Tropical Plant Pathology (2014) 39, 172-177

Lahyre Izaete Silveira Gomes, Líllian B.J. Bibiano, Gilvan Ferreira da Silva, Rogério Eiji Hanada and Eduardo S.G. Mizubuti (2014)
Baseline sensitivity of Brazilian Mycosphaerella fijiensis isolates to protectant and systemic fungicides
Tropical Plant Pathology 39 (2), 172-177
Abstract: Black Sigatoka caused by Mycosphaerella fijiensis is a foliar disease that affects banana plants and large amounts of fungicides are required to prevent crop losses. Intensive applications of single-site fungicides can select for fungicide-resistant isolates. The objective of this study was to assess the sensitivity of 60 isolates of M. fijiensis to commonly used fungicides. Using two different protocols, microtiter and Petri plate tests, the effective concentration at which mycelium growth is reduced by 50% (EC₅₀) was determined for thiophanatemethyl, tebuconazole, chlorothalonil and mancozeb. Additionally, partial sequences of the cytochrome b gene were obtained for 46 isolates to detect the G143A mutation, commonly associated with strobilurin resistance. The EC₅₀ values for tebuconazole and thiophanate-methyl ranged from 0.02 to 1.39 and from 0.008 to 8.22 µg mL^-1, respectively. For chlorothalonil, the lowest and highest EC₅₀ values were 0.39 µg mL^-1 and 53.7 µg mL^-1, respectively. For mancozeb, approximately 50% of the isolates had EC₅₀ values greater than 1000 µg mL^-1. No mutation was found in the isolates assayed for strobilurin resistance. There was no correlation between sensitivity levels to any fungicide and geographic region. Low EC₅₀ values were estimated for most fungicides but, some isolates had high EC₅₀ values for mancozeb.
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Database assignments for author(s): Eduardo S.G. Mizubuti

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pseudocercospora fijiensis	Banana/plantain (Musa)	Brazil (south)
	Pseudocercospora fijiensis	Banana/plantain (Musa)	Brazil (NW)
	Pseudocercospora fijiensis	Banana/plantain (Musa)	Brazil (NE)