Diagrammatic scale for quantifying severity of brown leaf spot on Carya illinoinensis



Document title: Diagrammatic scale for quantifying severity of brown leaf spot on Carya illinoinensis
Journal: Anais da Academia Brasileira de Ciencias
Database: PERIÓDICA
System number: 000436139
ISSN: 0001-3765
Authors: 1
2
2
1
2
2
1
Institutions: 1Universidade Federal de Santa Maria, Departamento de Defesa Fitossanitaria, Santa Maria, Rio Grande do Sul. Brasil
2Universidade Federal de Santa Maria, Departamento Fitotecnia, Santa Maria, Rio Grande do Sul. Brasil
Year:
Volumen: 92
Country: Brasil
Language: Inglés
Document type: Artículo
Approach: Analítico, descriptivo
English abstract Brown leaf spot disease, caused by the fungus Ragnhildiana diffusa, is responsible for losses in pecan orchards and quantification is essential in order to conduct epidemiological studies to establish levels of productivity losses, and assess control strategies. Therefore, the aim of this study was to develop and validate a diagrammatic scale for assessing the severity of brown leaf spot in pecan. 240 symptomatic leaflets were collected from adult trees in Anta Gorda, in the Brazilian state of Rio Grande do Sul, and used to assess the current percentage severity of the disease. The scale was based on the minimum and maximum observed severity of the disease, with six graduations defined according to the Weber-Fechner Visual Stimulus Law. The scale therefore consisted of eight levels (1.5, 4.6, 10.6, 17.3, 39.5, 65.1, 77.5, and 98%). The estimates of eight evaluators provided a basis for validating the scale. They made estimates of disease severity on 40 symptomatic digitalized pecan leaflets first, without using the scale and then referring to it. The scale provided greater precision, accuracy, and reproducibility of estimates and should result in more reliable epidemiological studies
Disciplines: Agrociencias
Keyword: Fitopatología,
Frutales,
Hongos,
Nogal pecanero,
Mancha parda de las hojas,
Daño foliar,
Hongos fitopatógenos,
Ragnhildiana diffusa,
Ascomycetes,
Carya illinoinensis,
Juglandaceae
Keyword: Phytopathology,
Fruit trees,
Fungi,
Pecan tree,
Brown leaf spot,
Leaf damage,
Phytopathogenic fungi,
Ragnhildiana diffusa,
Ascomycetes,
Carya illinoinensis,
Juglandaceae
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