SELECTION OF QUANTITATIVE RESISTANCE POTATO CLONES AGAINST PHYTOPHTHORA LATE BLIGHT IN KOREA

Abstract

Incidence and progress of potato late blight largely depends on susceptibility of the host in organic farming cultivation. In susceptible hosts, the disease completely destroys whole leaves within two weeks in organic farming fields. However, potato leaves of 14 quantitative resistance hosts remained healthy for 5 weeks after the first symptom appearance in the susceptible host. Area under disease progress curve (AUDPC) of quantitative resistance host ranged from 37.5 to 112.5 and slowly expanded compared with that of susceptible host. On detached leaves assay, seven clones of quantitative resistance host did not produce any sporangia against three isolates collected from different areas in Korea. Physiological races of the pathogen, Phytophthora infestans, were diversified as R0, 1,3,4,5,7,10,11 in organic farming fields and the races distributed with similar patterns in different areas