Control measures

The use of resistant (or tolerant) cultivars and the use of certified seed potatoes are measures essential to the control of infections due to viral diseases, in particular the development of necrosis caused by necrotic viral isolates in potato crops intended for consumption and processing.

Production of certified seed potato is based on a range of strict measures limiting the infection by viral diseases and involving:

• the use of certified seed tubers resulting from the multiplication of virus-free material in a certification programme (including multiplication systems such as micropropagation in vitro, intensive field inspections and large-scale post-harvest testing);

• production in a favourable environment in isolated areas with low virus/vector pressure and in fields away from household gardens or away from fields used for the production of ware/ processed potatoes;

• early roguing of diseased plants and eradication of all sources of inoculum, e.g. weeds, volunteer potatoes to inhibit the spread of viruses within the field;

• the treatment with mineral oils to reduce the transmission of non-persistent viruses such as PVY. Insecticides are only effective against persistent viruses such as Potato leaf roll virus.

Additional control measures in seed potato production taking into account risks of aphid infestations which are usually higher during warm periods, include:

• early dates of planting;

• early haulm destruction (by chemicals and/or by mechanical means) prior to maturity to limit the infection of daughter tubers.