In the conditions of the Astrakhan region Alternaria blight is one of the most widespread and harmful diseases. The application of only chemical preparations often leads to the emergence of resistant forms of pathogens. One of the methods to solve this problem is the combined usage of chemical and biological preparations. The article shows the possible loss of yield of potato tubers in the absence of measures to control this disease. Is it described biological preparations that are produced on the basis of one of the most diverse and naturally diffused bacteria of the Bacillus genus, which are able to inhibit the development of a wide range of plant pathogenic fungi. The characteristics of the variety, conditions and methods of research are given. The article presents the results of trials of the combined application of chemical and biological preparations against potato Alternaria blight under irrigated conditions of the Volga delta with cultivation of potato under on drip irrigation. It was noted that pre-planting treatment of potato tubers with biological and chemical preparations contributed to the growth of field germination rate by 4,3-7,6%. The combination of preplant treatment with spraying of vegetative plants positively influenced the biometric parameters of potato bushes, increasing the number and weight of leaves, the average height and number of productive stems, as well as the mass of tops and tubers. In comparison with the control variant without treatment the leaf surface area increased by 15-29%. The results of the estimation of effectiveness of the combined use of biological and chemical preparations against potato Alternaria blight are presented. It was established that the degree of the Alternaria blight development during the vegetation period was below the control by 30-76%. It was also mentioned an increase in the productivity of cultivated plants without a significant decrease in the quality of potato tubers.

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Agrocenoses of cultivated plants are more or less overgrown with unwanted weeds, which complicate and complicate the care of plants and harvesting. The purpose of our research was to assess the impact of modern herbicides on the infestation (clogging) of tomato seedlings with annual weeds and the productivity of cultivated plants in the natural and climatic conditions of the Republic of Kalmykia. It was revealed that the main weeds of tomato plantings for all the years of research from annual dicotyledonous species were-white mar, bindweed buckwheat, bird mountaineer, southern salt grass; less common - bedstraw tenacious, nightshade black, hibiscus triplet and others. Annual cereal species were more often represented by common oatmeal, blue and green bristles, and less often by barn grass. The introduction of herbicides Unimark, WDG and Lapis Lazuli, LP (loose powder) before planting seedlings did not have a negative effect on the survival rate of seedlings; it was 94-96% of the planned density of standing plants. It was found (established) that the use of herbicides in the planting of tomato seedlings restrained the increase in the number of annual grass weeds by 30-75%, annual dicotyledonous-by 70-90%. The introduction of preparations before planting seedlings was the most effective. The decrease in the number of annual weeds had a positive effect on the growth, development and productivity of tomato plants: there was an increase in the number of leaves by 10.4-16.5%, the mass of leaves (leaf weight) – by 11.8-21.2%, the area of the leaf surface – by 8.9-16.2%, the number of set fruits – by 18.9-23.8%, the average weight (mass) of a mature fruit – by 7.5-11.3%. The increase in the yield (the yield gain) of tomato fruits was in the range from 21.6 to 28.4%. The studied herbicides did not have a significant effect on the quality indicators of tomato fruits.

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