Experiments on the Control of Brown Rot of Apples and Plums: I. Laboratory Tests

The symptoms and some properties of five viruses isolated from celery crops in Britain are described. Cucumber mosaic and lucerne mosaic viruses were found to be prevalent in celery and other crops. Tomato aspermy virus, though widespread in chrysanthemum and occasional in tomato crops in England, and economically damaging in Continental celery crops, has not so far been reported in celery in Britain. British celery varieties tested were resistant to experimental infection with tomato aspermy virus. These three viruses were readily isolated, purified and identified.

Three viruses, designated celery yellow spot, celery yellow vein and celery ringspot, isolated from affected celery plants, were less readily transmitted from celery to celery, and could not be purified by techniques that succeed with many viruses.

Celery yellow spot was transmitted by sap-rubbing inoculation only when cucumber mosaic virus was also present ; it was tentatively identified with the celery yellow spot virus reported from the U.S.A. Celery ringspot virus showed some similarities to the poison hemlock ringspot virus found in the U.S.A., but none of the critical tests for virus identification could be applied to either of these two viruses. Celery yellow net virus differed from all the viruses so far recorded in celery. The chronic symptoms of the different viruses in celery were often similar, and therefore unreliable for diagnosis. The initial or “ shock ” symptoms, however, were usually distinctive.