Peracetic acid and chlorine dioxide for postharvest control of Monilinia laxa in stone fruits

The effects of different concentrations of peracetic acid (PAA; 62.5, 125, 250, 500, and 1,000 mu g/ml) and chlorine dioxide (ClO2; 12.5, 25, 50, 100, and 200 mu g/ml) on germination of Monilinia laxa conidia were tested. Con idia germination was related to the concentration of chemical product used, as well as duration of treatment. Complete inhibition of germination was o bserved with PAA at 500 mu g/ml after 5 min of contact with conidia and wit h ClO2 at 50 mu g/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 onl y on plums, for which a 1,000 mu g/ml treatment significantly reduced decay incidence by 50%. In a semi-commercial test, pathogen conidia dipped for 2 0 min in PAA at 250 mu g/ml or ClO2 at 10 mu g/ml or for 5 min in PAA at 25 0 mu g/ml were completely inhibited, and no brown rot was observed in inocu lated wounded nectarines and plums.