Status of groundnut bacterial wilt research in Vietnam.
This disease, caused by Pseudomonas solanacearum race 1, is widespread in both northern and southern Vietnam, causing considerable yield losses in some regions. Infection is most severe in dryland cropping systems, especially on sandy soils along river banks, and on uplands. Rotation of groundnut with rice in low-lying areas was effective in reducing incidence and severity. The disease is more severe in Jul.-Nov. crops than in those grown in Jan.-Jun. Seed transmission at a rate of 4-8% was detected. Most of the local cultivars and breeding lines are susceptible and research is being directed towards identifying wilt-resistant germplasm and breeding lines of the Spanish type. Surveys are needed to determine the extent of yield losses. Breeding stable resistant cultivars with resistance to this and other groundnut diseases is a priority.