Because celery growing in the coastal areas of California is the important host of the virus, celery free periods have been effective for control. The first celery free period was established in Los Angeles County in 1934 and has subsequently been established in other counties such as Monterey, Ventura and San Luis Obispo. Elimination of wild celery growing along ditchbanks by spray herbicide has also been a part of the celery free program. At times through the years, the celery free program has been allowed to lapse for various reasons and the virus quickly builds up to where it causes damage to the celery crop. Cucumber mosaic is infrequently seen on celery in California and is transmitted by various aphid species.
Symptoms are a light green to yellow mottle of the leaflets which occasionally become necrotic.
Plants are stunted and the petioles on many stalks may be necrotic. No control is known. Although the spotted wilt virus has a wide host range of vegetables and ornamentals, it is rarely found on celery in California. Small yellow spots or ringspots, which later become necrotic, appear on the leaves. Pithy tissue in petioles develop necrotic areas that later develop into brown, sunken pits.