The Fungistatic Activity of Methyl and Propyl Hydroxybenzoates and A Mixture of These Against Penicillium Spinulosum

The fungistatic activity of the methyl and propyl esters of p-hydroxybenzoic acid and of a mixture of these esters has been investigated. A mucilaginous substance is formed by fungal spores in contact with low concentrations of hydroxybenzoates in liquid medium. A difficulty in reading fungistatic end points from this cause was resolved by using a microscope.

Studies on the Kinetics of Fungicidal Action

The mean Q10 value for the mortality of Penicillium notatum spores in water from 50 to 55° was 881. In 1 to 1.25 per cent solutions of phenol from 15 to 40° it was 3.4; higher values were obtained for 0.75 and 0.875 per cent phenol.

Studies on the kinetics of fungicidal action. I. The effect of concentration and time on the viability of Penicillium notatum spores in solutions of phenol

About 98 per cent of Penicillium notatum spores produced germ tubes in liquid nutrient media within 12 hr. Viability was unaffected by storage in distilled water for 20 days at 4°. The sporicidal activity of phenol was measured by determining the percentage of germinated spores before and after contact with phenol solution. Spores were separated on membrane filters from fungicide by rapid filtration, and incubated in Horowitz fluid medium. The rate of death in solutions containing 0.5 to 1.25 per cent phenol followed a first order reaction. The values of the concentration exponent for 50 and 100 per cent mortalities were 12 and 10.5 respectively