Suppression of Cyperus rotundus L. in carrots with night applications of nitrofen or herbicidal oil*

Summary: Résumé: ZusammenfassungSelective control or suppression of Cyperus rotundus L. in carrot (Daucus carota L.) was investigated in Brazil using post‐emergence applications of nitrofen (2,4‐dichlorophenyl 4‐nitrophcnyl ether) or a herbicidal oil (11–7% aromatics). Night applications of nitrofen in water, nitrofen in the herbicidal oil and the herbicidal oil alone were more effective in suppressing the growth of C. rotundus foliage than day applications. Nitrofen and the herbicidal oil were, respectively, 50 and 30% more active in suppressing C. rotundus during the warm, wet season (October to March) than the cool, dry season (April to September) in Viçosa. Night applications of nitrofen (1, 2 and 4 kg/ha) in water and the herbicidal oil alone (100, 200 and 400 1/ha) suppressed C. rotundus by 60% or more, and resulted in similar carrot yields to the hand‐weeded control. Combinations of nitrofen in the herbicidal oil were more effective in suppressing C. rotundus than either herbicide applied alone, but the combinations tested were toxic to the carrots. Elimination du Cyperus rotundus L. dans les cultures de carrottes au moyen d'applications nocturnes de nitrofène ou d'une huile herbicide..