Granular vs. Liquid Formulations of Picloram, HRS 587, Fenac, and 2,3,6-TBA for Control of Field Bindweed

Better field bindweed (Convolvulus arvensisL.) control was obtained from granular formulations of 2,3,6-trichlorobenzyloxypropanol (hereinafter referred to as HRS 587), 4-amino-3,5,6-trichloropicolinic acid (picloram), (2,3,6-trichlorophenyl)acetic acid (fenac), and 2,3,6-trichlorobenzoic acid (2,3,6-TBA) than with equivalent amounts of liquid formulations. Two years after application, a granular formulation of picloram at 1 lb/A was as effective as a liquid formulation at 3 lb/A. One and 2 years after application, granular formulations of HRS 587, fenac and 2,3,6-TBA at 10 lb/A gave field bindweed control equal to that obtained with 20 lb/A of liquid formulations of these chemicals. Incorporation did not greatly affect the toxicity of either the liquid or granular formulations of the four herbicides. Increased effectiveness of granular formulations appeared to be associated with longer persistence in the soil.