TITLE:
Assessing the Efficacy of Lemongrass (Cymbopogon citratus) and Sambong (Blumea balsamifera) Extracts in Combating Black Pod Disease: Sustainable Solutions for Controlling Phytophthora megakarya in Cameroon’s Cocoa Plantations
AUTHORS:
Gertrude Membang, James Michel Tchotet Tchoumi, Godswill Ntsomboh Ntsefong, Emmanuel Yvan Mba Ela, Sylvere Landry Lontsi Dida, Ludovic Tchuenkam Tsango, Pascal Loïc Ekango Mbondjo, Fritz Oben Tabi
KEYWORDS:
Plant Extracts, Antifungal Agents, Synergistic Effect, Black Pod Disease, Cocoa
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.15 No.7,
July
25,
2024
ABSTRACT: The use of plant extracts as antifungal agents is gaining increasing attention, particularly for the control of black pod disease in cocoa. Despite extensive research, current strategies haven’t been entirely effective. This study evaluated the effectiveness of Cymbopogon citratus and Blumea balsamifora leaf extracts, both individually and in combination, against Phytophthora megakarya. We assessed the efficacy of the most promising combination (75% B. balsamifera, 25% C. citratus) after storage at room temperature for up to 9 days. Agar microdilution and in vivo bioassays were conducted to determine antifungal susceptibility and effectiveness. Blumea extract exhibited the highest overall inhibitory activity, with the lowest minimum inhibitory concentration (117 µl mL−1) while C. citratus had a narrower range of MIC (146 to 233 µl mL−1). The combination of C. citratus and B. balsamifera demonstrated a synergistic effect against P. megakarya, achieving growth inhibition on V8 media (92.72 ± 4.20% to 100%) and on artificially infected detached pod cortex (92.24 ± 4.53% to 98.75 ± 1.25%), which was not significantly different from the positive control (Ridomil). Furthermore, this combination maintained its effectiveness for up to 9 days at room temperature. These findings suggest that combining plant extracts can enhance their antifungal properties.