Improving the efficacy of apple scab control using tank-mixes with microfertilizers over 2023–2024

Abstract

While apple is the leading crop in Russian horticulture in terms of planted area and fruit production volume, high-quality yields are hindered by plant diseases that drastically reduce the market quality of fruit. The disease resistance of apple trees is largely determined by crop management practices. The most effective strategies include the systematic use of crop protection agents and the optimization of nutrient management. This approach enables a reduction in pathogen activity and an enhancement of natural defense mechanisms in apple trees. The present study aimed to investigate the effect of fungicides in tank-mixes with foliar fertilizers on the efficacy of apple orchard protection against apple scab, as well as on fruit yield and quality. The field trials were set up in the commercial plantings of the Dubovoye Company (Tambov Oblast) over 2023–2024. The evaluated cultivars included Bogatyr and Lobo. During the study period, weather conditions generally favored apple scab development, particularly in 2024. This can be attributed to spring frosts in early May following an early onset of vegetation growth and rapid plant development, subsequent cool weather, and heavy rainfall in June. The study evaluated apple scab development on leaves and fruits, biological efficacy, Zn and Mn concentrations in the leaves, and crop yield. Combining fungicides and microfertilizers within a single tank-mix reduced disease development and enhanced the biological efficacy of treatments. With such treatment, disease severity in Bogatyr trees ranged from 0.08 % to 0.7 %, while on the Lobo plot, it varied from 0.17 % to 2.5 %. The biological efficacy reached up to 96.7% for Bogatyr and 95.4 % for Lobo. Using tank-mixes of crop protection agents and foliar fertilizers secured fruit yields of 73.5 and 58.8 kg per tree, respectively, with the maximum proportion of fi rst-grade marketable fruit reaching 96 % and 92 %. The foliar fertilizer application contributed to an improved macroand micronutrient balance in the plants, which, in turn, enhanced the overall efficiency of fungicide treatments.