The agriculture ministry has expressed concern about the alarming spread of mosaic disease in cassava farms across Cambodia, which they say could worsen and cause an overall decrease in yields of the cash crop.
The disease is caused by mosaic viruses, which come from a range of unrelated lineages. Symptoms vary widely, with possibilities including mottled and distorted foliage, yellowed veins, stunted growth and reduced yields, fruit quality defects, rapid-drying stems, and necrosis.
Minister of Agriculture, Forestry and Fisheries Veng Sakhon told The Post that mosaic disease had been affecting farmers’ crops across the country for the past three to four years, causing a “dramatic” decline in cassava yields.
The root cause of the virus spread has been identified as the import of infected cassava seeds from Cambodia’s neighbouring countries. This was due to the lack of proper phytosanitary control, prompting these viruses to spread throughout the country, Sakhon said.
“The disease will reduce yields by about 80 per cent if it strikes cassava crops without being reined in. We are very concerned about this and are working hard to find ways to prevent the spread,” he said.
“We produce more than 35 million tonnes a year, with cassava contributing 14 million tonnes and $1 billion in value, so we have to find funds to help research to prevent disease to avoid more serious losses to cassava yields.”
Sakhon added that development partners, including the Cambodia-Australia Agricultural Value Chain (CAVAC) programme and Japan International Cooperation Agency (JICA), have been assisting with research at the National University of Battambang to clean cassava plants, prevent the virus from breeding in net houses and to conduct breed purification to stymie the disease in successive harvests.
“This project requires a lot of money, so we hope that the private sector will help more with [supplying and distributing] this new technology. We have already tested the technology in some provinces, such as Battambang and Banteay Meanchey,” he said.
Stung Treng provincial Department of Agriculture, Forestry and Fisheries director Tum Niro affirmed that mosaic disease has affected the cassava crops of farmers in the province significantly in recent years, leading to dramatic falls in yields.
Niro said that the department has been attempting to acquire more cassava seeds to replant promptly to prevent net harvest losses, and has been seeking support from development partners to jointly investigate how to grow disease-free, high-quality plants for provincial farmers.
“We hope that this CAVAC project will solve the problems faced by the farmers. We are helping to set up a net house for the rapid expansion of pure, disease-free cassava seeds that can provide high yields and guarantee of quality,” he said.
Though mosaic disease has been causing problems for cassava production nationwide, Battambang provincial agriculture department director Chhim Vachira said that cassava production in the province has not been facing serious problems due to officers changing the breed and preventing the disease’s spread in time.
“We have been less affected by the disease because we have instructed farmers to be careful and monitor it thoroughly. We advised them to remove any trees that have not been growing well so as to avoid infecting other trees,” he said.
Oddar Meanchey provincial agriculture department director Sot Sisokheang said the disease has been posing a large problem in the province, as farmers have been growing the Thai varieties Huai Bong and Rayong in large quantities, most of which wound up being infected with mosaic virus.
Sisokheang noted that his department has been running a campaign alerting farmers to change the type of cassava varieties they are growing, as well as conducting field research on the resilience of the new varieties.
“We have stopped importing the Huai Bong and Rayong varieties of Thailand to minimise mosaic infections. We’ve also begun collaborating with the [National] University of Battambang to research new cassava varieties.
“We expect that the new cultivars we are testing will have high yields and quality, and if that proves to be the case, we will encourage farmers to turn to planting these varieties,” Sisokheang added.
Cassava is one of Cambodia’s leading agro-industrial crops, contributing about three-to-four per cent of gross domestic product (GDP) per year. On January 14, 2021, the Kingdom formally launched the National Policy on Cassava 2020-2025 in a bid to increase commercial production for export.