Preliminary studies on sap‐transmissible viruses of red clover (Trifolium pratense L.) in England and Wales

Abstract

SUMMARYRed clover plants, collected from nine widely separated permanent pastures in England and Wales, were tested for sap‐transmissible viruses. Viruses were identified by the symptoms they caused in test plants, by electron microscopy, and by serological tests. Of the 265 plants tested 14% were infected. Only pea mosaic virus was common and widespread; it was found in 8% of the plants, and in seven of the fields. Other viruses isolated were arabis mosaic, bean yellow mosaic, red clover mottle, and red clover vein mosaic; only red clover mottle virus produced diagnostic symptoms in red clover. No viruses were detected in seedlings grown from seed from eighty‐nine commercial seed crops. Attempts to transmit red clover mottle virus by the Collembolan Sminthurus viridis L., which is common on red clover, failed.