Potato leaf roll virus
(PLRV)
Causative agent and transmission
The potato leaf roll virus is transmitted by certain aphids when they pierce the seed potato to feed on the sap. The potato leaf roll virus can be considered persistent because the aphid only becomes infectious after a latent period required for the passage of the virus through the insect's intestine and then through the salivary glands.
Description of the symptoms on crops
(clic on photos to enlarge)
The appearance of the symptoms on a crop depends on whether contamination takes place in the current year or during the previous year:
• Infection during the current year: the leaves at the top of the plant are slightly curled and show yellowing. Purple pigmentation can sometimes be seen on the edge.
• Infection during the previous year: the leaves at the base are tightly curled and hardened, sometimes with a mauve border; the plant growth habit is straighter and the internodes are shorter. The plant is yellowed and sometimes dwarfed.
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It is more difficult to break down the mother tubers and the daughter tubers remain small. In certain varieties, internal necroses can appear as networks on tubers.
Control
- Use of healthy seed resulting from genealogical selection;
- Production in a favourable environment;
- Roguing of virus-infected plants;
- Haulm defoliation before maturity;
- Treatment with insecticides.
