In organic farming systems the focus is on prevention with regards to plant protection. To follow the rules of Good Agricultural Practice one is able to avoid serious yield losses; if it is not possible the use of allowed materials are permitted. Organic farmers have less material to protect their plants so it is necessary to find effective potent...ial materials. Bacterial and fungal diseases of tomato and pepper can cause serious losses in yield. Different materials were tested against some plant pathogen bacterial (Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, Xanthomonas campestris pv. vesicatoria and fungal (Phytoptora infestans, Rhizoctonia solani, Sclerotinia sclerotium) strains in order to find potential materials in the field of organic seed treatment. In vitro trials have shown that vinegar, cider vinegar, red wine vinegar, white wine vinegar, cinnamon and thyme oil have inhibiting effect against the causative agent of bacteria and fungi. Germination test has shown that examined vinegar types do not decrease germination ability if the concentration is low, but in higher (more than 5%) concentration it ruins the germination ability. Even in 0,5% concentration of red — and white vine vinegar have good effect on germination capacity.
In ecological farming systems farmers can't use chemicals against pests. In ecological plant protection the aim is to prevent diseases; if it is not possible the use of allowed materials are permitted. Until now there haven't been enough effective and environmental friendly materials for seed treatment in organic farming. Seed borne diseases of to...mato and pepper can cause serious losses in yield, so finding appropriate inhibitors has a great importance. Different materials were tested against these bacterial strains for seed treatment in this study. In vitro trials have shown that vinegar, cider vinegar, red wine vinegar and white wine vinegar have inhibiting effect against the causative agent of bacterial canker (Clavibacter michiganensis subsp. michiganensis), bacterial speck (Pseudomonas syringae pv. tomato) of tomato. These materials also have inhibiting impact on the causative agent of bacterial spot of pepper (Xanthomonas campestris pv. vesicatoria). Seed treatment with (natural alkaline material) sodium hydrogen carbonate (NaHCO3) had no effect on the examined bacterial strains. Among examined essential oils cinnamon oil seemed to be the most effective, but all oils decreased the germination ability. Thyme and savory teas were effective against Pseudomonas syringae pv. tomato. Other examined materials had insufficient bactericide impact (sucrose, NaCI, ethanol, valerian extract, peppermint tea). The germination test has shown that examined vinegar types don't decrease germination ability.