Response of aphid vectors of potato leaf roll virus to different potato varieties in southern Idaho

Potato leaf roll virus (PLRV) seriously constrains potato production in the Pacific Northwest (PNW) USA and worldwide.  PLRV is transmitted in a persistent, circulative manner by several aphid species, but green peach aphid (Myzus persicae Sulzer) and potato aphid (Macrosiphum euphorbiae Thomas) are the two most important colonizing aphid species in potato in the PNW. A better understanding of the differences amongst potato cultivars in colonization by these aphid species and potential for PLRV transmission will improve integrated management of PLRV. We sampled aphids on field plots in Kimberly, ID on three cultivars that represent the majority of the acreage in the PNW: Russet Burbank, Ranger Russet, and Russet Norkotah. The objective of this study was to compare aphid densities and the proportion of aphids carrying PLRV among these varieties. The center row of 3-row, 7.6 m long plots (replicated 8 times in a randomized complete block design) was sampled weekly between plant emergence and vine kill. Aphids were collected from the underside of six lower leaves from each of five plants in each plot. In 2011, the predominant aphid species in Kimberly was green peach aphid, which was more abundant on Ranger Russet than on the other two cultivars. The proportion of aphids testing positive for PLRV with RT-PCR suggested inoculum levels were sufficient to cause injury. The experiment will be repeated during 2012 and the cumulative results, including PLRV infection rates in aphids and plants, will be presented.