Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/2004
Publication Date: 8/1/2005
Citation: Demers, A.M., Backman, P.A., Berner, D.K. 2005. Biological control of canada thistle (cirsium arvense ) using the rust puccinia punctiformis. Phytopathology 95:S156. Interpretive Summary:
Technical Abstract: Canada thistle (CT) is an introduced invasive weed in the U.S. and Canada and a target of biological control efforts. Puccinia punctiformis is an endemic, autoecious rust that limits flowering and vegetative growth of CT. Systemic infections of CT root buds by rust basidiospores, give rise to spindly, pale shoots that usually die after producing infective spores. The goal of this study was to determine the density of systemically infected plants per unit patch area that is needed to initiate an epidemic and achieve biological control. Systemically infected CT seedlings were planted in healthy thistle patches to serve as dynamic living sources of infective inoculum. Newly developed systemically infected shoots in each patch were counted regularly over the course of the season and compared to the proportion of healthy plants. A mathematical model, based on field data, is being developed to predict the rate of spread of P. punctiformis in CT patches and determine how many systemically infected plants are necessary to achieve CT control.