Winter wheat (Triticum aestivum) is a crop of which production is associated with rather large investments for nitrogen fertilization and disease control. The aim of this study was to estimate the effect of five variants of fungicide application and four levels of N (nitrogen) top-dressing rate on the yield and grain quality of winter wheat. Field trials were carried out in Latvia (56° 31′ N; 23° 42′ E) for four seasons. Grain yield and quality depended significantly on the conditions of the trial year, as three of them were characterized by drought in varying degrees. Although the average four-year grain yield increased significantly in all fungicide application variants, the effect of this factor was different in individual years. The application of fungicides increased the yield significantly in one year, decreased significantly in another year, while it had no significant effect on the yield in remaining two seasons. The enhancement of N top-dressing rate increased the grain yield significantly every year. The interaction between both examined factors was significant; however, the use of higher N rates not always means that also spraying with fungicides has to be more intensive. A clear effect of fungicide application was observed on 1000 grain weight and volume weight, while the effect of N top-dressing rate was observed on the crude protein, wet gluten and starch content, and Zeleny index.

The manuscript explores the valorization of forest logging residues, collected during forest management operations between summer 2023 and spring 2025 in mixed deciduous and coniferous forests, as a raw material for producing valuable bioactive products. These products offer a sustainable alternative to synthetic pesticides and fertilizers. Seven batches of biomass, comprising understory trees and branches from deciduous (mainly aspen, birch, and grey alder) and coniferous (mainly Scots pine) species, were collected during different seasons, crushed, and extracted using an ethanol–water solution. The yield of hydrophilic extracts containing proanthocyanidins (PACs) ranged from 18 to 25% per dry biomass. The highest PACs concentration (42% of extract dry mass) was found in small branches with a high bark content. The extracts and PACs at concentrations of 6.25–12.50 mg mL⁻¹ showed fungicidal activity against several pathogenic fungi, including Botrytis cinerea Pers., Mycosphaerella sp. Johanson, Heterobasidion annosum (Fr.) Bref., and Heterobasidion parviporum Niemelä & Korhonen. Residual biomass after extraction, enriched with sea buckthorn berry pomace and a siliceous complex, was characterized and evaluated for its impact on the growth of Scots pine seedlings and selected agricultural crops. Results from forest and agricultural field trials in 2023–2025 confirmed a positive effect of the fertilizer on crop yield and quality at a low application rate (40 kg ha⁻¹ per crop). Fertilizer increased the yield of radish, dill, potatoes, and wheat by up to 44% (highest for potatoes and dill) compared to the reference, confirming its agronomic value.

The common control method of leaf blotches is the application of fungicides; however, the results of trials are inconsistent. The aim of the present study was to evaluate the impact of the fungicide treatment intensity on the severity of leaf blotches and to assess the correlation between the development of diseases and winter wheat (Triticum aestivum) yield in 2018–2021. The development of diseases was evaluated regularly. In this study, the severity of leaf blotches at the medium milk ripening (GS 75–77) was used. Tan spot dominated in 2018, 2019, and 2021, but Septoria tritici blotch dominated in 2020. Fungicides significantly decreased the severity of tan spot and Septoria tritici blotch, but the efficacy of used fungicide treatment schemes differed during trial years – it was more pronounced under higher pressures of leaf blotches. In the year with a high severity of Septoria tritici blotch, the best efficacy was obtained when fungicide was used two times (at GS 32–33 and GS 55–59), but for tan spot – when the dose of fungicide was done in two or three applications. Usage of fungicides increased wheat yield only under high pressure of diseases. A strong significant correlation between the severity of Septoria tritici blotch at GS 75–77 and grain yields was established only in 2020, when the severity of the disease was higher.

Tan spot (caused by Pyrenophora tritici-repentis) and Septoria tritici blotch (caused by Zymoseptoria tritici) are the most widespread winter wheat leaf blotches in Latvia. Precipitation and air temperature are important factors in the development of fungal diseases. The aim of the present research was to clarify the development of leaf blotches in winter wheat depending on meteorological conditions. A field trial was conducted at the Research and Study farm “Peterlauki” (Latvia) of the Latvia University of Life Sciences and Technologies in 2018–2021. The disease impact during the vegetation periods was estimated by calculating the area under the disease progress curve (AUDPC). The severity of leaf blotches in winter wheat leaves differed significantly during the four vegetation seasons. Tan spot was the dominant disease in 2018, 2019 and 2021 (respectively 2.12%, 18.7% and 4.1% in the untreated variant at the time of grain ripening (GS 75–79)), when weather conditions were dry and warm. The first symptoms of tan spot were observed already at GS 31–32, but rapid development of the disease began at the time of grain ripening (GS 73–79 depending on year). In such conditions, Septoria tritici blotch started later and its progression was slower than that of tan spot. Septoria tritici blotch dominated in 2020 (11.4% in the untreated variant at GS 75–79), when precipitation amount was high. The first symptoms were observed at GS 31–32, but rapid disease development started at GS 73 (2.7% in untreated variant) which coincided with rainfall. The differences in average AUDPC values during investigation years fluctuated within a range of 13–142 units for tan spot and 1–57 units for Septoria tritici blotch. The research was supported by the EIP–Agri project “The development of the decision–making support system for restriction of the diseases, affecting leaves and ears of winter wheat”.

The aim of research was to evaluate the impact of low rates of application of environmentally friendly organo-mineral soil amendments on yields components (number of productive tillers m2, 1000 grain weight, grain number per ear), grain yield and yield quality of spring and winter wheat under organic farming conditions. Soil amendments were obtained based of forest logging residues - lignocellulosic biomass, after isolation of polyphenols by water extraction and enrichment with silicon (Si), included the content of polyphenolic compounds. The soil amendments were used for seed material treatment. Field experiments were carried out in the certified organic farming field. The control variant and organo-mineral soil amendments, containing inorganic oligomer in various mass ratios (three variants) were tested. The varieties (spring wheat ‘Robijs’, winter wheat ‘Edvins’), certified for growing under organic farming conditions, were used in trial. It was shown that the treatment of seed material with organo-mineral soil amendments increased the number of productive tillers as well as have a beneficial effect on the yield (the increase till 21.6% compared to the control) but decreased the number of grains per ear of spring wheat, depending on concentration of inorganic oligomers). In variant with the highest tested concentration of inorganic oligomer, a trend towards yield growth for winter wheat can be observed. The obtained results show that the treatment of seed material with promotes plant growth and development, researches should be continued.

The purpose of this work was to evaluate the impact of low rates of application of environmentally friendly organo-mineral soil amendments on grown under organic farming conditions dill’s green mass yield and it’s composition, including the content of polyphenolic compounds. Soil amendments were obtained based on forest logging residues – lignocellulosic biomass, after isolation of polyphenols by water-ethanol extraction and enrichment with silicon (Si)-containing inorganic oligomer in various mass ratios. Lignocellulosic biomass is rich in polyphenols which can damage the functionality of the bacterial cell membranes thus inhibiting the growth of soil microorganisms. Polyphenols can be isolated from the lignocellulosic substrate and evaluated in further studies for their potential to protect plants from pathogenic microorganisms. The influence of the prepared soil amendments on soil microorganisms was tested. Field experiments were carried out in a certified biological field intended for scientific purposes. It was shown that soil amendments have a beneficial effect on the yield (42%) and a slight influence on the composition of dill at low amendment application rates. The addition of soil amendments also contributed to insignificant changes in the amount of polyphenols. The soil amendments didn’t influence the soil microorganisms under study. The results confirmed the ability of the soil amendments based on the forest logging residues to activate dill growth.