Symptoms of additional cucumber-mosaic viruses on sugar beets

Symptoms of these two diseases on mechanically inoculated sugar beets resemble those of western cucumber mosaic, which does occur on this host plant in California. In all three, chlorotic areas, veinbanding, and necrosis occur. The first symptom of celery calico—large, irregular, pale-green areas on the leaves—serves to distinguish it from common cucumber mosaic. Common cucumber mosaic can be distinguished from both celery calico and western cucumber mosaic by the first symptom—small, white dots with pinpoint necrotic centers; later by small, rust-colored necrotic centers in circular, chlorotic areas; still later by holes in some leaves caused by the dropping out of the necrotic centers. Neither celery calico nor common cucumber mosaic show, in mechanically inoculated beets, the blisterlike elevations that characterize systemic infection with western cucumber mosaic.