Screening of Trichoderma Isolates and Potential of Their Organic Extract to Control Phytophthora megakarya, the Causative Agent of Cocoa Black Pod Disease

Abstract

The aim of this work was to isolate Trichoderma agents of cocoa trees and to select the best antagonists able to reduce cocoa black pod disease caused by Phytophthora megakarya. Sampling was carried out in the Western region of Cameroon, locality of Bafang. Trichoderma and P. megakarya isolates were made on PDA medium in a Petri dish. In vitro antagonist activity of Trichoderma was evaluated by dual culture and antibiosis tests, and the best isolates were selected. The production of hydrolytic enzymes by the best isolates was done in specific solid media. The antimicrobial effect of the crude organic extract extracted from the selected Trichoderma isolates was performed in vitro by poisoned method. Results showed that 12 Trichoderma spp were isolated. Based on the rating scale of Bell, 4 isolates were selected, namely IS4, IS7, IS9 and IS11. These isolates were found to produce non-volatile and volatiles compounds as well as hydrolytic enzymes (cellulase, amylase, lipase and protease); Their organic crude extract significantly inhibited the growth of mycelial of P. megakarya with IC7 as the best isolates. IS7 Trichoderma isolate significantly produced cellulase, amylase, lipase and protease and at 100μg/ml, its organic crude extract total inhibited the mycelial growth of P. megakarya. It could be suggested that, Trichoderma IS7 isolate should be further investigated as promising biocontrol agent to manage P. megakarya infection.