Plant viruses can cause many diseases in our crops. The effects of viruses can range from discolorations and deformities – which make products less valuable or worthless – to loss of the plant.
But virus infection can also be symptom-free; in that case the host plant appears to be healthy. However, undetected infections can have serious consequences for the export of agricultural products, especially if the virus concerned has a quarantine status in other countries.
Standard plant protection agents do not work against plant viruses; once plants are infected by a virus they can no longer be cured. Farmers and growers therefore do everything they can to keep their crops virus-free. They begin the crop with certified virus-free material (seeds, cuttings or other planting material). In addition, they take measures to minimise virus transmission to their crop and within their crop. To do this effectively, it is important to understand how viruses spread and move from one plant to another.
Spread of viruses
The method of spreading (dispersal) differs substantially between virus groups. A few examples of dispersal routes used by viruses are the following:
- Insects (aphids, whiteflies)
- Soil (nematodes, soil fungi)
- Direct contact and cultivation activities.
It is often assumed that viruses within a specific group use the same dispersal mechanism.
Torradovirus in lettuce
An example of our current research concerns a recently discovered virus in lettuce that belongs to the Torradovirus genus. It was previously known that viruses from this group are transmitted by whiteflies. However, our research has shown that the Lettuce necrotic leaf curl virus is not transmitted by whiteflies, but by aphids. Farmers and growers can use this information to take effective control measures and prevent the virus from spreading.