Volatilization of Formulated Butyl Esters of 2,4-D From Pyrex and Leaves

The volatilities of iso and normal butyl esters of 2,4-D [(2,4-dichlorophenoxy)acetic acid] in a commercial formulation applied as thin films on pyrex and as aqueous droplets on pyrex and leaf surfaces increased directly with the available surface area/applied dose ratio (Q), and inversely with the adsorptive and absorptive characteristics of the surface, under the same conditions of temperature (39 ± 1.5 C), relative humidity (RH) (0%), geometry, airflow rate (750 ± 7 ml/min) and light. Partial pressures and rates of volatilization were computed. Herbicide in droplets below 200μin diameter tended to volatilize faster than it penetrated, but the reverse occurred above this diameter.