Two new pathogens of pyrethrum, described as Paraphoma chlamydocopiosa and Paraphoma pye, isolated from necrotic leaf lesions on pyrethrum plants in northern Tasmania, Australia, were identified using morphological characters, phylogenetic analysis of the internal transcribed spacer (ITS), elongation factor 1-α (EF1-α) and β-tubulin (TUB) genes, and pathogenicity bioassays. Bootstrap support in the combined and individual gene region phylogenetic trees supported the two species that were significantly different from the closely related P. chrysanthemicola and P. vinacea. Morphological characteristics also supported the two new species, with conidia of P. chlamydocopiosa being considerably longer and wider than either P. chrysanthemicola or P. vinacea, and P. pye being distinct in forming bilocular pycnidia. Glasshouse pathogenicity tests based on root dip inoculation resulted in P. chlamydocopiosa and P. pye infecting the crown and upper root tissues of pyrethrum plants, and significant reduction in biomass 2 months after inoculation. Both of these Paraphoma species caused leaf lesions during in vitro and in vivo bioassays 2 weeks after foliar spray inoculation. Although P. chlamydocopiosa and P. pye were shown to be crown rot pathogens, they were also commonly isolated from leaves of diseased plants in pyrethrum fields of northern Tasmania.

Item Type:	Refereed Article
Keywords:	pyrethrum, taxonomy, Paraphoma chlamydocopiosa, plant disease, bilocular pycnidia, longer conidia, Paraphoma pye, pathogenicity, phylogenetic analsysis
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant pathology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Horticultural crops
Objective Field:	Horticultural crops not elsewhere classified
UTAS Author:	Scott, JB (Dr Jason Scott)
ID Code:	118049
Year Published:	2018
Web of Science® Times Cited:	13
Deposited By:	TIA - Research Institute
Deposited On:	2017-07-03
Last Modified:	2019-03-19
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