In vitro EFFECTS OF ESSENTIAL OILS ON Colletotrichum spp.

Apple production is largely affected by the fungi Colletotrichum gloeosporioides and C. acutatum, causal agents of fruit bitter rot. Economic losses account for 30-80%. Colletotrichum spp. are the most destructive if the infection occurs after harvest and storage. The disease is managed by fungicide application during the season. Due to increased concern for human health and the environment, as well as to problems with pathogen resistance development, ecofriendly alternatives to chemical control measures, such as essential oils, became the object of many researches. The aim of the study was to investigate which essential oils have a potential to be used as control agents against Colletotrichum spp. Effects of volatile phase of 56 essential oils on C. gloeosporioides and C. acutatum were investigated. For both fungal species, oregano oils A, B, C and D were fungicidal at rates ranging from 0.02 to 0.04 ?l/ml of air, and oregano oil E at rate of 0.08 ?l/ml of air. Minimum inhibitory concentration for thyme oil ranged from 0.02 to 0.04 ?l/ml of air. Out of 56 tested essential oils, 47 oils did not stop mycelial growth even at concentration of 0.16 ?l/ml of air. The results indicate that oregano and thyme essential oils have a potential in management of investigated apple pathogens.