La mancha mantecosa del café causada por Colletotrichum spp.

Abstract

"Mancha mantecosa" a disease of coffee also known as "Blister spot" and "Wellman´s fruit and leaf spot", was originally attributed to a virus. However, repeated attempts made in the course of this study to transmit it by graft, by insects and mechanically have always failed. Appearence of field symptoms was correlated with high relative humidity. Progeny of infected plants eventually showed symptoms of the disease when grown in the field, but not under dry greenhouse conditions. Monosporic isolates of a Colletotrichum spp. reproduced the disease when spore suspensions were inoculated on fruits and leaves of plants derivated from seed formed on diseased parents, provided high humidity was supplied. Progeny of healthy plants, and F1 of crosses between healthy and diseased ones, could not be infected. Pathogenic isolates of the fungus, tarying in virulence, were obtained more frequently from lesions on young leaves, but also ocurred in old ones, diseased fruits, symptomless leaves and suberized tissue of the branches. The fungus can remain latent in symptomless tissue. Symptom development in the leaves appeared to be checked by a host defense reaction, but could be very severe in tender tissues, the fungus seemed to be inactivated as infected tissues became older.