DETERMINACIÓN DE RAZAS Y GRUPOS DE COMPATIBILIDAD VEGETATIVA DE Fusarium oxysporum f. sp. cubense EN Musa, EN LOS ESTADOS CARABOBO, COJEDES, GUÁRICO Y MIRANDA, VENEZUELA

Existen diversos problemas que afectan la produccion de bananos, sin embargo, el Mal de Panama, causado por Fusarium oxysporum f. sp. cubense (Foc) es considerada la mas devastadora a nivel mundial. En Venezuela, la enfermedad ha sido reportada en diez de los veintitres estados; en esta investigacion, se estudio la presencia del hongo en cuatro estados no analizados hasta ahora (Guarico, Cojedes, Carabobo y Miranda). Se generaron vitroplantas de cambur ‘Manzano’, ‘Topocho’ y ‘Gran Enano’, a fin de identificar las razas de Foc. Se tomo como criterio el uso de la tierra, estableciendose un muestreo no probabilistico. Se ubicaron 12 fincas donde se observaron plantas con sintomas de la enfermedad Mal de Panama, y se muestrearon 2 a 3 plantas por finca mediante el metodo de puncion del pseudotallo. Se obtuvieron 50 aislados. Para la prueba de patogenicidad se utilizo arroz inoculado con Foc a una concentracion de 6 x 105 conidios/mL; y se incubo a temperatura ambiente por 8 dias para su crecimiento. Posteriormente, se mezclo con el sustrato, se sembro la vitroplanta y se incubaron hasta por dos meses; para ello se aplicaron disenos estadisticos como arreglo factorial completamente al azar. Se observaron sintomas de la enfermedad en plantas de Cambur Manzano y Topocho, concluyendo que en las zonas estudiadas la enfermedad es causada por las razas 1 y 2 de Foc. De forma simultanea, se realizaron los estudios para determinar el grupo de compatibilidad vegetativa (GCV), para lo cual se generaron e identificaron mutantes nit y se usaron patrones GCV. Los aislados resultaron incompatibles con los patrones utilizados. Palabras clave: GCV, mutantes nit, Mal de Panama. ABSTRACT There are various problems affecting banana production, however, Panama disease, caused by Fusarium oxysporum f. sp. cubense (Foc), is considered the most devastating disease worldwide. In Venezuela, the disease has been reported in ten of the twenty three states; in this research, the presence of the fungus was studied in four states not studied before (Guarico, Cojedes, Carabobo y Miranda). Banana plantlets were generated from 'Apple', 'Bluggoe' and 'Grand Nain' cultivars, in order to identify the races of Foc. Using a non probabilistic sampling, 12 farms were surveyed and symptomatic plants with Panama disease were located, selecting 2-3 plants per farm which were sampled by puncturing the pseudostem. Fifty isolates were obtained. For pathogenicity test, inoculated rice with Foc was used at a concentration of 6 x 105 conidia/mL, and was maintained at environmental temperature for 8 days to grow. Afterwards, it was added to the substrate, the plantlets were planted and incubated for up to 2 months. A complete random design with a factorial arrangement was used. At 1-4 weeks, disease symptoms were observed on ‘Bluggoe’ and ‘Apple’ cultivars, concluding that in the areas studied the disease is caused by races 1 and 2 of Foc. Simultaneously, studies were performed to determine the vegetative compatibility group (VCG), for which nit mutants were generated, identified and challenged with GCV testers. Isolates were incompatible with the standards used. Key words: GCV, nit mutant, Panama disease.