Phytotoxic Compounds produced by Fusarium equiseti

Culture filtrates of several strains of Fusarium equiseti (Corda)Sacc. were found to be highly phytotoxic. Several phytotoxicsubstances were isolated; the most important of these was acolourless crystalline compound, diacetoxyscirpenol, m.p. 161-2°,C₁₉H₂₆O₇. Though highly phytotoxic in many respects, it markedlystimulates elongation of cress roots at 0.01–0.5 µg./ml.This is not an anti-auxin effect. Diacetoxyscirpenol is at mostonly slightly inhibitory to fungi and bacteria, but is highlytoxic to rats. Two minor metabolic products, m.p. 135-6°and 185-8° respectively, are also described. They, too,were highly phytotoxic, though their spectra of activity weresomewhat different from that of diacetoxyscirpenol. They alsowere highly toxic to rats. Production of these substances isprobably not important in the aetiology of disease symptomsin plants parasitized by F. equiseti, but may be significantin cases of toxicosis of animals fed with grain infected byFusaria. Scirpentriol, a hydrolysis product of diacetoxyscirpenol,is much less phytotoxic but of equal toxicity to rats.