Evaluation of the relative resistance of different olive cultivars to olive peacock spot disease caused by Venturia oleaginea

Olive peacock spot is one of the most serious olive fungal diseases in the world, which causes serious problems in olive plantations. The study of relative resistance of different olive cultivars in each region will be of special importance in the integrated management of this disease. In this study, 61 well-known promising olive cultivars planted in the olive research station center of Tarom region in Zanjan province were evaluated for their susceptibility to olive peacock spot disease. Incidence and severity of infection were the criteria for determining the susceptibility of each cultivar. The results showed a significant difference in the sensitivity to this disease among different tested olive cultivars. Based on the results of the mean comparison table, 18 cultivars including Koroneiki, Frantoio, Coratina, Manzanilla de sevilla, Lechin de sevilla, Piculin, Mastoidis, Lucques, Cipressino, Cailetier, Baladi, Valanolia, Oblonga, Corfolia, Chalkidikis, Megaron, Patrini and Amin were recognized as the most tolerant cultivars, according to Arunachalam ranking method. On the contrary, Mari, Toffahi, Mavi, Roghani, Nabali, Abou-satl, Clonavis, Verdial de Jaén, Souri, Grossane, Sorani, Jlot, Khodeiri, Caridolia and Shengeh cultivars were known as the most susceptible cultivars to the disease. Based on the results of cluster analysis, the studied cultivars were divided into five groups: most tolerant, tolerant, moderately tolerant, susceptible and most susceptible. A very high correlation was observed in the results of cluster analysis and Arunachalam ranking.