Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2007
Publication Date: 2/5/2008
Citation: Bajet, N., Unruh, T.R., Druffel, K., Eastwell, K.C. 2008. Occurrence of Two Little Cherry Viruses in Sweet Cherry in Washington State. Plant Disease Vol 92(2)234-238. Interpretive Summary: Little cherry disease is one of the most damaging virus diseases of sweet cherries worldwide but it is difficult to diagnose it as a causal agent when other factors can cause little cherry symptoms. We developed a DNA sequence based method to diagnose little cherry virus when present in trees expressing symptoms. This method allows detection of the disease agent in the field and we used it to provide the first evidence of the presence of the little cherry virus types 1 and 2 in several Washington State cherry orchards. This highly sensitive detection method will help the sweet cherry industry manage the disease in the field and is being by us to screen potential new root stocks and cherry varieties to prevent further introductions of diseased cherries.
Technical Abstract: Little cherry disease is one of the most damaging virus diseases of sweet cherries worldwide but remains poorly understood in both its distribution in the USA and the number of varieties of the disease that may occur. Diagnostic methods based on PCR for the LChV-1 strain were designed from the replicase gene. When used with a previously described primer pair specific for the replicase gene of LChV-2 we were able to use a one-tube RT-PCR multiplex assay for determining the causal agent of little cherry disease in sweet cherry trees exhibiting symptoms. LChV-1 and LChV-2 were detected either alone or in combination in several orchards in sweet cherry producing regions Washington State. Sequence analysis of 240 bp of the replicase gene revealed 20% sequence difference between two LChV-1 isolates from Eurasia compared to eight North American isolates and 9 % or less differences among the eight NA isolates. This variation did not appear to influence our ability to detect LCV-1 in the 10 isolates tested. This paper represents the first report LChV-1 and LChV-2 in Washington.