Glyphosate and Carfentrazone Herbicides for Difficult-to-control Weeds in Citrus

摘要

Experiments were conducted in greenhouse and field to examine the efficiency of tank mixing glyphosate and carfentra-zone to control the difficult-to-control weeds of citrus, Brazil pusley (Richardia brasilienses) and dayflower (Commelina bengalensis). Glyphosate was applied at 2145 and 3220 g a.i./ha and carfentrazone at 17.7 and 35.5 g a.i./ha as sole and tank mixed applications. In a greenhouse study, percent control of Brazil pusley and dayflower was increased successively to 100% by the fourth week with the application of the lower rate of glyphosate examined in greenhouse study. Application of the lower rate of carfentrazone at 17.7 g a.i./ha achieved 100% control of dayflower, but on Brazil pusley, carfentrazone had only a negligible effect.It was not possible to distinguish any synergistic effect on the phytotoxicity of their tank mixed application. In the field, application of glyphosate and carfentrazone at higher rates had significantly better control of dayflower than the lower rates.The control of Brazil pusley was significantly better with the higher rate of glyphosate compared to the lower rate. Carfentrazone had a negligible effect on the control of Brazil pusley. Tank mix application of glyphosate and carfentrazone had a synergistic effect on the control of dayflower. Tank mix did not show any added effect on the phytotoxicity of Brazil pusley. Application of tank mix glyphosate and Landmaster II (glyphosate + 2,4-D) provided similar control in greenhouse and field as achievedby a tank mix of glyphosate and carfentrazone. The study indicated that the effect of carfentrazone or glyphosate varied with the weed species. However, tank mix application of glyphosate and carfentrazone had some positive control effects on both plants.