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Abstract
SUMMARY: The hypothesis that the fungicide 2-heptadecyl-2-imidazoline might owe its effectiveness to interference with the synthesis of histidine or purines was tested in experiments with Sclerotinia fructicola. The toxicity of the fungicide was significantly decreased by guanine, xanthine, or xanthosine; a number of other related compounds and histidine had no effect.
Annulment of the action of 2-heptadecyl-2-imidazoline by either xanthine or guanine was competitive. The inhibition index for 2-heptadecyl-2-imidazoline/ xanthine was 0·000581, while that for 2-heptadecyl-2-imidazoline/guanine was 0·000832. Attempts to demonstrate the accumulation of the purine precursor 5-amino-4-imidazolecarboxamide in culture filtrates of Sclerotinia fructicola grown in the presence of the fungicide were negative.
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