Mangoes are an important crop, and growers are looking for more sustainable ways to protect them. One threat is stem-end rot (SER), a disease caused by the fungus Lasiodiplodia theobromae that damages mangoes after harvest. While chemical fungicides have been the traditional response, their adverse effects on health and the environment have spurred the search for eco-friendly alternatives. A group of researchers has ventured into natural solutions, exploring biopesticides derived from essential oils and plant extracts. The aim is to find options that rely less on synthetic chemicals.

In a study led by Yefoungnigui Souleymane Yeo of University Félix Houphouët-Boigny in Côte d’Ivoire, with Dio Dramane Dembele, Brahima Camara, Soualo Ouattara, Jean-Yves Rey, Diana Fernandez and Daouda Kone, a greener approach to battling mango SER is examined. Published in the Journal of Agriculture and Food Research, their study assesses the potential of biopesticides made from essential oils and plant extracts.

Focusing on three natural biopesticides – ASTOUN (derived from lemongrass), NECO (sourced from African basil), and FERCA (extracted from lemon-scented eucalyptus) – and extracts from the leaves of Moringa oleifera, the team evaluated their efficacy against the fungal threat. This assessment involved a two-stage process: firstly, analyzing these agents’ ability to suppress the fungus in lab settings, and secondly, examining their impact on actual mango fruits.

For the fruit tests, the team made small wounds near the stem of Kent mangoes from northern Côte d’Ivoire, added fungal spores, and then treated the wounds. They checked for rot after 12 days of storage.

The results were encouraging: in the laboratory, ASTOUN and NECO held back the fungus more strongly than FERCA. ASTOUN stopped its growth completely at the two highest concentrations tested, and NECO did so at the highest. FERCA was less potent but still slowed growth by just over half. Interestingly, the M. oleifera leaf extract made with methanol, a type of alcohol, cut fungal growth by about two-thirds, compared with about two-fifths for the water-based extract.

On the fruit, the higher doses of all three biopesticides and of the methanol-based Moringa extract reduced how often rot developed and how large it grew, compared with untreated fruit. ASTOUN and NECO worked better than FERCA. At the highest dose, no wound treated with ASTOUN developed rot, and NECO limited rot to about one wound in twelve. With the strongest methanol-based Moringa extract, fewer than one in seven wounds became infected, compared with every wound on untreated fruit.

This research points to possible natural alternatives to chemical fungicides. These biopesticides and plant extracts could offer a way to manage mango SER that relies less on synthetic chemicals. The study did not test the treatments under different weather conditions, with other methods such as spraying or dipping, or for cost, so further research is needed.

In conclusion, the study shows that some plant-based products can limit stem-end rot in harvested mangoes, at least when applied directly to wounded fruit under controlled conditions. That makes them a possible alternative to synthetic fungicides that is worth testing further.

Journal Reference

Yefoungnigui Souleymane Yeo, Dio Dramane Dembele, Brahima Camara, Soualo Ouattara, Jean-Yves Rey, Diana Fernandez, Daouda Kone, “Effect of some biopesticides based on essential oil and plant extracts on postharvest mango Stem-end rot disease caused by Lasiodiplodia theobromae”, Journal of Agriculture and Food Research, 14, 100798, 2023. DOI: https://doi.org/10.1016/j.jafr.2023.100798