Effect of Barrier on Rain Splash Dispersal of C. gloeosporioides from Infected Strawberry Plant

Abstract

Strawberry plants infected with C. gloeosporiodes which causes anthracnose were placed in nursery beds to investigate the relation of the disease spread and the effect of some physical barriers. The dispersion distance of conidia of the pathogen was examined by the appearence of early disease symptoms, black leaf spots, on leaves in every direction. Disease incidence on leaflets and petioles was severe under 0.5m horizontally from the inoculum source, and conidia dispersed more than 3min heavy rain. Vertical spread of disease incidence decreased at a distance from the inoculum source, especially far from 60cm. Barriers of plastic film over 40cm high were effective to prevent the disease spread on strawberry plants. Leaf spots developed when leaflets were inoculated with more than 10² conidia/young leaflet. The number of black leaf spots appeared was correlated with the concentration of conidia in the inoculum (r=0.63, p=0.01). Thus, it was shown that barriers are useful to protect strawberry plants from anthracnose infection on the leaflets due to rain dispersion even in heavy rain.