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The life cycle and field epidemiology of Uromycladium acaciae (Pucciniales) on Acacia mearnsii in South Africa

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Fraser, S., McTaggart, A. R., Roux, J., Nel, J., Potgieter, J., Shuey, L. S., Somchit, C. and Wingfield, M. J. (2021) The life cycle and field epidemiology of Uromycladium acaciae (Pucciniales) on Acacia mearnsii in South Africa. Annals of Applied Biology, n/a (n/a). ISSN 0003-4746

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Article Link: https://doi.org/10.1111/aab.12677

Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1111/aab.12677


Abstract Uromycladium acaciae has damaged plantations of Acacia mearnsii in southern Africa since 2013. Uredinia of a species of Uromycladium have been known on A. mearnsii in South Africa since the 1980s. However, the recent damage is associated with telia and spermogonia. Uredinia and telia were previously treated as conspecific with a phylogenetic species concept. However, uredinia did not form after previous artificial inoculation experiments with teliospores. Controlled studies identified the optimum conditions for basidiospore infection, but the optimum conditions for sporulation and dispersal have not been identified. To investigate the life cycle and field epidemiology of Uromycladium on A. mearnsii, spores were trapped weekly and development of disease symptoms and plant phenology were monitored monthly at three plantations. Telia and spermogonia developed independently from uredinia, and nucleotide polymorphisms between rDNA of uredinia and telia were fixed based on high throughput sequencing and PCRs. All three weather variables measured had a significant effect on teliospore abundance at two of the three sites. Teliospore abundance was greatest during trapping periods when mean relative humidity was high, mean rainfall was 4–5 mm day-1, and mean temperature was 15–16°C. Teliospore counts peaked at the end of summer, potentially the result of epidemic build-up. Results support the hypothesis that despite sharing a most recent common ancestor, uredinia on A. mearnsii in southern Africa are independent to the life cycle of the telial rust, which likely constitutes a new introduction. Furthermore, teliospores of U. acaciae disperse under wet conditions; and, the wet season between October and March is the optimal period for wattle rust development. This article is protected by copyright. All rights reserved.

Item Type:Article
Business groups:Horticulture and Forestry Science
Keywords:Spore traps disease development spore dispersal water‐splash niche differentiation fungi
Subjects:Plant culture > Tree crops
Plant pests and diseases > Plant pathology
Forestry > Research. Experimentation
Live Archive:18 Feb 2021 02:16
Last Modified:03 Sep 2021 16:46

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