The potential of the fungus Sclerotinia sclerotiorum as a biological herbicide for controlling thistles in pasture

G.W. Bourdôt and I.C. Harvey, AgResearch, PO Box 60, Lincoln, New Zealand.


Research is reviewed on the development of Sclerotinia sclerotiorum, isolated form Californian thistle (Cirsium arvense) as a biological herbicide for controlling thistles in pastures. It has been shown, in glasshouse tests, to be virulent against two other thistles (C. vulgare and Carduus nutans), but not against Carduus tenuiflorus. In field trials against C. arvense it causes high mortality of vegetative shoots, thus reducing the cover of the thistle foliage. Only 8% of treated shoots survived to flowering compared to 28% on untreated plots. Root biomass is also reduced, resulting in lower shoot growth in the season following treatment. The fungus did not infect the key pasture species Lolium perenne or Trifolium repens. The potential for the development of S. sclerotiorum as a mycoherbicide against Cirsium arvense, C. vulgare and Carduus nutans is discussed.


Plant Protection Quarterly (1996) 11 (Supplement 2) 259-262.