ACTIVITY OF ANTIBIOTICS AGAINST ASCOCHYTA PISI

Abstract

A number of antibiotic substances which have been reported to possess antifungal properties were tested at various dilutions for their fungistatic activity upon spore germination of Ascochyta pisi. Actidione, antibiotic XG, and viridin (pH 3.5) were found to be fungistatic at dilutions of 10 p.p.m., gliotoxin and gladiolic acid at 20 p.p.m. The remaining antibiotics were less active, citronin showing no fungistatic activity even at 100 p.p.m. In fungicidal tests on spores of A. pisi, antibiotic XG, gliotoxin, actidione, humulon, gladiolic acid, and viridin were active at concentrations of 50 p.p.m. with a 12 hr. exposure, whereas clavacin, lupulon, and citronin required concentrations of 100 p.p.m. The action of these antibiotics upon germination of pea seed on filter paper and upon emergence in soil were tested and, in general, those which possessed the greatest fungistatic and fungicidal activity to A. pisi spores were the most phytotoxic. Only antibiotic XG and actidione gave adequate control of A. pisi when naturally infected pea seed was treated by soaking the seed in the antibiotic. Actidione, however, seriously reduced germination.