Correlation Between Leaf Epinasty Symptoms on Two Apple Cultivars and Results of cRNA Hybridization for Detection of Apple Scar Skin Viroid. L. J. Skrzeczkowski, Visiting Professor, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser 99350-9687. W. E. Howell, and G. I. Mink. Scientific Assistant, and Plant Pathologist, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser 99350-9687. Plant Dis. 77:919-921. Accepted for publication 6 June 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0919.

Within 2 mo following double bud inoculation with apple scar skin viroid (ASSV), apple (Malus domestica) trees of the cultivars Stark’s Earliest and Sugar Crab expressed pronounced leaf epinasty when maintained for 24-hr photoperiods in growth chambers at 18 or 28 C. Similar uninoculated trees and trees infected with the common apple latent viruses remained symptomless. Typical viroidlike symptoms were observed on fruit produced within 2 mo after inoculation of greenhouse-grown trees. Dot blot hybridization of leaf midrib and petiole extracts using a cRNA probe specific for ASSV indicated that ASSV accumulated in these tissues at 18 or 28 C but not at 38 C. The two apple cultivars not only were sensitive indicators for this viroid but also appeared to be useful amplification hosts for nucleic acid hybridizations.