ANTIFUNGAL ACTIVITY OF THREE PLANT EXTRACTS AGAINST PHYTOPHTHORA MEGAKARYA, THE CAUSAL AGENT OF COCOA POD BROWN ROT (THEOBROMA CACAO L.) IN CÔTE D'IVOIRE

In Côte d'Ivoire, cocoa (Theobroma cacao L.) is cultivated for its socio-economic importance as well as its various uses, both nutritional and medicinal. Despite its value, cocoa cultivation is seriously threatened by brown pod rot, a major disease. The commonly used chemical fungicides to control this disease often have harmful effects. In this context, a study was conducted to explore alternatives to chemical control methods. The pathogenicity of Phytophthora megakarya was evaluated through wound inoculation on cocoa pods, confirming its pathogenic nature. The antifungal activity of aqueous extracts from three local plants (Syzygium aromaticum, Carica papaya, and Ricinus communis) as well as a synthetic fungicide was assessed in vitro against P. megakarya, the causal agent of brown pod rot. PDA culture medium supplemented with extract concentrations of 20%, 40%, and 60% was used for the tests. The plant extracts demonstrated antifungal activity, resulting in inhibition of mycelial growth ranging from 46.43% to 100%. Depending on the concentration, the extracts exhibited fungistatic and/or fungicidal effects. Aqueous extracts of Syzygium aromaticum and Carica papaya completely inhibited mycelial growth at the 40% concentration, similar to the effect of the synthetic fungicide commonly used in conventional agriculture. Notably, Carica papaya extract fully inhibited P. megakarya mycelial growth even at 20% concentration. These results suggest that such extracts may offer a promising avenue for the control of this pathogen under field conditions, warranting further investigation. Keywords: Antifungal activity, Brown pod rot, Phytophthora megakarya