The effect of Pythium oligandrum and chitosan used in control of potato against late blight and the occurrence of fungal diseases on tuber peel.

The aim of two year investigation was the valuation the effect of biopreparate Polyversum (B.A.S. Pythium oligandrum) and preparate Biochikol 020 PC (B.A.S. chitosan) used in control of potato against Phytophthora blight on the tuber infestation during storage by Helminthosporium solani and tuber infestation by sclerotia of Rhizoctonia solani. As the standard fungicide Vitavax 200 FS (B.A.S. karboxin and thiuram) was used. After harvesting 100 tubers from each plots was collected and put in storage. The analysis of tuber infestation by Rhizoctonia solani and Helminthosporium solani was made after harvesting (September) and later every 3 months during storage period (December, March). The percent of diseased tubers in tested sample and also infestation degree of bulbs using 5-degree scale was estimated. The received results of investigations ascertained, that all tested preparations during potato vegetation influenced on lower (in comparison with control) degree of bulbs infestation by sclerots of Rhizoctonia solani and the mean degree of infestation by Helminthosporium solani. Moreover the percent of diseased tubers infected by pathogens with tested preparations combination was significant lower than in control.