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Potato Virus Y (PYV)

Leaf drop streak, rugose mosaic






Dark spots or streaks appear on infected leaves before they fall off (leaf drop streak) leaving a bare stem with a tuft of mottled leaves at the top. Plants grown from infected seed are stunted, pale and mottled, with small, crinked and twisted (rugose) leaves. Tubers are small and may be misshapen or cracked.


The virus is transmitted by aphids, principally Myzus persicae, during July and August. The virus is non-persistent and can be attached to the aphid stylet and transferred immediately to the next plant that the aphid feeds on. This spread is mainly local as aphids lose the ability to transmit the virus after 12 hours. Infected tubers are the main source of virus inoculum.

Favourable Factors

Seasons when winged aphids are numerous.


Up to as much as 50% yield loss.


Identification and Management of potato diseases

Find out more information on the key disease threats to your potato crop. For each disease you will find out the importance of the disease in terms of potential yield penalty, how to identify the disease in its early stages and our advice on the best control strategies.

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