Fungal Pathogens of Cacao in Puerto Rico.

Cacao production is a rapidly expanding industry in Puerto Rico, with new farmers planting ~20,000 trees in the past few years. To determine the etiology and extent of diseases affecting cacao in Puerto Rico, a survey was performed at eight sites around the island. Pod rot and/or branch dieback were observed at all sites. Most organisms isolated from symptomatic pod and stem samples were identified as spp. (48%) and spp. (25%) based on sequences of the internal transcribed spacer and large subunit regions. Within these genera, and were the most prevalent species and were used in inoculation studies to determine their relative virulence on pods and stems. served as a positive control due to its well-established pathogenicity in all tissues. On pods, and caused significantly larger lesions (6.1 and 5.9 cm, respectively) than (2.7 cm) four days post-inoculation. All three species caused disease on stems, with no differences found among species. Although was thought to be the primary pathogen affecting cacao in Puerto Rico, this study identifies and as the common pathogens on the island. This improved understanding will help scientists and farmers control disease by selecting fungicides effective against both oomycetes and fungi.