Potato tuber necrosis ringspot disease (PVYNTN)
Potato tuber necrosis ringspot disease has recently been observed in Europe. It is characterized by superficial brown lesions on potato tubers, appearing in bows and rings at harvest or some weeks later during storage. Lesions are first protruding and later becoming sunken and dark brown with occasional skin cracks. In the field, yellow mosaic and leaf crinkling of variable intensity can be observed. The disease obviously affects the quality of the tubers and causes yield reduction. The potato tuber necrosis ringspot disease is caused by a new strain (PVYNTN) belonging to the tobacco veinal necrosis sub-group (PVYN) of potato Y potyvirus. PVYNTN is aphid-transmitted in a non-persistent manner and can multiply on a wide range of host plants, most of them belonging to Solanaceae (e.g. tomato, pepper, tobacco, aubergine, and weeds like Solanum nigrum, Datura stramonium etc.). Among potato cultivars, variation in susceptibility has been observed (e.g. cvs. Lola, Nicola are highly susceptible – cvs. Bintje, BF-15 or Stella are less susceptible), and studies are carried out on breeding resistant cultivars. No simple and rapid identification method for PVYNTN is available. Serological methods can be used, but they only identify the PVYN subgroup and not specifically PVYNTN. However, specific molecular methods (eg. RT-PCR) are now available.
Although the tobacco veinal necrosis strain group (PVYN) first became epidemic in several European countries in the 1950s, it was only in the 1980s that PVYNTN appeared in Central Europe. It was first reported in 1984 from Hungary and then spread to north-west and south-west European countries and Mediterranean countries. So far, there have not been reports of natural occurrence of potato tuber necrosis ringspot disease in North America, however some PVYN isolates from ware potatoes in California (US), did cause typical symptoms of the disease on potatoes grown under glasshouse conditions. So far, the disease is present in the following countries:
EPPO region: Austria (1990), Belgium, former Czechoslovakia (1988), Denmark (1992), France (1993), Germany (1985), Hungary (1984), Israel (1996), Lebanon (1990), Portugal (1994), Romania (1993), Slovenia, Spain, Tunisia (1993), United Kingdom (1992), former Yugoslavia (1989).
Control of potato tuber necrosis ringspot disease is based on the use of certified seed potatoes, of more tolerant potato cultivars, and on methods to limit virus propagation through aphid vectors or plants (e.g. volunteer plants, weeds etc.).
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Kerlan, C.; Ramage, K.; Hulle, M.; Tribodet, M. (1997) Study of varietal susceptibility to potato tuber necrosis ringspot disease under field conditions in France.
Proceedings of the 10th Congress of the Mediterranean Phytopathological Union, 1997-06-01/05, Montpellier (FR), 583-587.
Le Romancer, M.; Kerlan, C.; Nedellec, M. (1994) Biological characterization of various geographical isolates of potato virus Y inducing superficial necrosis on potato tubers.
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Weidemann, H.L.; Maiss, E.; Rüffert, C.; (1995) Identification of the tuber necrotic ringspot strain of potato virus Y (PVYNTN).
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