Insect transmission, host range, and properties of the crinkle-leaf strain of western-celery-mosaic virus

Abstract

Abstract does not appear. First page follows. In the last five years several viroses affecting celery have been observed to occur naturally in California. These, except western celery mosaic, have been only briefly described in previous papers (Freitag and Severin, 1939); (Severin and Freitag, 1938)4. A mosaic disease apparently different from western celery mosaic was first observed near Milpitas in the Santa Clara Valley during November, 1937. The symptoms resemble those of western celery mosaic except that the leaves are, as a rule, severely crinkled. The disease is not common and has been found only rarely during routine observation of celery fields. An investigation was undertaken to determine the symptoms, properties, and host range; likewise, the relative ability of various aphid species that breed on celery to transmit the virus. Aphids were compared with mechanical inoculation as a means of transmitting the virus. The retention of the virus by three species of aphids was studied experimentally. Materials and Methods The virus was obtained from a. naturally infected celery plant collected at Milpitas. A continuous supply was maintained in the greenhouse through repeated mechanical inoculation of healthy celery plants by the carborundum method described by (Rawlins and Tompkins (1936)). The general methods employed in these studies resemble those described earlier (Severin and Freitag, 1938). The aphid species used were maintained, with two exceptions, on celery in the greenhouse. The green peach aphid, Myzus persicae (Sulzer), was reared on sugar beets; and the potato aphid, Macrosiphum solanifolii (Ashm.), on squash. The experiments performed were carried out under greenhouse conditions at Berkeley.