Cause Several viruses are able to infect clovers including bean yellow mosaic virus, alfalfa mosaic virus, clover yellow mosaic virus, pea streak virus, red clover vein mosaic virus, and white clover mosaic virus. Some of these viruses are transmitted by aphids, some by clipping equipment, and some are seedborne.
Symptoms Leaves exhibit varying degrees of yellowing, chlorosis along the veins, mottling, and rugosity. Plants may exhibit a loss of vigor, general decline, excessive winterkill, and an associated degeneration of the root system. Seed and forage yields may decline drastically in the second year of production.
Cultural control
- If practical, seed clover in late summer or early fall to reduce the exposure period to insect vectors.
- Harvest forage or seed only 1 year, then rotate with cereals.
- Do not plant a new seeding adjoining an established field.
- Destroy clover plants on ditch banks or waste areas.