Modes of primary infection caused by Sclerotinia sclerotiorum in navy bean

Se demostro que existen por lo menos 4 tipos de infeccion primaria en frijol blanco por Sclerotinia sclerotiorum: 1) infeccion resultante de ascosporas en petalos de flores contaminadas que se albergan en los tallos; 2) infeccion asociada con hojas contaminadas de ascosporas en contacto con suelo humedo; 3) infeccion asociada con lesiones y tejido necrotico y 4) hojas que entran en contacto con esclerocios en la superficie del suelo. Los tejidos infectados o contaminados con ascosporas no necesariamente producen una lesion infecciosa; la progresion de la enfermedad podria impedirse si no hubiera la presencia continua de HR alta. Estas observaciones muestran que la infeccion no solo ocurre a partir de ascosporas que colonizan el tejido senescente, sino tambien mediante germinacion miceliogenica de esclerocios. (RA- CIAT) spa

This investigation has demonstrated that there are at least four types of primary infection in navy bean by Sclerotinia sclerotiorum: (1) infection resulting from ascospores on contaminated flower petals which lodge on the stems; (2) infection associated with ascospore contaminated leaves in contact with moist soil; (3) infection associated with injuries and necrotic tissues; and (4) leaves coming in contact with sclerotia on the soil surface. Ascospore contaminated or infected tissues do not necessarily result in a disease lesion and the progression of disease may be impeded if high relative moisture were not continuously available. These observations show that infection not only occurs from ascospores colonizing senescent tissue, but also by myceliogenic germination of sclerotia. (AS) eng