Submitted to: Proceedings of Northeastern Weed Science Society
Publication Type: Abstract only
Publication Acceptance Date: 10/31/2006
Publication Date: 1/2/2007
Citation: Berner, D.K., Backman, P.A. 2007. Biological control of Canada thistle in pastures and parks: a call for collaborators on simple field tests. Proceedings of Northeastern Weed Science Society. 61:1 Interpretive Summary:
Technical Abstract: In 2003-2005, we conducted replicated experiments in two field sites naturally infested with Canada thistle and the rust fungus Puccinia punctiformis. Our hypotheses were that a) mowing could remove apical dominance and result in emergence of more systemically infected shoots within the current season and in the subsequent growing season, and b) mowing could re-distribute teliospores from systemically infected shoots and result in more homogeneous distribution and greater number of diseased shoots the following season. Our results supported both hypotheses, and these results were consistent with results obtained from a study in the early 1900s which indicated that, in unplowed pastures, systemically infected shoots would increase in an exponential fashion. Predictions from both studies indicated that 100 percent disease incidence could be expected in mowed and unmowed plots within 2.7 - 5.2 years of disease establishment. We propose to field-test, in multiple pasture and natural area sites, the ability of the rust to reduce healthy thistle density and provide biological control. To do this we would produce systemically diseased seedlings in our facilities and place them in Canada thistle patches. This should provide prolonged production of teliospores and more homogeneous distribution of inoculum. We seek collaborators to help establish field test sites and monitor disease progression and healthy thistle density. Our proposed procedures for establishing disease and monitoring field sites will be presented.