A slow, steady decline in growth and productivity occurs in all cultivars. Infected bushes occur in a roughly circular pattern in the field; some may die.

Disease cycle
The virus is vectored by the dagger nematode (Xiphinema americanum) and may be introduced by infected planting stock. The disease spreads about 1 m per year. Weeds (dandelion, narrow-leaved plantain, and common chickweed) may serve as a reservoir for the virus.

Management
Do not plant in virus-infested sites without fumigation; plant virus-tested, clean planting stock; remove infected plants including crown and major roots; apply nematicides.