Exploring the Biocontrol Potential of Endophytes against Phytophthora megakarya in Cocoa Cultivation

Cocoa (Theobroma cacao L., Malvaceae) is a perennial tree crop, which over the years been negatively affected by black pod disease which is caused by Phytophthora megakarya. This is a major pathogen responsible for black pod disease in cocoa, significantly reducing the yield and threatening cocoa production. Endophytes are asymptomatically within plant tissues, with antagonistic properties. The potential of using endophytic fungi that were isolated from healthy cocoa tissues as biocontrol agents against Phytophthora megakarya was observed in this study. After isolating from an infected cocoa pod, the strains of P. megakarya were used to inoculate healthy cocoa tissues against endophytes using a dual culture test. The endophytes were evaluated for antagonistic activities against Phytophthora megakarya in vitro. The efficiency of these endophytes was assessed by identifying a few secondary metabolites. Results from this research showed that the endophytic isolates namely: Trichoderma asperellum (84.92%), and Trichoderma harzianum (78.53%) exhibited strong inhibitions against the Phytophthora megakarya, indicating their potentials as biocontrol agents against the pathogen, while Colletotrichum gloesporidodes (16.80%), and Botryoshaeria dothidea (17.90%) recorded weak inhibitions against Phytophthora megakarya in vitro. Secondary metabolites elaborated by isolates were alkaloids (0.984%), apicidin (0.630%) harzianic (0,577%), helvolic acid (0.531%), ergotamine (0.491%) and flavonoids (0.009%) which were present in the isolates (T. harzianum, T. asperellum, C. gloesporiodes, and B. dothidea). Findings from this study demonstrated that endophytes from cocoa tissues could significantly reduce P. magakarya infection rates on cocoa. Thus, the potentials inherent in the use of endophytes as sustainable eco-friendly biocontrol strategy in the controlling of black pod disease of cocoa.