KENAF TOLERANCE TO ACIFLUORFEN, CYANAZINE, DIURON, FLUOMETURON, FOMESAFEN, LACTOFEN, OR PROMETRYN APPLIED POSTEMERGENCE-DIRECTED

Field experiments were conducted in 1993 (Dundee clay loam, 1.8% OM, p H 6.2), and 1994 (Tunica clay loam, 1.8% OM, pH 5.5) to evaluate kenaf (Hibiscus cannabinus L.) tolerance to acifluorfen (0.42, 0.56, and 0. 84 kg al ha(-1)), cyanazine (0.89, 1.2, and 1.8 kg al ha(-1)), diuron (0.67, 0.89, and 1.3 kg al ha(-1)), fomesafen (0.42, 0.56, and 0.84 kg al ha(-1)), fluometuron (1.12, 1.45, and 2.24 kg al ha(-1)), lactofen (0.22, 0.29, and 0.45 kg al ha(-1)) or prometryn (0.56, 0.73, and 1.1 2 kg al ha(-1)), applied postemergence-directed. Herbicides were appli ed with a compressed air spray system calibrated to deliver 187 l ha(- 1) of spray solution. Four-row plots (3 x 6 m) were simultaneously cul tivated and sprayed. Herbicides were directed towards the base of kena f plants which were 30 to 35 cm tall in 1993 and 35 to 51 cm tall in 1 994. X-77(R) (0.25% v/v) was used as an adjuvant in 1993 for all treat ments. In 1994, Agri-Dex(R) (1.0% v/v) was used with diuron and fomesa fen and Latron, AG-98(R) (0.25% v/v), was used with all other herbicid es. All rates of diuron or fomesafen caused kenaf injury (necrosis) bu t did not exceed 22 and 14%, respectively. Only fomesafen at the highe st rate resulted in kenaf height reduction 24 days after treatment (DA T). All injury symptoms disappeared as leaves abscised and no visual i njury symptoms were observed either year by mid season. Kenaf was defo liated in the fall of each year and 5.3 m of the center two rows was h and-harvested at ground level. No treatment caused yield reductions wh en compared to the untreated control except the high rate of diuron in 1994.