Testing the efficacy of the Sanodyna® product for the control of Gnomoniopsis castaneae

Gnomoniopsis castaneae (syn. Gnomoniopsis smitholgivyi) is an emerging fungal disease causing nut rot of sweet chestnut (Castanea sativa), currently affecting chestnut fruits production in several Italian regions. There is a lack of effective management and control strategies against this fungus due to the little knowledge about its epidemiology and its endophytic lifestyle. To date, post-harvest treatments, like the “curatura”, which consists of submerging the fruits in hot water (50 °C) for 45-50 min and cooling them in a water bath at 15-18 °C for an equal time, are the only methods applied to control and manage the disease, also because in pre-harvest, i.e., in the chestnut groves, the application of fungicides is strictly limited by law. This study aimed at testing the efficacy of Sanodyna®, an environmentallyfriendly product commercially sold as a sanitizer, to control G. castaneae in post-harvest treatments. Three concentrations, minimum (15 ppm), medium (110 ppm) and maximum (520 ppm), were tested for their ability to inhibit G. castaneae. The test was first carried out in vitro, by using different strains of G. castaneae and adding Sanodyna® into the culture-media. Then, the product was tested on chestnut nuts. A reduction in growth was observed in vitro compared to the control, but the treatment did not eradicate the disease from chestnut fruits. Indeed, the product was effective in sanitizing the external surface of the fruit, without being able to reduce significantly the frequency of the fungus. Results obtained in this work are a preliminary step towards implementing a control method against G. castaneae using Sanodyna®.