Incidence and identification of virus diseases of tobacco in three provinces of Zambia

Abstract

Nine tobacco fields of small‐ and large‐scale farmers in Central, Lusaka and Southern provinces of Zambia with an experimental area in the range of 4–52 ha were surveyed for the incidence, prevalence and identification of virus diseases during the growing season of 1997. Samples were collected from three tobacco fields in each of the three provinces, and a total of 72 samples was analysed. Virus identification was based on field disease syndrome, host range studies, DAS‐ELISA and electron microscopy of virus particles in some cases. The study demonstrated the occurrence of Tobacco mosaic virus (TMV), Potato virus Y (PVY), Alfalfa mosaic virus (AMV) and Tobacco ringspot virus (TRSV). TMV and PVY occurred widely and were common in all three provinces, while AMV and TRSV were relatively less common. The prevalence of the four viruses was TMV 78%, PVY 67%, AMV 33% and TRSV 22%. Serological tests for Tomato spotted wilt virus (TSWV) and Cucumber mosaic virus (CMV) showed that these viruses were not present in the tobacco samples analysed.