Glyphosate‐resistant Italian ryegrass (Lolium multiflorum) on rice paddy levees in Japan. Issue 1 (6th March 2013)

• Record Type: Journal Article
• Authors: Niinomi, Yuki; Ikeda, Mutsuhiro; Yamashita, Masayuki; Ishida, Yoshiki; Asai, Motoaki; Shimono, Yoshiko; Tominaga, Tohru; Sawada, Hitoshi
• Is Part Of: Weed biology and management. Volume 13:Issue 1(2013)
• Page Start: 31
• Page End: 38
• Publication Date: 2013-03-06
• Subjects: Weeds -- Periodicals; Weeds -- Control -- Periodicals; 632.5
• DOI: 10.1111/wbm.12007
• Languages: English
• ISSNs: 1444-6162

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The rapid range expansion of naturalized Italian ryegrass (<italic>Lolium multiflorum</italic> Lam.) in farmland is a serious problem in Fukuroi city in Shizuoka Prefecture, Japan. Glyphosate has been used to control Italian ryegrass in the levees of rice paddy fields and wheat fields for ∼20 years, but this weed in Fukuroi city is poorly controlled by glyphosate. In order to elucidate the level of resistance to glyphosate in Italian ryegrass populations, seed bioassays and a foliar application experiment, using seeds collected from 16 wild populations in and around Fukuroi city and from three susceptible cultivars, were conducted. For the susceptible cultivars and one population from a site where glyphosate had not been applied for >10 years, the shoot length in the seed bioassays was greatly suppressed at a glyphosate concentration of 10 mg ai L<sup>−1</sup> and no seedling survived after the foliar application of glyphosate at a rate of 2.3 kg ai ha<sup>−1</sup>. Nine wild populations from levees in the southern part of Fukuroi city showed vigorous shoot growth at a glyphosate concentration of 10 mg ai L<sup>−1</sup> and had at least a 78% survival rate after the application of glyphosate at 2.3 kg ai ha<sup>−1</sup>. Four wild populations from levees in the northern part of Fukuroi city showed a slight suppression of the shoot growth as a result of the glyphosate treatment and their survival rates ranged from 20 to 64%. The results suggested that resistance to glyphosate has evolved in the wild populations of Italian ryegrass that are growing on the levees. This is the first report of a glyphosate‐resistant weed in Japan.</p> </abstract>