Chemical control of weeds in tobacco in northern New South Wales

Abstract

Herbicides were tested for weed control in tobacco in northern New South Wales at two sites in 1964-65 and 1965-66, and at one site in 1966-67. Herbicides used were diphenamid (N, Ndimethyl- 2, 2-diphenylacetamide) and trifluralin (a,a,a-trifluro-2, 6-dinitro-N, N-dipropyl-p-toluidine) in 1964-65, and trifluralin, benefin (N-butyl-N-ethyl-a,a,a-trifluro-2, 6-dinitro-p-toluidine), DCPA (dimethyl 2, 3, 5, 6 tetrachloroterephthalate), and EPTC (ethyl N, N-di-n-propylthiol-carbamate) in 1965-66. All were incorporated with spike tooth harrows. Various rates of trifluralin and benefin were compared using spike tooth harrow and disc harrow incorporation in 1966-67. Trifluralin at 0.37 to 1.0 lb active ingredient (a.i.) an acre and benefin at 0.75 to 1.8 lb a.i. an acre on a coarse sandy soil, and 2.0 lb a.i. an acre on a sandy loam soil gave good control of weeds without adversely affecting the yield or quality of cured tobacco. Some indications of phytotoxicity to tobacco occurred with trifluralin rates of 1.5 to 2 lb a.i. an acre and a benefin rate of 3.6 lb a.i. an acre. Method of incorporation produced no difference in weed control in 1966-67. EPTC at 3 and 6 lb a.i. an acre was phytotoxic to tobacco. Diphenamid at 4 to 12 lb a.i. an acre controlled weeds without adversely affecting tobacco growth. DCPA at 7 and 14 lb a.i. an acre on a coarse sand and 14 lb a.i. an acre on a sandy loam gave good control of weeds without adversely affecting the yield or quality of cured tobacco.