Sclerotinia scletoriorum (Lib.) de Bary is a serious pathogen of carrots that can cause up to 50% losses of stored roots. Fungicides were found not to be completely effective for its control and due to residues they are not permitted for the use in storage. Biological control agents such as Pythium oligandrum may be a chance. The aim of research was to determine the level of carrot infection with S. sclerotiorum during few-month storage with qPCR and the potential control ability of this pathogen by Polyversum WP containing oospores of P. oligandrum. We analyzed carrot roots in combinations treated with Polyversum WP on the field, fumigated with biopreparation before storage and untreated control. S. sclerotiorum developed on carrots treated and untreated with Polyversum WP. During the storage, pathogen was isolated from 44.4% samples and P. oligandrum from 53.8% ones, respectively in the range from 0.0001 to 130 200.0; pg and from 0.004 to 0.3440 pg per sample. The number of roots with S. sclerotiorum and degree of their infection increased with prolonged storage. Analyses suggest that Polyversum WP may potentially limit the growth of S. sclerotiorum.

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