SUMMARYThein vitrofungicidal activity of 2‐methyl‐4,6‐dinitrophenol (DNC) and fifteen of its esters was determined in mycelial growth tests. The aliphatic esters possessed similar activity to that of DNC and the aromatic esters were much less fungitoxic. The benzoic ester was only weakly active against mycelial growth and in preventing spore germination but as a protectant fungicidein vivoit was very effective. It was established that DNC‐benzoate is stable in light, under conditions of high humidity and in the presence of fungal spores, but it was shown that some degree of hydrolysis occurs on the leaves of broad bean to yield the parent cresol. This hydrolysis does not lead to phytotoxicity but the small quantities of DNC produced could account for the protectant fungicidal activity of this c