Antifungal activity of essential oil-encapsulated lipid nanoemulsions against Neopestalotiopsis rosae causing leaf spot on strawberry

This study aims to generate a highly effective nano-bioformulation from essential oils (lemongrass oil, mustard oil, thyme oil, eucalyptus oil, chili oil, cinnamon oil, mint oil) for controlling N. rosae , a fungus responsible for causing leaf spot disease on strawberries in Vietnam. Firstly, the plant pathogen was isolated from diseased strawberry samples and identified using potato dextrose agar medium. After that, essential oil-encapsulated lipid nanoemulsions (EO-LNs) were prepared by a combining method of homogenization and sonication. Their binary and ternary combined formulations were also prepared by mixing with an equal volume ratio of each EO-LNs. In vitro antifungal activity of 7 EO-LNs and their combined formulations were evaluated using petri dish assay. The resultant findings were then used so that the most optimal EO-LN of all is found. Next, it was field-tested for its effectiveness regarding ex vitro disease-preventing and disease-treating. The test produced three results; first, it confirmed that the isolated fungus that causes leaf spots on strawberries was Neopestalotiopsis rosae . Second, in vitro results indicated that cinnamon oil-encapsulated LNs (CiLN) exhibited highest antifungal activity among 7 EO-LNs (single formulations) and even higher than that of the binary and ternary combined formulations, reached to 95.59% at 500-time dilution. Third, in the field tests, CiLN showed high effectiveness in strawberry’s disease-preventing and disease-treating at 100% and 90.42%, respectively. This is the first report mentioning EO-LNs formulation as a biofungicide for effectively controlling N. rosae causing leaf spot disease on strawberry plants without causing any negative effect on the plant growth.