Effect of Potato virus Y on Yield of Three Potato Cultivars Grown Under Different Nitrogen Levels.

Previous studies have shown that Potato virus Y (PVY) reduces yield in many cultivars. Typical foliar symptoms can include veinal necrosis, leaf drop, and a mosaic pattern sometimes accompanied by leaf roughness. Infection by PVY in Russet Burbank produces identifiable PVY symptoms, whereas cv. Russet Norkotah expresses mild, almost latent symptoms. Yield also is influenced by nitrogen fertilizer levels. This research was conducted to determine whether increased nitrogen mitigates yield reduction caused by PVY. Russet Norkotah, CO80011-5, and Russet Burbank were used in replicated plots of non-PVY-infected and PVY-infected plants at three nitrogen levels in 1995 and 1996. There was a significant yield reduction between PVY-negative and PVY-positive plots in all cultivars, at most nitrogen levels. PVY yield reduction was similar (approximately 38%) in the mild symptom expression clones of Russet Norkotah and CO80011-5, whereas the yield reduction in Russet Burbank, which exhibits typical symptom expression, was 63.5%. We conclude that increased nitrogen can influence total yield, but does not significantly mitigate the yield reduction due to PVY infection.