In vitro effects of essential oils from aromatic and medicinal plants on soil borne pathogens

Abstract

Mint(Menta piperita L), basil (Ocimum basilicum L), rosemary (Rusmarinus officinalis L), thyme (Thymus vulgaris L) and tea tree (Melaleuca altemifolia (Maid, and Bet) Cheel) essential oils were tested for their effectivness against soil borne pathogens including; Pythium sp., Rhizoctonia sp., Fusarium oxysporum f. sp. lycopersici, F. oxysporum f. sp. pisi Verticillium sp. and Clavibactermichiganensis ssp. Michiganensis. The isolates were exposed to volatile phase of the oils for seven days. Afterwards, the plates were opened and ventilated in order to remove volatiles and determine if the effect of the oil was fungistatic/bacteriostatic or fungicidal/bactericidal. The concentrations of the oil were considered to be fungicidal/ bactericidal if the microbial growth had not been observed seven days after the ventilation. The growth rate of all the tested microorganisms was partially or completely inhibited by the oils applied at concentrations 0.04-0.65 μl/ml air. Thyme and basil oils were the most toxic to all the pathogens investigated, having fungicidal/bactericidal effect at 0.04-0.65 μl/ml of air, depending of the pathogen. Rosemary oil showed the lowest inhibitory effect - minimal lethal concentrations were 0.32 μl/ml air for C. m. ssp. michiganensis, 0.65 μl/ml air for Verticillium sp. Pythium sp. and Rhizoctonia sp., and more than 0.65 μl/ml air for Fusarium species, respectively. These results indicate that thyme and basil essential oils could be effectively used for the control of soil borne pathogens.

Prikazani su rezultati in vitro testiranja efekata etarskih ulja nane (Menta piperita L), bosiljka (Ocimum basilicum L), ruzmarina (Rusmarinus officinalis L), timijana (Thymus vulgaris L) i čajnog drveta (Melaleuca altemifolia (Maid, and Bet) Cheel) na biljne patogene koji se prenose zemljištem Pythium sp., Rhizoctonia sp., Fusarium oxysporum f. sp. lycopersici, F. oxysporum f. sp. pisi, Verticillium sp. i Clavibacter michiganensis ssp. michiganensis. Izolati su izlagani dejstvu para proučavanih ulja tokom sedam dana, a po završetku ekspozicije kutije su provetravane strujanjem vazduha u laminarnoj komori. Ocenjivan je efekat potpune inhibicije fungistatičnost/bakteriostatičnost (izolat posle uklanjanja etarskog ulja provetravanjem nastavlja da raste) i fungicidnost/baktericidnost (ulje deluje letalno tako da nema porasta izolata posle provetravanja). Sva proučavana etarska ulja u koncentracijama 0.04-0.65 μl/ml vazduha delimično ili potpuno inhibiraju porast proučavanih mikroorganizama. Ulja timijana i bosiljka ispoljila su najveću toksičnost za sve proučavane patogene sa vrednostima minimalne letalne koncentracije između 0.04 i 0.65 μl/ml vazduha, zavisno od patogena. Najslabiji efekat pokazalo je ulje ruzmarina-minimalna letalna koncentracija za C. m. ssp. michiganensis iznosila je 0.32 μl/ml vazduha, za Verticillium sp. Pythium sp. i Rhizoctonia sp. 0.65 μl/ml vazduha, a za vrste roda Fusarium vise od 0.65 μl/ml vazduha. Rezultati in vitro ogleda ukazuju na mogućnost korišćenja ulja timijana i bosiljka u suzbijanju patogena koji se prenose zemljištem.