Altered growth, population structure and realised niche of the weed Campuloclinium macrocephalum (Asteraceae) after exposure to the naturalised rust Puccinia eupatorii (Pucciniaceae)

摘要: The alien forb Campuloclinium macrocephalum (Less.) DC. (Asteraceae, pompom weed) invades disturbed rangelands in South Africa. After >40 years of naturalisation, infestations around Pretoria were severely damaged 2006 by the biotrophic rust Puccinia eupatorii Dietel (Pucciniaceae). disease spread rapidly and has now established at most weed country. This study reports on efficacy pathogen as a biocontrol agent weed, its effect retention weed’s realised niche tolerance to disease. Eighty rangeland originally assessed over two 2003 2004 re-surveyed 2009. Data from untreated plots experimental sites where was first detected also used. induced premature senescence late summer stimulated production compensatory growth autumn. Plants without symptoms senesced autumn remained dormant throughout winter. Pompom density did not change significantly time both plots. Disease incidence 2009 severe dense infestations, with sparse having highest natural fewer pustules. reduce niche; grasslands, savanna wetlands persisted despite significant damage Persistence, high annual stem mortality, suggests that remains adapted fungus after prolonged separation supports earlier findings disturbance key invasion even under biological control. may enhance control augmentation additional insect agents, but is unlikely inflict reduction population own. be an important consideration for weeds involving fungi.