Increasing In-Row Spacing Enhances Potato Virus Y and Potato Leafroll Virus Spread in Potato

For potato, variety, tuber size, and chip or fresh markets all play a role in deciding which in-row spacing is used. Aphids are attracted to wide row spacings and as plant densities decrease, aphid densities increase. Wide in-row spacing could render ineffective any pest management tactic that exploited aphid colonization behavior through habitat manipulation if it prevented adequate row closure and enhanced aphid landing rates. To understand this, we studied the effect 20.3, 30.5, 45.7, 68.5, and 101.6 cm in-row spacing treatments had on PVY and PLRV spread. PVY infection reached 14.8 % at 101.6 cm in-row spacings and was the lowest (5.9 %) at 20.3 cm spacings. PLRV infection was highest at 101.6 cm spacings (69.1 %) and lowest at 20.3 cm spacings (44.2 %). Optimal potato production occurs on in-row spacing of 25 to 30 cm. Based on our results, current potato cultural practices in relationship to row spacing are not enhancing virus spread.