Vol 18, No 4 (2023): Pesticides. Looking to the future

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The research was conducted to synthesize and study fungicidal activity of synthesized chemical compounds of various classes, triazole and imidazole, and their mode of action due to the wide spectrum of action and low application rates. The developed synthesis methods resulted in several groups of nitrogen-containing heterocyclic compounds and evaluated their fungicidal activity. Inhibitory activity of compounds to strains of Fusarium solani (medium resistance to fungicides) and Sclerotinia sclerotiorum (susceptible to most fungicides) from the collection of phytopathogenic microorganisms of Agrobiotechnological Department, RUDN University, was tested. In the synthesis of new chemical compounds with fungicidal activity, urea derivatives 1-(3-(Difluoromethyl)-1-methyl-1H-pyrazole-5-yl)-3-(2-chlorophenyl) urea were identified and structurally confirmed. All target compounds were evaluated for their antifungal activity to inhibit mycelium growth. Preliminary screening results showed that all synthesized compounds have good fungicidal activity against S. sclerotiorum . The compound 1-(3-(Difluoromethyl)-1-methyl-1H-pyrazole-5-yl)-3-(3-fluorophenyl) urea showed antifungal activity against S. sclerotiorum . At concentration of 100 ppm, the compound suppressed growth of S. sclerotiorum strain by 90.5 %. An in vitro experiment revealed that the compound 1-(3-(Difluoromethyl)1-methyl-1H-pyrazole-5-yl)-3-(3-fluorophenyl) urea was effective for suppressing white mold - S . sclerotiorum , at the dose of 100 mg/L. The significance of the research lies in the fact that production of eco-safe products in agroindustry is impossible without development of new biologically active compounds with low application rates and toxicity indicators, controlled persistence, corresponding to the world level. The results obtained can be implemented in real sector of economy engaged in production of chemical plant protection products. Synthesis and use of new fungicides are relevant in agricultural production as an element of development and intensification of existing agricultural technologies.

The problem of contamination of agricultural products with toxic substances is an urgent problem in production. One of the most chemically treated crop is vineyards. Multiple treatments during one growing season have led to the fact that grape plantings have become an accumulator of unsafe chemical plant protection products. Moreover, grapes are consumed fresh. Accordingly, the selection of environmentally friendly pesticides and the replacement of chemicals with biological ones has become a priority for producers of this crop. Our research was devoted to evaluation of bioinsecticide based on entomopathogenic bacteria B. thuringiensis in the system of protecting grapes from pests. Such studies are of great interest and, according to the literature, 90 % of registered insecticides are based on Bacillus thuringiensis . Microorganisms isolated from nature as plant protection agents, when reintroduced into natural conditions, preserve beneficial species in biocenoses. At the same time, they are selective and, while affecting certain harmful objects, do not cause harm to humans and the environment. The purpose of this work was to study the effect of the bioinsecticide Biometch Insecto, WP on grapevine pests: European grape worm ( Lobesia botrana Den. & Schiff.) and leafy form of phylloxera ( Viteus vitifolii Fitch.). Biometch Insecto, WP is based on strains of Bacillus thuringiensis var. kurstaki HG207 and Beauveria bassiana HG208. The effect of entomopathogens was compared with the effect of insecticide Bioslip, BW, L, the active ingredient of which is Beauveria bassiana . The results of the research revealed high biological effectiveness (90…100 %) of Biometch Insecto, WP in protecting grapevines from pests when applied during the period of mass hatching of European grape worm caterpillars and emergence of phylloxera larvae from galls.

In the Non-chernozem zone of Russia, the recurrent spring cold up to 1-2 °C can cause damage and death of thermophilic amaranth seedlings. Pre-sowing treatment of seeds with growth regulators is an inexpensive and effective method to reduce the negative effect of hypothermia on seed germination. The aim of the research was to study the effect of low-temperature stress on etiolated and de-etiolated seedlings of amaranth cv. ‘Valentina’ ( A. tricolor L.) grown from seeds treated with growth stimulants. Seeds were pretreated with aqueous solutions of Albit (1 g/L), hydrogen peroxide (H2O2) - 5 mM and succinic acid (ScA) - 500 mg/L. Seeds were germinated in peat pots at 23 ± 2 °C (T23) for 7 days. On the 7th day, peat pots with seedlings grown in the light and in the dark were moved to thermostat at 2.0 ± 0.5 °C (T2) for 8 hours. Determination of the amount of amaranthine, chlorophylls and carotenoids were carried out according to generally accepted methods. Pretreatment of seeds with the growth regulators Albit, H2O2, and ScA increased hypocotyl length, root length, and biomass of light and etiolated seedlings. Low positive temperatures increased the content of amaranthine and carotenoids but reduced the content of chlorophylls. It was shown that all used growth regulators - H2O2, Albit and ScA trigger or at least maintain the system of antioxidant protection in light and etiolated seedlings of amaranth cv. ‘Valentina’ under low positive temperatures.

Edamame is a special soybean ( Glycine max (L.) Merr .) harvested as a vegetable when the seeds are immature (R6 and R7 stage) and have expanded to fill 80 to 90 percent of the pod width. The study was conducted in the experimental field of Federal Scientific Vegetable Center in the Moscow Region in 2020-2022 and Agro-biotechnological department, Agrarian and Technological Institute, RUDN University. The object of research was 3 accessions of soybean ( Glycine max L.): accession A, accession F, Hidaka and Lira. Before sowing, soybean seeds were inoculated with Optimays 400 ( Bradyrhizobium japonicum ) and Biobesta ( Sinorhizobium fredii ). In the field experiment, 10 soybean samples were taken from each plot at the stage of biological ripeness to determine plant height (cm), number of pods per plant, number of stems per plant, stem width (mm), average number of seeds per plant, weight of 1000 seeds (g) and yield (t/ha). The experiment was designed in a complete random block with a factorial arrangement. Thus, we had 4 accessions and 3 treatments (C - control, V1 - Bradyrhizobium japonicum and V2 - Sinorhizobium fredii ) with 3 replacations. The study showed that accession A had the highest average yield per hectare (2.70 t/ha) and weight of 1000 seeds (159 g). Under conditions of the Moscow region, variant V2 ( Sinorhizobium fredii ) had the highest average yield (2.57 t/ha) and weight of 1000 seeds (100.25 g). Therefore, more than 90 % of the results obtained for these two indicators are associated with the use of V2 treatment. For the rest of the studied indicators, no significant differences were found, and they did not affect the efficiency indicators. The combination of accession A and treatment V2 led to the highest average yield (2.99 t/ha). The product based on Sinorhizobium fredii showed the best indicators for all the studied samples.

According to the long-term observations of the FAO, losses of plant-based agricultural products are estimated to be between 10 and 30 %. The main causes of these losses are plant pathogens, spoilage microorganisms, and insect pests. The study discusses the problems of ensuring phytosanitary safety of agricultural products and proposes the use of radiation technology instead of chemical treatment. Radiation technology has a long history of research and application, spanning over 75 years. The most extensive and detailed data on the application of this technology have been obtained for gamma installations, which use natural radioactive isotopes. Lowenergy (less than 300 keV) electron accelerators were invented relatively recently, so the question of their use in agriculture is relevant. Treatment with low-energy electron radiation combines all the advantages of radiation treatment of food and agricultural products with gamma radiation, and at the same time, significantly reduces the risk of damage to biological structures inside the irradiated object due to the low penetrating power of the radiation. This study notes that low-energy electron accelerators can be successfully used to combat plant infectious diseases, reducing the amount of plant pathogens on seeds, without affecting their growth parameters. The use of low-energy electron irradiation to prevent microbiological spoilage is also discussed. The nutritional qualities of irradiated products are not significantly altered. The method of radiation disinfestation (control of insect pests) using low-energy electron radiation has also proven to be effective. However, it should be noted that additional research is necessary to determine the optimal doses of low-energy radiation for each type of product and to ensure safety for human health and the environment. Generally, the use of radiation technology in agriculture has great potential and can become an effective means of improving productivity and food safety. This method of food processing has been recognized as safe for human health by several authoritative international organizations, including the UN (FAO), WHO, IAEA, and others.

The aim of the research was to establish the effect of precision irrigation with varying mineral fertilizer availability on winter wheat productivity. Studies were carried out on irrigated arable land in the Rostov region. The test scheme included 3 replications. The climate of the research area is arid but not hot enough. The sum of temperatures for growing period is in the range of 3000…3200 ºC, the average annual precipitation is 470 mm, for the growing period - 285 mm. The soil cover of the experimental site is chernozem. According to the granulometric composition of the soil, the entire profile is represented mainly by heavy loam, turning into medium loam at a depth of 130-160 cm. The structural state in dry sieving and the water resistance of the aggregates are characterized as excellent. The lowest water-holding capacity for 0-60-centimeter layer is 28.3 %, which is good according to the existing classification. Soil density in 0.6 m layer is 1.27 t/m3, and in 1.0 m layer - 1.33 t/m3. Differentiated doses of fertilizers against the background of irrigation technologies studied in variants had a significant impact on productivity of winter wheat. Thus, in the variants with no irrigation, water consumption coefficient of winter wheat was 890.8 to 1343.6 m3/t; using the recommended irrigation system reduced its value to 725.9…1327.3 m3/t, and the precision irrigation technology provided a reduction in the value of water consumption coefficient to 681.6…1147.6 m3/t. The conducted studies revealed advantage of precision irrigation technology and mineral fertilizers, the use of which in different years provided higher winter crop yield by an average of 0.55 t/ha in comparison with the recommended technology, and, in comparison with variants without irrigation - by 3.49 t/ha. The introduction of modern high-precision irrigation technologies will make agricultural products produced on irrigated land more competitive.

Among the most frequently reported diseases of rabbits, the main place is occupied by diseases of bacterial etiology, the pathogens of which are characterized by multidrug resistance. The aim of the study was to analyze the dynamics of morphometric indicators during experimental infection of rabbits with Pseudomonas aeruginosa bacteria. When assessing colonization resistance of organs, the following indicators were taken into account: colonization index, ratio of the number of microorganisms isolated from nasal cavity washes, contents of cecum of clinically healthy and sick animals. Significant changes in morphological parameters (p ≤ 0.05) were revealed during the isolation of P. aeruginosa from blood, lymph nodes, spleen, liver, and kidneys of sick rabbits. Overgrowth of isolates producing adhesive antigens, hemolysins, bacteriocins should be considered as prognostic markers of connective tissue dysplasia. The initiation, development, and outcome of microbial overgrowth syndrome are mediated by morphofunctional changes in compensatory mechanisms of mucociliary clearance system and colonization resistance.