Integrating Biological Control into IPM of Black Pod Disease
Project Leader: Marie-Claude BON
Another research direction is post-release monitoring of microbial control agents against pathogens. Molecular markers are being developed to facilitate the tracking of deployed microbial organisms, which in turn will aid in developing spatial and temporal models of the epidemiology and observe the persistence of the released organism.
I am coordinating an international collaborative research initiative involving USDA-ARS-EBCL and SBML, CIRAD, IRAD, Masterfoods-US and IPARC for the biological control of Phytophthora megakarya, the major causal agent of the Black Pod Disease (PDB) in Cameroon.
PDB is the most serious disease affecting the cocoa production in Cameroon where losses can reach up to 100% of annual production in absence of control measures. Typically, the control of PDB focuses on the uses of metalaxyl and copper fungicides, phytosanitation, and the availability of less susceptible planting material. In the near future, biological control agents may have an important role because chemical fungicide costs can be quite high for smallholder farmers, and there is a need to reduce PBD near to the time to harvest without risking high residual levels of fungicide in marketable cocoa beans.
The transformation of a natural antagonism into an efficient and reliable biological protection strategy implies numerous requirements. Among these, the ability to monitor a biocontrol agent released in the field is crucially important for understanding and predicting the biocontrol efficiency as the protective effect is related to the colonization and dispersal of the biocontrol agent. Moreover, the ability to track an agent in the field contributes to the establishment of a quality control procedure for the mycofungicides and may facilitate the registration procedure. A monitoring method based on molecular typing and tagging of these biocontrol agents has been developed mainly by Corinne Hurard in our lab. The genetic typing of four T. asperellum isolates sprayed as mycofungicides is undoubtedly leading through the monitoring of their environmental fate to an optimization of formulations, applications with beneficial effects on the level of protection obtainable.
Results from the field trials clearly demonstrated that T. asperellum strains are persistent on the trees and are able to parasitize the pathogen (biological phytosanitation). An unexpected effect of the biocontrol sprays noticed was a significant stimulation of pod setting. Drawing on an array of disciplines, this international collaborative research project will be able to provide an important base for the development of a sustainable black pod control in Africa.
Corinne Hurard, Tim Widmer and Walker Jones (EBCL)
Michel Ducamp, Peninna Deberdt and Christian Cilas (CIRAD, France)
Pierre Tondje, Didier Begoude, Michel Ndoumbe, Etienne Nyemb, Virginie Mfegue and Salomon Nyasse (IRAD)
Prakash Hebbar (Masterfoods-US)
Gary Samuels (USDA-ARS-SBML)
Roy Bateman (IPARC)
More details on this research are to be found in the Annual reports 2001-2006 for the ARS specific cooperative agreement n°58-4012-1-F123. It is available upon request from the National program Staff.
For a summary, look at:
BON, M.C., DEBERDT, P., TONDJE, P., HEBBAR, P., SAMUELS, G. AND BATEMAN, R. (2006a). Integrating Biological Control into IPM of Black Pod in IRAD, Cameroon, Africa. World Cocoa Foundation RESEARCH UPDATE June 2006, 2p.
http://www.chocolateandcocoa.org/Library/Research/usda_June_2006.asp (broken link)
Figure 1 Dual confrontation between Trichoderma asperellum and the pathogen Phytophthora megakarya (click to enlarge)
Figure 2 Cocoa pod with symptoms of Phytophthora pod rot (click to enlarge)