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Title: ENDOPHYTIC FUNGI AS BIOCONTROL AGENTS OF THEOBROMA CACAO PATHOGENS

Author
item MEJIA, L - PANAMA
item ROJAS, E - PANAMA
item MAYNARD, Z - PANAMA
item ARNOLD, E - UNIV OF AZ, TUCSON, AZ
item VAN BAEL, W - PANAMA
item Samuels, Gary
item ROBBINS, N - PANAMA
item HERRE, A - PANAMA

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2008
Publication Date: 1/31/2008
Citation: Mejia, L.C., Rojas, E.I., Maynard, Z., Arnold, E.A., Hebbar, P., Samuels, G.J., Robbins, N., Herre, A.E. 2008. Endophytic fungi as biocontrol agents of Theobroma cacao pathogens. Biocontrol Control. 46:4-14.

Interpretive Summary: Many kinds of fungi occur in living cacao (chocolate) plants and are called endophytes. Although no one knows why they exist inside plants, preliminary evidence suggests that endophytes may protect the plants against plant diseases. In this research three species of endophytic fungi were tested to determine if they could control the most serious diseases of cacao. In both the laboratory and the field, some of the endophytes helped to control the diseases. The mechanisms by which the endophyte controlled the diseases were determined. This research will be used by plant pathologists who are working to control diseases of cocoa.

Technical Abstract: Results are presented of in vitro screening of fungal endophytes against three important pathogens of cacao; colonization studies of endophytes on cacao leaves; and a field evaluation of three endophyte species on the control of two diseases of cacao. 40% (21/52), 65% (28/43) and 27% (4/15) of tested endophytic morphospecies showed an in vitro antagonistic interaction against Moniliophthora roreri, Phytophthora palmivora and Crinipellis perniciosa, respectively. The most common antagonistic mechanism was outgrowing the pathogen. We found 13%, 21%, and 0% of tested morphotypes showed antibiosis against M. roreri, P. palmivora, and C. perniciosa, respectively. Only one strain of Trichoderma was observed to be parasitic on M. roreri. We also evaluated colonization capacity of endophytic species commonly found in cacao leaves. Finally, we conducted field tests of three endophytic fungi, viz. Colletotrichum gloeosporioides, Clonostachys rosea and Botryosphaeria dothidea, to evaluate their effects on pod loss due to Frosty Pod Rot and Black Pod. Although the overall incidence of Black Pod was very low during the tests, we observed that treatment with C. gloeosporioides produced a significant decrease in pod loss. We observed no decrease in pod loss due to Frosty Pod Rot, but there was a reduction of 10% in the incidence of cacao pods with sporulating lesions of M. roreri with C. rosea. The reduction in pod loss due to Black Pod and the reduced sporulation of M. roreri support the potential of endophytes as biological control agents within an IPM program.