Abstract:
Aims: To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of
lemongrass.
Methods and Results: Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic
strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test
pathogen at 0Æ6 and 1Æ0 mg ml)1, respectively. Aflatoxin production was completely inhibited at 0Æ1 mg ml)1.
The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b
as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation
and the mycelial growth of the test pathogen were inhibited at the concentrations of 2Æ80 and 3Æ46 mg ml)1,
respectively.
Conclusion: Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored
rice.
Significance and Impact of the Study: Currently, fungicides are not used to control fungal pests or mycotoxin
production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests
as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as
synthetic chemical fungicides can cause adverse health effects to consumers.
