The Effect of Selected Plant Materials and Extracts on the Development of Bacterial Diseases on Onion

The effects of Brassicaceae and Solanaceae plant residues and water extracts from these residues on the growth of onion (Allium cepa L.) pathogenic bacteria Pectobacterium carotovorum subsp. carotovorum, Burkholderia cepacia and Burkholderia gladioli pv. alliicola were examined. The influence of these materials on the development of bacterial diseases on onion bulbs was also investigated. The toxic effect depended on the kind and amount of the agent used and also on the species of examined bacteria. The water extract from Brassica napus cv. Kana and water extract from Lycopersicon esculentum cv. Remiz decreased a density of three examined bacteria in nutrient broth medium. Also milled seeds of Brassica juncea cv. Małopolska expressed an inhibitory effect towards B. cepacia and B. gladioli pv. alliicola. However, milled seeds of B. napus cv. Kana used as an addition to liquid medium did not decrease the density of these bacteria. In the experiment on onion bulbs the most promising results were obtained for milled seeds of B. juncea cv. Małopolska. This material used both as a source of volatile compounds and also in direct contact with the inoculated place on the onion bulb, inhibited diseases development caused by all three examined bacteria. B. juncea contains very high concentration of 2-propenyl ITC and probably this compound caused decrease in density of bacteria and the reduction of disease development. Purified, commercially obtained 2-propenyl ITC proved a very strong antibacterial activity and also inhibited disease development on onion. The commercial products Funguran Easy 50 WP and Biosept 33SL were also used but they showed very weak activity in protection of onion against the tested bacteria.