Association of multiple virus infections with apple disease in western Colorado

• Published in: Phytopathology Vol. 100; no. 6; p. S101
• Main Authors: Pokharel, R, Mock, R, Li, R, Kinard, G, Larsen, H
• Format: Journal Article
• Language: English
• Published: 01.06.2010
• Subjects: Apple mosaic virus; Apple scar skin viroid; Apple stem grooving virus; Cherry rasp leaf virus; Malus; Pear blister canker viroid
• ISSN: 0031-949X

Gala and Golden Delicious apple trees with small leaves and small, deformed fruit were observed in an apple orchard in western Colorado. The symptoms on Gala were more severe than on Golden Delicious. To understand the possible association of viruses and viroids with the disease, three leaf and 20 fruit samples were collected from these trees, and asymptomatic Red Delicious trees, in October 2009 and tested for Apple chlorotic leafs pot virus (ACLSV), Apple mosaic virus (ApMV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV) and Cherry rasp leaf virus (CRLV) by RT-PCR, and Apple dimple fruit viroid, Apple fruit crinkle viroid, Apple scar skin viroid and Pear blister canker viroid by dot-blot hybridization. All five viruses were detected in fruit samples with different incidences, but no viruses were found in leaf samples. ACLSV was detected in all samples, and ASGV was detected in all Red Delicious and Golden Delicious trees but only in 3 of 8 Gala trees. CRLV was detected in all Golden Delicious samples, 7 of 8 Gala samples, and was not found in Red Delicious samples. ASPV was detected in 3 Golden Delicious and 1 Gala samples. ApMV was detected in only one Gala sample. Viroids were not detected in any samples. Asymptomatic Red Delicious trees were infected with only two viruses, while symptomatic Gala and Golden Delicious trees were infected with up to four viruses, suggesting a possible synergistic role of these viruses in symptom expression.