Grapevine phytoplasma disease in Georgia

Results of grapevine yellows disease (GY) studies in 2005-2015 are reported. Based on symptoms and Dienes' staining method the disease was detected in Kartli, Kakheti and Guria regions on Vitis vinifera (L.) Rkatsiteli, Saperavi, Shavkapito, Tavkveri, Aladasturi, Kachichi, Ganjuri, Chardonnay, Vitis labrusca (L.) cultivar Isabella, species hybrid cultivar Noah. The phytoplasmas were also visualized by using electron microscopy. The disease seriously modifies the structure of leaf the grapevine phloem, the chlorophyll content and the functioning of sink-source system. According to anatomical characters the studied cultivars showed a decreasing resistance from Noah, to Aladasturi, Rkatsiteli, Kachichi and Saperavi. In the areas of disease epidemic 12 leafhopper species were identified: Agalmatium grylloides (Fabricius, 1794), Cicadella viridis (Linnaeus, 1758), Dictyophara europaea (Linnaeus, 1767), Empoasca vitis (Gothe, 1875), Erythroneura imeretina Dekanoidze, 1962, Hyalesthes mlokosieviczi Signoret, 1879, Hyalesthes obsoletus Signoret, 1865, Lepironia coleoptrata (Linnaeus, 1758), Pentastiridius leporinus (Linnaeus, 1761), Philaenus spumarius (Linnaeus, 1758), Metcalfa pruinosa (Say, 1830), Ricania japonica (Melichar, 1898), which may be possible vectors of grapevine phytoplasmas in Georgia.