Selectivity of Nitrofen and Oxyfluorfen BetweenPortulaca oleraceaEcotypes and Two Cabbage(Brassica oleraceavar.capitata)Cultivars

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Abstract
A collection of common purslane (Portulaca oleracea L.) ecotypes from various locations around the world was assembled at the University of Illinois. Applications of nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) to the various ecotypes showed that 3 of the 26 ecotypes [India, Mexico, and Florida (Sanford)] exhibited some degree of tolerance. This marginal tolerance rapidly disappeared as the rate of nitrofen increased beyond 0.56 kg/ha. All of the ecotypes tested were susceptible to applications of oxyfluorfen [2-chloro-2-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]. Oxyfluorfen was toxic to common purslane plants at rates as low as 5 g/ha. Treatment of ‘Hybelle’ (tolerant) and ‘Rio Verde’ (susceptible) cabbage (Brassica olerace var. capitata L.) cultivars with 3.36 kg/ha nitrofen reduced plant fresh weight to 82% and 62%, respectively, of control. Oxyfluorfen at 0.15 kg/ha reduced fresh weight to 60% and 27% for Hybelle and Rio Verde, respectively. Applications of nitrofen at 3.36 kg/ha reduced plant fresh weight in Hybelle the same amount as 100 g/ha oxyfluorfen and 70 g/ha in Rio Verde.