Target pest: Cirsium arvense (Asterales: Asteraceae), Californian thistle
Agent introduced: Puccinia punctiformis (Uredinales: Pucciniaceae), Californian thistle rust
Waipara et al. (2009) - P. punctiformis was first recorded in New Zealand as early as 1881.
Landcare Research (2014c) - self-introduced.
Waipara et al. (2009) - subsequent to its accidental introduction to New Zealand, P. punctiformis was used as an augmentative biocontrol agent against Cirsium arvense and a recent comparative survey has shown that this pathogen occurs in New Zealand at levels similar to its native range of Europe.
Landcare Research (2014c) - common.
Impacts on target:
Landcare Research (2014c) - damage not usually widespread.
Kentjens et al. (2023) - it seems that C. arvense is unselective in the fungal species it allows to colonise and its endophytic populations [fungi that live inside the plant] are a function of location. Endophytes can alter outcomes of a host-pathogen interaction; they can interact with a pathogen directly or induce resistance in the host. Puccinia punctiformis performs inconsistently on C. arvense as a biocontrol agent. Problems with P. punctiformis establishment and control of C. arvense may be attributable to differing plant endophytic populations in various environments.
Impacts on non-targets:
Waipara et al. (2009) - to assess non-target impacts of pathogenic weed biocontrol agents, including Puccinia punctiformis, introduced to New Zealand, nationwide surveys were conducted 2000-2009, focussing on plants closely related to the target weeds. No non-target damage was observed for P. punctiformis, despite positive infection being observed on many of the host (target) plants at the same sites.
Kentjens W, Casonato S, Kaiser C (2023). Californian thistle (Cirsium arvense): endophytes and Puccinia punctiformis. Pest Management Science, 2023, Jan 29 https://onlinelibrary.wiley.com/doi/full/10.1002/ps.7387
Landcare Research (2014c). Who's who in biocontrol of weeds? What's new in biological control of weeds? 69: 10-11 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/WhatsNew69.pdf
Waipara NW, Barton J, Smith LA, Harman HM, Winks CJ, Massey B, Wilkie JP, Gianotti AF, Cripps MG (2009). Safety in New Zealand weed biocontrol: a nationwide pathogen survey for impacts on non-target plants. New Zealand Plant Protection 62: 41-49