Postharvest decay control of plums using orange oil
Postharvest decay of stone fruit causes up to 75% losses. A major contributor to this problem is grey mould caused by the ascomycete fungal pathogen Botrytis cinerea. The aim of this study is to establish whether orange oil is a viable alternative to conventional synthetic fungicides for postharvest control of grey mould. Orange oil is generally regarded as safe and has been shown to effectively inhibit fungal growth in vitro for several postharvest pathogens (Aspergillus spp., B. cinerea, Penicillium spp. and Rhizopus spp.). D-limonene, one of citrus oils active compounds, is a known antimicrobial compound and likely to be the key contributor to the fungistatic effects of orange oil. The efficacy of orange oil as an aqueous dip application (0.05, 0.50, 1.00% v/v for 30 s) was tested on two plum cultivars (African Delight and Letitia) either applied preventatively or curatively on fruit that was wound-inoculated with B. cinerea conidiospores. The incidence and severity of grey mould decay were evaluated 7 and 12 days after inoculation. In both cultivars, the curative treatments resulted in a reduced level of infection compared to the protective treatments. In African delight, the incidence was reduced from 50% in the untreated control to 20% and Laetitia from 85 to 40% when orange oil was applied at 1.00% in a curative application. Grey mould decay severity was reduced up to 70% in both cultivars as a curative application at 1.00%, the highest tested orange oil concentration compared to the untreated control. In this study, plum fruit trial data confirmed the efficacy of orange oil as a potential postharvest decay treatment.
Njombolwana, N., Meitz-Hopkins, J.C., Monteiro, S. and Lennox, C.L. (2022). Postharvest decay control of plums using orange oil. Acta Hortic. 1349, 189-194
Botrytis cinerea, grey mould, orange oil