Plotnytska N. The peculiarities of potato late blight development (Phytophthora infestans (Mont) de Bary) and the substantion of protection measures the condition of Ukraine's Polissya

At the result of the research conducted it has been proved that late blight infects all potato plantations on Polissya territory. The largest spread of the disease during the period of investigation has been observed on the Volynsk oblast territory - 89%. The harmful effect of the Ph. infestans on potato is growth decrease, and decrease of potato tubers yielding capacity. The greatest loses of the sensitive to the pathogen Nezabudka breed - 27,3%, and for Lugovska resistant to the disease breed the index was 14,8%. Depending on the species resistance for the late blight the symptoms of the disease were different. At the example of sensitive to the disease Nezabudka breed the pathogen has lead to the quick dieing off the leaves. Typical features of the leaves infested by the late blight can be observed at the resistant to the disease species: Lugovska, Slovjanka. The author proves the possibility of oospores formation by Ph. infestans. The biggest quality of oospores has been noted at the beginning of the natural leaves dying off for Slovjanka breed - 12,3 oospores per 1 mm?. It has also been calculated the duration of Ph. infestans disease incubation period. Mathematic model and regress equation based on June hydrothermal indices have been worked out. The estimation of the potato species to the late blight resistance proved that the highest resistance according to the indices have such potato species: Viryneya, Dubravka, Lugovska. The application of fungicides and phytoncides plant extracts during vegetation period decreases the development of the Ph. infestans. The application of the fungicide Likar Roslyn (2,5 kg/ha) during the period of vegetation reduced plants effection by Ph. infestans to 2,2-2,5 and decreases tubers yielding capacity to 9,4-18,33 t/ha depending on the breed resistance to the disease. Spraying by 10% extract of garlic reduced plants effection to 1,5-1,7 during the period of vegetation and increases potato tubers yielding capacity to 6,11-11,28 t/ha.