Research covered investigation of efficacy of biopreparations in vegetable protection (onion, carrot, parsley, red beet, dill, radish) against fungal diseases. Seeds were coated with a biopreparation formulated on the basis of Trichoderma viride prior to sowing. After a series of experiments it was found that proper technology enables coating with biopreparation. This process should be as short as possible because of the need to maintain enough number of living colony forming units (cfu). Coated seeds may be stored for a period of several months. Microbiological cleanliness of coat components is also of great importance. Biopreparation in coats to some extent limited the occurrence of rot diseases during germination. During growing season plants were sprayed with Biosept, Chitosan and Bioczos. Effectiveness of these treatments was differentiated. The best results were observed with the use of Biosept. In a year favourable for development of downy mildew of onion (Peronospora destructor) spraying with this biopreparation significantly limited disease compared with the control