2011 Annual Report
1a.Objectives (from AD-416)
The objectives of this research are to test, in the laboratory and in the field, the efficacy of selected biological agents for the selective control of cacao diseases, specifically, Moniliophthora roreri and Moniliophthora perniciosa. The research will focus on endophytic Trichoderma spp. native to Ecuador that were previously identified as having biocontrol potential, but other agents such as Bacillus species may be considered. The development of biocontrol formulations with enhanced disease control efficacy in the field is of special interest. Little is known about how biocontrol formulations influence the establishment and efficacy of endophytic agents in tropical ecosystems, especially as applied to trees such as Theobroma cacao (cacao). The economic sustainability of optimized biocontrol strategies will be determined in order to demonstrate biocontrol’s merit as a “best practice” for cacao farmers.
1b.Approach (from AD-416)
Candidate endophytes (Trichoderma species) have been screened to demonstrate their ability to colonize cacao and for biocontrol efficacy against cacao pathogens. At present, isolates to be considered for further study include 15 isolates previously screened for biocontrol and endophytic efficacy in cacao by ARS, and several isolates of specific interest to INIAP scientists. Four Bacillus isolates previously collected in Ecuador and screened by collaborators for biocontrol and endophytic activity in cacao may also be considered. The capacity of different formulations to enhance biocontrol efficacy will be determined. The formulations used to date in biocontrol research in cacao have incorporated starches (as carriers), surfactants, or water alone. Lab-based research on formulations with Trichoderma isolates indicate a significant benefit to Trichoderma efficacy in response to added nutrients, humectants, and vegetable oils (corn oil). Initially, these formulations (including nutrients, humectants, and oils) will be evaluated for their abilities to enhance Trichoderma biocontrol efficacy in small scale and short term field studies. Formulation concepts will be optimized as to specific components (for example, readily available nutrient sources), concentrations, and application timing. Standard protocols will be developed for rapid evaluation of biocontrol agents, formulations, and their interactions in the field. In collaboration with cooperating institutions, large scale field trials of promising endophyte formulations with biocontrol potential will be conducted. The economic impact of biocontrol strategies for the control of disease will be determined.
Small plot experiments were initiated studying the impact of the bacteria Bacillus on control of witches’ broom. Cacao seedling were treated with Bacillus in the greenhouse and transplanted into the field underneath cacao trees heavily infected with witches’ broom disease. The seedlings were rated for infection and the data are being analyzed. A second small plot experiment was carried out studying the impact of Bacillus on frosty pod rot, another disease of cacao. Two month old cacao pods were inoculated with Bacillus in the field. Ratings for frosty pod rot were made at monthly intervals. The Bacillus does not appear to have reduced frosty pod rot. Plans have been formalized for studying the impact of combining Bacillus species with another biocontrol organism, Trichoderma species, for management of cacao diseases. Field plots have been identified and experimental procedures developed. The progress of this agreement, which is described in this report, was monitored by, e-mails and phone or personal communications between the principal investigator and the principal collaborators listed for this project.