Revista Brasileira De Herbicidas 2006; 5(1): 10-18
PHYTOTOXICTY OF SULFONYLUREA IN TWO POTATO CULTIVARS
DOI: 10.7824/rbh.v5i1.40
In 2004, abnormalities in the formation of potato tubers were observed in the region of Casa Branca and Aguaí, São Paulo State, Brazil, due to the contamination of sprayer tanks with sulfonylurea. Most of the tubers from all plants presented many cracks and other deffects that disqualified them commercially. Potato response to simulated tank contamination of three sulfonylurea herbicides was evaluated in pot studies in Águas da Prata, São Paulo State, Brazil. Metsulfuronmethyl, nicosulfuron and sulfometuron-methyl were applied in post-emergence in Atlantic and Lady Roseta cultivars at rates corresponding to 0, 0.00001, 0.0001, 0.001, 0.01, 0.1 and 1 times the recommended use rate of each one, corresponding to 3 g ha-1, 60 g ha-1 aand 15 g ha-1, respectively. Potato foliar injury was evaluated visually 5, 20, 35 and 42 days after treatment on a scale of 0 to 100, with 0 indicating no injury, and 100 a complete kill. There was not product effect on average plant height. None of the dosage applied kill the potato plants. Potato foliar injury was generally most severe with metsulfuron-methyl and least severe with nicosulfuron. In general, for the Atlantic cultivar, the phytotoxicity increased exponentially with increased sulfometuron-methyl dosage, for all evaluations. For metsulfuron-methyl and nicosulfuron, the phytotoxicity increased according to a second order equation. For the Lady Rosetta cultivar, the phytotoxicity increased exponentially at 5 and 20 days, but at 35 days, for metsulfuron-methyl and sulfometuron-methyl, increased following a second order equation. All products, specially metsulfuron-methyl and sulfometuron-methyl, delayed notably the vegetative cycle, even at lowest dosages.
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