Abstract

Grapevine fanleaf virus (GFLV), Grapevine leafroll associated virus 1, 2, and 3 (GLRaV-1,-2, and -3), Grapevine virus A (GVA) and Grapevine fleck virus (GFkV) were monitored monthly throughout a year in naturally infected field-grown vines by ELISA and RT-PCR. The organs tested were: opening buds in September, tips or unfolded leaves in September and October, leaf petioles from October to April, completely expanded leaves from November to April, green phloem tissues from October to February and cortical scrapings from December to August. Phloem of lignified canes, when available, is the best source for all viruses tested, allowing 100% detection by ELISA and RT-PCR. This is the first study carried out in South America to establish the best plant material and sampling times to optimize grapevine virus detection by ELISA and RT-PCR.