Pseudomonas syringae pv. actinidiae (PSA) is the agent of bacterial canker of kiwifruit, which in recent years has proved to be a difficult disease to control. Prolonged antibiotic treatments result in failure and enhance the resistance of bacteria to the treatments, so the kiwifruit industry laments the need to develop innovative pest management strategies as alternatives to conventional antibiotic control.Italian scientists have analyzed the morphological differences of PSA strains isolated from trunk and from exudates, and have tested the effectiveness of new natural substances, such as essential oils (EOs) in killing or containing the bacterial canker of kiwifruit. The scientists have assessed the potential bactericidal activity of Mentha suaveolens, Rosmarinus officinalis and Melaleuca alternifolia EOs mixture against PSA.
The scientists especially studied:
1) the morphological differences of PSA isolates through the scanning electron microscope;
2) the synergistic action and effectiveness of different essential oils with Time-kill and checkerboard methods.
The results showed that PSA is able to produce extracellular polysaccharides when isolated from the trunk, and, for the first time, it was possible to kill PSA with a mixture of essential oils after 1 h of exposure to the treatment.
The scientists conclude that this mixture could have a potential use in fruit production.
Source: Vavala E., Passariello C., Pepi F., Colone M., Garzoli S., Ragno R., Pirolli A., Stringaro A., Angiolella L., "Antibacterial activity of essential oils mixture against PSA", March 2015, Natural Product Research: Formerly Natural Product Letters. http://dx.doi.org/10.1080/14786419.2015.1022543