbicide as a tool for an integrated management system. A diquat+paraquat liquid formulation (7.0% diquat dibromide and 5.0% paraquat dichloride) was sprayed at a rate of 1,000ml/10 a directly onto wild oat seeds placed on the soil surface, and the soil was not disturbed during the following year. Fewer viable wild oat seeds were recovered from the diquat+paraquat treatment relative to a glyphosate ammonium salt (41.0%, 500ml/10 a) treatment. A treatment of diquat+paraquat greater than 3,000ml/10 a markedly reduced wild oat seedling emergence if the seeds were incorporated into the soil soon after the application. However, when the wild oat seeds were covered with chopped straw, no suppression of emergence could be detected with diquat+paraquat application even at a rate of 4.6 times the recommended dose. Increasing the dilution water volume also decreased the effectiveness of emergence suppression. Our results suggest that diquat+paraquat spray following wheat harvest would not be effective for reducing wild oat germination and seedling emergence in the summer.
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  • A simple method to assess wheat yield loss by Italian ryegrass (Lolium multiflorum Lam.) in the fields
    Tomoko Suzuki, Yusuke Adachi, Minoru Ichihara, Masayuki Yamashita, Hit ...
    2010 Volume 55 Issue 3 Pages 174-182
    Published: 2010
    Released on J-STAGE: October 15, 2010
    DOIhttps://doi.org/10.3719/weed.55.174
    JOURNAL FREE ACCESS
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    A field assessment method to visually evaluate the wheat yield loss by Italian ryegrass (Lolium multiflorum Lam.) was developed. This survey was conducted in soybean-wheat rotational fields during 2004 to 2007 at Toyozumi, Fukuroi city, Shizuoka Prefecture, Japan. In June of each year, Italian ryegrass infestation levels for each field were visually rated according to six grades, and wheat and weed yield were quantified. Visual grading of ryegrass infestation was a reliable predictor of the relative wheat yield loss and weed abundance (plant density and dry matter). Ryegrass density and dry matter correlated with wheat yield loss;the relationship was described with a quadratic hyperbolic regression curve. Wheat yield loss up to 20% was regressed at weed densities of 8 to 12 plants m-2. Our results suggest that visual estimation of weed infestation is easy and effective for regional assessment of weed monitoring, crop loss and economic damage.
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Short Report
Technical Report
Special article: Evaluation methods for soil seed bank of weeds
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