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Most apple cultivars tend to bear biennially, i.e. produce many fruits in one and few fruits in the next year, or do not have a nature of self-thinning. The effectiveness of chemical thinning depends on conditions, particularly temperature, at the time of application. In some other fruit-growing regions, the mechanical thinning of flowers is adapted to some cultivars by changing the speed of moving and rotation of the mechanisms to conduct partial thinning — removing of flowers. The investigation aimed to evaluate the effectiveness of total flower removal mechanically on one side of the tree row, and on the other side the next year, during the full production period (8th to 12th year after planting) to obtain regular yields. Seven cultivars on dwarfing rootstocks M.9 and B.396 were compared. Apple trees on the dwarfing rootstock B.396 were less affected by biennial yielding. Cultivars had a strong relation to yield — ‘Gita’ (Vf), ‘Konfetnoye’ and ‘Kovalenkovskoye’ had less fluctuation yearly, while ‘White Transparent’, ‘Rubin’ (Kazah.), ‘Antei’, and ‘Ligol’ performed opposite. There was a positive influence observed on reduction of periodicity by mechanical flower thinning, however, there is a discussion on cumulative yield reduction.

The negative influence of pathogens on plant development is well known. However, the negative impact depends on various factors: cultivar and rootstock resistance, nutrition, the environment, the virulence, and concentration of pathogens in the plant tissue. The evaluation of apple chlorotic leaf spot virus (ACLSV) influence on apple tree growth and production was performed at Institute of Horticulture (LatHort) from 2012 to 2020. Virus-free and ACLSV-infected trees from the traditional cultivar ‘Antonovka’ and new scab resistant cultivar ‘Gita’ were evaluated on dwarfing rootstock B.396. The presence of four common apple viruses (apple mosaic virus (ApMV), ACLSV, apple stem grooving virus (ASGV), apple stem pitting virus (ASPV)) was assayed in the planting year and repeated at the end of the study period. The vigour of planting material, growth, yield, and yield efficiency were compared between virus negative and ACLSV-infected trees. During eight growing seasons (2013–2020), no statistically significant negative impact of ACLSV infection on tree growth or yield was observed for the cultivars. A larger canopy volume was observed for ACLSV-infected trees (p = 0.01), but the cumulative yield per canopy volume was equivalent between virus-negative trees and ACLSV-infected trees (p = 0.07).