Potato Virus Y (PYV)
Leaf drop streak, rugose mosaic
Pathogen
Virus
Hosts
Potatoes
Symptoms
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.
Development
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.
Importance
Up to as much as 50% yield loss.
Control
Less susceptible varieties can be selected as documented on National List
Plant certified seed
Treat with a programme of soil-applied and foliar insecticides to control the aphid vectors
