Vegetables and fruits are often infected by postharvest pathogens that cause diseases like crown rot, fruit core rot, blue/grey/green mould, anthracnose and soft rot. Fungal infection of fruit and apples can result in significant postharvest losses when storage conditions are not optimal or damages occur during handling or storage. China produced 50% (about 89 million tones) of the world production of apples and in August 2018, soft rot symptoms suspected of being caused by Rhizopus were detected on apple fruit at local markets in the Haidian district of Beijing, China.
Rhizopus oryzae on apple. (a) Soft rot symptoms on fruit collected from local markets, (b) isolate growing on PDA for 3 days at 25 °C, (c) soft rot symptoms on incubated fruit after 2 days incubation, (d) soft rot symptoms on incubated fruit after 7 days incubation, (e) sporangiophore bearing a sporangium, (f) sporangiospores.
The earliest symptom on the surface of infected fruit were small, water soaked lesions which soon turned brown and rapidly expanded, resulting in a sunken, soft rot of the entire fruit. White hyphae developed on the rotten tissue and within three days grey sporangiophores bearing sporangia were produced from the hyphae. The infected fruit were collected from local markets and the fungus associated with the symptoms was isolated on potato dextrose agar (PDA). Based on the morphological characteristics and molecular analyses, the causal fungus was identified as Rhizopus oryzae.
"Postharvest soft rot of apple, sweet potato, and banana fruit caused by R. oryzae have been reported in Korea and Saudi Arabia- is explained by the scientists of Chinese Academy of Agricultural Sciences in Beijing - The pathogen has also been reported to be associated with postharvest root rot of Codonopsis lanceolata in Korea. However, to our knowledge, this is a new record of R. oryzae as a postharvest causal agent of soft rot on apple in China".
Fonte: Ibatsam Khokhar, Irum Mukhtar, Junhuan Wang, Yang Jia, YanChun Yan, 'A report of Rhizopus oryzae causing postharvest soft rot of apple fruit in China', 2019, Australasian Plant Disease Notes, Vol. 14(7).