Demography and control of Cirsium vulgare (Savi) Ten. in relation to grazing.

Forcella, F.; Wood, Helen

<em>Cirsium vulgare</em> (Savi) Ten. is a serious biennial alien weed only in pasture land in Australia. To identify reasons for such preferential infestation and to isolate sensitive stages in the life history of <em>C. vulgare</em>, comparative demographic analyses were conducted in grazed, ungrazed and herbicide-treated Mediterranean-like pastures in south-eastern Australia. Grazing by sheep (i) reduced competition from neighbouring plants, (ii) increased <em>C. vulgare</em> growth, flowering and seed (achene) production, and (iii) promoted survival of <em>C. vulgare</em> seedlings. The most sensitive period in the life of <em>C. vulgare</em> appears to be the transition from the seedling to rosette life stages where, for example, an average survival rate of only 0.2 and 1.0% occurred in ungrazed and grazed pastures, respectively. In contrast, 10 and 15% of seeds successfully emerge on average as seedlings, and 49 and 51% of rosettes successfully develop into adult plants. Control of <em>C. vulgare</em> with dicamba was most effective just after initiation of autumn rainfall. This time corresponds to the period of naturally high seedling mortality in <em>C. vulgare</em> induced by competition from neighbouring plants.

CIRSIUM; PASTURES; HERBICIDES; GRAZING; SEEDS; SEEDLINGS

Weed Research, 1986, Vol 26, Issue 3, p199

0043-1737

Academic Journal

10.1111/j.1365-3180.1986.tb00697.x