Phytopathogenic fungi induced considerable economic losses in strawberry production industry; therefore, more attention should be paid to development and implementation of preventative treatment that is environmentally friendly. Coniferous trees produce a wide variety of compounds, such as terpenoids and phenolics. Several studies are known on fungicidal activity of different components of coniferous tree bark. The aim of this study was to evaluatein vitropine (Pinus sylvestrisL.) and spruce (Picea abies(L.) Karst.) bark ethanol extracts impact on pathogenous fungi causing diseases of strawberries. Products of processed pine (Pinus sylvestris) and spruce (Picea abies) bark were tested. During 2011 to 2013, severalin vitroexperiments were carried out to test the effectiveness of pine and spruce bark extracts against various phytopathogenic fungi isolated from strawberries:Botrytis cinerea, Colletotrichum acutatum, Phytophthora cactorumandMycosphaerella fragariae.Radial growth tests showed that coniferous bark extracts inhibit mycelial growth ofB. cinerea, C. acutatum, P. cactorumandM. fragariae. Extracts had the highest antifungal effect onB. cinereatwo and five days after inoculation (p< 0.05). Bark extracts can reduce the sporulation ofB. cinerea, C. acutatumandP. cactorum.

Numerous investigations have been carried out to determine the impact of genetically modified plants, such as potato, maize, alfalfa and tobacco, on soil microorganisms and the results are contradictory. We applied classical microbiology methods to study quantitative changes of bacterial and fungal abundance in substrate and rhizosphere from barley (Hordeum vulgare L.) transgenic line H228.2A containing Rpg1 and bar genes, and its parent nontransgenic variety 'Golden Promise'. In addition, molecular biology methods were used to determine, if horizontal gene transfer from barley transgenic line to soil bacteria has occurred under experimental conditions by screening bacterial genomes for the presence of Rpg1 gene sequences using polymerase chain reactions. Results did not show significant impact on substrate and rhizosphere microorganisms. In the second pot experiment the average number of filamentous fungi in the rhizosphere of parent line 'Golden Promise' was higher than in the rhizosphere of transgenic line, but the variation among samples was very high probably caused by the high variation of substrate moisture content. None of bacterial deoxyribonucleic acid (DNA) samples isolated from substrate of rhizosphere of barley transgenic line resulted in positive amplification of Rpg1 gene-specific primer product.

Anthropogenic pollution is considered as a one of the main factors that affects soil in urban areas. In 2014, soil quality of grasslands in Rīga was determined. The aim of the study was to determine microbial biomass and describe microarthropod communities in soils of different grasslands in Rīga city and to assess their use as indicators of soil health and quality of the urban environment. Six sampling plots with different building characteristics, density of street and rail network and transport load, and potential impact of pollution were selected for studies. The substrate-induced respiration method was used for determination of soil microbial biomass. Soil invertebrates were collected in sampling plots. Soil Mesostigmata mites, Oribatida and Collembola were extracted from samples and counted. In total over 9300 soil microarthropod individuals were recorded, of them 4500 Collembola, 3400 Oribatida and 1400 Mesostigmata mites. Statistically significant differences in soil microbial biomass among sampling sites were observed. Soil microbial carbon content significantly increased in most of sampling plots from July to October. To obtain more precise results in the future some modifications and optimisation of the standard method based on indicators will be necessary.

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