Antifungal activities of Monsonia burkeana and Euphorbia ingens extracts against Penicillium digitatum, the causal agent of citrus green mould.
Citrus green mould, caused by Penicillium digitatum, is a serious postharvest disease which affects oranges during storage and in transit. The disease is mainly managed by application of postharvest fungicides. Some plant extracts have been shown to effectively inhibit P. digitatumgrowth. The aim of the study was to determine the efficacy of methanolic extracts of Monsonia burkeana and Euphorbia ingens on P. digitatum growth and citrus green mould severity under laboratory conditions. M. burkeana and E. ingens samples were collected from Sekhukhuni district in Limpopo, dried under shade and extracts were prepared using methanol. The final extract powder was used to amend growth medium and to prepare a water-based spray for artificial fruit infection. Both tested plant extracts inhibited P. digitatum growth in vitro. All concentrations of E. ingens had an equally significant effect on the pathogen growth when compared with the control. M. burkeanaconcentrations displayed varying suppressive effect on pathogen growth. Extracts of both plants were also able to significantly reduce disease severity in artificially infected citrus fruits when compared with the control. In conclusion, these results showed both extracts of M. burkeanaand E. ingens had suppressive effects against P. digitatum.