In vitro effectiveness of different essential oils in control of Alternaria alternata

Abstract

The effectiveness of volatile phase of essential oils of menthe, eucalyptus and rosmarinus in control of A. alternata, a postharvest pathogen on fruits and vegetables, expressed through inhibition of mycelium growth, in vitro, has been tested. The inhibitory effect of tested oils has been determined four days after setting the trial by calculating the percentage of inhibition of radial growth of pathogen mycelium (PIRG), while the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) have been determined seven i.e. fourteen days later. The highest value of PIRG (100%) was found in essential oil of menthe when applied in concentration of 0,15μl/ml of air and essential oil of rosmarinus applied in 0,6μl/ ml of air. Essential oil of eucalyptus had the highest PIRG value (89,74%) when applied in concentration of 0,6μl/ml of air. MIC of essential oil of menthe was 0,3μl/ml of air while other two essential oils did not show total inhibitory effect in tested concentrations (MIC >0,6μl/ ml of air). Essential oil of menthe did not have a fungicide effect on pathogen, not even in the highest concentration (MFC > 0,6μl/ml of air). In other two oils MFC has not been determined since they did not express the inhibitory effect in the first. Therefore, menthe essential oils could be an alternative to chemicals to control A. alternata, a postharvest pathogen on fruits and vegetables, and can control this pathogen in vitro. These results will help in further testing of effectiveness of essential oils in vivo.

Ispitivana je efikasnost isparljive faze etarskih ulja mente, eukaliptusa i ruzmarina u suzbijanju A. alternata, patogena uskladištenih plodova povrtarskih i voćarskih kultura, izraženo kroz inhibiciju porasta micelije, in vitro. Inhibitorni efekat posmatranih ulja izračunavan je četiri dana nakon postavljanja ogleda i izražen je procentom inhibicije radijalnog porasta micelije patogena (PIRG) dok su minimalna inhibitorna koncentracija (MIC) i minimalna fungicidna koncentracija (MFC) izračunavane nakon sedam odnosno četrnaest dana. Etarsko ulje mente imalo je najveću vrednost PIRG (100%) pri koncentraciji ulja od 0,15μl/ ml vazduha. Stoprocentni inhibitorni efekat (PIRG) ulje ruzmarina ispoljilo je pri koncentraciji 0,6μl/ml vazduha, dok je ulje eukalipusa imalo najvišu vrednost PIRG (89,74%) pri koncentraciji 0,6μl/ml vazduha. Najnižu vrednost MIC imalo je ulje mente (0,3μl/ml vazduha) dok ulja eukaliptusa i ruzmarina nisu pokazala totalni inhibitorni efekat u ispitivanim koncentracijama (MIC > 0,6μl/ ml vazduha). Etarsko ulje mente nije pokazalo fungicidni efekat prema posmatranom patogenu ni u najvišoj koncentraciji (MFC > 0,6μl/ml vazduha). Kod druga dva ulja MFC nije ni određivana jer nisu imala ni inhibitorni efekat prema miceliji patogena. Na osnovu ovih rezultata možemo zaključiti da je primena etarskog ulja mente u cilju kontrole A. alternata, patogena uskladištenih plodova, opravdana i da se na taj način može kontrolisati ovaj patogen, in vitro. Ovi rezultati će poslužiti kao polazna tačka za dalja ispitivanja u cilju primene etarskih ulja i in vivo.