EFFECT OF EXPOSURE TO RADIO-FREQUENCY ELECTRIC FIELDS ON SEED-BORNE MICROORGANISMS

Exposure of naturally infected and artificially inoculated seeds to radio-frequency (rf) electric waves of 59 to 64 Mc/sec was of varying effectiveness in eradicating internally borne fungi and bacteria. Diaporthe phaseolorum was eliminated from soybean seeds with little reduction in seed germination. Survival of Ascochyta pisi and A. pinodes (Mycosphaerella pinodes) in field pea seed was greatly reduced by similar treatment, but the fungi were not usually eradicated without appreciable reduction in germination. Germinability of pea seeds was unaffected by increasing the moisture content of the seed to 16% from 10.3%. The A. pinodes content of such seeds, however, was reduced by approximately 50%. Both seed and fungus were more susceptible to damage by rf treatment at the higher moisture level. Bean seed infected with Xanthomonas phaseoli var. fuscans and cabbage seed inoculated with X. campestris were killed by exposures which reduced but did not eradicate the bacteria. Colonies of both xanthomonads on nutrient agar media were destroyed by rf treatment.