The usefulness of chitosan and Pythium oligandrum in potato tuber protection against Helminthosporium solani

The effect of tuber dressing and plant spraying with Biochikol 020 PC (B.A.S. chitosan) and with Polyversum bio-preparation (B.A.S. Pythium oligandrum) on the infestation of stored tubers by Helminthosporium solani was studied. Vitavax 2000 FS (B.A.S. karboxin and thiuram) was used as a standard fungicide. The effect of these preparations applied at three different concentrations on H. solani mycelium linear growth was investigated under in vitro conditions according to the Kowalik and Krechniak method (1961). The application of all tested preparations during potato vegetation resulted in both lower (in comparison to the control) mean infestation degree and lower percent of tubers infected by this pathogen. Results showed that all preparations inhibited H. solani mycelium linear growth.