The purpose of the research is to assess the damageability of varieties and forms of domestic plum, Chinese and Russian plum aphids in the conditions of the Republic of Tatarstan and to identify the best of them in terms of resistance to this pest. The damageability of varieties and forms of plums by aphids was assessed according to the methodology of the All-Russian Research Institute of Breeding of Fruit Crops. In the conditions of the Republic of Tatarstan, the most resistant to plum aphids are the varieties of domestic plum Sverkhrannyaya (k.), Sineokaya, Renklod Tenkovsky (k.) and Kazanskaya. Variability of damageability to leaves and shoots of plum aphids in 2017-2020 the varieties and forms of domestic plum were significant (V=22.2-66.7%), in Chinese and Russian plum varieties – medium (V=10.5-12.8%). An insignificant positive correlation is observed between the degree of damage to the leaves and shoots of plum aphids and the damage to the leaves of plum varieties by clusterosporiosis (r = 0.57). An insignificant negative correlation was established between the degree of damage to varieties and forms of aphid plum and the amount of precipitation during the summer (r = -0.32) and vegetation periods (r = -0.42), the hydrothermal coefficient in the summer (r = -0.33) and vegetation (r=-0.54) periods. The damageability of leaves and shoots of plum aphids is more influenced by the genotypes of plum varieties and forms (74.1%) than the conditions of the year (11.2%) and the interaction of genotypes with the conditions of the year (12.2%).

УДК 634.11:632.7 ПОВРЕЖДАЕМОСТЬ СОРТОВ И ФОРМ ЯБЛОНИ ЗЕЛЕНОЙ ЯБЛОННОЙ ТЛЕЙ В РЕСПУБЛИКЕ ТАТАРСТАН Осипов Г.Е., Осипова З.А. Abstract. The paper includes an assessment of damageability of varieties and forms of apple by green apple aphids in the Republic of Tatarstan. An insignificant variability of damageability of leaves and annual shoots of green aphids was established by year in one half of the studied apple varieties and the average variability -in the second half of the varieties. An insignificant positive correlation is established between the degree of damage to the leaves and shoots of green apple aphids and damage to the leaves by the scab (r = 0.85), the hydrothermal coefficient of the vegetation (r = 0.78) and summer periods (r = 0.68), the amount of precipitation the summer period (r = 0.70), the average temperature in the summer period (r = 0.57) and the average temperature in April (r = 0.64). An insignificant negative correlation was found between the degree of damage to varieties and forms of apple trees by aphids and the amount of precipitation in April (r = -0.14). The manifestation of the sign "damaging the leaves and shoots of green apple aphids" is more influenced by the conditions of the year than the genotype of varieties, forms and the interaction of the genotype with the conditions of the year. The varieties Renet Povolzhya, Kamskaya and Komsin are distinguished according resistance to green apple aphid.

The purpose of the research is a comparative assessment of the use of the biological preparation «Baktofit» and the chemical preparation «Skor» in the protection of apple plants from scab in the conditions of the Republic of Tatarstan. The scab susceptibility of apple cultivars was assessed according to the methodology of the All-Russian Scientific Research Institute of Fruit Crop Breeding. The weather conditions of the spring–summer period of 2021 in the Tenkovsky Department of Horticulture of the Tatar Research Institute of Agriculture had a negative impact on the development and spread of scab on the leaves and fruits of the Kamskaya, Tenkovskaya and Renet Tatarsky apple tree varieties. Average for 2020-2021 The chemical drug «Sko» turned out to be much more effective than the biological drug «Baktofi» in protecting apple leaves from scab. Three-way analysis of variance showed that the share of the influence of drugs (factor A) on the damage of leaves by scab is 48.0%, genotypes of varieties (factor B) - 13.4%, conditions of the year (factor C) - 13.0%, interactions of factors A and C - 0.6%, interactions of factors B and C - 18.1%. Average for 2020-2021 the chemical drug «Skor» turned out to be significantly more effective than the biological drug «Baktofit» in protecting apple fruits from scab. Three-factor analysis of variance showed that the share of the influence of drugs (factor A) on fruit damage by scab is 49.5%, genotypes of varieties (factor B) - 24.2%, conditions of the year (factor C) - 8.4%, interactions of factors A and C - 1.9%, interactions of factors B and C - 11.7%.

The aim of the research was to establish the features of the inheritance of the size of the fruit in the hybrid families of Prunus domestica. The objects of study were hybrid seedlings of plum selection of the Tatar research Institute of agriculture. Fruit sizes were estimated according to the methodology of the all-Russian research Institute of fruit crops selection. The analysis of the splitting of plum in hybrid families by the size of fruits showed that seedlings with small fruits dominated in the breeding gardens of the Tatar research Institute. The size of the plum fruit is controlled by polygens. All of the original parental forms are heterozygotes for the genes determining the size of the fruit. A small fruit is a dominant trait, a large fruit is a recessive trait. In most hybrid families, plum seedlings have a significant variability in the size of the fruit. Transgressive genotypes with large fruits are formed in hybrid families Eurasia 21 x Renklod Tenkovsky, Eurasia 21 x free pollination and Zyuzinskaya x free pollination. The varieties Eurasia 21 and Zyuzinskaya must be used as sources in breeding of plums for large-fruited.