Effect of glyphosate and its 2,4-d formulation on some difficult to control weeds

M. Singh, S. D. Sharma

Abstract


Glyphosate formulations (Rodeoreg;, Roundup®, Roundup® Ultra) and glyphosate + 2,4-D as Landmaster® II were evaluated against Brazil pusley (Richardia brasiliensis L.), dayflower (Commelina communis L.), and hairy beggarticks (Bidens frondosa L.). Landmaster® provided 99% control of R.brasiliensis while glyphosate formulations (1.0 lb a.i./acre) had only marginal control (14 to 18%). Landmaster® also provided higher control of C. communis, 87% at 0.13 qt. product/ acre and 100% at 2.0 qt./acre while glyphosate formulations (1.0 lb and 1.25 lb a.i./acre) had no control. The response of B. frondosa to herbicide treatment varied with age. Glyphosate formulations (1.0 lb a.i./acre) provided 38 to 55% control of B. frondosa as compared to 78% with Landmaster® (0.50 qt./acre) at the 12-week stage. The control of B. frondosa further decreased when the treatments were applied to the plants with regrowth. Glyphosate formulations were effective only at the 4- to 5-week stage, when even a lower dose of 0.25-0.50 lb a.i./acre effectively controlled B. frondosa. Overall, Roundup® and Roundup ® Ultra were superior to Rodeoreg; but Landmaster® provided the best control in general. Poor performance of Rodeoreg; was probably due to lack of adjuvant in the formulation and superior performance of Landmaster® was due to presence of 2,4-D.

Keywords


glyphosate; Landmaster® II; weed control

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283