The effect of herbicide and goats on survival and seed production of Illyrian thistle (Onopordum illyricum L.)
L. TorranoA, P.J. HolstB and D.F StanleyB
A Department of Animal Production, APDO 727, Zaragoza 50080, Spain.
B NSW Agriculture , Agricultural Research and Advisory Station, PO Box 129, Cowra, New South Wales 2794, Australia.
Summary
An experiment was conducted at Galong, New South Wales, to compare separate and combined effects of herbicide and grazing with bush goats on a site moderately infested (20% of ground cover at late vegetative stage) with Illyrian thistle. Sheep were also grazed in August, September and November to remove excess pasture dry matter.
Goats included thistle in their diet in the rosette stage and selected flowering stems and seedheads as they developed. Both goats and herbicide alone reduced thistle plant number by up to 90% and together they controlled 80% of the seed production of the surviving plants. It was concluded that for Illyrian thistle seedhead control there needs to be one goat per hectare for each 3% thistle ground cover at one month post herbicide application. On non-arable sites goats alone at a sufficient stocking rate to graze all thistles, could provide an effective method of controlling seed production.v
Plant Protection Quarterly (1999) 14 (1) 13-15.