Snow mold is an economically important and progressive disease of winter rye caused by several species of low temperature fungi (ascomycetes and basidiomycetes) and fungal-like organisms (oomycetes), with yield losses of up to 30–50 %. The aim of this work is to improve methods for field evaluation of winter rye resistance to snow mold, both under artificial infestation and natural conditions. The research was carried out in 2019–2024 in the Republic of Tatarstan. Since 2021, the most aggressive strains of pink (Microdochium nivale), grey (Typhula incarnata) and speckled (T. ishikariensis) snow mold pathogens collected in the Volga Federal District have been used for artificial infection. The experiment involved 60 winter rye samples, including cultivars bred by Tatar Research Institute of Agriculture, FRC Kazan Scientific Center of RAS. For a more accurate assessment of the degree of damage and identification of resistant genotypes, a detailed 9-point scale was developed, with 1 − no damage and 9 − complete damage. Under natural conditions, the average damage point ranged from 2.41 to 5.15, while under artificial infestation it was significantly higher, from 4.48 to 8.40. Most winter rye cultivars showed a moderate to moderately susceptible type of reaction on a natural background in four out of 5 years of observation. The frequency of susceptible samples on the artificial infection background reached 96 % in 2024. The use of artificial infection backgrounds allows snow mold damage to be assessed independently of weather conditions and speeds up the breeding process, providing an objective assessment of genotype resistance. As a result of research, the methodology for establishing autonomous infection backgrounds has been optimized. It involves the selection of a site with a long snowmelt period and flat relief, the use of inoculum containing virulent strains of pathogens characteristic of the region and a special method of introducing the pathogen.

Fusarium head blight (FHB) is a major threat to cereal crops, causing yield losses and mycotoxin contamination. This study investigated Fusarium species associated with spikes and grains of cereals in the Volga region, focusing on species diversity, virulence, and mycotoxin production. F. sporotrichioides, F. avenaceum, and F. poae were the most prevalent species isolated from wheat, rye, barley, triticale, and stored grains in the Volga region. Individual strains of F. culmorum and F. graminearum were also identified. High intraspecific variability in virulence was observed for the first time within F. sporotrichioides and F. poae species, and highly virulent strains were identified for the first time within these species. Not only symptomatic but also asymptomatic (weakly expressed) infections caused by F. sporotrichioides were shown to be associated with the accumulation of high levels of T-2 toxin in the grains of infected plants. F. sporotrichioides strains were first demonstrated to exhibit intraspecific variability in zearalenone-producing potential. A F. graminearum strain possessing the nivalenol chemotype was first identified in Russia. The study highlights the diversity of the regional FHB pathocomplex and the risks it poses to grain safety.

Pink snow mold, caused by the low-temperature ascomycete Microdochium.nivale (Fr.) Samuels and I.C. Hallett), is a regular occurrence in winter triticale (x Triticosecale, Wittm.). It is the most common and damaging phytopathogen in temperate and cold climates. Field experiments were conducted at the laboratory of winter rye and triticale breeding of the Tatar Scientific Research Institute of Agriculture FRC KazSC of RAS in 2020–2022. The experiments were carried out under both natural and artificial infectious conditions. The samples were screened in the laboratory by infecting detached leaves with the most virulent strain of Microdochium.nivale, F00608. The study focused on 50 hexaploid samples of winter triticale from the N.I. Vavilov VIGRR gene collection. The results demonstrated that the mean disease damage score for winter triticale samples on the artificial infection background was 6.39 ± 1.52, while in natural conditions of infection development, the score was 3.34 ± 0.94. A correlation coefficient of r = -0.708 was observed between snow mold damage on the artificial infectious background and yield. The development of snow mold resulted in a significant loss in yield, amounting to 50.4%. The results of the field studies demonstrated that the majority of winter triticale cultivars were susceptible to pink snow mold. The forms with relatively high levels of field and laboratory resistance were identified. The sources of field resistance to snow mold have been identified as potential candidates for further use in breeding. The varieties Beta 2, Doctrine 110, Capral, Nemchinovsky 56, Bashkirskaya korotkostebelnaya, Tsekad 90 and Altaysky 5 have been identified as resistant to both natural infection and epiphytotic load. The varieties Pyatrus, Kroha, Privada, Gorka, Almaz, Capella, Tribun have demonstrated high resistance to pink snow mold in detached leaves, and are therefore recommended for use in genetic studies.

Snow mold is a major constraint to winter cereal production in regions with prolonged snow cover. Because the disease is caused by phylogenetically distinct pathogens with different infection strategies, resistance is commonly treated as a single trait despite limited evidence that host responses are consistent across causal agents. Sixty winter rye accessions were evaluated over two seasons under one natural infectious background and three backgrounds experimentally enriched with Microdochium nivale, Typhula incarnata, and T. ishikariensis. Mean snow mold damage (SMD) increased from 3.69 points under the natural background to 6.54–7.41 points under the three experimentally enriched backgrounds. Accession rankings for SMD differed among backgrounds: rank correlations were weak and mostly non-significant, and the accession × background interaction was significant, indicating background-dependent, possibly partly pathogen-specific responses. Post-winter regenerative capacity was more strongly associated with grain yield than disease severity, highlighting the importance of recovery after snowmelt. The Multi-Trait Genotype–Ideotype Distance Index identified accessions combining favorable disease resistance, winter hardiness, regenerative capacity, and productivity across all backgrounds, while the best-performing accessions under individual backgrounds were identified separately from SMD rankings. These findings support multi-pathogen, multi-trait evaluation for breeding winter cereals with improved adaptation to changing winter environments.

Fusarium head blight (FHB) is one of the most devastating diseases of cereal crops worldwide, causing yield losses and mycotoxin contamination. Traditionally associated with warm and humid climates, FHB has increasingly affected cooler and drier regions, including the Volga region of Russia—a major grain-producing area once considered low-risk. In this three-year field study, we evaluated FHB resistance in 50 winter rye accessions under natural infection and artificially enriched infectious backgrounds using high-virulence Fusarium strains from the Volga region. Post-invasive resistance to FHB was generally weak across the tested germplasm. Nevertheless, considerable variability in FHB damage was observed among accessions. Accessions showing the lowest overall FHB severity were identified as promising donors for breeding programs. Specific resistance sources to individual Fusarium species were identified, notably Fusarium sporotrichioides—previously regarded as a weak pathogen but demonstrated here as a serious food safety threat. No significant positive correlation was found between FHB severity and mycotoxin levels, confirming these as partially independent traits; several accessions maintained low mycotoxin content despite severe symptoms. Our study highlights the necessity of multi-environment screening with local pathogen strains and endorses pyramiding approaches for durable FHB resistance in winter rye breeding.