Effects of Epoxiconozale and Pyraclostrobin Fungicides in the Infection Process of Hemileia vastatrix on Coffee Leaves as Determined by Chlorophyll a Fluorescence Imaging

Autor:	Fabrício Ávila Rodrigues, Laércio Zambolim, Jaime Honorato Junior, Carlos Eduardo Aucique-Pérez, Henrique Duarte
Rok vydání:	2015
Předmět:	Hemileia vastatrix Chlorophyll a biology Physiology Coffea arabica food and beverages Plant Science biology.organism_classification Photosynthesis Photosynthetic capacity Rust Fungicide Horticulture chemistry.chemical_compound Agronomy chemistry Genetics Epoxiconazole Agronomy and Crop Science
Zdroj:	Journal of Phytopathology. 163:968-977
ISSN:	0931-1785
DOI:	10.1111/jph.12399
Popis:	Coffee is the most traded commodity in the world, and Brazil is its largest producer. Coffee leaf rust, caused by the biotrophic fungus Hemileia vastatrix, is the most important coffee disease, reducing coffee yield by 35–50%. This study aimed to use the ratio of variable and maximum fluorescence of dark-adapted tissue (Fv/Fm) as a parameter to differentiate presymptomatic tissue from healthy tissue during disease development in plants sprayed with pyraclostrobin and epoxiconazole after 4 days postinoculation. Visual severity was considered as an indicative of apparent disease and true severity as an indicative of both apparent and non-apparent disease. There was a significant linear relationship between the areas of true severity and visual severity, and for each additional unit in the visual severity, there was an increase of 1.53 units on the true severity. For the epoxiconazole and pyraclostrobin treatments, coffee leaf rust symptoms decreased according to both visual and Fv/Fm images. Pustules on the leaves sprayed with epoxiconazole were smaller in size than those on the leaves of non-sprayed plants but bigger than those sprayed with pyraclostrobin. The reduction in Fv/Fm values at the pustule epicentres present on the leaves of plants sprayed with epoxiconazole, and pyraclostrobin was greater than those of the non-sprayed plants. This finding was expected and reflects the importance of these fungicides in prohibiting the progress of coffee leaf rust. The photosynthetic capacity of Coffea arabica was affected by H. vastatrix infection, and the Fv/Fm parameter was able to show this effect before the visual symptoms were noticed.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::4a0825b0a9ab6f1a609d31c8760e44c6 https://doi.org/10.1111/jph.12399 Zobrazit plný text záznamu Plný text ve formátu PDF Plný text ve formátu HTML
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