Fungi Trichoderma spp. are present in nearly all soils and other habitats. Most of Trichoderma strains are efficient for control of some pathogens. Some strains induce plant native defence mechanisms. Botrytis cinerea [Pers.: Fr.] causes economic losses on a wide range of cultivated plants and stored fruits. In presented work Trichoderma asperellum [strain T1] isolated from commercial product was selected to apply in the field experiments. The trade bioproduct containing 5 × 10⁸ of Trichoderma conidium per one gram was used in organic field strawberry. Treatments with microorganism-antagonist at concentration 10 g · l^-1 were performed as a foliar spraying, three times during the growing season. Applied Trichoderma caused bigger and more vigorous growth. The insignificant presence of B. cinerea on harvested and stored fruits was found. The possibility of use of T. asperellum as biological control agent for post-harvest diseases and for prolongation of time storage was observed until 7 days after harvest. In the second season of research, statistical significantly higher yield of the treated plants (30.2%) was obtained compare to the untreated plants. Also the weight of aboveground part of plants (24.0%) and number of runners were increased.

107-114