Comparison of bioassays and laboratory assays for apple stem grooving virus

The standard field double-budding assay with the indicator Virginia Crab an d the glasshouse test with the indicator Malus micromalus were compared wit h ELISA and immunocapture PCR for the detection of Apple stem grooving viru s (ASGV) in 102 apple trees and three oriental pear. Twenty-two trees were positive for ASGV by both ELISA and IC-PCR but three of these trees were ne gative by Virginia Crab, three were negative by M. micromalus and one was n egative by both these bioassays. The infected trees were re-tested by IC-PC R and ELISA in a second year; the IC-PCR results were confirmed but two of the 22 infected trees were negative by ELISA. On this evidence, IC-PCR is a more reliable assay for ASGV than the slow and expensive bioassays. (C) 20 01 Elsevier science B.V. All rights reserved.