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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #392891

Research Project: Biology, Epidemiology, and Detection of Emerging Plant Pathogenic Oomycetes

Location: Foreign Disease-Weed Science Research

Title: Branch dieback on Theobroma cacao infected with Cacao mild mosaic virus

item Puig, Alina

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/11/2022
Publication Date: 12/26/2022
Citation: Puig, A.S. 2022. Branch dieback on Theobroma cacao infected with Cacao mild mosaic virus. Phytopathology. 112:S3.1.

Interpretive Summary:

Technical Abstract: Until 2020, cacao mild mosaic virus (CaMMV) had only been reported in Trinidad, and was believed to have been mostly eradicated following a government tree removal program in the 1950s. However, in the past couple of years, CaMMV has been detected in Puerto Rico, Brazil, and Florida, and is considered an emerging disease on Theobroma cacao, the plant used to produce chocolate. In additional to symptoms such as leaf mosaic and pod mottling, the virus has been reported to cause branch dieback in infected plants. A study conducted on infected trees in the USA found that over 20% had severe branch dieback. A subset of these (n=13) were assayed to determine the causal fungi. Five genera of fungi were identified: Lasiodiplodia (46.2%), Nigrospora (23.1%), Fusarium (15.4%), Colletotrichum (7.7%), and Phomopsis (7.7%). To determine whether CaMMV-infected trees were more susceptibility to dieback, infected (n=6) and uninfected (n=5) seedlings were inoculated with Lasiodiplodia theobromae. L. theobromae is one of the most widely reported organisms causing dieback on T. cacao. Five days after inoculation, infected trees developed lesions twice as large as those observed on uninfected trees (2.5 vs 5.0 mm2, respectively), indicating that the virus makes plants more susceptible to dieback. These results suggest that CaMMV negatively impacts plant health and reduce productivity in the field. The negative impacts of CaMMV on plant health, and potential for reduced productivity in the field will be discussed.