The soil degradation of the herbicide florasulam

✍ Scribed by Roy Jackson; Dipankar Ghosh; Glen Paterson

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 120 KB
• Volume: 56
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/1526-4998(200012)56:12<1065::aid-ps252>3.0.co;2-y

✦ Synopsis

The route and rate of degradation of ¯orasulam, a low-rate triazolopyrimidine sulfonanilide herbicide, was investigated in six soil types under aerobic conditions at 20 or 25 °C. Degradation products were isolated and identi®ed by mass spectroscopy. Florasulam was rapidly degraded by microbial action with an average half-life of 2.4 days (range 0.7 to 4.5 days). The ®rst step in the degradation pathway involved conversion of the methoxy group on the triazolopyrimidine ring to a hydroxy group to form N-(2,6-di¯uorophenyl)-8-¯uoro-5-hydroxy[1,2,4]triazolo[1,5-c]pyrimidine-2sulfonamide. This metabolite degraded, with a half-life of 10 to 61 days, via partial breakdown of the triazolopyrimidine ring to form N-(2,6-di¯uorophenyl)-5-aminosulfonyl-1H-1,2,4-triazole-3-carboxylic acid. This was followed by cleavage of the sulfonamide bridge to form 5-(aminosulfonyl)-1H-1,2,4-triazole-3-carboxylic acid. Other degradation processes involved decarboxylation of the carboxylic acid metabolites and mineralisation to form carbon dioxide and non-extractable residues.