The persistence and management of thistles in Australian pastures

Abstract

Thistles have historically been among the most troublesome weeds of temperate Australian pastures. This paper examines whether the key to effective management lies in understanding the reasons for their persistence. In addition to being protected against grazing by spines, thistles form competitive rosettes which maintain niches for future recruitment and produce numerous wind-borne seeds. Their persistence, however, is dictated mostly by long-lived seed banks at depth and the annual replenishment of seeds to surface soil. Thistle management should aim to increase the level of control by combining the suppressive effects of competitive pastures with techniques which cause high seed loss.