Occurrence of Three Viruses (GFkV, GLRaV-1, and GLRaV-3) in Major Grapevine-Growing Regions of Korea

This study assessed the incidence and distribution of major viral infections in grapevines across South Korea. A total of 534 grapevine samples representing five cultivars were collected and tested for three economically important viruses: grapevine fleck virus (GFkV), grapevine leafroll-associated virus (GLRaV)-1, and GLRaV-3. The overall infection rate among all samples was 92.7%, indicating a high prevalence of viral infections in domestic vineyards. Individual virus detection rates were 88.8% for GFkV, 33.5% for GLRaV-1, and 31.6% for GLRaV-3. Regional infection rates varied, with 100% incidence observed in Daejeon and Gangwon-do, followed by Chungcheongbuk-do (99.4%), Chungcheongnam-do (95.2%), Jeollabuk-do (94.2%), Gyeongsangbukdo (88.4%), Gyeongsangnam-do (87.5%), and Gyeonggi-do (77.0%). Among grapevine cultivars, infection frequencies were highest in Chungrang (100%), followed by Shine Muscat (95.5%), Muscat Bailey-A (90.5%), Campbell Early (90.1%), and Kyoho (84.6%). Single infections accounted for 44.8% of cases, double infections for 34.5%, and triple infections for 13.5%. The most prevalent double infections were GFkV + GLRaV-1 (19.5%) and GFkV + GLRaV-3 (14.8%), while co-infection with GLRaV-1 + GLRaV-3 occurred rarely (0.2%). The incidence of triple infections was highest in Shine Muscat (17.2%), followed by Campbell Early (11.7%), Kyoho (7.7%), and both Chungrang and Muscat Bailey-A (4.8%). Our findings highlight the widespread occurrence of grapevine viruses across regions and cultivars in Korea, underscoring the urgent need for effective management strategies to control virus diseases in grapevine.