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Journal of Applied Sciences
  Year: 2008 | Volume: 8 | Issue: 21 | Page No.: 3903-3909
DOI: 10.3923/jas.2008.3903.3909
Resistance of Verticillium theobromae to Benzimidazole Fungicides in Morocco
H. Boubaker, B. Saadi, E.H. Boudyach and A. Ait Benaoumar

Abstract:
In response to growers report of reduced efficacy of benzimidazole fungicides for control of cigar end-rot, a survey was conducted from 2002 to 2005 in four banana-growing locations, with various histories of benzimidazole use, in the Souss-Massa-Drâa Valley, Agadir to determine the proportion of isolates that were in vitro resistant to benomyl and thiophanate-methyl. Of the 274 isolates, collected in Biougra, Belfâa and Ouled-teima locations with more than 10 years of benzimidazole use, 65% (180/274) were resistant to benomyl, 67% (184/274) were resistant to thiophanate-methyl and 65% were resistant to both fungicides tested at a discriminatory concentration of 10 μg mL-1. Only 1.5% of isolates exhibited a differential reaction to the two fungicides. No resistance to benomyl and thiophanate-methyl were detected in isolates collected from banana plantations in the Tamri location which has no known history of benzimidazole use. The mean effective concentrations that reduced growth by 50% (EC50) for resistant-isolates of V. theobromae were between 80 and 97 μg mL-1 for benomyl and between 194 to 233 μg mL-1 for thiophanate-methyl. In contrast, wild-type isolates exhibited mean EC50 values for benomyl and thiophanate-methyl of 0.47 and 0.91 μg mL-1, respectively. All 305 isolates from the four locations sampled in this study were sensitive in vitro to chlorothalonil at 10 μg mL-1. Conidial germination of sensitive-isolates collected from banana plantations never exposed to benzimidazole fungicides were completely inhibited by 1000 μg mL-1 of benomyl or thiophanate-methyl. However, conidial germination of resistant-isolates was not affected by both fungicides tested at 1000 μg mL-1.
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How to cite this article:

H. Boubaker, B. Saadi, E.H. Boudyach and A. Ait Benaoumar, 2008. Resistance of Verticillium theobromae to Benzimidazole Fungicides in Morocco. Journal of Applied Sciences, 8: 3903-3909.

DOI: 10.3923/jas.2008.3903.3909

URL: https://scialert.net/abstract/?doi=jas.2008.3903.3909

 
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