Oospore production of Phytophthora infestans potato leaves

Late blight caused by Phytophthora infestans is one of the most important and destructive diseases of potato. In this study carried out in the province of Bolu which is one of the important potato production areas, oospor formation potential of the pathogen was investigated under different conditions. For this purpose, 46 P. infestans isolates were obtained from the cultivation areas within the survey program. Both mating types were determined by molecular methods using the primer set S1-a / S1-b and W16-1 / W16-2, followed by cutting of the W16 amplification product with HaeIII enzyme. Analysis revealed that all isolates were A2 mating type. Metalaxyl susceptibility tests, one of the parameters used to determine the phenotypic characteristics of the isolates, revealed that 19 isolates were moderately resistant to fungicide and 27 isolates were resistant. The in-vitro and semi-in-vivo conditions of the isolates were tested for oospore-forming ability in metalaxyl-treated and untreated pea agar medium, and on discs from the leaves of 6-8-week-old plants. In addition, the pathogen's ability to form oospores in diseased leaves and inoculated tubers under field conditions was investigated. The results of the research showed that the pathogen could easily produce oospores in in-vitro and semi-in-vivo conditions, but not oospores in the field conditions. As a result, the study found that it is important to include fungicides and mixtures with active ingredients other than metalaxyl in the disease management strategies and showed that the pathogen does not have sexual reproduction ability under Bolu conditions.