EPIDEMIOLOGY STUDIES ON THE SEPTORIA DISEASE OF OATS

Abstract

Ascospores were found to be the principal cause of primary infection in the disease of oats caused by Leptosphaeria avenaria f. sp. avenaria. Macrospores produced in the leaf lesions on oat plants were responsible for the secondary spread of the fungus and the subsequent development of the black stem phase of the disease. Viable ascospores were present throughout the growing season and provided the means for widespread development of the disease. The purpose of the microspores is not clearly understood but they would appear to be of little importance in the initiation and subsequent spread of the disease. Seed-borne infection was found to be of no importance in the epidemiology of this disease.