HIGH-CONCENTRATION HYDROGEN CYANIDE FUMIGATION OF FUNGI AND BACTERIA

Abstract

THE highly toxic effects of hydrogen cyanide on J. animals are almost proverbial, and it is now well known that its main action causing their death is through interference with the respiratory enzymes1'2. Since these systems appear in general to be similar in animals and plants (including yeasts and bacteria3), the chief of them being found in representatives from all of the plant and animal phyla4, it might be expected that exposure to hydrogen cyanide would also kill plants easily. So far is this from being the case that hydrogen cyanide 'fumigation' is commonly employed as a means of killing insect pests on greenhouse plants which are little if at all adversely affected by the process ; it is also extensively used in plant quarantine and against scale insects of citrus trees5. Even as it appears that a high rate of respiration is more important than the size factor in determining the susceptibility of different animals to the higher concentrations of hydrogen cyanide6, so it now seems likely that the usually greater resistance of plants to hydrogen cyanide is largely bound up with their generally much slower rate of metabolic activity.