Spreading of diseases caused by phytoplasma on local and foreign grape varieties grown in Bulgaria from 2005 to 2018

Zhelyu Avramov, Marco Mihaylov

Abstract: Viticulture and winemaking existed from time immemorial. This is determined by the favourable soil and climate conditions in this country. In an effort to promote the development of an ever-growing winegrowing sector and to avoid new quarantines and the spread of economically-relevant diseases caused by phytoplasma, the Bulgarian Food Safety Agency (BFSA) has developed a monitoring programme. The purpose of the study is to look into the spread of grape vine diseases caused by phytoplasma and then, on the one hand, to establish the specific non-autochthonous and autochthonous grape varieties prone to grapevine yellows and, on the other hand, to compare data on infections affecting wine, rootstock and dessert grapes used in Bulgaria. Between 2005 and 2018, the study involved over 89 grape varieties of all grape growing regions and over 7 lines of rootstock material in Bulgaria. The tests were carried out in the Central Laboratory of Plant Quarantine (CLPQ) and 5519 plant samples of indigenous and foreign varieties in total were analysed for the entire period. Despite the tremendous efforts of the BFSA, the PCR tests only found Bois noir infections to different varieties. In total, there were 258 infected samples out of 37 varieties. Chardonnay, Merlot, Cabernet Sauvignon, Pinot Noir and Alicante Bouchet were found to be the most susceptible ones. The study found 25 infected samples out of 15 Bulgarian local varieties which is a considerably low percentage of infection. The findings are a good basis and will contribute to finding solutions in the selection of grape varieties and improving the health of new vineyards in Bulgaria.

Keywords: Bois noir; Bulgaria; Ca. Phytoplasma solani; grapevine; susceptible cultivars

Date published: 2019-12-19