Influence of Prunus Necrotic Ringspot Virus on Growth, Productivity, and Longevity of Peach Trees. P. L. Pusey, Research Plant Pathologist, USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008. U. L. Yadava, Professor of Horticulture, Agricultural Research Station, Fort Valley State College, Fort Valley, GA 31030. Plant Dis. 75:847-851. Accepted for publication 25 February 1991. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1991. DOI: 10.1094/PD-75-0847.

Peach trees in experimental plantings at Byron and Fort Valley, GA, were assayed for Prunus necrotic ringspot virus (PNRSV) each year for 3 yr. Three orchards consisted of two peach cultivars (Redhaven and either Loring or Redskin) on seven or eight peach seedling rootstocks, whereas a fourth orchard consisted of only Redhaven scion on Lovell and Siberian C rootstocks. PNRSV was detected by enzyme-linked immunosorbent assay using antiserum prepared against PNRSV-G. Initially, when the orchards were 5–9 yr old, incidence of positive tests ranged from 26 to 63%. The average annual increase in positive assays for these orchards ranged from 3.6 to 17.4%. Trees that tested positive for the virus tended to have a smaller trunk circumference than those that tested negative, but statistical differences in growth during 3 yr were detected in only one orchard. Bark splitting was associated with positive tests in three out of eight cases in which data were collected. Yield of infected trees was reduced by 8.2–47.3% (P ≤ 0.05) in three out of nine cases, and fruit maturity was affected depending on rootstock. Defoliation, flower bud density, flower and leaf emergence, fruit size, and peach tree gummosis caused by Botryosphaeria dothidea were generally not affected by the virus. Although PNRSV has been suspected as a possible factor in the development of peach tree short life, no relationship was found between PNRSV and factors associated with peach tree short life such as cambial browning or bacterial canker caused by Pseudomonas syringae pv. syringae. Furthermore, PNRSV did not contribute to tree mortality, which in all orchards was the highest (7.1–30.8%) for Redhaven trees. Interactions between virus and rootstock were frequently detected, indicating that the use of virus-free propagation material in rootstock evaluation programs is important.