Potato VIrus Y management

Background

Seed potato growers around the world must meet seed certification requirements that limit the amount of PVY in seed stock. In Idaho, if a seed lot exceeds 1% PVY, it is no longer eligible for re-certification, meaning it cannot be used for another generation of seed increase. Failure to meet this re-certification threshold results in an immediate loss in value of 35% or more (this is a conservative estimate based on seed prices).

This particular potato virus is especially difficult to manage. The reason:  PVY is vectored by many different species of aphid, in a relatively fast manner. Though colonizing aphids such as the green peach aphid is particularly efficient at vectoring PVY, dozens of non-colonizing winged aphids that pass through the potato crop and probe repeatedly as they seek a suitable host are actually more important in moving PVY. 

Since aphids can pick up and transmit PVY relatively fast, insecticides alone to manage aphid populations are not reliably effective. In fact, research from the University of Idaho and elsewhere has also shown such an approach can make the problem worse in some years. 

Unfortunately, no single method to manage PVY is sufficiently effective, and even combined methods can lead to variable outcomes. Nevertheless, seed growers are urged to adopt more than one of the following strategies:

• Choose isolated areas for seed increases

• Plant extremely low or zero levels of PVY, especially if an additional year of increasing for seed is desired or, for commercial growers, if the seed is planted to a commercial crop that is near other seed increases

• Destroy sources of PVY such as cull (waste) potato piles, volunteer potatoes, and solanaceous weeds (e.g., hairy nightshade) in a timely manner

• Rogue out any visibly infected plants as early as possible (prior to row closure and earlier)

• Minimize bare areas with border crops, mulches, and intercropping

• Implement a program of weekly applications of mineral oil, tank-mixed with a carefully selected aphid behavior-modifying pesticide every other week, starting at early emergence until vine kill