Planter Skips and Impaired Stand Favors Potato Virus Y Spread in Potato

High incidence of virus infection in potato crops can cause stand loss, reduced yields, and undersized tubers, leading to reduced quality and downgrading or rejection of potato seed lots. Initial colonization of potato fields by aphid vectors of potato viruses is predominately concentrated on field margins. In fields with poor stands, there are gaps in the crop canopy that can be attractive to alighting aphids. Thus, occurrence of stand gaps could render ineffective any pest management tactic that exploits the colonization behavior of aphids, such as barrier crops or reflective mulches. Field studies were undertaken to determine if the occurrence of localized stand gaps in potato fields would increase potato virus Y (PVY) infections and, if so, whether there was a relationship between gap size and PVY spread. PVY infection was 13% around stand gaps of a parts per thousand currency sign0.6 m(2), while PVY infection was 29% around gaps a parts per thousand yen0.6 m(2). Our results indicate that a stand gap equivalent to a loss of three or more consecutive plants within a row favored PVY spread. Trials were conducted to compare effects of roguing (physical removal of plants), seeding with oats to reduce potato canopy/soil contrast, and insecticide applications to gaps on PVY spread. Roguing, seeding gaps with oats and insecticides did not prevent PVY spread. This research indicates that suboptimal plant stands increase PVY incidence and may be contributing to the current PVY epidemic.