Paul Gans - Plant Health Management

Severe virus symptoms in Estima - could this be PVY^N ? (30 July 2007)

Estima is well known for its tolerance to PVY.  Especially the PVY^N strain is difficult to spot.  So it was a surprise when the symptoms shown in the picture appeared in a crop grown from farm saved seed.  ELISA tests had indicated that PVY^N was present but the grower considered that this was unlikely to compromise the performance of the crop because the symptoms are usually very mild.  Samples were sent of for further virus tests and  another virus, PVV was found.  PVV is also a virus for which the symptoms are also difficult to recognise in Estima.  However the combined effect of the two viruses had produced this symptom, which one would normally not associate with PVY^N in Estima.  The last time I came across this phenomenon, was in the training field of the Scottish Agricultural Science Agency at Gogar Bank.  There also there were examples of double infection with more than one virus, each of which would normally cause a mild symptom but in combination they caused severe symptoms.