Uptake, translocation and metabolism of the herbicide florasulam in wheat and broadleaf weeds

• Published in: Pest management science 2006-04, Vol.62 (4), p.316-324
• Main Authors: DeBoer, G.J, Thornburgh, S, Ehr, R.J
• Format: Article
• Language: English
• Subjects: application rate; biochemical pathways; Biological and medical sciences; Biological Transport; chemical structure; cleavers; florasulam; Fundamental and applied biological sciences. Psychology; Galeopsis tetrahit; Galium - metabolism; Glucose; Herbicides; Herbicides - chemistry; Herbicides - metabolism; Herbicides - pharmacokinetics; Lamiaceae - metabolism; Mass spectrometry; mechanism of action; Metabolism; Molecular Structure; Nitrogen; Parasitic plants. Weeds; Pest control; Phytopathology. Animal pests. Plant and forest protection; phytotoxicity; Plant Leaves - metabolism; Plant Roots - metabolism; Polygonum - metabolism; Polygonum lapathifolium; Pyrimidines - chemistry; Pyrimidines - metabolism; Pyrimidines - pharmacokinetics; structure-activity relationships; Sulfonamides - chemistry; Sulfonamides - metabolism; Sulfonamides - pharmacokinetics; translocation; translocation (plant physiology); Triticum - metabolism; Triticum aestivum; uptake; uptake mechanisms; weed biology; weed control; Weeds; Wheat
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.1163

Florasulam is a triazolopyrimidine sulfonanilide post-emergence broadleaf herbicide for use in wheat (Triticum aestivum L.). The selectivity of florasulam to wheat has been determined to be related primarily to a differential rate of metabolism between wheat with a half-life of 2.4 h and broadleaf weeds with half-lives ranging from 19 to >48 h. To a lesser extent, selectivity, at least for the broadleaf weed cleavers (Galium aparine L.), involves uptake differences. Rate of metabolism data were generated using greenhouse-grown plants injected with radiolabelled florasulam and subsequent extraction and processing by high-performance liquid chromatography (HPLC). Structures of metabolites were determined by isolation for nuclear magnetic resonance and liquid chromatography/mass spectrometry. Wheat plants metabolised florasulam by hydroxylation of the aniline ring para to the nitrogen, followed by conjugation to glucose. Metabolism by broadleaf weeds was so slow that isolation of metabolite was not possible, but comparison of HPLC data suggested hydroxylation as the major pathway.