The control of slender thistle, Carduus pycnocephalus L. and C. tenuiflorus Curt. (Compositae), in pasture by grazing management

Abstract

The effect of grazing management on slender thistle populations and botanical composition of improved pasture was studied in two field trials in southern Tasmania. Deferring grazing until winter or spring reduced slender thistle populations in both trials. The reasons underlying these observations are discussed. Spring grazing favourably altered pasture botanical composition by increasing the frequency of perennial ryegrass and subterranean clover and reducing the frequency of weed grasses. These changes arc discussed in relation to thistle control. It is suggested that deferred autumn grazing may be incorporated into the farm programme as an economical method for the control of slender thistle in pasture.