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Molecular characterisation, pathogenesis and fungicide sensitivity of Pythium spp. from table beet (Beta vulgaris var. vulgaris) grown in the Lockyer Valley, Queensland

Scott, P.T. and Martin, H.L. and Boreel, S.M. and Wearing, A.H. and Maclean, D.J. (2005) Molecular characterisation, pathogenesis and fungicide sensitivity of Pythium spp. from table beet (Beta vulgaris var. vulgaris) grown in the Lockyer Valley, Queensland. Australasian Plant Pathology, 34 (3). pp. 361-368.

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Article Link(s): http://dx.doi.org/10.1071/AP05042

Publisher URL: http://www.publish.csiro.au/

Abstract

Table beet production in the Lockyer Valley of south-eastern Queensland is known to be adversely affected by soilborne root disease from infection by Pythium spp. However, little is known regarding the species or genotypes that are the causal agents of both pre- and post-emergence damping off. Based on RFLP analysis with HhaI, HinfI and MboI of the PCR amplified ITS region DNA from soil and diseased plant samples, the majority of 130 Pythium isolates could be grouped into three genotypes, designated LVP A, LVP B and LVP C. These groups comprised 43, 41 and 7% of all isolates, respectively. Deoxyribonucleic acid sequence analysis of the ITS region indicated that LVP A was a strain of Pythium aphanidermatum, with greater than 99% similarity to the corresponding P. aphanidermatum sequences from the publicly accessible databases. The DNA sequences from LVP B and LVP C were most closely related to P. ultimum and P. dissotocum, respectively. Lower frequencies of other distinct isolates with unique RFLP patterns were also obtained with high levels of similarity (>97%) to P. heterothallicum, P. periplocum and genotypes of P. ultimum other than LVP B. Inoculation trials of 1- and 4-week-old beet seedlings indicated that compared with isolates of the LVP B genotype, a higher frequency of LVP A isolates caused disease. Isolates with the LVP A, LVP B and LVP C genotypes were highly sensitive to the fungicide Ridomil MZ, which suppressed radial growth on V8 agar between approximately four and thirty fold at 5 μg/mL metalaxyl and 40 μg/mL mancozeb, a concentration far lower than the recommended field application rate.

Item Type:Article
Additional Information:© Australasian Plant Pathology Society. Reproduced with permission from © CSIRO Publishing. Access to published version may be available via Publisher’s website.
Keywords:Beta vulgaris; Beta vulgaris subsp. vulgaris; Pythium aphanidermatum; Pythium dissotocum; Pythium heterothallicum; Pythium periplocum; Pythium ultimum.
Subjects:Plant pests and diseases > Individual or types of plants or trees
Plant culture > Vegetables
Plant pests and diseases > Plant pathology
Deposited On:05 Mar 2009 05:16
Last Modified:15 Mar 2011 00:03

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