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Title: FIRST REPORT OF MONILIOPHTHORA RORERI CAUSING FROSTY POD ROT (= MONILIASIS DISEASE) OF CACAO IN MEXICO

Author
item PHILLIPS, W - COSTA RICA
item COUTINO, A - MEXICO
item ORTIZ, C - MEXICO
item HERNANDEZ, J - MEXICO
item Aime, Mary

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2006
Publication Date: 2/24/2006
Citation: Phillips, W., Coutiño, A., Ortiz, C.F., López, A.P., Hernández, J., Aime, M.C. 2006. First report of Moniliophthora roreri causing frosty pod rot (moniliasis disease) of cocoa in Mexico. Plant Pathology 55:584. (Doi: 10.1111/j.1365-3059.2006.01418.x)

Interpretive Summary: Cacao is a tropical tree crop that forms the basis for the multibillion dollar chocolate industry in the United States. One of the most devastating diseases of cacao in the world, frosty pod rot, is caused by the fungus Moniliophthora roreri. M. roreri, which is currently confined to the Americas, originated in northern South America and has been invasively spreading northward into Central America. This research reports the first discovery of the fungus causing frosty pod rot in Mexico, in the chocolate-growing regions of Chiapas and Tabasco The identity of the causal fungus was confirmed based on morphological characteristics and molecular sequence data. This research will be used by plant pathologists to track the recent northward distribution of frosty pod rot of cacao.

Technical Abstract: Theobroma cacao, the source of chocolate, has been cultivated in Mexico since pre-Columbian times. Approximately 37,000 farmers and 82,000 ha in the Tabasco and Chiapas States are dedicated to production of this important crop. In March 2005, deformed and prematurely-ripening cacao pods were noted on several farms in the vicinity of Ignacio Zaragoz, Pichucalco in northern Chiapas. Pods were covered with dark brown lesions with creamy-colored fungal mycelium that became darker with age, and contained multiple necrotic areas internally. One month later, local organizations estimated that 1.076 ha in the municipalities of Pichucalco, Juárez, and Ostuacán in Chiapas and Huimanguillo in Tabasco (near the border with Chiapas), were affected by the new disease. The presence of Moniliophthora roreri (Cif.) Evans et al., the causal agent of frosty pod rot (FPR), was independently confirmed through the distinctive symptomatology, colony morphology and DNA sequencing. On modified V8 medium the fungus showed an initial whitish growth, which became salmon-cream and finally dark brown due to the massive formation of spores as described by Evans (1981). Microscopically, the fungus produced chains of thick-walled, pale yellow, heteromorphic, but most frequently globose/subglobose (74%) to ellipsoid (24%), 8.4 - 8.6 x 12.2 'm conidia. Two regions of the nuclear ribosomal DNA repeat—internal transcribed spacer region (ITS) and 28S large subunit (LSU)—were amplified and sequenced. This is the first report of FPR, one of the most destructive diseases of cacao worldwide in Mexico, where cacao production is now threatened. This report also indicates that M. roreri, which began spreading northward from Panama in 1956 has now reached the northern limit of cacao cultivation in continental America.