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Purification schemes were developed which yielded 0.7 to 1.0 mg of alfalfa latent virus (ALV) and pea streak virus (PSV) and 0.1 to 0.3 mg of red clover vein mosaic virus (RCVMV) per gram pea cullivar Lincoln ) plant tissue (excluding roots). The freezing of the tissue and the use of an appropriate extraction buffer were crucial. Virus from sap was precipitated by 6%(w/v) polyethylene glycol (PEG, MW 6,000) and concentrated by two cycles of differential centrifugation. Partially purified virus preparations had a single nucleoprotein component in rate-zonal sucrose and equilibrium cesium chloride density gradient centrifugation. The virus preparations did not contain detectable impurities. The ALV, had a sedimentation coefficient of 161 ± 1.5 S, a value similar to other members of the carlavirus group. Both ALV and PSV multiplied and accumulated when they were inoculated to the same host plant, thus supporting the previous evidence that they are indeed different viruses.