EN
Antagonistic activity of 63 bacterial isolates, originating from soil and apple leaves, against Venturia inaequalis was studied in dual culture on PDA medium. Based on measurement of inhibition zones, 16 isolates appeared to be most active. Three of them /57M, 59M (Pseudomonas spp.) and 103M (Collimonas sp.), significantly protected apple trees against apple scab on Gala trees in the net-glasshouse. Of 6 ethanol plant extracts (sage leaf, rhizomes of Potentilla, oak and willow bark and the aboveground parts of St. John's-wort and tetterwort), the highest activity in inhibition of V. inaequalis conidia germination, even after 10- and 20-fold dilution in water, showed extract from rhizomes of Potentilla. Applied at two concentrations (5 and 10%) on Gala apple trees it totally protected leaves against apple scab.