Abstract
Samples from mature plants and plants grown fromseed tubers collected from two major potato-growing areas in Malawi were serologically tested for viruses X, and S and with an antiserum reactive against the paracrinkle (PVM+PVS) virus. The infection rate determined from 3165 serological tests was 88·4 per cent for PVX 91·5 per cent for PV and 95·8 per cent for paracrinkle in samples from mature plants, while for plants grown under glass from tubers the rates were 83·9 per cent for PVX, 99·3 per cent for PV and 99·0 per cent for paracrinkle. The combined infection caused cash losses estimated at about £40 000 to £80 000 sterling per annum.
