Alternaria dauci causes leaf spots and leaf blight of coriander ( Coriandrum sativum ) in Brazil
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Alternaria dauci causes leaf spots and leaf blight of coriander (Coriandrum sativum) in Brazil Paloma S. Mansur 1 & André L. Silva 1 & Sara S. Salcedo 1 & Robert W. Barreto 1 & Adans A. Colmán 1,2 Received: 18 November 2019 / Accepted: 8 October 2020 # Australasian Plant Pathology Society Inc. 2020
Abstract Alternaria dauci is fully confirmed to cause leaf spots and leaf blight of coriander (Coriandrum sativum) in Brazil based on observations made of blighted plants at a demonstration plot (Infectarium) at Viçosa (state of Minas Gerais) Brazil. Identification was supported by a combination of morphological, cultural and molecular features. A representative herbarium sample and an isolate were deposited in public collections as well as DNA sequences. Pathogenicity tests were conducted and Koch’s postulates were fulfilled. Keywords Etiology . Phylogeny . Section Porri . Pathogenicity . Pleosporaceae
Coriander (Coriandrum sativum), also known as cilantro (coentro in Brazil) is an annual herb of the Apiaceae. It is widely cultivated and used as a condiment herb worldwide (Simpson and Connor-Ogorzaly 2001) and also in Brazil. Several fungal pathogens have been reported as causing leaf spots on coriander in Brazil (Farr and Rossman 2019) and Alternaria leaf spot is considered an important disease of coriander in Brazil (Reis and Lopes 2016). In July 2018, all plants growing in a demonstration plot in the Infectarium – the plant disease garden - of the Departamento de Fitopatologia of the Universidade
* Adans A. Colmán [email protected] Paloma S. Mansur [email protected] André L. Silva [email protected] Sara S. Salcedo [email protected] Robert W. Barreto [email protected] 1
Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
2
Present address: Facultad de Ciencias Agrarias, Universidad Nacional de Asunción, San Lorenzo, Paraguay
Federal de Viçosa (municipality of Viçosa, state of Minas Gerais, Brazil) were found to be attacked by a disease leading to severe leaf blight symptoms. Firstly small round to oval, 3–5 mm diam., leaf spot appeared which quickly coalesced and turned into necrotic blight of entire leaves. Samples were collected and examined under a dissecting microscope and a dematiaceous fungus was found to be regularly associated with the necrotic tissues. Under a dissecting microscope (Olympus SZX7) conidia were taken from infected leaves with a sterile fine pointed needle and transferred onto previously marked positions of V8 juice-agar plates. Each position of those plates was then examined, under the high power of the dissecting microscope, to select positions where single conidia were deposited. Those points of the plates were further marked, at the underside of the plates, indicating that colonies from these positions represented single-spore isolates. After 1 week of growth in the incubator, at 25 °C, a fragment of the margin of one selected single spore colony was taken and transferred to a tube containing potato carrot-agar. This represen
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