Sj Lambert

Spatiotemporal spread of Potato virus S and Potato virus X in seed potato in Tasmania, Australia

The spatial and temporal distribution of Potato virus S (PVS) and Potato virus X (PVX) was studied in two trials within each of four commercial fields of seed potato var. Russet Burbank in Tasmania, Australia. In the first trial (plots) 20 leaflets were collected from each of 49 plots (each approximately 8 m wide by 10m long), with plots arranged in a 7-×-7 lattice. In the second trial (transects), leaflets were collected at 1-m intervals along seven adjacent, 50-m long rows. The mean incidence of PVS increased during the season by 5.2% in one of four plot trials and 25.5% in one of four transect trials. The mean incidence of PVX increased during the season by 10.1%, in one of two transect trials. Spatial Analysis by Distance Indices and ordinary runs analysis detected aggregation of PVS infected plants early in the season in one and two fields respectively, suggesting transmission during seed-cutting or during planting. An increase in PVS incidence mid- to late season in one field was associated with aggregation of PVS along, but not across rows, which may be related to the closer plant spacing within rows and hence increased potential for mechanical transmission along rows. Results suggested limited spread of PVS and PVX occurred within crops during the season.