Productivity and viral diseases of seed potatoes depending on the period of potato desiccation

The aim of the research was to determine the crop productivity, yield of tubers of seed fraction and infection of basic potato seeds with viral infection depending on the period of potato desiccation, application of mineral oil Sunspray, the number and species of winged aphids in the Polissia region of Ukraine. The study was conducted in the prebasic seed production nursery garden of the Institute for Potato Research, NAAS under the conditions of spatial isolation from the main sources and vectors of viral infections of potatoes, located in Nemishaieve, Borodiаnka distr., Kyiv region in the southern part of the Polissia region of Ukraine. The subject of the research is pre-basic and basic seed material of potatoes of mid ripening varieties Myroslava, Predslava, Alians. On average for 2018-2020 years of studies, the highest seed yield was obtained by potato desiccation 10 days after flowering of potatoes - 82.4-85.3 %. However, the level of total and seed yields was low. The efficiency of seed potato production increased with the haulm removal after 20 days - with the total yield depending on the variety 20.6-30.0 t/ha, the yield of seed tubers was in the range of 20.6-22.9 t/ha with the seed content in the crop structure - 71.0-76.3 %. Late haulm removal – on 30th and 40th days after potatoes flowering caused an increase in the yield of tubers of non-standard fraction, with desiccation on 30th day, the seed content in the crop decreased by 61.1-66.0 %, and with desiccation on 40th – by 54-59.8 %. Thus, during the early haulm removal, part of the crop was lost, which during haulm removal in the late stages consisted of large tubers. It has been found out, that potato plants, where the haulm removal during 2018, 2019 was carried out within 10 days after flowering, which was 4.0 % (9.0 % for the check) for the Myroslav potato variety, 3.0 % (10.0 % for the check) for the Predslava potato variety and 4.0 % (9.0 % for the check) for the Alians potato variety were the least infected with PVM. The level of PVM infection when removing the haulm on the 10th day after flowering with the application of Sunspray mineral oil at a rate of 6.0 l/ha decreased on average for the three varieties by 1.5–2.5 %. The best option to preserve the quality characteristics of seed potatoes was to desiccate the potato haulm on 20th day after flowering of potato varieties Myroslava, Predslava and Alians and the application of mineral oil Sunspray - 6.0 l / ha. The yield was 28.8-30.0 t/ha, seed fraction 20.6-22.9, seed yield - 71.0-76.3 %, viral PVM infection was 2.0 3.0