Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

First report of Lasiodiplodia pseudotheobromae and Colletotrichum siamense causing cacao pod rot, and first report of C. tropicale causing cacao pod rot in Puerto Rico.

Abstract

During a disease survey from June to September 2017 at the USDA-ARS cacao germplasm collection in Mayagüez, Puerto Rico, cacao pod rot was observed in 14 different varieties with an incidence of 36%. Sometimes small pods were mummified, but mostly pod rot was found in mature pods. Two isolates (I41 and I46) of Lasiodiplodia pseudotheobromae (Lps), two isolates (K21 and K51) of Colletotrichum siamense (Cos), and one isolate (K07) of Colletotrichum tropicale (Ctr) were identified using taxonomic keys and sequencing of the internal transcribed spacer, sections of β-tubulin, translation elongation factor 1 alpha for Lasiodiplodia spp. and ITS rDNA, BT, chitin synthase, and glyceraldehyde 3-phosphate dehydrogenase genes for Colletotrichum. This result was further confirmed by morphological observations and pathogenicity tests. Ctr has been reported causing anthracnose on cacao pods in Japan, whereas Cos has only been reported in asymptomatic cacao tissues in Australia. This is thought to be the first report of Lps and Cos causing pod rot of cacao and the first report of Ctr causing pod rot of cacao in Puerto Rico.