Phytotoxicity of trifluoromethyl- and methyl-substituted dinitroaniline herbicides on resistant and susceptible populations of black-grass Alopecurus myosuroides

A - Papers appearing in refereed journals

James, E. H., Kemp, M. S. and Moss, S. R. 1995. Phytotoxicity of trifluoromethyl- and methyl-substituted dinitroaniline herbicides on resistant and susceptible populations of black-grass Alopecurus myosuroides. Pesticide Science. 43 (4), pp. 273-277.

AuthorsJames, E. H., Kemp, M. S. and Moss, S. R.
Abstract

A Petri-dish assay was used to determine the phytotoxicities of the dinitroaniline herbicides pendimethalin, trifluralin, benfluralin and ethalfluralin, and the methyl-substituted analogues of the last three herbicides, on susceptible (Rothamsted) and multiple-herbicide resistant (Peldon) populations of blackgrass Alopecurus myosuroides Huds. The Peldon population showed a high degree of resistance to pendimethalin, which possesses a 3,4-dimethyl substitution. The two populations were equally sensitive to trifluralin, benfluralin and ethalfluralin which do not possess ring-methyl groups but contain a 4-trifluoromethyl group. Substitution of the 4-trifluoromethyl with a methyl group, as demonstrated by the analogues, reduced phytotoxicity, but to a much greater degree in Peldon than in the Rothamsted population. The study indicates that resistance to pendimethalin in the Peldon population is attributable to an oxidative degradation of the 4-methyl group, analogous to that which occurs with resistance to chlorotoluron. The lack of cross-resistance to the other dinitroaniline herbicides appears to be due to the absence of ring-methyl or other groups which are vulnerable to oxidative degradation, trifluoromethyl groups being particularly resistant to this form of reaction.

KeywordsAgronomy; Entomology
Year of Publication1995
JournalPesticide Science
Journal citation43 (4), pp. 273-277
Digital Object Identifier (DOI)doi:10.1002/ps.2780430405
Open accessPublished as non-open access
Funder project or code904
202
ISSN0031613X
PublisherWiley

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