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Title: Description and identification of two new diseases of guariroba palm (Syagrus oleraceae) in Brazil

Author
item CARDOSO, JESSICA - Universidade Estadual De Maringá
item NANAMI, DANIELLE - Universidade Estadual De Maringá
item ZANUTTO, CARLOS - Universidade Estadual De Maringá
item GRABICOSKI, EDILAINE - Universidade Estadual De Maringá
item VIDA, JOAO - Universidade Estadual De Maringá
item Bock, Clive
item NUNE, WILLIAM - Universidade Estadual De Maringá

Submitted to: Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2017
Publication Date: 7/3/2017
Citation: Cardoso, J.K., Nanami, D.S., Zanutto, C.A., Grabicoski, E.M., Vida, J.B., Bock, C.H., Nune, W.M. 2017. Description and identification of two new diseases of guariroba palm (Syagrus oleraceae) in Brazil. Journal of Phytopathology. 165:610-619.

Interpretive Summary: Guariroba is a palm species native to central Brazil. Seedlings of guariroba with a leaf spot disease of unknown cause were found in Patos de Minas, Minas Gerais, Brazil. The leaf spots had two different symptom types: the first lesion type consisted of necrotic spots with a rounded to elongate shape, with a light color and dark edges; the second lesion type had a rounded shape, was dark brown in color with a light brown edge. The objective of this study was to identify the cause of both diseases. Based on isolations, inoculation and reisolation, morphological analysis and DNA sequencing the fungal species were identified as Pestalotiopsis adusta (causing necrotic spots with a rounded to elongate shape, with a light color and dark edges), and Alternaria tenuissima (causing lesions with a rounded shape, dark brown in color with a light brown edge). Identification of these two organisms will help guide management approaches that might reduce their impact on Guariroba, including the use of fungicides and cultural approaches.

Technical Abstract: Guariroba is a palm species native to central Brazil. Seedlings of guariroba with leaf spots of unknown etiology were found in Patos de Minas, Minas Gerais, Brazil. The leaf spots were manifest as two different symptom types: the first lesion type consisted of necrotic spots with a rounded to elongate shape, with a light color and dark edges; the second lesion type had a rounded shape, was dark brown in color with a light brown edge. The objective of this study was to elucidate the etiology of both diseases. The likely causal agents were isolated and Koch’s postulate fulfilled. Subsequently, the ITS region of rDNA from both microorganisms were amplified and sequenced. According to the morphological characteristics and molecular analyses, the fungal species were identified as Pestalotiopsis adusta (causing necrotic spots with a rounded to elongate shape, with a light color and dark edges), and Alternaria tenuissima (causing lesions with a rounded shape, dark brown in color with a light brown edge). Identification of the causal organisms of these two diseases will help guide management approaches that might be tested to reduce impact of the disease on Guariroba, including the use of fungicides and cultural approaches.