OCCURRENCE AND PREVALENCE OF VIRUSES OF LEAFY VEGETABLES IN LAGOS, NIGERIA

Abstract

Four commercial leafy vegetable farms in Lagos State were surveyed from October 1989 to September 1990 for the occurrence and prevalence of leafy vegetable viruses. Mechanically transmissible viruses were isolated from Amaranthus hybridus, Celosia argentea, Cucurbita moschata, Telfairia occidentalis and Brassica oleracea, while virus-like symptoms (causal agents not sap-transmissible), were observed on Solanum macrocarpon. Two previously uncharacterized viruses, one each from C. argentea and C. moschata were isolated. The identification of viruses such as telfairia mosaic virus (TeMV) and amaranthus mosaic virus (AMV), that had been reported in the literature, were confirmed on the basis of host range, symptomatology, insect transmission and particle morphology. Virus-like symptoms were not observed on Corchorus olitorus and five other exotic vegetables. Amaranthus mosaic virus and celosia mosaic virus (ClMV), the latter isolated for the first time in Nigeria in the course of this study, were recorded from all the farms and were therefore the most prevalent. The incidence of AMV was 19.7% at Amuwo Odofin while it was 0.7% and 0.6% at Tejuoso and Abule Ado farms respectively. For ClMV, an incidence of 27.5% was recorded at Amuwo Odofin while Tejuoso and Abule Ado had 0.6% and 1.4% respectively. Telfairia mosaic virus and viruses on C. moschata and B. oleracea were limited to the Tejuoso farm. Generally, virus incidence was higher during the wet season for most of the viruses. Elimination of plant remains and volunteer crops may be exploited in the control of the viruses. KEY WORDS: Survey, Leafy vegetables, viruses. Global Jnl Pure & Applied Sciences Vol.10(1) 2004: 61-67