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Cassava mosaic disease (CMD), a serious threat to cassava production, is caused by two begomovirus species in Asia, Indian cassava mosaic virus (ICMV) and Sri Lankan cassava mosaic virus (SLCMV). Cassava mosaic disease has recently spread into Southeast Asia and it is urgent to establish an efficient system to monitor its spread. Cassava fields were surveyed for CMD on the web using a smartphone-based farming support application, AGRIBUDDY, to obtain photos of CMD and their time, location, and contact information posted to the AGRIBUDDY cloud by farmers. To diagnose a pathogen, we designed novel PCR primers for CMD identification. By combining these two techniques, we detected SLCMV occurrence in Kampong Thom, Cambodia.

The biodiversity of geminiviruses associated with the Cassava Mosaic Disease (CMD) in India was investigated using PCR to specifically amplify the DNA of Indian cassava mosaic virus (ICMV) or Sri Lankan cassava mosaic virus (SLCMV) and also by using PCR to amplify specific viral genes, followed by digestion with different restriction endonucleases to obtain polymorphic patterns (PCR-RFLP). Results showed that both ICMV and SLCMV were present in mosaic-affected cassava; ICMV was geographically restricted to certain regions, whereas SLCMV was widespread. PCR-RFLP analysis showed that, in addition to ICMV-type and SLCMV-type patterns, a high proportion (40%) of the samples displayed novel patterns, some of which were localized in certain areas, whereas others were widely distributed.