Studies on the weed pathosystems Cirsium arvense - Puccinia punctiformis

The biology and epidemiology of the rust fungus Puccinia punctiformis (Str.) Röhl was investigated to evaluate the potential of this rust as a biological agent against the clonal plant species Cirsium arvense (L) Scop., which is considered world-wide as a weed. The studies focussed on systemic infection of C. arvense shoots by P. punctiformis, the most damaging form of infection. The temporal and spatial distribution of teliospores, the inoculum for systemic infection, was quantified to explain the relatively low incidence of systemic infection at the study sites. These studies were extended by experiments under controlled conditions to determine the influence of temperature and resistance on root bud infection, a necessary step to systemic infection. Escape and resistance were factors that reduce the impact of P . punctiformis on C . arvense populations. Subsequent studies on transport of teliospores in the soil and selection of aggressive P . punctiformis strains are proposed as contributions to the development of P. punctiformis as a bioherbicide against C . arvense.