Resistance of Local and Introduced Varieties of Potato to Alternaria in Western Georgia

Introduction and research objective. Potato is one of the important crops due to its versatile use and valuable nutritional properties. According to the United Nations Food Security Program, it is named the main subsistence food product after bread. Diseases are one of the limiting factors of potato yield. Alternaria causes important losses and stands out for its wide distribution among them. Alternarias species can be found everywhere where representatives of the Nightshade family are grown.  Diseases Early blight (causal agent: Alternaria solani Sorauer  (Ell. et Mart.) Sor. (syn. Macrosporium solani Ellis & Martin)  and  Brown Leaf Spot (causal agent: Alernaria alternata (Fries.) Keissler (syn.A.tenuis Nees.)  are distinguished by their spread and harmfulness in the conditions of Western Georgia. The research aimed to identify resistant varieties to these diseases from thirty-six introduced potato varieties, as well as three samples from international nurseries adapted to Georgian conditions. Methodology. To achieve the goal, in 2022-2023, potato samples were planted in Kobuleti, on the experimental field of the Institute of Phytopathology and Biodiversity of BSU, for further testing under a natural infection background,  according to the generally accepted methodology [2,3]. Results. The study showed that among the tested samples, a resistant reaction (R) to Early blight was found in the varieties: Milva (Netherlands), Slavyanka, and Glazurnaya (Ukraine). A moderately resistant reaction (MR) was shown by the Fabula variety (Netherlands); the remaining samples had a susceptible (S) and moderately susceptible (MS) reaction to the pathogen. The following varieties turned out to be resistant to Brown Leaf Spot: Milva (Netherland), Alvara (Germany), and Glazurnaya (Ukraine), and moderately resistant (MR) - Slavyanka (Ukraine), Nevskaya (Russia), Pekaro and Jelly (Netherland). Three varieties were found to be resistant to both diseases: mid-early Milwa (Dutch), Ukrainian varieties Glazurnaya (mid-early), and Slavyanka (mid-late). Some cultivars, moderately resistant to Alernaria alternata - Alvara (Germany), Pecaro, and Jellie (Netherland) were moderately susceptible to Alternaria solani Sorauer. A different reaction was also shown by the Nevsky , which was moderately resistant to Alernaria alternata, and moderately susceptible to Alternaria solani Sorauer. Conclusion. Resistant and medium-resistant potato varieties (Milwa, Glazurnaya, Slavyanka), identified from tested samples can be used as sources of resistance to Alternaria.