Target pest: Nassella neesiana (Poales: Poaceae) = Stipa neesiana, Chilean needle grass
Agent introduced: Uromyces pencanus (Pucciniales: Pucciniaceae)
Hill (2017) - five isolates were collected in Argentina. Strain UP 27 was selected for assessment for the 2011 EPA application to import and release the fungus and for eventual introduction to New Zealand. However, evidence suggests that all U. pencanus strains will have essentially the same host range.
Landcare Research (2022c) - after approval from the Argentinian government to export U. pencanus to New Zealand, 10 years after EPA approval to import the fungus, spores were shipped from Argentina on 23 December 2021. However, they did not arrive at the containment facility in Auckland, New Zealand until 18 January 2022, and the starter culture had not survived. Another importation is planned; a new export permit will need to be issued by the Argentinian government, but the international compliance certificate and Memorandum of Understanding remain valid until the end of 2022, and the EPA application time waiver for U. pencanus was recently extended until 30 April 2024 [see 'EPA applications' section]. The next culture will be hand-carried from Argentina to New Zealand to minimise the transit time.
Landcare Research (2014c, 2015i, 2017d, 2021f) - no releases made yet as waiting for export permit from Argentina to be granted.
Landcare Research (2021h) - a permit to export the rust from Argentina has been granted [see the 'General comments' section]. If the final host range testing goes well, the first releases may be possible in spring of 2022.
Landcare Research (2022c) - Uromyces pencanus will not be released in 2022 because of failure of the imported culture [see Landcare Research (2022c) in the â€˜Import notesâ€™ section]. Another importation is planned; if host range testing indicates the fungus is safe to release and EPA grants approval to release it, the first releases could be possible in the spring of 2023.
Impacts on target:
Landcare Research (2014c) - only South Island populations likely to be susceptible.
Anderson et al. (2017) - an isolate (UP 27) of U. pencanus was tested against 3 populations of N. neesiana from New Zealand (Auckland, Hawke's Bay, Marlborough). Results showed that if this isolate was released it should cause severe damage to the most serious (Marlborough) infestation. However, the Auckland and Hawke's Bay populations are unlikely to be damaged and it is possible that further isolates of U. pencanus would be required.
Impacts on non-targets:
Marlborough District Council (2011) - host range testing carried out in Argentina, involving 65 closely related taxa (including 12 populations of the target weed), indicated the host range is almost certainly restricted to Chilean needle grass. It is so specific, in fact, that certain populations within the target species are not affected. During testing no spores formed on any non-target species, suggesting they were all capable of resisting infection. Therefore, the rust poses very little risk to native plants.
Anderson et al. (2017) - an isolate (UP 27) of U. pencanus was tested against 11 populations of N. neesiana from Australia, 3 populations from New Zealand (Auckland, Hawke's Bay, Marlborough), and 58 other grass species. Nine populations of N. neesiana from Australia, one from New Zealand (Marlborough) were found to be susceptible. In addition, the rust was able to complete its life cycle and produce pustules on plants of two non-target species: the Australian natives Austrostipa compressa and A. macalpinei. The number of pustules formed on A. compressa and A. macalpinei was much lower than on the target species, and the size of pustules and spores smaller, so the rust would be expected to cause less, if any, significant damage on these species.
Hill (2017) - the literature records that U. pencanus has a narrow host range that is confined to the genus Nasella. There are about 70 Nasella species in Argentina, only five of which are listed as hosts of this rust, including Chilean needle grass. Extensive field surveys were conducted in Argentina but U. pencanus was never observed on any plants other than Nasella species. There are no native Nasella species in New Zealand, and none with agronomic or ornamental potential. To confirm the literature field records, tests were conducted in Argentina to experimentally determine the fundamental host range of the rust [see Marlborough District Council (2011) entry], results of which indicated that U. pencanus strain UP 27 could only complete its life cycle and sporulate on some populations of the target weed. Since the 2011 EPA application, addition testing has been carried out [see Anderson et al. (2017) entry] to support the introduction of the rust to Australia, with the conclusion that if strain UP 27 was introduced to New Zealand it is expected to only cause disease on certain populations of N. neesiana and pose no direct threat to non-target plants. It is unlikely that other strains of the rust would pose any more of a threat.
Anderson et al. (2017) - small populations of N. neesiana occur in the North Island (near Auckland and in Hawke's Bay) but the worst infestations occur in the Marlborough region, near the top of the South Island. The weed was also found more recently (2008) in North Canterbury in the middle of the South Island.
Landcare Research (2021h) - 10 years after application, the Argentinian government has granted permission to export U. pencanus from Argentina. The holdup was due to Argentina implementing the Convention for Biological Diversity (CBD) treaty. Assuming successful importation of the fungus (the permit is only valid for three months, a tight timeframe) final host range testing (against the only three native grass species in New Zealand that belong to the same tribe as Nassella) will be completed in New Zealand.
EPA (2011c) - 18 Mar 2011: application by the Marlborough District Council to import and release the rust fungus Uromyces pencanus as a biological control agent for the weed Chilean needle grass. EPA Application # ERMA200754, approved without controls, 23 Jun 2011.
EPA (2017c) - 11 Dec 2017: application by the Marlborough District Council to release the rust fungus Uromyces pencanus as a biological control agent to control Chilean needle grass. EPA Application # APP203314. [This is the second application to import U. pencanus; (see Hill (2017) entry below]. This application is currently subject to a time waiver to allow time for further testing of the biocontrol agent.
Hill (2017) - the 2017 application to EPA (Application # APP203314) to introduce U. pencanus to New Zealand is the second application to introduce this species. Approval to introduce U. pencanus was granted by EPA in 2011 [Application # ERMA200754]. This approval could not be exercised within the statutory timeframe because of regulatory difficulties in sourcing the agent from Argentina and the approval lapsed.
EPA (2020) - 9 April 2020: the applicant, Marlborough District Council, is advised that the time waiver for this application will continue. The applicant has indicated they may not be ready to proceed with the application before April 2022. EPA will review the waiver again in April 2022 if they have not heard from they applicant before then.
EPA (2022a) - 18 March 2022: the applicant, Marlborough District Council, is advised that the time waiver for this application will continue. EPA will review the waiver again in April 2024 if they have not heard from they applicant before then.
Anderson FE, Gallego L, SÃ¡nchez RM, Flemmer AC, Hansen PV, McLaren D, Barton J. (2017). Plant/pathogen interactions observed during host range testing of the rust fungus Uromyces pencanus, a classical biological control agent for Chilean needle grass (Nassella neesiana) in Australia and New Zealand. Biocontrol Science and Technology 27 (9): 1096-1117
EPA (2011c). EPA application ERMA200754 to release the rust fungus Uromyces pencanus as a biological control agent for the weed Chilean needle grass. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/ERMA200754
EPA (2017c). EPA application APP203314 to release the rust fungus Uromyces pencanus as a biological control agent to control Chilean needle grass. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP203314
EPA (2020). Time waiver for Chilean needle grass biological control agent (APP203314), 9 April 2020. Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP203314/APP203314-time-extension-confirmation-2020-2022.pdf
EPA (2022a). Time waiver for Chilean needle grass biological control agent (APP203314), 18 March 2022. Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP203314/APP203314-Time-extension-confirmation-2022-2024.pdf
Hill R. (2017). Application to EPA (APP203314) to import and release the fungus Uromyces pencanus as a biological control agent for the weed Chilean needle grass. Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP203314/d2e6e1c0f8/APP203314-Application-FINAL.pdf
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
Landcare Research (2015i). Who's who in biological control of weeds? Weed Biocontrol: What's New? 73: 10-11 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-73
Landcare Research (2017d). Still tussling with tussocks. Weed Biocontrol: What's New? 81: 2-3 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-81
Landcare Research (2021f). Who's who in biological control of weeds? Weed Biocontrol: What's New? 97, August 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/whos-who-in-biological-control-of-weeds
Landcare Research (2021h). Permit for rust export renews hope for biocontrol of Chilean needle grass. Weed Biocontrol: What's New? 98, November 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/permit-for-rust-export-renews-hope-for-biocontrol-of-chilean-needle-grass/
Landcare Research (2022c). Disappointed but not defeated. Weed Biocontrol: What's New? 100, May 2022 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/disappointed-but-not-defeated/
Malborough District Council (2011). Application to import for release or release from containment a new organism: release of the rust fungus Uromyces pencanus as a biological control agent for the weed Chilean needle grass. EPA Application Number ERMA200754 https://www.epa.govt.nz/assets/FileAPI/hsno-ar/ERMA200754/376242be09/ERMA200754-ERMA200754-Application-FINAL.pdf