Determination of Resistance of Some Potato Clones to Alternaria solani

: One of the most important problems in the cultivation of potato plants is their susceptibility to diseases. There are many disease agents that cause significant loss in yield and limit cultivation. One of these agents is Alternaria solani (Ell. and G. Martin) Sor., a facultative saprophytic fungus. The pathogen fungus causes early blight disease in potatoes. In this study, which was carried out in the field and laboratory of the Central Black Sea Transition Zone Agricultural Research Institute in 2019, the reactions of 594 clones created by crosses between some commercially registered potato varieties, local potato varieties, and some clones with superior characteristics against A. solani were identified using the detached leaf method. In order to determine the disease reactions, 5 mm diameter fungus discs taken from the actively growing tips of the cultures of A. solani isolate under sterile conditions were placed on the leaflets in five replications, and only the PDA medium was placed on the leaflets used for control purposes. As a result of the research, of the clones belonging to the A3/15 x Bafana combination, 70 were immune, 2 were tolerant, 9 were susceptible, 18 were highly susceptible. 168 of the clones belonging to the Başçiftlik Beyazı x Lady Olympia combination were immune, 1 was resistant, 4 were tolerant, 5 were susceptible, 23 were highly susceptible. 209 of the clones belonging to T5/4 x Bafana combination were immune, 2 were tolerant, 7 were sensitive and 46 were highly susceptible. Thus, in order to contribute to the development of resistant varieties, the conditions of the breeding material were revealed and evaluated as selection criteria.