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First Report of Chalara elegans Causing Wilt on Lisianthus in Switzerland

2015; American Phytopathological Society; Volume: 99; Issue: 8 Linguagem: Inglês

10.1094/pdis-12-14-1329-pdn

1943-7692

Vincent Michel,

Flowering Plant Growth and Cultivation

HomePlant DiseaseVol. 99, No. 8First Report of Chalara elegans Causing Wilt on Lisianthus in Switzerland PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Chalara elegans Causing Wilt on Lisianthus in SwitzerlandV. V. MichelV. V. MichelSearch for more papers by this authorAffiliationsAuthors and Affiliations V. V. Michel , Agroscope, Institute for Plant Production Sciences, Research Center Conthey, CH-1964 Conthey, Switzerland. Published Online:29 Jun 2015https://doi.org/10.1094/PDIS-12-14-1329-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Lisianthus (Eustoma grandiflorum L.) is grown in Switzerland for cut flower production. The production occurs mainly in greenhouses. In 2009, new soilless production systems were tested at the Agroscope Research Center Conthey to improve productivity, especially during the cooler season. In March 2009, individual plants grown in a hydroponic production system started to wilt shortly before flowering. Within a few days, healthy plants surrounding the wilting ones showed similar symptoms. The leaves of the 25- to 35-cm-high plants lost turgor starting from the bottom leaves. A few days later, all leaves wilted and the top of the erected stems exhibited reduced turgor and drooped. No discoloration or necrosis on the external or internal aboveground part were observed. In contrast, the roots of the plants with wilt symptoms turned brownish, whereas the roots of healthy plants remained white. Dark brown chlamydospores (average size 41 × 13 µm) were distinguishable on brown roots and were identifiable as Chalara elegans (Nag Raj & Kendrick (syn. Thielaviopsis basicola (Berk. & Broome) Ferr.) (Domsch et al. 1993). The pathogen was isolated on potato dextrose agar (PDA) containing an antibiotic (chlortetracycline), where it produced, in addition to the chlamydospores, the typical rectangular conidiospores (average size 14 × 4 µm) of C. elegans. In summer 2009, young commercial seedlings of lisianthus (cv. Paloma deep rose) were transplanted in seed trays filled with steam-sterilized peat substrate and maintained in a greenhouse at 20 to 25°C. In August 2009, two strains of C. elegans isolated from lisianthus and carrot (Daucus carota L.) were propagated. Mycelium edges of each isolate were added to three 500-ml Erlenmeyer flasks containing 250 ml of an autoclaved, clarified V8 broth. The flasks were placed on a rotary shaker set at 110 rpm and incubated at 24°C for 10 days. Content of the flasks were filtered through Whatman 113 filter paper and the suspended in 0.9% NaCl solution. The concentration for inoculation was 1.5 × 107 conidiospores/ml and 1 × 105 chlamydospores/ml. Before inoculation, the substrate surrounding the roots of the lisianthus seedlings (10 true leaves, 8 to 12 cm high) was removed under running tap water. Water was absorbed from roots with a paper towel, then roots were suspended for 5 min in the inoculation suspension. For the plants of the control treatment, the roots were suspended in sterile 0.9% NaCl solution. Each plant was planted in 0.5 liter pots filled with a mixture of a sterile sandy loam soil (pH of 7.4; soil:water, 1:1 (w:v)) and expanded clay (2:1 (v:v)). Plants were maintained in a greenhouse at 18 to 22°C and watered with tap water. Inoculated and control pots were kept in three separate trays to avoid cross-contamination by drainage water. After one month, plants inoculated with both strains of C. elegans showed wilted leaves and the roots were colonized with chlamydospores. No such symptoms were observed on the control plants. C. elegans was reisolated from the roots of the inoculated plants on PDA with chlortetracycline. To the best of my knowledge, this is the first report of C. elegans as pathogen of E. grandiflorum (Farr and Rossman 2015).References:Domsch, K. H., et al. 1993. Compendium of Soil Fungi, Vol. 1. IHW-Verlag, Eching, Germany. Google ScholarFarr, D. F., and Rossman, A. Y. Fungal Databases, Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/, March 24, 2015. Google ScholarDetailsFiguresLiterature CitedRelated Vol. 99, No. 8 August 2015SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 6 Aug 2015Published: 29 Jun 2015Accepted: 1 Apr 2015 Page: 1187 Information© 2015 The American Phytopathological SocietyCited byBerkeleyomyces basicola (black root rot)CABI Compendium, Vol. CABI CompendiumDiseases of Lisianthus7 January 2018Diseases of Lisianthus13 December 2016