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First Report of Rhizoctonia Zeae on Turfgrass in Ontario T NEWBlackwell Publishing Ltd DISEASE REPORTS Plant Pathology (2007) 56, 350 Doi: 10.1111/j.1365-3059.2006.01467.x First report of Rhizoctonia zeae on turfgrass in Ontario T. Hsiang* and P. Masilamany Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada In May 2004, a disease appeared on Poa annua and Agrostis stolonifera this organism is similarly confused since R. zeae is considered to be a sub- at a golf course near Toronto. Narrow yellow rings enclosing areas up to species of Waitea circinata which contains at least two other subspecies 30 cm across appeared after air temperatures reached 25°C. The disease including R. oryzae (Oniki et al., 1985; Leiner & Carling, 1994). More resembled yellow patch caused by Rhizoctonia cerealis, but the weather work is required to clarify the taxonomic disposition of R. zeae. was too warm for normal occurrences of that disease. The rings persisted until the end of July. In late May 2005, the disease appeared again after the Acknowledgements weather became hot. A mixture of azoxystrobin and chlorothalonil was applied which seemed to suppress the disease within a week, until it reap- We are grateful for the financial support of the Natural Sciences and peared in July. Samples were collected, and leaves with symptoms were Engineering Research Council of Canada, the Ontario Ministry of surface sterilized in 1% hypochlorite, and transferred to potato dextrose Agriculture and Food, as well as technical support from Darcy Olds and agar (PDA) amended with streptomycin. After one week at 25°C, the Russ Gowan. plates contained white colonies 5 cm diameter. Sequencing of the ITS region of ribosomal DNA showed a 99·6% match with a R. zeae sequence References in GenBank. Pathogenicity was tested by inoculating 2-wk-old plants with mycelial plugs of R. zeae. Within one week at 25°C, significant blighting Joshi V, 2004. Diseases diagnosed on commercial crops submitted to the on leaves and sheaths was observed, together with spherical orange scle- BCMAFF Plant Diagnostic Lab in 2003. Canadian Plant Disease Survey 84, 7–13. rotia on sheaths. Affected leaves were incubated on PDA, and hyphae of Leiner RH, Carling DE, 1994. Characterization of Waitea circinata R. zeae were recovered. (Rhizoctonia) isolated from agricultural soils in Alaska. Plant Disease 78, In Canada, R. zeae has been reported from turfgrass samples in British 385–8. Colombia (Joshi, 2004), but this is the first report from Ontario. In the Oniki M, Ogoshi A, Araki T, Sakai R, Tanaka S, 1985. The perfect state of USA, this fungus has been reported to cause diseases of several turfgrass Rhizoctonia oryzae and R. zeae and the anastomosis groups of Waitea species (Smiley et al., 2005), which have been called variously hot weather circinata. Transactions of the Mycological Society of Japan 26, 189–98. brown patch, leaf and sheath spot/rot/blight or brown ring patch. We Smiley RW, Dernoeden PH, Clarke BB eds, 2005. Compendium of Turfgrass propose that it should be referred to as sheath spot. The taxonomy of Diseases, 3rd Edition. St. Paul, MN, USA: APS Press. *E-mail: [email protected]. Accepted 18 April 2006 at www.bspp.org.uk/ndr where figures relating to this paper can be viewed. Plant Pathology (2007) 56, 350 Doi: 10.1111/j.1365-3059.2006.01468.x First report of root rot of stevia caused by Sclerotium rolfsii in India A. Kamalakannana*, V. Valluvaparidasanb, K. Chitraa, E. Rajeswaria, K. Salaheddinb, D. Ladhalakshmib and A. Chandrasekarana aAgricultural Research Station, Tamil Nadu Agricultural University, Bhavanisagar – 638 451, Erode District, Tamil Nadu; and bDepartment of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore-641 003, Tamil Nadu, India Stevia (Stevia rebaudiana) is an important medicinal crop grown in India. The pots were kept at 25 ± 2°C with soil moisture content maintained at The leaves of stevia contain a noncalorific sweetener, stevioside, which is 70%. The plants were assessed 30 days after planting. Inoculated plants used as an alternative to artificially produced sweeteners. Between June developed typical symptoms on leaves, stem and roots, and S. rolfsii was and September 2005, a disease survey was conducted in different stevia- consistently re-isolated. Uninoculated plants did not show any symptoms. producing villages of Erode district in Tamil Nadu State. A new root rot Chang et al. (1997) observed a stem rot disease of stevia for the first disease was observed on 2-month old stevia plants in all areas surveyed. time in India and identified the causal agent as Sclerotinia sclerotiorum. Symptoms first appeared as yellowing and drooping of leaves, with wilting Megeji et al. (2005) recorded a stem rot disease on stevia at Palampur, of plants and white cottony mycelial growth at the collar region. The myc- Himachal Pradesh, India by visual observation without confirming the elial growth spread to the stem and roots, with associated tissue rotting. pathogen. However, this is the first report of S. rolfsii infecting stevia in On the diseased areas, brown sclerotia were observed. A fungus was con- India. sistently isolated from diseased roots on potato dextrose agar medium incubated at 25 ± 2°C. The mycelium of the fungus was hyaline, branched at clamp connections and septate, corresponding with published References descriptions for Sclerotium rolfsii (Mordue, 1974). The abundant sclerotia Chang KF, Howard RJ, Gaudiel RG, 1997. First report on Stevia as a host for were round to oblong, initially white and later brown, with an average Sclerotinia sclerotiorum. Plant Disease 81, 311. diameter of 0·5–2·0 mm. Megeji NW, Kumar JK, Virendra S, Kaul VK, Ahuja PS, 2005. Introducing To confirm pathogenicity, 25–30 day old seedlings were planted in pots Stevia rebaudiana, a natural zero-calorie sweetener. Current Science 88, 801–4. containing 100 parts of sterilised soil and 1 part of mycelial inoculum, Mordue JEM, 1974. Corticium rolfsii. CMI Descriptions of Pathogenic Fungi using an isolate of S. rolfsii from stevia multiplied in a sand/maize medium. and Bacteria No. 410. Wallingford, UK: CAB International. *E-mail: [email protected]. Accepted 23 May 2006 at www.bspp.org.uk/ndr where figures relating to this paper can be viewed. © 2007 The Authors 350 Journal compilation © 2007 BSPP.
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