Studies on Polyoxins, Antifungal Antibiotics

Abstract

Polyoxin is the antibiotic having extensive activities against various fungi, especially, Alternaria spp.Tests were carried out to evaluate fungicidal activities of Polyoxin against Alternaria mali and Alternaria kikuchiana in vitro and in vivo.Among Polyoxin A, B, D, F, G fractions, B fraction especially inhibited development of mycelium, spore germination and sporulation. G fraction showed the high activity in vitro test, but low activity in vivo test. On the one hand, A and D fractions showed the reverse tendency.All fractions of Polyoxin caused abnormal bulbous phenomenon on germ tube of spore and mycelium at low concentration.Polyoxin complex permeated little into spore. Therefore, Polyoxin did not inhibit spore germination at the usual concentration, but made bulbing germ tube as soon as spore germinated.Antisporulation activity of Polyoxin was very strong and kept for a long time.Results of Field test showed that Polyoxin is more effective than the compared fungicides.Polyoxin penetrated into apple leaf and was absorbed from the cut end of apple stem.