Surveillance for Sri Lankan cassava mosaic virus (SLCMV) in Cambodia and Vietnam one year after its initial detection in a single plantation in 2015

Abstract

Cassava mosaic disease, one of the ten most economically important crop viral diseases in the world, was first reported in Southeast Asia from a single plantation in Cambodia in 2015. To determine the presence and incidence of Sri Lankan cassava mosaic virus (SLCMV) one year after first detection, a total of 6,480 samples from 419 fields were systematically collected from cassava production areas across Cambodia (3,840 samples; 240 fields) and Vietnam (2,640samples; 179 fields) in the 2016 cropping season. Using PCR-based diagnostics, we identified 49 SLCMV-infected plants from nine fields, representing 2% of the total number of fields sampled. Infected fields were geographically restricted to two provinces of Eastern Cambodia, while no infection was detected from any of the other sampled sites in either country. Symptom expression patterns in infected plants suggested that SLCMV may have been transmitted both through infected planting materials, and by Bemisia tabaci , the known whitefly vector of SLCMV. In addition, 14% of virus infected plants did not express typical symptoms of cassava mosaic disease on their leaves, highlighting that molecular-based validation is needed to confirm the presence of SLCMV in the field. None of the owners of the SLCMV-infected fields indicated acquired planting materials from the plantation in Ratanakiri where SLCMV was first reported. The surveillance baseline data generated for both countries is discussed in light of future options to control and manage cassava mosaic disease.

Phenotypic and molecular screenings for determination of cassava mosaic disease (CMD) status in farmers’ fields in Ebonyi State, Nigeria

“…LGAs of Ebonyi State, and the scored symptoms were similar to the previously reported ones [39,[48][49][50][51]. Considering the status of CMD in the studied LGAs, the highest mean percentage incidence of RE (11%) was identified in Afikpo North, followed by Ebonyi LGA (2%); Ezza South (1%); Izzi, Abakaliki and Ikwo with 0.1% each, but there was no RE expression on cassava leaves obtained from Ezza North, Ohaukwu, Afikpo South and Onicha, indicating that most of the farmers' fields have been exposed to the CMD epidemic.…”

User guide to the toolbox for working with root, tuber and banana seed systems. RTB User guide

“…In 2017, Sri Lankan cassava mosaic virus (SLCMV) was reported in Cambodia and has since spread to four other countries in the region. Southeast Asia lacks resistant varieties, and the disease quickly spread with the aid of whitefly vectors and exchange of infected planting stems (Minato et al 2019). Response was especially hampered by the absence of systematic knowledge of cassava seed networks.…”

Cassava breeding and agronomy in Asia: 50 years of history and future directions

“…This array has also been tested among farmer-grown varieties released in Vietnam to measure the impact of cassava breeding as described above (Le et al 2019). Although significant progress in cassava genetics has been made through conventional and marker-assisted breeding (Ceballos et al 2015), new regional challenges and the effect of impending climate change (Ghini et al 2011), on pest and disease outbreaks such as SLCMV (Minato et al 2019), presents additional challenges to the breeders. From an industrial viewpoint, development of value-added cassava with improved starch quality and new starch type (Bechoff et al 2018) are always in high demand.…”