Assessment of the growth inhibiting effect of some plant essential oils on different Fusarium species isolated from sorghum and maize grains

The antifungal activity of essential oils from clove, cedar wood, Cymbopogon species, peppermint, Eucalyptus and neem were tested for their efficacy against nine Fusarium species, namely F. verticillioides, F. proliferatum, F. o x y spo r u m, F. a n -thophilum, F. pallidoroseum, F. sporotrichioides, F. sol ani, F. g ra m i n ea r u m and F. lateritium, isolated from maize and sorghum. The results showed that essential oils were anti-fungal at concentrations of 500–2500 ppm or higher. The oil Cymbopogon nardus (referred to as citronella oil) was inhibiting all the Fusarium species growth at 500 ppm and higher. The next most potent inhibitors, the oil from C. citratus (referred to as lemongrass oil) and peppermint oils, were fully inhibitory from a concentration of 1500 and 2000 ppm and higher, respectively. Eucalyptus and neem oils were less effective in inhibiting the growth of Fusarium species tested, irrespective of their concentration. Among the seven essential oils tested against all the Fusarium species, the citronella oil showed highest inhibitory effect (minimum inhibitory concentration, MIC) at = 1500, 2000, 1000, 500 ppm against F. verticillioides, F. oxy sp orum, F. sporotrichioides, F. lateritium mycelial growth development respectively. However clove, lemongrass oil and citronella showed highest inhibitory effect (= 1500 ppm) against F. pr o lif e ra t u m and F. pallidoro-seum respectively. Further lemongrass oil showed highest inhibitory effects at = 1500 and 500 ppm against F. a n t h o p h i -lum and F. lateritum respectively. The least MIC for F. gra -minearum was observed in peppermint oil at = 500 ppm. The results indicate that the tested toxigenic Fusarium spp. are sensitive to the essential oils, and particularly sensitive to the citronella oil. These findings clearly indicate that essential oils should find a practical application to control the growth of Fusarium species in stored maize and sorghum grains.