Biological control of Carduus pycnocephalus and C. tenuiflorus using the rust fungus Puccinia cardui-pycnocephali

J.J. BurdonA,B, P.H. ThrallA, R.H. GrovesA,B and P. ChaboudezC

A Centre for Plant Biodiversity Research, B CRC for Weed Management Systems, CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.

C le Fontenelle bât. G2, 663 rue Pré aux Clercs, Montpellier 34000, France.


Following extensive host-specificity testing in southern France and in quarantine facilities in Canberra, two isolates of the rust fungus Puccinia cardui-pycnocephali were released in southern Australia in October 1993 as biological control agents for the slender thistles Carduus pycnocephalus and C. tenuiflorus. Initially, establishment was poor due to prolonged dry conditions. Subsequent releases in 1994-1995 became well established and consistently cause noticeable disease particularly in western Victoria and Tasmania. In 1998, comparative assessments of fungicide-treated (disease absent) and untreated (disease present) plots in both these areas showed reductions in the size of individual C. tenuiflorus plants and the number of inflorescences as a consequence of infection by P. cardui-pycnocephalus. While the impact of the pathogen alone was insufficient to reduce thistle densities permanently, it will have a role as an additional tool in the integrated control of these thistles


Plant Protection Quarterly (2000) 15 (1) 14-17.