The Development of Selective Herbicides for Kale in the United Kingdom

Abstract

The purpose of this paper is firstly to describe the background of an investigation started in 1961 to develop new herbicides for the control of weeds in agricultural kale, Brassica oleracea vars, acephala D.C, SinA fruticosa Metz, and secondly to present the results of four experiments concerned with the effects of weeds on the yield of' kale. The results of the herbicide investigation are to be presented in subsequent papers.Kale as grown in the United Kingdom is a valuable fodder crop and relatively easy to grow, but beset by weeds against which existing mechanical and chemical methods of control have not usually been successful. The effect of weed competition on the yield of four farmers' crops was investigated in 1961 and 1962, When grown entirely free of weeds, the crops provided yields in the range of 20-9-34-5 tons of green material per acre. Where no attempt was made to control the weeds, the yields were reduced by 9'4, 14-5 and 18-9 tons/ac, respectively, in three experiments. In no case did kale, hoed only between the rows, produce as high a yield as the weed-free crop. Although variable in effect, uncontrolled weed growth early in the life of the crop always lowered the yield of kale, Le developpement de I'usage des herbicides selectifs pour le chou fourrager dans le Royaume-Uni. La plante cultive'e, les mauvaises herbes et le probleme J. G. Elliott and T. I. Cox keine Unkrautbekampfung, so wurde der Ertrag in drei Versuchen um 23,2, 35,8 bzw. 46,7 to/ha reduziert. Wurde zwischen den Reihen gehackt, so war der Ertrag in alien Fallen niedriger als in den unkrautfreien Parzellen. Unkrautkonkurrenz wahrend der fruhen Entwicklung des Kohls beeintrachtigte den Ertrag in jedem Fall, wenn auch jeweils in unterschiedlichem Masse.

3,5‐Dichloro‐2,6‐Difluoro‐4‐Hydroxypyridine as a Selective Herbicide in Kale

“…In the trial reported above the presence of weeds did not affect crop growth during the first month after crop emergence. It has, however, been found that weed growth early in the life of the crop can reduce the yield of kale (Elliott & Cox, 1965). Since it is not yet possible to predict for any particular situation the effects early in the life of the crop, only a selective soil-acting herbicide applied pre-emergence would provide a reliable method of eliminating the effects of weed competition in kale.…”