Aislamiento e identificación de hongos asociados a esclerocios de Sclerotium Cepivorum, causante de la pudrición blanca de la cebolla, en la zona alta de Cartago, Costa Rica
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Fecha
2005-01
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artículo original
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Granados Montero, María del Milagro
Wang Wong, Amy
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Se aislaron e identificaron hongos asociados a esclerocios de Sclerotium cepivorum, causante de la pudrición blanca de la cebolla, con el fin de determinar la existencia de hongos con potencial antagónico nativos de la zona alta de Cartago.
Se estudiaron 10 fincas durante el período comprendido entre febrero y mayo del 2002. Cada una se dividió en tres áreas de acuerdo al nivel de incidencia histórica de la enfermedad, en cada área se realizó un trampeo de hongos por medio de la técnica de entierro de esclerocios; además se hizo muestreo de plantas enfermas, se colectó suelo para cuantificar de la densidad de inóculo y para realizar análisis microbiológico, químico sencillo, de textura y determinación de materia orgánica. Los géneros encontrados a partir del trampeo fueron Alternaria spp., Fusarium spp., Gliocladium sp., Mucor sp., Penicillium spp., Rhizoctonia sp., Rhizopus sp. y Trichoderma spp.; en bulbos enfermos se aislaron Fusarium spp., Monilia sp., Mucor sp., Penicillium spp., Pythium sp., Rhizopus sp., y Trichoderma spp. Los géneros Gliocladium sp., Penicillium spp. y Trichoderma spp. se hallaron también a partir de análisis microbiológico de suelo.
Las poblaciones más altas de microorganismos se recuperaron en el área intermedia de todas las fincas.
Este trabajo comprueba que es posible aislar hongos con potencial antagónico, como Trichoderma spp., Gliocladium sp. y Paecilomyces sp., en suelos a los que por muchos años se les ha aplicado una gran cantidad de fungicidas.
A survey to determine the presence of fungi with possible antagonistic effect, associated with sclerotia of Sclerotium cepivorum, causal agent of white rot of onion, was performed in the highlands of Cartago province, the main onion-production area in Costa Rica. From February to May, 2002, 10 farms were studied. Each farm was divided into 3 areas according to the historical incidence of the disease: high, intermediate and low. In each of these areas, the fungus-trapping survey was performed using the slcerotia-burial technique. Besides, diseased plants were collected and a soil sample was taken to determine inoculum density and to perform microbiological, chemical, texture and organic matter analyses. Alternaria spp., Fusarium spp., Gliocladium sp., Mucor sp., Penicillium spp., Rhizoctonia sp., Rhizopus sp. and Trichoderma spp. were the most predominant fungus genera found in association with sclerotia; Fusarium spp., Monilia sp., Mucor sp., Penicillium spp., Pythium sp., Rhizopus sp. and Trichoderma spp. were isolated from diseased onion bulbs and Gliocladium sp., Penicillium spp. and Trichoderma spp. were also found in the microbiological soil analysis. For all 10 farms, the highest population of microorganisms was found in the area considered as intermediate in level of infection. This study indicates that it is possible to isolate fungi with antagonistic effect, such as Trichoderma spp., Gliocladium sp. and Paecilomyces sp., from soils were fungicides have been applied for several years.
A survey to determine the presence of fungi with possible antagonistic effect, associated with sclerotia of Sclerotium cepivorum, causal agent of white rot of onion, was performed in the highlands of Cartago province, the main onion-production area in Costa Rica. From February to May, 2002, 10 farms were studied. Each farm was divided into 3 areas according to the historical incidence of the disease: high, intermediate and low. In each of these areas, the fungus-trapping survey was performed using the slcerotia-burial technique. Besides, diseased plants were collected and a soil sample was taken to determine inoculum density and to perform microbiological, chemical, texture and organic matter analyses. Alternaria spp., Fusarium spp., Gliocladium sp., Mucor sp., Penicillium spp., Rhizoctonia sp., Rhizopus sp. and Trichoderma spp. were the most predominant fungus genera found in association with sclerotia; Fusarium spp., Monilia sp., Mucor sp., Penicillium spp., Pythium sp., Rhizopus sp. and Trichoderma spp. were isolated from diseased onion bulbs and Gliocladium sp., Penicillium spp. and Trichoderma spp. were also found in the microbiological soil analysis. For all 10 farms, the highest population of microorganisms was found in the area considered as intermediate in level of infection. This study indicates that it is possible to isolate fungi with antagonistic effect, such as Trichoderma spp., Gliocladium sp. and Paecilomyces sp., from soils were fungicides have been applied for several years.
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Sclerotium cepivorum, Sclerotia, White rot, Onion, Biological control, Esclerocios, Pudrición blanca, Torbó, Cebolla, Control biológico, 635.259 Cebollas