In vitro biocontrol of tomato pathogens using antagonists isolated from chicken-manure vermicompost Translated title: Biocontrol in vitro de fitopatógenos de tomate mediante antagonistas aislados de vermicomposta de gallinaza

Abstract

The objectives of this study were to (1) isolate and identify pathogenic fungi from vegetative material with wilt symptoms in tomato plantations belonging to the Cienega of Chapala, Michoacán, Mexico, and (2) determine the antagonistic capacity of Trichoderma sp. and Aspergillus spp. isolated from chicken-manure vermicompost. Pathogens were isolated by means of a completely randomized sampling in 6 locations; 9 plantations were inspected and 45 plants with symptoms of the disease were selected. Portions of root and stem were disinfected and placed on potato-dextroseagar acidified (PDA). Antagonists isolation was made from a dilution of chicken-manure vermicompost of 1 x 10-2 in PDA medium culture more streptomycin and tetracycline. The antagonistic activity was tested by the dual culture confrontation methods. Two pathogens were obtained on tomato in the study area, Fusarium spp. and Rhizoctonia sp., presenting an incidence of 92% and 5%, respectively. Morphological characteristics were determined in cultivation of PDA. Molecular analysis identifed F. oxysporum, F. solani, F. subglutinans and Rhizoctonia sp. Of 11 isolates of chicken manure vermicompost, only Trichoderma sp. and Aspergillus sp., had significant diferences (p≤0.05) with respect to the control. Inhibition of F. oxysporum growth ranged from 45% to 48%, and 24% to 27%, in presence of Trichoderma sp. and Aspergillus sp., respectively; these antagonistic species inhibited growth of Rhizoctonia sp. by 38% and 25% , respectively.

Translated abstract

Los objetivos de este trabajo fueron (1) aislar e identificar hongos patógenos de plantas de tomate con síntomas de marchitez, en plantaciones de seis localidades de la Ciénega de Chapala, Michoacán, México, y (2) determinar la capacidad antagónica de Trichoderma sp. y Aspergillus sp. asociados a vermicomposta de gallinaza. Los patógenos se aislaron a partir de un muestreo al azar en nueve plantaciones de las cuales se seleccionaron 45 plantas de tomate con síntomas de la enfermedad. Porciones de raíz y tallo fueron desinfectados y colocados en medio papa-dextrosa-agar acidificado (PDA). El aislamiento de antagonistas se hizo a partir de una dilución de vermicomposta de gallinaza de 1 x 10-2 en medio de cultivo PDA más tetraciclina y estreptomicina. El antagonismo fue evaluado mediante confrontación por cultivos duales. Dos fitopatógenos fueron obtenidos del área de estudio; Fusarium spp. y Rhizoctonia sp. con una incidencia de aislamientos de 92% y 5%, respectivamente. Las características morfológicas se determinaron en cultivo de PDA, y mediante un análisis molecular se identificó a F. oxysporum, F. solani, F. subglutinas y Rhizoctonia sp. De 11 cepas aisladas de la vermicomposta de gallinaza, solo Trichoderma sp. y Aspergillus sp., tuvieron diferencias significativas (p≤0,05) con respecto al testigo. La inhibición del crecimiento "in vitro" de F. oxysporum por Trichoderma sp. y Aspergillus sp. varió de 45% a 48%, y de 24% a 27%, respectivamente; estos antagonistas inhibieron el crecimiento de Rhizoctonia sp. en un 38% y 25%, respectivamente.