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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
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Resistance of Verticillium theobromae to Benzimidazole Fungicides in Morocco

H. Boubaker, B. Saadi, E.H. Boudyach and A. Ait Benaoumar

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






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