Pink snow rot (pathogen Microdochium nivale) is the most common low-temperature pathogen worldwide. Sensitivity of two geographically distant populations of the pink snow rot pathogen (southern Russia and the Republic of Belarus) to nine modern fungicides was studied. The fungicides included in the State Catalogue of pesticides and agrochemicals permitted for use in the Russian Federation and recommended for treatment against snow rot were selected for the study. The material for the study was a pure culture of the fungus M. nivale. The agar block method was used in this study. The fungicide solutions were introduced into the nutrient medium using two standard methods: by interfering with the medium and by rubbing the preparation on the medium surface with a spatula. The preparations with 100% fungicidal effect against both studied populations were identified: Polaris, OE, Quinto Duo, SC and Bariton Super, SC. Oplot Trio, WS, Vybrance Trio, FC, Maxim Forte, SC showed 100% efficacy only against the Belarusian population of the pathogen. It was determined that the use of two methods of introducing the preparation into the nutrient medium (intervention and rubbing on the agar surface) has a high correlation coefficient (for the Belarusian population - rxy = 1.0, for the North Caucasian population - rxy = 0.99). However, intervention is less likely to inhibit colony growth and is therefore preferable in drug sensitivity studies of pure culture of the fungus M. nivale. A statistically significant difference was found between the sensitivity to fungicides of populations from geographically distant regions (Ft 5.32 < Ff 23.2 for the intervention method, Ft 5.32 < Ff 37.7 for the rubbing method). The data indicate the heterogeneity of the snow rot pathogen in terms of sensitivity to the modern assortment of seed dressing agents.

The article presents the results of an immunological assessment of the North Caucasian (NC) and Belarusian (BL) populations of pink snow mold (pathogen Microdochium nivale (Fr.) Samuels & I.C. Hallett) of 2 triticale varieties, 3 rye varieties, 2 winter barley varieties of Belarusian selection and 11 varieties barley, 20 varieties of winter wheat of Russian selection in the seedling phase. Infectious material was selected from two geographically distant zones - the population of the fungus of the North Caucasus region of the Russian Federation (NC) and the population selected on the crops of the Republic of Belarus (BL). It was revealed that resistance to NC was shown by one variety of winter triticale Grenado with a degree of damage of 3.2 points. Winter rye varieties showed different degrees of susceptibility to both populations: Zazerskaya 3 (NC - 5.0 points, BL 8.2 - points), Forzetti (NC5.2 - points, BL 6.4 - points), Golubka (NC - 5.4 points, BL 7.2 points). High resistance to both pathogen populations was found in the winter barley variety Vivat (NC - 2.8 points, BL - 2.6 points). High resistance relative to both populations was found in winter wheat varieties: Helios (NC - 2.0 points, BL - 2.4 points), Iliad (NC - 2.0 points, BL - 2.8 points) and Soberbash (NC 2, 8 - points, BL 2.8 - points). The degree of plant damage by the Belarusian population of the pathogen of pink snow mold was higher than the North Caucasian population (Ft4.0<Ff4.5) with a moderate degree of correlation of damage by different populations (rxy=0.33), which indicates a higher aggressiveness of the pathogen common on crops grain crops of Belarus.

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The purpose of the current study was to estimate immunity of the winter grain varieties sown in the south of Russia to the pink snow mold pathogen (Microdochium nivale (Fr.) Samuels & I.C. Hallett) in the sprouting phase. For resistance to M. nivale there have been studied 35 winter wheat varieties sown in the south of the Russian Federation, 19 winter barley varieties and 4 variety samples and 13 winter triticale varieties developed in the LLC “Agrostandart”, FSBSI RCG named after P.P. Lukyanenko, FSBSI FRC Kabardino-Balkarian Research Center of the RAS, FSBSI “ARC Donskoy”, FSBSI “North Caucasian FRSC”, FSBSI “FRAC”, NPO “KUBANZERNO”, FSBEI HE “KubSAU”. There has been substantiated a methodological approach to conducting research on immunological estimation of winter grain varieties in the laboratory conditions. The optimal temperature for the cultivation of the pathogen was +10/+15 °C (with a photoperiod of 12 hours). There was found that the required temperature to stimulate sporulation was +5 °C. The optimum temperature for the incubation period was +5 °C at 85% humidity. There has been established that the only winter wheat variety ‘Dolya’ had a very high resistance degree to pink snow mold; the varieties ‘Antonina’ and ‘Brigada’ had a high resistance degree; 21 varieties were classified as resistant. M. nivale resistance was demonstrated by 9 winter barley varieties and 3 variety samples (‘Versal’, ‘Iosif’, ‘KA-12’, ‘KA-5/KA-3’, ‘KA-5/KA-1’, ‘Karrera’, ‘Kondrat’, ‘Kubagro-1’, ‘Lazar’, ‘Master’, ‘Romans’, ‘Sarmat’). Among the studied winter triticale varieties, 4 varieties had a very high resistance degree (‘Argus’, ‘Slon’, ‘Tikhon’, ‘Ullubiy’) and 9 varieties had a high resistance degree to pink snow mold pathogen (‘Aznavur’, ‘Argo’, ‘Arioso’, ‘Valentin 90’, ‘Iliya’, ‘Sotnik’,’ Styuard’, ‘Forte’, ‘Khleborob’).

Net blotch (Pyrenophora teres Drechsler) is the dominant pathogenic complex of barley leaf diseases worldwide. The study of various methods of controlling hemibiotrophic fungus requires careful preparation and development of a sufficient amount of pathogenic inoculum. The aim of our research was to select appropriate nutrient medium for obtaining P. teres inoculum with maximum aggressiveness parameters (colony growth rate, sporulation, short latency period) and ergonomics in preparation. Three nutrient media were used: carrot-beet agar (CBA), potato-glucose agar (PGA), Czapek's medium for standard methods and cultivation conditions. The selection consisted of 10 isolates for each nutrient medium and had statistically significant differences among the experimental variants. It was found that appropriate combination of parametres such as growth rate (5.3±0.5 mm/day), colony diameter (53.4±1.1 mm), latent period (4 days), sporulation intensity (4100 conidia in 1 ml) was observed in case of cultivation of P. teres isolates on carrot-beet agar on the 6th day. When cultivating the fungus on potato-glucose agar, rather high growth rates (5.2±0.8 mm/day), colony diameter (52.0±2.9 mm), sporulation intensity (3700 conidia per 1 ml) were revealed, the latent period was the longest among the studied variants, the first sporulation was detected on the 6th day. In case of usage of the standard Czapek medium, the minimum aggressiveness of P. teres isolates was revealed (growth rate - 3.2 ± 0.3 mm/day; colony diameter - 31.6 ± 1.9 mm; latent period - spores were revealed on the 4th day in 1 cup; the intensity of sporulation was 500 conidia per 1 ml). It was noted that there is a larger range of morphological types of colonies on carrot-beet agar, including morphotypes of isolates which grow on other media. Almost all experimental variants cultivated on CBA medium had a clear structured mycelium with a dark color, which indicates a sufficient availability of nutrients in the culture medium. Thus, it is reasonable to use carrot-beet agar in order to obtain P. teres inoculum with maximum aggressiveness parameters and low labor costs when using standard cultivation methods.