Response of Hieracium in Two Long Term Manipulative Agricultural Trials

Hieracium, or hawkweed species, serious weeds in South Island high country, may be controlled by appropriate pastoral management. Experimental trials at Lake Tekapo, related to S and P fertiliser rates of 0-100 kg ha-l yr-l, 27 different combinations of over-drilled and resident species and different seasons or intensities of grazing treatments on Hieracium dominated fescue tussock were conducted. These were monitored for 9 years in terms of fertiliser inputs used, sheep stocking rates, and vegetation changes. Hieracium decreased or disappeared under high fertiliser and sowing inputs, but remained an increasingly important component under successively lower fertiliser inputs.