MORPHOLOGY, NUTRITION, AND HOST RANGE OF A SPECIES OF PYTHIUM

Abstract

A species of Pythium (probably P. acanthicum Drechs.) is described which is able to parasitize 80% of a wide range of 98 species of fungi tested. Nine of the test fungi were not parasitized, and 10 actively inhibited the Pythium, with Ustilago maydis exhibiting the strongest inhibition. The roots of sunflower, corn, wheat, flax, beet, morning glory, sweet pea, Polish rape, and green pea were attacked, producing browning of the root tips. The organism produced a rapid, watery soft rot when inoculated into cucumber and potatoes. The organism requires a fat-solvent extractable substance for development of its sexual stages. It can obtain this substance from both living and dead host tissues, but not from its own killed vegetative mycelium.