Object of research - grouping of microbiota of agrocenosis of fruit crops. Purpose - to find out the influence of modern pesticides for various purposes on plant-associated microbiota as a structural and functional component of agrocenosis of fruit crops and to reveal the participation of plant-associated bacteria in microbiological destruction of pesticides.It has been found that the total number of groups of epiphytic microbiota of apple and pear is in the range of 104-106 cells/g of buds, flowers, leaves. The largest number of epiphytic microorganisms is observed in the phenophase of bud swelling and flowering (106 cells/g of buds and inflorescences), much smaller number – during fruit formation (104 cells/g of leaves), during periods of fruit growth and ripening the number of microorganisms increases (105 cells/g leaves). According to the set of properties, bacterial isolates are assigned to the genera Pseudomonas, Bacillus, Xanthomonas, Panthoea, fungal isolates – to the genera Fusarium, Pennicilium, Mucor, Alternaria. The species composition of the epiphytic microbiota the period of fruit formation and growth active shoot growth is represented by microorganisms: Ps. fluorescens (45,5 %) >P.agglomerans (27,5 %) > Bacillus spp. (10,5 %) > Pseudomonas spp. (7,5 %) > mycelial fungi and yeast (3,5 %) > Xanthomonas sp. (up to 3,0 %) ≥ others (2,5 %). The proportion of bacteria resistant to pesticides is in the range of 48,4-90,5 %. The highest pesticide-resistant to is shown by the epiphytic microbiota (55,6-90,5 %); the middle is the rhizosphere (50,0-87,5 %), the smallest is the soil (48,4-75,0 %). The studied microorganisms are more resistant to the fungicide Horus and the insecticide Karate, more sensitive to the fungicide Scor and the herbicide Roundup. The share of microorganisms capable of decomposing pesticides and using them as a source of nutrients is in the range of 12,5-53,9 % and is high. Destructors of pesticides are 16,9-53,9 % of epiphytic bacteria, 14,1-31,3 % – rhizosphere and 12,5-20,3 % of soil. That is, the largest share of biodestructors – among epiphytes. The nature of the effect of pesticides on bacteria was analyzed, of which: 22,0 % have a bactericidal effect, 12,9 % - inhibitory, 65,0 % – do not affect the growth of bacteria at the recommended rates. According to the action on bacteria of the genera Pseudomonas, Klebsiella and Erwinia, pesticides are divided into: fungicides > herbicides and desiccants > acaricides and insecticides. It has been found that fungicides Rydomil Gold, Gorus, Kurzat suppress by 10,0-30,0 % the manifestation of phytopathogenic properties of bacteria-pathogens of plant bacteriosis (P. syringae pv. Syringae, P. syringae pv. аtrophaciens, R. ( P.) solanacearum, Er. аmylovora) and pathological processes they cause. For the first time, a high level of phytostimulating biopotential of extracellular metabolites of saprophytic bacteria of the genus Klebsiella during cultivation under pesticide loading has been established. Saprophytic strains Kl. terrigen 8008, Кl. planticola 33531 are promising for use in the practice of organic farming and the creation of biological products based on them. It has been found that pesticides affect the activity of the enzymatic system of bacteria, which participates in the processes of biodegradation and self-restoration of agroecosystems, which correlates with the recommended rate of pesticide consumption. At 24-hour exposure, the fungicides Rydomil Gold, Acrobat reduce the total catalase activity of saprophytic bacteria of the genera Klebsiella and Pseudomonas by 23,8-34,0 %; and the activity of phytopathogenic enzymes by 100,0 %; Horus reduces the catalase activity of saprophytes by 4,0-7,3 %, phytopathogens - by 38,8-49,1 %. The ecological features and ways of microbiological destruction of pesticides with the participation of bacteria-plant associates are revealed. It has been proven that one of the ways of biodegradation of pesticides and reduction of pesticide load is carried out with the indirect participation of extracellular metabolites of bacteria. With the participation of exametabolites of saprophytic bacteria of the genera Pseudomonas and Klebsiella, the fungicidal activity of Horus, Acrobat, Ridomil is reduced by 9,33-46,11 % after 48 hours of exposure to bacteria. Another way of degradation of pesticides is due to the ability of bacteria-associates of plants to use pesticides as a source of nutrients, due to which they grow and reproduction. Saprophytic strains are characterized by the highest destructive activity. Key words: plants associated bacteria, community, grouping of microorganisms, destruction, pesticides, agrocenosis, apple-tree, pear-tree, plant protection
