HOST-PARASITE RELATIONS IN A POPULATION OF WILD EMMER IN EASTERN GALILEE

Abstract

In the years 1983 to 1993 populations of wild emmer growing on pasture land near Kibbutz Ammiad in eastern Galilee were subjected to a study of fungal diseases. In their natural environment in a rainfall and temperature range suitable for the pathogens studied, the plants were practically free of disease. They showed only extremely low incidence of infection by foliage fungi and the take-all root disease. However, over a nine-year period, during which self progenies of some four thousand plants from different habitats on the site were grown in 20 field- or nethouse-nurseries, heavy spontaneous infection with the three common wheat rusts and powdery mildew and moderate infection with septoria leaf blotch were observed. Artificial inoculation of a field planting with septoria glume blotch also resulted in heavy infection. Seedlings of some of the sets of progenies derived from disease-free plants were inoculated in controlled environments with different isolates of seven fungal species. In these tests, almost all accessions showed susceptibility to all or part of the isolates. Races of the three rust diseases and of powdery mildew, which had been isolated from the wild Ammiad populations, elicited responses of total susceptibility. The strategies that suppress expression of disease in susceptible wild-growing plants are not well understood, and the need for studying them is stressed.