Myrtle Rust – Austropuccinia psidii - in South Africa
Myrtle Rust – Austropuccinia psidii - in South Africa
Please keep an eye out for fungi on Myrtaceae. If you are interested, please join:
https://www.inaturalist.org/projects/myrtle-rust-in-southern-africa
It appears that the following plants may be affected in southern Africa from iNaturalist. This is a subset of those known to be susceptible:
Eugenia 2
Eugenia capensis 3
Myrtus 10 observations (in cultivation)
Unknown: 3 (Milkwood?)
See below, this is an Australian project on the invasive myrtle rust, Austropuccinia psidii. I am sure I have heard from you or others that it is having a serious impact on Eugenia spp along the KZN coast. Could you please send out to your network that people please put sightings onto iNaturalist. This will help not only the Australians, but also us by providing SA workers with publically accessible distribution and severity data on this serious invader.
regards
Alan Wood
PPRI
Subject: Myrtle Rust Distribution
Sent: Friday, 12 January 2024 08:50
We are currently revising climate suitability modelling for myrtle rust – Austropuccinia psidii – with a particular focus on the threat to the mediterranean and tropical regions of Western Australia.
In doing so, we are pulling together a comprehensive myrtle rust distribution record, and we are keen to include locations from South Africa given it also has a Mediterranean climate in the Cape.
To date we have limited reliable distribution records, all from iNaturalist, that boil down to only a few locations:
Would any of you know where we might be able to access more distribution data for South Africa that we could use to help develop and validate our models?
Noting that there were definitely locations identified in: Roux et al. (2016). "A unique genotype of the rust pathogen, Puccinia psidii, on Myrtaceae in South Africa." Australasian Plant Pathology 45(6): 645-652.
We are interested in any occurrence record – natural/garden records to help build the model and nursery associations/interception records to help understand relative pest pressure/risks.
Kind regards,
Kylie Ireland
Plant Diseases Program Leader | Ecosystem Health Branch | Kensington
Department of Biodiversity, Conservation and Attractions
0447 353 953 | kylie.ireland@dbca.wa.gov.au
More here:
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Roux, J., Granados, G.M., Shuey, L. et al. A unique genotype of the rust pathogen, Puccinia psidii, on Myrtaceae in South Africa. Australasian Plant Pathol. 45, 645–652 (2016). https://doi.org/10.1007/s13313-016-0447-y
The rust pathogen, Puccinia psidii, was first detected in South Africa in 2013 on a single non-native ornamental Myrtus communis tree. This prompted surveys of the country to determine its geographic distribution and host range. Previously developed microsatellite markers where used to characterize the genetic diversity of P. psidii isolates collected from these surveys. In addition, artificial inoculation studies and field observations were used to evaluate the susceptibility of native Myrtaceae to infection by P. psidii. The pathogen was found on native Myrtaceae in isolated natural situations and it was also common on exotic Myrtaceae in nurseries and gardens. Marker analysis showed that a single genotype of the rust is present in South Africa and that this is different to the so-called “pandemic” strain recorded in countries outside Brazil. It was found to have a broad distribution in South Africa with collections as far as 1500 km apart. The data provide firm evidence for a single introduction of the pathogen from an as yet unknown source. Its wide distribution, particularly in relatively isolated natural areas, suggests that P. psidii has been present in South Africa for much longer than implied by its first detection in the country.
Hosts recorded in study – South Africa
• Backhousia citriodora Private Garden, Irene, Gauteng
• Eugenia erythrophylla (Near threatened) Nursery, Port Edward
• Eugenia natalitia Natural forest, Grootbos, Modjadjiskloof, Natural forest, Wolkberg
• Eugenia umtamvunensis (Endangered)
• Eugenia verdoorniae (Near threatened)
• Heteropyxis canescens
• Heteropyxis natalensis Nursery, Port Edward
• Myrtus communis Private Garden, Pennington,Nursery, Tshwane
• Syzygium cordatum
• Syzygium jambos (alien)
• Syzygium legatii
other potential hosts?
• Metrosideros angustifolia
Thank you for this
Would we add the project to the umbrella research project?
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