THE INFLUENCE OF AUTUMN MANAGEMENT AND COMPANION GRASS ON THE DEVELOPMENT OF WHITE CLOVER OVER WINTER IN MIXED SWARDS

Three experiments designed to investigate different facets of autumn m anagement on white clover stolen development are described, The effect s of defoliation interval (2, 4, 6 and 8 weeks during 16 weeks from 27 July) were investigated. The shortest interval resulted in the shorte st length of stolen material per unit area but cutting interval had no effect on growing point density nor on hardiness of stolen tips evalu ated in October, December and January. Chemical grass suppressants wer e employed to reduce grass biomass during winter in two experiments to evaluate the influence of grass on white clover development, One expe riment involved varying grass tiller density by spraying a perennial r yegrass/white clover sward in October with three rates of three chemic al suppressants (Clout, Kerb and Checkmate), Although tiller and clove r growing point density were inversely related in January, the overall relationship was not strong. Clout at 1.5 kg a.i. ha(-1) was sprayed in October on one of two subplots in each of twelve grazed grass/white clover plots that had been maintained at 7 or 9 cm from July to Octob er then grazed to 3-4 cm with sheep, Sward height had no effect on clo ver population density but the shorter sward had a greater mean node n umber per secondary stolen branch, By March, suppressing grass resulte d in more than double the stolen population density, a higher proporti on of plants with tertiary and quaternary branches, and on marked stol ons, five times more branches and 60% higher dry matter (DM) produced during winter but with shorter petioles compared with clover in untrea ted plots. It is concluded that white clover has the capacity to branc h during a mild winter and as stolen branch numbers can suffer a net l oss as a result of the presence of the grass canopy, management that c ontrols grass growth during winter should aid overwintering and improv e persistence of white clover.