Incidence and Distribution of Grapevine Leafroll‐associated viruses in Tunisian Vineyards

Abstract

Abstract Surveys were carried out in Tunisian table grape vineyards for assessing the occurrence and distribution of grapevine leafroll‐associated viruses (GLRaVs). Leafroll symptoms were commonly observed in most of the surveyed vineyards. Samples were randomly collected from 712 individual vines for laboratory testing. Enzyme‐linked immunosorbent assay (ELISA) tests showed that 81.5% of the vines were infected by one (35.7%) or more (45.8%) viruses. GLRaV‐3 was the most widespread virus (76.3%), followed by GLRaV‐5 (38.5 %), GLRaV‐6 (13.2%), GLRaV‐1 (9.1%), GLRaV‐2 (6.3%), and GLRaV‐7 (0.9%). GLRaV‐3 and GLRaV–5, two mealybug‐transmissible Ampeloviruses, were present in mixture in 35.9% of samples. The highest infection rate was found in Cape Bon region (81.7 %), where cv. Italia had an infection rate of 79.5%. Superior seedless, the main cultivar in Sidi Bouzid, had 75% infection. GLRaV‐6 and ‐7 were detected for the first time in Tunisia.