Biodiversity, epidemiology and virulence of Colletotrichum gloeosporioides. IV. Epidemiology of Stylosanthes anthracnose at the centre of host-pathogen diversity

Selected lines of Stylosanthes guianensis, S scabra, S. capitata and S. macrocephala were established at field sites at Planaltina and Campo Grande in Brazil and at Carimagua and Caquetá in Colombia. Weather conditions at each site were monitored continuously using an automatic weather station. Data on anthracnose severity caused by Colletotrichum gloeosporioides were collected by visually assessing these lines at monthly intervals and analysed to study disease progress on susceptible and resistant lines in relation to weather variables. Anthracnose was most severe at Planaltina, followed by Carimagua, Campo Grande and Caquetá. S. scabra cv. Fitzroy, susceptible to all Australian races of C. gloeosporioides, was not the most susceptible at Carimagua and Caquetá. Relationships between anthracnose severity and weather variables were explored using multiple regression analysis. These explained between 30 and 95% of the variation in the severity of anthracnose on Fitzroy at the 4 sites. The study highlights the need for improved understanding of anthracnose epidemiology