Peracetic Acid and Chlorine Dioxide for Postharvest Control of Monilinia laxa in Stone Fruits

Abstract

The effects of different concentrations of peracetic acid (PAA; 62.5, 125, 250, 500, and 1,000 μg/ml)and chlorine dioxide (ClO2; 12.5, 25, 50, 100, and 200 μg/ml) on germination of Monilinia laxa conidia were tested. Conidia germination was related to the concentration of chemical product used, as well as duration of treatment. Complete inhibition of germination was observed with PAA at 500 μg/ml after 5 min of contact with conidia and with ClO2 at 50 μg/ml after 1 min of contact with conidia. The results of in vitro tests were confirmed by inoculation of fruits with treated conidia. The PAA treatment also was effective 1 h after pathogen inoculation but only on plums, for which a 1,000 μg/ml treatment significantly reduced decay incidence by 50%. In a semi-commercial test, pathogen conidia dipped for 20 min in PAA at 250 μg/ml or ClO2 at 10 μg/ml or for 5 min in PAA at 250 μg/ml were completely inhibited, and no brown rot was observed in inoculated wounded nectarines and plums.