Epidemiology of Cassava Mosaic Disease Viruses in Western Democratic Republic of Congo

Cassava mosaic disease (CMD) is one of the most destructive constraints to cassava production in sub-Saharan Africa. This study aimed to assess the genetic diversity of viruses causing CMD in the Kwango, Kwilu, and Maï-Ndombe provinces of western Democratic Republic of Congo (DRC), where data remain limited. The objective was to identify and to map the viral strains associated with CMD. A field survey was conducted, during which 216 cassava leaf samples were collected from plants aged from 3 to 6 months. Disease severity was evaluated using a scale of 1 to 5. Molecular detection was performed using polymerase chain reaction (PCR) with both specific and universal primers targeting most of CMD begomoviruses. Results revealed a high prevalence of ACMV in Kwilu (70.9%) and Kwango (66.6%), with Kwango also showing substantial incidences of EACMV (51.5%) and unidentified begomoviruses (48.5%). Co-infections of ACMV and EACMV were observed in 33.3% of samples, indicating complex viral interactions. In contrast, Maï-Ndombe was characterized by a predominance of unidentified begomoviruses (45%). These findings highlight the need to strengthen phytosanitary surveillance and molecular diagnostic capacities, particularly through high-throughput sequencing technologies. The study also recommends to develop and disseminate resistant cassava varieties and to adopt integrated disease management strategies to ensure sustainable CMD control.