Black root rot (BRR) is a major seedling disease in cotton in Australia. BRR is caused by a soilborne fungus Thielaviopsis basicola, recently re-described as Berkelyomyces spp., that was reported for the first time in 1990 in northern New South Wales (NSW), Australia. The disease is now prevalent across NSW. Since the first detection, much research has been focused exclusively on management; however, little has been investigated to understand the BRR pathogen population. Isolation and collection of pure fungal cultures are essential for investigation of the pathogen diversity and pathogenicity. However, isolation of T. basicola is recalcitrant. In this study, T. basicola were successfully recovered from BRR diseased cotton seedlings in the past three seasons by using a simple 5% carrot agar amended with 100 ppm streptomycin. T. basicola was recovered within three days with the percentage of recovery ranging from 55–76% during the first isolation attempt. This carrot medium provided a simple and vigorous means for isolation of T. basicola.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Allen SJ (1990) Thielaviopsis basicola, a new record on cotton in Australia. Australas Plant Pathol 19:24–25
Baxter LW, Fagan SG (1974) A simplified method of indcuing sexual sporulation in Glomerella cingulata. Plant Dis Reptr 58:300–303
CRDC (2018) CRDC Annual Report 2017–2018. Cotton Research and Development Corporation, Narrabri, Australia
Holtz BA, Weinhold AR (1994) Thielaviopsis basicola in San Joaquin valley soils and the relationship between inoculum density and disease severity of cotton seedlings. Plant Dis 78:986–990
Kirkby KA, Lonergan PA, Allen SJ (2013) Three decades of cotton disease surveys in NSW. Australia Crop Pasture Sci 64:774–779
Mauk PA, Hine RB (1988) Infection, colonization of Gossypium hirsutum and G. barbadense, and development of black root rot caused by Thielaviopsis basicola. Phytopathology 78:1662–1667
McGovern RJ, Seijo TE (1999) Outbreak of black root rot in Catharanthus roseus caused by Thielaviopsis basicola. Plant Dis 83:396–396
Mondal AH, Nehl DB, Allen SJ (2004) First report of Thielaviopsis basicola on soybean in Australia. Australas Plant Pathol 33:451–452
Monfort WS, Carroll AG, Emerson MJ, Fortner J, Rothrock CS (2010) First report of black root rot caused by Thielaviopsis basicola on soybean (Glycine max) in Arkansas. Plant Dis 94:1168–1168
Le DP, Gregson A (2019) Alternaria leaf spot of cotton seedlings grown in New South Wales, Australia is predominantly associated with Alternaria alternata. Australas Plant Pathol 48:209–216
Le DP, Gregson A, Tran TT, Jackson R (2020) Co-occurrence of defoliating and non-defoliating pathotypes of Verticillium dahliae in field-grown cotton plants in New South Wales, Australia. Plants (Basel-Switzerland) 9, 750.
Nakane R, Miki S, Ikeda K, Sakai H, Hayashi K, Usami T (2019) First report of black root rot of lettuce in Japan caused by Berkeleyomyces rouxiae. J Gen Plant Pathol 85:436–439
Nehl DB, Allen SJ, Mondal AH, Lonergan PA (2004) Black root rot: A pandemic in Australian cotton. Australas Plant Pathol 33:87–95
Nel WJ, Duong TA, de Beer ZW, Wingfield MJ (2019) Black root rot: A long known but little understood disease. Plant Pathol 68:834–842
Nel WJ, Duong TA, Wingfield BD, Wingfield MJ, de Beer ZW (2018) A new genus and species for the globally important, multihost root pathogen Thielaviopsis basicola. Plant Pathol 67:871–882
O’Brien RG, Davis RD (1994) Lettuce black root rot – A disease caused by Chalara elegans. Australas Plant Pathol 23:106–111
Otto L (2020) Quantitative report on the 2018–2019 season: A survey of consultants. Cotton Research and Development Corporation, Narrabri, Australia, pp 1–32
Paulin-Mahady AE, Harrington TC, McNew D (2002) Phylogenetic and taxonomic evaluation of Chalara, Chalaropsis, and Thielaviopsis anamorphs associated with Ceratocystis. Mycologia 94:62–72
Pereg LL (2013) Black root rot of cotton in Australia: the host, the pathogen and disease management. Crop Pasture Sci 64:1112–1126
Rothrock CS (1999) Thielaviopsis basicola. Wallingford, UK. C.A.B. International, Crop Protection Compendium
Specht LP, Griffin GJ (1985) A selective medium for inumerating low populations of Thielaviopsis basicola in tobacco field soils. Can J Plant Pathol 7:438–441
This research was supported through funding from the Cotton Research and Development Corporation and NSW Department of Primary Industries (projects DAN2101 and DAQ2002). I greatly thank CottonInfo team for sampling assistance; and Aphrika Gregson from NSW DPI Narrabri for technical assistance. I specially thank Dr Bernie Dominiak from NSW DPI Orange for critically reviewing and commenting for the improvement of the manuscript.
About this article
Cite this article
Le, D.P. A simple carrot agar medium for isolation of black root rot pathogen of cotton seedlings. Australasian Plant Pathol. 50, 319–322 (2021). https://doi.org/10.1007/s13313-021-00775-3
- Gossypium hirsutum
- Seedling disease
- Selective media
- Carrot discs
- Water agar