A virus is a small piece of DNA or RNA in a protein shell. A virus does not have its own metabolism and depends on living cells in other organismsfor reproduction. These are the host cells. Viruses can infect all organisms, so there are also many plant viruses. Plant viruses are transmitted from one plant to another by other organisms called vectors. Different viruses have different vectors.
The best known and most common virus in potato cultivation in the Netherlands is PVY (Potatovirus Y). This virus causes fur in the potato plant, ultimately resulting in yield loss. Contaminated seed potatoes or storage plants are the first source of this virus at the beginning of the growing season. Aphids spike an infected plant, after which they can spread to healthy plants. The newly formed tubers will also become infected and produce variegated plants in the following year. Seed potatoes are therefore strictly monitored for the presence of the virus. Field inspections are carried out as well as tuber inspections.
Tobacco rattle virus (TRV) is transmitted by trichodorides (nematodes) and can cause stem fur in the plant or tuber ringing. TRV mainly causes quality damage, but yield loss is also associated with the virus. Fighting the virus is only possible by controlling the nematodes that transmit this virus.
Weed control is also an important measure because weeds are often host plants for the virus or the trichodorides.
Several countries have strict import requirements concerning the TRV virus.
Leafroll is caused by the potato virus PLRV (Potato leafroll virus). In primary infection, from the tuber, the symptoms appear in the top leaves, which are rolled up and pale/yellow in colour. In the case of secondary infection via aphids, the symptoms start at the very bottom. Early selection and the proper control of aphids means that PLRV is almost non-existent in the Netherlands.
PVX is a potato virus that is only transmitted by contact between diseased and healthy plants or by people and machines. In general, PVX causes only mild symptoms, but serious symptoms can occur in combination with an infection with the PVY virus. The use of clean seed potatoes means PVX has now become almost a thing of the past in the Netherlands.
The PVA virus, like PVY, can be transmitted by aphids in the field from infected to clean plants. Many potato varieties grown in the Netherlands are resistant, so the virus hardly occurs here anymore.