Risk factors

The development of PVA infection results from a combination of:

• different sources of infection, either internal (volunteers, seed tubers, weeds) and/or external (nearby potato crops, gardens, weeds);

• the relative signifi cance of fl ights of aphids during the growing season (related to climatic conditions and nearby crops);

• the level of control measures taken in seed potato production (roguing, crop management such as weed control, crop protection, haulm destruction and field and/or lot inspection);

• the susceptibility of the potato cultivar.