Antifungal potential of local plant extracts in the biological control of soil-borne diseases of tomato and eggplant in Daloa, Centre-West, Côte d'Ivoire

Tomato and eggplant play a significant role in peri-urban agriculture. However, their production in the city of Daloa is limited by biotic diseases. This study aimed to evaluate the antifungal activity of six plant extracts against soil-borne fungal pathogens affecting tomato and eggplant. A microbiological study of the soil was conducted using a composite sample from the experimental plot. Two tomato cultivars (Petomech and F1 Cobra 26) and one eggplant cultivar (N'drowa) were used in the varietal sensitivity test. The first application of the plant extracts was carried out immediately after transplanting. Mancozeb was used as a reference control. Health monitoring of the tomato and eggplant plants involved assessing the incidence, severity and mortality rate. Samples taken from diseased plants were subjected to microbiological analysis. The collected data were analysed using Statistica 7.1 software. The results revealed the presence of four fungal genera on the plot: Botrytis sp, Trichoderma sp, Sclerotium sp and Aspergillus sp. The fungal genera isolated from the diseased plants were Phytophthora sp, Alternaria sp and Trichoderma sp. The biological control test showed that eggplant plants treated with Securidaca sp exhibited the greatest tolerance to disease, with a severity index of 2.1%. The F1 Cobra 26 variety, with a severity index of 5%, was less susceptible than the Petomech variety, with a severity index of 11.5%. Aqueous extracts of Securidaca sp and Solanum sp reduced mortality rates more effectively than synthetic fungicide. These aqueous extracts can therefore be recommended as an alternative for controlling soil-borne fungal diseases in tomato and eggplant.