Virus disease surveys of ware potato crops, Franklin County, North Island, New Zealand

Abstract

Surveys for virus disease in potato (Solanum tuberosum L.) ware crops were completed over three successive seasons. Overall mean incidence of viruses in plants derived from pathogen-tested (PT®) seed lines and non-PT seed lines was 2.2 and7.6% (1991),4.1 and 11.2% (1992), and 2.5 and 6.5% (1993) respectively. The levels of potato leaf-roll virus and severe mosaics were particularly low in crops grown from PT® seed. Virus incidence was generally low apart from individual crops with high potato virus X, potato virus S (PVS), or potato virus Y (PVY) levels (these crops were often from saved seed tubers). The incidence of PVYN appears to have been contained through the use of PT® seed, but the identification of PVSA and the rediscovery of potato virus A and potato virus M are of some concern. Suggestions for improvements to seed quality control are discussed. © 1996 Taylor & Francis Group, LLC.