Effectiveness and efficacy of superficial disinfectants to prevent mechanical transmission of Cryphonectria parasitica from chestnut scion woods

Chestnut blight caused by Cryphonectria parasitica is a severe disease worldwide affecting chestnut trees. One pathway for its long-range transmission is grafting by using non-symptomatic scions. The effects of five disinfectants, 80% ethanol, 2.5% NaOCl, 5% H2O2, 2% copper sulphate and Lysol® (Brand III), were evaulated on artificially inoculated scions of 15–20 cm with a spore suspension (1 × 106 conidia/ml) of C. parasitica. Effects of these disinfectants on natural fungal flora and the viability of the scion woods were also investigated in vitro and in vivo conditions. Effectiveness of the disinfectants was evaluated by plating 10 buds taken from five random scions on PDA and counting the growing fungal colonies after 7 days of incubation at 22 °C, with a 12-h lighting period. A total of 40 buds, 10 from each repetition, were cultured for each treatment. The growth of C. parasitica and other fungi were investigated under a stereomicroscope. No growth of C. parasitica was observed on the treated scions while it grew on all of the contaminated control buds (100%). The growth of other fungi was the lowest for the Lysol® treated scions. The effect of the disinfectant treatment on the viability of the scion woods were tested by using 45 scion woods for each treatment and the maximum viability ratio was obtained in distilled water, followed by NaOCl, copper sulphate, ethanol, H2O2 and Lysol® treatment.