Sensitivity distribution of phytopathogenic bacteria and fungi to antibiotics.

The minimal inhibitory concentrations (MIC) of various antibiotics and fungicides for Erwinia carotovora, Pseudomonas coronafaciens var. atropurpurea, P. lachrymans, Alternaria mali, A. kikuchiana, Pyricularia oryzae, Botrytis sp. and Sclerotinia sp. isolated from diseased plants in various localities of Japan were examined to enable the isolates to be gruoped into sensitive and resistant strains. To minimize the effects of various variable conditions, MIC of isolates were pooled for either 2 or 3 years and were plotted in a single figure. The grouping values were determined on the basis of MIC values of the antibiotics and agricultural chemicals on phytopathogenic bacteria and fungi under investigations. The relationships between grouping values for isolates of bacteria and fungi and the control of disease on the plants correlated to each other were studied.