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ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #373438

Research Project: Development and Application of Genomic-assisted Breeding Strategies to Produce Disease-resistant Cacao Genetic Resources

Location: Subtropical Horticulture Research

Title: Diseases affecting Theobroma cacao in Puerto Rico’s emerging cacao industry

Author
item Puig, Alina
item BROWN, JUDITH - University Of Arizona
item RAMOS-SOBRINHO, ROBERTO - University Of Arizona
item KEITH, CORY VON - University Of Arizona
item Goenaga, Ricardo
item Gutierrez, Osman

Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Cacao production is a rapidly expanding industry in Puerto Rico; new farmers have planted ~20,000 trees in the past few years. The first cultivation on the island in 1636 failed due to adverse weather and a disease of unknown etiology. The US Department of Agriculture (USDA) conducted cacao research throughout the 1900’s but the large increase in commercial production occurred following an initiative in 2000 to develop a cacao industry. To determine the etiology and extent of diseases affecting Theobroma cacao in Puerto Rico, a survey was conducted in August 2019 at eight sites including commercial farms, field trials, and the USDA cacao germplasm collection. Pods exhibiting necrotic lesions were observed on cacao trees from all survey sites. Hyphal-tip cultures of isolated organisms were identified as Diaporthe spp. (60%), Lasiodiplodia spp. (30%), and Phytophthora palmivora (8%) based on sequences of the internal transcribed spacer and large subunit regions. Only the latter two have been reported as cacao pathogens. Several pods from a commercial farm showed red blotchy discoloration symptoms, reminiscent of badnaviral infection. Amplification and sequencing of a 870bp fragment indicated the presence of a badnavirus ~95% identical to Cacao mild mosaic virus (CaMMV) (KX276640), previously identified from cacao trees in the Trinidad Gene Bank collection. In Trinidad, CaMMV was thought to have been eliminated from commercial cacao plantations during the 1950’s. This is the first report of CaMMV in Puerto Rico or outside Trinidad, and of Diaporthe spp. as a pathogen of cacao.