ISOLATION, INCIDENCE, AND VIRULENCE OF ASCOCHYTA SPP. OF PEAS FROM THE SOIL

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Abstract
Ascochyta pinodella, cause of footrot, and Ascochyta pinodes, cause of blight, of peas were isolated from field soil by heating the soil to 100 C for 12–15 h followed by plating the soil on a medium containing rose bengal and chlortetracycline. A. pinodella was present in most soils where peas were growing and also in some soils where peas had not been grown for 1 to 5 years. Soil cultures of A. pinodella were weakly virulent but by host passage, re-isolated cultures produced typical symptoms of footrot on young plants. A. pinodes was isolated less frequently from soil; however, cultures were strongly virulent and inoculated plants showed typical disease symptoms in 5 days. Although infected seed has been considered to be the main source of inoculum, the frequent isolation of A. pinodes and A. pinodella from soil demands a re-appraisal of the epidemiology of this disease complex.