VIRUSES OF COWPEA, VIGNA UNGUICULATA L. (WALP.), IN NIGERIA

The cowpea strain of tobacco mosaic virus was isolated from a range of leguminous hosts at Ibadan, but was rare in cultivated crops. Systemic symptoms in species infected experimentally are described.
A new virus of cowpea was also found in Nigeria. The physical properties (thermal inactivation point 56° C., dilution end-point 1/50,000 and longevity in vitro 4 days at 25° C.) differ from those for cowpea viruses reported elsewhere and the name cowpea yellow mosaic virus is proposed. This virus produces local lesions in French bean ( Phaseolus vulgaris L.) and local and systemic lesions in Bengal bean ( Mucuna aterrima Holland), but does not infect other leguminous hosts. The virus was purified and an antiserum prepared against it.
Both viruses are transmitted by a beetle ( Ootheca mutabilis Sahlb.) which loses infectivity within 48 hr. of leaving plants infected with either or both viruses.