Possible incursion of cassava virus diseases: risks and potential threats to the Philippine cassava industry

Cassava (Manihot esculenta Crantz) is an important root crop in the Philippines. Worldwide, it is attacked by various disease-causing fungi, bacteria, nematodes, and viruses, negatively affecting its yield potential. However, in the Philippines, no viral disease in cassava has yet been scientifically reported. In other cassava growing regions, the three economically important cassava virus diseases, worldwide, are cassava mosaic disease, cassava brown streak disease, and cassava frogskin disease. These three diseases, and their associated viruses, have not been detected in the country. Other viruses are also associated with cassava but their symptomatology and characteristics are yet to be elucidated. Cassava viruses can be disseminated through infected stem propagules and transmitted effectively by whitefly (Bemisia tabaci). The exchange of planting materials, migratory behavior of insect vectors, and current disease distribution can put the country at high risk of a possible virus disease outbreak that can threaten the cassava industry. Eradication is difficult once the disease has been established in the field, which means stricter border control measures are needed. This paper reviews the current knowledge of cassava virus diseases not yet reported in the Philippines but have biosecurity importance. The paper highlights measures that can help prevent, prepare for, and respond to cassava viruses' possible incursion. Given the potential threats, the country should remain vigilant to these cassava virus diseases.