FALL AND SPRING APPLICATIONS OF EPTC AND TWO ANTIDOTES FOR WEED CONTROL IN CORN

Abstract

EPTC and the antidotes, R25788 (N, N-diallyldichloroacetamide) and R29148 (2, 2, 5-trimethyl-3-dichloroacetyl oxazolidine) were applied to field plots of corn (Zea mays L.) in the fall or spring from the fall of 1975 to the spring of 1978. Soil samples were taken from selected treatments in the fall of 1977 and spring of 1978. Residues of EPTC, R25788, and R29148 were measured by gas liquid chromatography. Much better weed control and higher corn yields were obtained with spring applications than with fall applications. EPTC at the highest rate of 13.4 kg/ha, without the antidotes, did not injure corn. Over 95% of the EPTC present in the soil on 24 Oct. 1977 had disappeared by 30 May 1978. Levels of EPTC on 30 May 1978 were appreciably higher following spring application. Neither R25788 nor R29148 disappeared faster than EPTC from the surface layer of soil.Key words: EPTC, R25788, R29148, soil residues, corn