Jae-Eup Park

Weeding Effect of Echinochloa oryzoides Resistant to ACCase and ALS Inhibitors by the Leaf Stages

ABSTRACT Weeding effect was investigated based on the leaf stages to several different herbicide treatments for an integrated weed management of herbicide resistant Echinochloa oryzoides to ACCase and ALS inhibitors in a rice field. Efficacy of soil-applied herbicide treatments before resistant E. oryzoides occurred was very effective. Pentaxazon 5% SC showed over 98% of weeding effect although E. oryzoides were emerged 31 days after the treatment. Until the leaf stage of 2.5, five herbicides, azimsulfuron․carfenstole 1.05% GR, bensulfuron-methyl․benzobicyclone․mefenacet 24.52% SC, bensulfuron-methyl․fentrazamide 7% SC, bensulfuron-methyl․mefenacet․oxadiargyl 21.6% SC and mefenacet․pyrazosulfuron-ethyl 3.57% GR showed perfect weeding effect. Benzobicyclone․mefenacet․penoxulam 21.5% SC and mefenacet․pyrazosulfuron-ethyl 3.57% GR were effective at the leaf stage of 3.0. It is very important to select the right herbicides for timing and their systematic application for controlling of E. oryzoides resistant to ACCase- and ALS-inhibitors.Key words: ACCase; ALS; Echinochloa oryzoides; herbicide resistance.

Competitiveness and Yield Loss Prediction of Water-seeded Rice by Densities of Scirpus juncoides Roxb

This study was conducted to predict the rice yield loss and determine the economic threshold levels for water direct seeded rice from competition of the most serious weeds, Scirpus juncoides Roxb. (bulrush) and Echinochlor crusgalli L. (barnyardgrass) in Daegu of Korea. To predict crop yield as a function of weed density used a rectangular hyperbola, and determine their economic threshold levels used the equation developed by Cousens. The rice yield loss model of S. juncoides was predicted as y

Herbicide Production (1964 to 2007) for Paddy Field and Aspects of Weed Occurrence

국립농업과학원 농업생물부, 441-707 경기도 수원시 권선구 수인로 150(Department of Agricultural Biology, National Academy of Agricultural Science, RDA., Suwon 441-707, Korea).*연락저자(Corresponding author)：Phone)+82-31-290-0582, Fax)+82-31-290-0508, E-mail)smoh530@hanmail.net(Received June 9, 2011; Examined June 20, 2011; Accepted June 23, 2011)

Identification of Major Broad Leaved Weed Seedlings Based on Morphological Characteristics

This study was conducted to develope identification method with major broad leaved weed seedlings. Characteristics of weed seedlings were investigated at two to four true leaf stage. Qualitative characteristics were more useful to identification of weed species than quantitative characteristics at the seedling stage. Many species were elliptic and broadly elliptic type in their cotyledon shape. Cotyledon shape of Cassia nomame and Calystegia sepium were broadly oblong. Four species were transverse broadly elliptic in their cotyledon shape. Rumex japonicus, Persicaria hydropiper, Euphorbia supina and Acalypha australis have three or more types in their cotyledon shape. Cotyledons of Vigna angularis var. nipponensis remained below ground after its germination. Many species were round in apex and were cuneate in base of cotyledon. Humulus japonicus and Polygonum aviculare were sessile in cotyledon base. The second true leaf shape of some species changed after first leaf stages. Glycine soja, V. angularis var. nipponensis and Kummerowia striata were broadly ovate, heart-shaped, orbicular or broadly obovate in their first true leaf, respectively, but the second true leaf shape of them were tripalmately compound. Aeschynomene indica and Cassia nomame were paripinnately compound leaf in their first and second true leaves. Margin of true leaves were entire in many species but six species including Xanthium occidentale were dentate in their true leaf margins. Margin of Euphorbia supina was entire in first true leaf and dentate in second true leaf. Margin of Chenopodium album and C. serotinum were entire in their first true leaf stage and erose in their second true leaf stage. The key for weed seedling identification of major weed species were made based on quantitative and qualitative morphological characteristics.