Abstract
Watermelon and melon crops are affected by some important soil-borne fungal diseases like carbonaceous rot (Macrophomina phaseolina), collapse (Monosporascus cannonballus), or the most important pathology at an economic level, the Fusarium wilt (Fusarium oxysporum f. sp. niveum, F. oxysporum f. sp. melonis, F. solani f. sp. cucurbitae, Neocosmospora falciformis, and N. keratoplastica). The methods commonly used for their control are often ineffective, thus new approaches, as the use of biological control agents, are constantly being sought. This work aimed to isolate, identify, and test endophytic fungi for their antagonistic properties against the three mentioned diseases. For this, about 350 endophytic fungal strains were isolated from asymptomatic watermelon plants. Among these, 7 fungal species were selected to evaluate their antagonistic potential against 14 pathogens. Dual culture assays allowed to select two Trichoderma strains according to the high inhibition rates observed (up to 93%), that were further employed in melon and watermelon plants, showing that some of the pathogens were controlled in terms of disease incidence, exhibiting a decrease up to 67% for T. lentiforme. In addition, three concentrations of Epicoccum purpurascens extract was selected to evaluate the germicide effect, obtaining significant differences in the growth of the pathogens depending on fermentation parameters.
Highlights
Watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai) and melon (Cucumis melo L.) are horticultural species of the Cucurbitaceae, widely cultivated throughout the world
Dual culture assays allowed to select two Trichoderma strains according to the high inhibition rates observed, that were further employed in melon and watermelon plants, showing that some of the pathogens were controlled in terms of disease incidence, exhibiting a decrease up to 67% for T. lentiforme
In Spain and other producing areas of the Mediterranean, diseases like collapse produced by Monosporascus cannonballus Pollack and Uecker (Diatrypaceae), the so-called charcoal rot caused by Macrophomina phaseolina (Tassi) Goid. (Botryospharieceae) and Fusarium wilt are responsible for annual important yield losses in both greenhouses and open–air fields [5,6,7,8]
Summary
Watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai) and melon (Cucumis melo L.) are horticultural species of the Cucurbitaceae, widely cultivated throughout the world. & Nakai) and melon (Cucumis melo L.) are horticultural species of the Cucurbitaceae, widely cultivated throughout the world Both species represent economically important crops, especially in Spain, which is the most important producer in Europe, with an annual production of 853,600 tons [1]. An important limiting factor for these cultures around the world has long been the several diseases and pests that affect them, causing significant losses [2,3]. Some of these pathologies have been recently characterized, while others are known for more than a century [4]. The most visible symptoms of its infection are located at the root level, consisting of active rot and necrotic lesions, which causes wilting and Agronomy 2020, 10, 820; doi:10.3390/agronomy10060820 www.mdpi.com/journal/agronomy
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