Potato virus M
PVM = Potato Virus M
Causative agent and transmission
The virus M belongs to the same group as virus S (Carlavirus). It is transmitted by aphids in a non-persistent mode. It has a limited range of hosts (Nightshades, Pulses/Legumes).
Description of symptoms on crops
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The most common symptom is the appearance of "spoon-shaped" leaves corresponding to a soft curling of the leaves (while the potato leaf roll virus produces "cracking" of the roll). It occurs on developed plants, preferentially on the topmost leaves.
The following symptoms can also be observed:
- slight discolouration of the veins on the top leaves;
- curling of the leaf edges;
- mosaic, etc.
The symptoms appear particularly in cool and cloudy weather.
The virus M has a limited effect on yield (10-20%) and control essentially consists in testing the starting and pre-basic material to obtain a healthy seed potato.