Studies upon the copper fungicides. IX. Investigations with the exudate from fungus spores

Abstract

Determinations have been made of the copper dissolved from pure copper compounds by water, by a standardized solution of the exudate of Neurospora sitophila spores, by standard solutions of malic and succinic acids and their sodium salts, and by glycine and mannitol. The results compared with the known fungicidal performances of the copper compounds show that the amounts of copper yielded to water and to the standardized spore extract or glycine solution provide an indication of fungicidal properties. Although soluble copper in excess of that dissolved by water can only appear from alkaline Bordeaux deposit by complex ion formation, results show that this is not necessarily the only means by which copper can dissolve from other copper compounds. In a chemical investigation of the exudate of N. sitophila spores, mannitol, succinate and fumarate have been isolated. None of these materials can dissolve an appreciable amount of copper from alkaline Bordeaux deposit. Malate, found by other workers to be a constituent of the exudate of N. sitophila spores cultured on potato dextrose agar, has not been detected in such a solution from spores grown on malt agar. The quantity of mannitol in spore exudate has been shown to depend on the nutrient medium on which the fungus is grown.