Diseases of cereals caused by pathogenic fungi can significantly reduce crop yields. Many cultures are exposed to them. The disease is difficult to control on a large scale; thus, one of the relevant approaches is the crop field monitoring, which helps to identify the disease at an early stage and take measures to prevent its spread. One of the effective control methods is disease identification based on the analysis of digital images, with the possibility of obtaining them in field conditions, using mobile devices. In this work, we propose a method for the recognition of five fungal diseases of wheat shoots (leaf rust, stem rust, yellow rust, powdery mildew, and septoria), both separately and in case of multiple diseases, with the possibility of identifying the stage of plant development. A set of 2414 images of wheat fungi diseases (WFD2020) was generated, for which expert labeling was performed by the type of disease. More than 80% of the images in the dataset correspond to single disease labels (including seedlings), more than 12% are represented by healthy plants, and 6% of the images labeled are represented by multiple diseases. In the process of creating this set, a method was applied to reduce the degeneracy of the training data based on the image hashing algorithm. The disease-recognition algorithm is based on the convolutional neural network with the EfficientNet architecture. The best accuracy (0.942) was shown by a network with a training strategy based on augmentation and transfer of image styles. The recognition method was implemented as a bot on the Telegram platform, which allows users to assess plants by lesions in the field conditions.

Leaf rust (Puccinia triticina Eriks.) is one of the most dangerous diseases of common wheat worldwide. Three approaches: genome-wide association study (GWAS), marker-assisted selection (MAS) and phytopathological evaluation in field, were used for assessment of the genetic diversity of Russian spring wheat varieties on leaf rust resistance loci and for identification of associated molecular markers. The collection, consisting of 100 Russian varieties of spring wheat, was evaluated over three seasons for resistance to the native population of leaf rust specific to the West Siberian region of Russia. The results indicated that most cultivars showed high susceptibility to P. triticina, with severity ratings (SR) of 60S–90S, however some cultivars showed a high level of leaf rust resistance (SR < 20MR-R). Based on the results of genome-wide association studies (GWAS) performed using the wheat 15 K genotyping array, 20 SNPs located on chromosomes 6D, 6A, 6B, 5A, 1B, 2A, 2B and 7A were revealed to be associated with leaf rust resistance. Genotyping with markers developed for known leaf rust resistance genes showed that most of the varieties contain genes Lr1, Lr3a, Lr9, Lr10, Lr17a, Lr20, Lr26 and Lr34, which are not currently effective against the pathogen. In the genome of three wheat varieties, gene Lr6Ai = 2 inherited from Th. intermedium was detected, which provides complete protection against the rust pathogen. It has been suggested that the QTL mapped to the chromosome 5AS of wheat cultivar Tulaikovskaya-zolotistaya, Tulaikovskaya-10, Samsar, and Volgouralskaya may be a new, previously undescribed locus conferring resistance to leaf rust. Obtained results also indicate that chromosome 1BL of the varieties Sonata, Otrada-Sibiri, Tertsiya, Omskaya-23, Tulaikovskaya-1, Obskaya-14, and Sirena may contain an unknown locus that provides a resistance response to local population. This study provides new insights into the genetic basis of resistance to leaf rust in Russian spring wheat varieties. The SNPs significantly associated with leaf rust resistance can be used for the development and application of diagnostic markers in marker-assisted selection schemes.

Stem rust in recent years has acquired an epiphytotic character, causing significant economic damage for wheat production in some parts of Western Siberia. On the basis of a race composition study of the stem rust populations collected in 2016–2017 in Omsk region and Altai Krai, 13 pathotypes in Omsk population and 10 in Altai population were identified. The race differentiation of stem rust using a tester set of 20 North American Sr genes differentiator lines was carried out. The genes of stem rust pathotypes of the Omsk population are avirulent only to the resistance gene Sr31, Altai isolates are avirulent not only to Sr31, but also to Sr24, and Sr30. A low frequency of virulence (10–25 %) of the Omsk population pathotypes was found for Sr11, Sr24,Sr30, and for Altai population – Sr7b,Sr9b,Sr11,SrTmp, which are ineffective in Omsk region. Field evaluations of resistance to stem rust were made in 2016–2018 in Omsk region in the varieties and spring wheat lines from three different sources. The first set included 58 lines and spring bread wheat varieties with identified Sr genes – the so-called trap nursery (ISRTN – International Stem Rust Trap Nursery). The second set included spring wheat lines from the Arsenal collection, that were previously selected according to a complex of economically valuable traits, with genes for resistance to stem rust, including genes introgressed into the common wheat genome from wild cereal species. The third set included spring bread wheat varieties created in the Omsk State Agrarian University within the framework of a shuttle breeding program, with a synthetic wheat with the Ae. tauschiigenome in their pedigrees. It was established that the resistance genes Sr31, Sr40,Sr2 complexare effective against stem rust in the conditions of Western Siberia. The following sources with effective Srgenes were selected: (Benno)/6*LMPG-6 DK42, Seri 82, Cham 10, Bacanora (Sr31), RL 6087 Dyck (Sr40), Amigo (Sr24,1RS-Am), Siouxland (Sr24,Sr31), Roughrider (Sr6, Sr36), Sisson (Sr6,Sr31,Sr36), and Fleming (Sr6,Sr24,Sr36,1RS-Am), Pavon 76 (Sr2 complex) from the ISRTN nursery; No. 1 BC 1F2 (96 × 113) × 145 × 113 (Sr2,Sr36,Sr44), No. 14а F 3(96 × 113) × 145 (Sr36,Sr44), No. 19 BC 2F3(96 × 113) × 113 (Sr2, Sr36, Sr44), and No. 20 F 3 (96 × 113) × 145 (Sr2,Sr36,Sr40, Sr44) from the Arsenal collection; and the Omsk State Agrarian University varieties Element 22 (Sr31,Sr35), Lutescens 27-12, Lutescens 87-12 (Sr23,Sr36), Lutescens 70-13, and Lutescens 87-13 (Sr23,Sr31,Sr36). These sources are recommended for inclusion in the breeding process for developing stem rust resistant varieties in the region.

Management of wheat stem rust in Western Siberia has gained importance since the first outbreaks in 2007–2010 and 2016. The race composition and virulence patterns were investigated for the enlarged Puccinia graminis f. sp. tritici (Pgt) samples collected in three neighboring regions Omsk, Novosibirsk, and Altai during 2017–2018. Most of Pgt isolates were identified as virulent to wheat lines with genes Sr5, Sr9a, Sr10, Sr38, SrMcN, and avirulent to Sr24, Sr31. Differentiation ability of genes Sr6, Sr7b, Sr8a, Sr9b, Sr9d, Sr9g, Sr9e, Sr11, Sr17, Sr21, Sr30, Sr36, and SrTmp to distinguish between the regional populations was established. A total of 33 virulence phenotypes or races were detected among 115 Pgt isolates tested. Based on virulence phenotypes, two different Pgt subpopulations were identified in the Altai and Omsk regions likely originating from asexual and sexual cycles, respectively. The Novosibirsk pathogen population seems to be a mixture of isolates originated from both neighboring regions with virulence phenotypes that developed in the west, Omsk (TKRPF, QHHSF, and MLLTF), and in the south, Altai (NFMSF, LKCSF, LKMSF, and PKCSF), of Western Siberia.

Stem rust caused by Puccinia graminis f. sp. tritici Eriks. is a dangerous disease of common wheat worldwide. Development and cultivation of the varieties with genetic resistance is one of the most effective and environmentally important ways for protection of wheat against fungal pathogens. Field phytopathological screening and genome-wide association study (GWAS) were used for assessment of the genetic diversity of a collection of spring wheat genotypes on stem rust resistance loci. The collection consisting of Russian varieties of spring wheat and introgression lines with alien genetic materials was evaluated over three seasons (2016, 2017 and 2018) for resistance to the native population of stem rust specific to the West Siberian region of Russia. The results indicate that most varieties displayed from moderate to high levels of susceptibility to P. graminis; 16% of genotypes had resistance or immune response. In total, 13,006 single-nucleotide polymorphism (SNP) markers obtained from the Infinium 15K array were used to perform genome-wide association analysis. GWAS detected 35 significant marker-trait associations (MTAs) with SNPs located on chromosomes 1A, 2A, 2B, 3B, 5A, 5B, 6A, 7A and 7B. The most significant associations were found on chromosomes 7A and 6A where known resistance genes Sr25 and Sr6Ai = 2 originated from Thinopyrum ssp. are located. Common wheat lines containing introgressed fragments from Triticum timopheevii and Triticum kiharae were found to carry Sr36 gene on 2B chromosome. It has been suggested that the quantitative trait loci (QTL) mapped to the chromosome 5BL may be new loci inherited from the T. timopheevii. It can be inferred that a number of Russian wheat varieties may contain the Sr17 gene, which does not currently provide effective protection against pathogen. This is the first report describing the results of analysis of the genetic factors conferring resistance of Russian spring wheat varieties to stem rust.