Occurrence of Monosporascus cannonballus in Watermelon Fields in Tunisia and Factors Associated with Ascospore Density in Soil

Authors

  • Naima Boughalleb,

    1. Authors’ addresses: Institut Supérieur Agronomique de Chott Mariem, Département des Sciences Biologiques et de la Protection des Plantes, 4042 Sousse, Tunisia
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  • Ibtissem Ben Salem,

    1. Authors’ addresses: Institut Supérieur Agronomique de Chott Mariem, Département des Sciences Biologiques et de la Protection des Plantes, 4042 Sousse, Tunisia
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  • Roberto Beltrán,

    1. Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
    2. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria - Centro de Ensayos de Valencia, C/ Joaquín Ballester 39, 46009 Valencia, Spain (correspondence to Josep Armengol. E-mail: jarmengo@eaf.upv.es)
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  • Antonio Vicent,

    1. Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
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  • Ana Pérez Sierra,

    1. Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
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  • Paloma Abad-Campos,

    1. Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
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  • José García-Jiménez,

    1. Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
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  • Josep Armengol

    1. Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
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Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Valencia, Spain

Abstract

Surveys of 11 watermelon fields throughout production areas of this crop in southern and central regions in Tunisia were conducted in 2007 to determine the aetiology and distribution of watermelon vine decline. Monosporascus cannonballus was isolated from diseased roots in all surveyed fields. All the isolates were identified according to morphological features and confirmed by amplification of a fragment of the ITS region with specific primers. Ascospores of M. cannonballus were recovered from soil in all watermelon fields surveyed and the average population densities ranged from 3.65 to 10.14 ascospores per g of soil. Multiple linear regression analysis revealed that only four of the crop and soil factors evaluated had a significant correlation with ascospore density at the end of the growing season: vertisol vs. other soils, disease incidence, percentage of clay and pH. The pH of the soil showed a strong significant negative linear relationship with ascospore density, while the other three factors correlated positively.

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