Occurrence of cassava brown streak disease and associated Cassava brown streak virus and Ugandan cassava brown streak virus in the Comoros Islands.
In April 2015, symptoms of yellowing on leaves and brown necrotic rot on tuberous roots on cassava (Manihot esculenta) were observed in Mayotte and in July and September 2016 in 3 other islands of the Comoros archipelago: Grande Comore (Ngazidja), Anjouan (Ndzuwani) and Mohéli (Mwali). To evaluate the disease epidemic in the south-western Indian Ocean Islands and to verify the identity of the causal agents, symptomatic leaf samples of 67 affected plants were collected and tested. Based on molecular data (nucleotide sequences and phylogenetic analysis), the causal pathogens were identified as Cassava brown streak virus and Ugandan cassava brown streak virus. This is thought to be the first report of Cassava brown streak virus in Grande Comore, Anjouan and Mohéli which demonstrate the expanding epidemic of CBSD in the south-western Indian Ocean islands.