The most significant in the technology of growing potatoes are the timing of removal of the tops, as this factor directly affects the physiological state of the tubers and their quality. Therefore, the aim of the study was to determine the effect of the timing of removal of tops on yield, quantitative yield and quality of elite seed of early maturing potato varieties Snegir, Delphin, Udacha and Zhukovskij rannij. Experience, observations and accounting were carried out according to generally accepted methods. The study was conducted in a field experiment of the Smolensk Institute of agriculture (ex. Smolensk GOSHOS). As a result of phenological observations, it was found that the mass flowering did not occur simultaneously in all studied potato varieties. Before all the phase of mass flowering occurred in the Zhukovskij rannij variety. The percentage of plant viral diseases in all studied varieties in the variant with the term of removal of the tops 21 days after mass flowering was higher, compared with the options for removing the tops in earlier flowering periods. The maximum yield of seed fraction of potato tubers in varieties Delphin and Snegir (12.6 and 26.1 t/ha, respectively) was noted in the version with the second term of removal of the tops, in varieties Zhukovskij rannij and Udacha (23.2 and 23.4 t/ha, respectively) – in the version with the term of removal of the tops 21 days after mass flowering. The yield of tubers seed fraction and their mass were the highest varieties of Dеlphin and Zhukovskij rannij. According to the results of the tuberous analysis, an increase in the total number of tubers affected by fungal diseases was observed in variants with later dates of removal of the tops. The most affected disease of all the studied varieties was the grade of bullfinch (1.5-4%), the most resistant to disease – cv. Udacha.

Relevance. The aim was to study the reaction of new potato varieties early ripening group Zabava and middle-ripening group Smolyanochka on the timing of planting and doses of mineral fertilizers for obtaining maximum yield of seed potatoes. As mineral fertilizers used azophoska, superphosphate and potassium chloride.Results. It was found that the variety Zabava compared to the variety Smolyanochka, had a higher stem-forming ability and exceeded the parameters of the stem in all variants of the experiment. This is due to the biological characteristics of the studied varieties, since the Zabava variety, unlike the Smolyanochka variety, had more multiple eyes on the surface of the tuber. Against the background of applying mineral fertilizers N60P72K90, the density of the stem was higher, compared with the background of applying N32P32K32 in both the Zabava variety and the Smolyanochka variety. It should also be noted that there was a tendency to reduce the stem at a later date of planting in all variants of the experiment. The percentage of viral diseases affected increased with later planting dates and was highest with the planting dates of 14 and 20 may. The highest yield of tubers of the seed fraction was obtained in the variant with a planting date of may 14 against the background of balanced doses of mineral fertilizers (N60P72K90) and amounted to 13.3 t/ha in the Zabava variety, 13.0 t/ha in the Smolyanochka variety. It should be noted that different backgrounds of mineral fertilizers did not have a significant impact on the percentage of potato tubers affected by diseases. At the same time, the incidence of tubers with diseases did not exceed the regulatory requirements of GOST R 53136 – 2008 "Seed potatoes. Technical conditions».