The analysis was conducted on the general biogenicity and phylogenetic structure of fungi in the soil microbiome of greenhouse cucumbers grown as a monoculture and after the precursors of pepper and lettuce. The relationship between the following indicators has been proved: the total biological activity of the soil, the species composition of micromycetes, the development of Fusarium root rot, and yield. The effect of biological preparations based on strains of Trichoderma viride and Gliocladium virens antagonistic fungi on the development of Fusarium root rot, nematodes and yield of cucumbers was studied. The results of the experiment show that when cucumbers are grown after the precursor pepper and lettuce, the development of Fusarium root rot and nematodes does not exceed critical values.The introduction of Trichoderma and Gliocladium fungi into the soil in the form of a dry preparation with a titre 2.0 x 10 10 conidia/g when transplanting plants to a permanent place at a consumption rate of 40 kg/ha increases the yield of greenhouse cucumbers by 20-23%. The experiment is part of the study of the "soil exhaustion" syndrome and the possibilities of overcoming it. The obtained results will serve as bioindicators that can be used for preliminary diagnostics of the sanitary condition of degraded soils, selection of agrotechnical, breeding and protective measures of plants.

Among factors affecting snap bean production in organic growing systems, pests and diseases are of paramount importance. The current study was aimed to determine the impact of organic production practices on snap bean pests and diseases infestation, soil fertility and yield. Five treatments of plants during the whole growing season with a Bordeaux mixture at a dose of 3000 g/ha, provided more than 50 percent protective effect against the development of the bacterial blight Xanthomonas axanopodis pv. phaseoli and anthracnose Colletotrichum lindemuthianum. In organic fields, commercial bioproducts containing pyrethrins or entomopathogenic fungi Beauveria bassiana can be successfully applied to control the black bean aphid (Aphis fabae Scop.). To limit the attack of bean weevil (Acanthoscelides obtectus Say), phytopesticide containing pyrethrins can also be used. Against the two-spotted spider mite (Tetranychus urticae Koch.), products containing the active ingredient azadirachtin were seen to be effective five days after treatment. Soil amendment with vermicompost at a dose of 2850 L/ha slightly increased the amounts of water-soluble nutrients; however, soil remained nutrient deficient across the growing season. Among the tested Bulgarian varieties, Evros possessed higher yield, and appear to be suitable for organic system than the Tangra variety.