RESPONSE OF A PASTURE TO REMOVAL OF DOCKS (RUMEX SPP.) BY TREATMENT WITH ASULAM

Abstract

Summary. Asulam at 1 lb/acre was sprayed on forty‐two plots in a dock‐infested ryegrass/timothy sward in May, 1970. Each plot was paired with an untreated plot, containing nearly the same ground cover of docks. The plots were selected to represent the whole range of dock cover existing on the site (3–54%). Harvest cuts of dorks and grasses separately were taken one week post‐treatment, and twice subsequently in 1970 and twice in 1971. The percentage change in grass and total herbage yield ratios was plotted against initial dock cover for each pair of plots at each harvest and subjected to regression analysis.Significant correlations were obtained between grass yield ratios and initial dock cover for harvest 2, 3 and 2–5 combined: those plots which initially contained the largest dock populations gave the largest increases in grass yields after asulam treatment. Total herbage yield ratios were not correlated with initial dock cover at any harvest.Overall, total herbage yields for the 2 years were not altered by asulam treatment, but grass formed 98·3% of the total yield on the treated plots, compared with 87·5% on the untreated. Asulam gave complete control of docks in 1970 and 73% on a dry weight basis in September, 1971. Reaction d'une pâture traitée avec l'asulam contre les rumex (Rumex spp.)