Development forecast of root rot and perspective material of spring soft wheat breeding of FARC of the North-East

The aim of the study is to predict the level of damage to the root system of spring soft wheat by fusarium infection in the conditions of the Kirov region and to identify promising disease-resistant lines. Methods. The object of research was 146 lines of spring soft wheat of the FARC of the North-East selection, which were sown annually against an infections background of fusarium root rot. Results. As a result of many years of research (2004-2006 u 2009˗2020) it was found that a high level of infection of plants of spring soft wheat by root rot was observed in years with an average daily air temperature in the first decade of July in the range from 15 to 23 °C and precipitation in the first decade of august of 30 or more millimeters. A rectilinear regression equation was obtained that reflects the quantitative variability of the disease development indicator from the total year of the weather index. A retrospective analysis of the expected (according to the forecast) and actual development of fusarium root rot on spring wheat showed a fairly high level of coincidence of the date obtained (67 %). Among the promising spring soft wheat lines of the FARC of the North-East selection, 3 (E-310, U-163 and T-79) with resistance to root rot were identified. Combining high resistance to the fusarium root rot and the yield of significantly higher than the standards, the breeding line E-310 can be recommended for transfer to variety testing. The selected highly and moderately resistant lines can be used in further breeding as sources of resistance to the disease. The decrease in grain weight from 1 m2 in susceptible lines compared to resistant ones was on average 83.4 g. The degree of development of the disease in plants affected the yield and weight of grain to a greater extent (d = 15.3 and 11.0 % respectively). In midseason lines the damage and development of root rot was 77.5 and 82.9 % respectively, determined by the duration of the “stands – heading” period. In early maturing lines showed a positive significant correlation between the duration of the “stands – heading” period and the development of root rot (r = +0.66).

Fusarium root rot complex in soybean: Molecular characterization, trichothecene formation and cross-pathogenicity.

Soybean is threatened by many pathogens that negatively affect this crop's yield and quality, e.g., different Fusarium species that cause wilting and root rot diseases. Fusarium root rot (FRR) in soybean can be caused by F. graminearum and other Fusarium spp. that are associated with Fusarium head blight (FHB) in cereals. Therefore, it was important to enquire whether Fusarium pathogens from soybean can cause disease in wheat, and vice versa. Here, we investigated the Fusarium root rot complex in Manitoba (Canada) from symptomatic plants, using both culture- and molecular-based methods. We developed a molecular diagnostic toolkit to detect and differentiate between several Fusarium spp. involved in FHB and FRR, then we evaluated cross-pathogenicity of selected Fusarium isolates collected from soybean and wheat, and the results indicate that isolates recovered from one host can infect the other host. Trichothecene production by selected Fusarium spp. was also analyzed chemically using LC-MS in both soybean (root) and wheat (spike) tissues. Trichothecenes were also analyzed in soybean seeds from plants with FRR to check the potentiality of trichothecene translocation from infected roots to the seeds. All of the tested Fusarium isolates were capable of producing trichothecenes in wheat spikes and soybean roots, but no trichothecenes were detected in soybean seeds. This study provided evidence, for the first time, that trichothecenes were produced by several Fusarium spp. (F. cerealis, F. culmorum and F. sporotrichioides) during FRR development in soybean.

Effects of Spore Density and Interaction with Heterodera glycines on Soybean Root Rot caused by Fusarium solani and F. tricinctum

Fusarium root rot, caused by Fusarium solani and F. tricinctum, is a major soybean disease in the North Central United States. This study investigated the effects of the macroconidia density and the additive effects of soybean cyst nematode (SCN), Heterodera glycines, on the severity of Fusarium root rot. To determine the effect of spore density on severity, experiments were conducted in La Prairie silt loam soil in a greenhouse using conidial suspensions ranging from 101 to 106 macroconidia/ml soil. Root discoloration and lesion lengths on taproots increased as spore numbers increased, with significant effects of spore densities starting at 104 and 105 macroconidia/ml soil for F. solani and F. tricinctum, respectively. A non-linear sigmoid model was fitted to root discoloration against density, while a linear regression model was fitted to root lesion length against density. The interaction between the nematode at different egg densities with the two Fusarium species at 105 macroconidia/ml soil was investigated. In the greenhouse, root discoloration and lesion length were significantly greater in plants inoculated with Fusarium spp. and H. glycines at 10 eggs/ml soil or greater, compared to Fusarium spp. alone. In field trials, co-infestation of soil with the two Fusarium spp. and H. glycines significantly increased root rot severity at an egg density of 16.7 eggs/ml soil. The results indicated that the presence of SCN can increase severity of root rot caused by F. solani and F. tricinctum and egg density in the soil is an important factor in the interaction.

Biological effectiveness of the range of disinfectants winter wheat seeds used in Krasnodar Territory

In the conditions of the Krasnodar Territory, the pre-sowing treatment of seeds with drugs against diseases has firmly entered the system of protection of winter wheat. The use of seed dressing agents minimizes the risk of reducing field germination, ensures good overwintering of the crop, while being one of the most environmentally friendly plant protection methods. The idea of the biological efficiency of the seed disinfectants applied in the conditions of the region will allow not only to purposefully select a disinfectant, but also to prevent the resistance of pathogens causing diseases of seeds. An analysis of the range of fungicidal disinfectants used in the Krasnodar Territory in 2019 showed that the range was based on combined disinfectants based on several active substances with a different mechanism and spectrum of action, as well as that the shares of one-component and four-component drugs in it were - 10%, two-component - 20%. Combined dressers based on three active ingredients were the basis of the range used, the share of such preparations was 60%. Analysis of the data obtained allows to conclude that the modern range of dressing agents used in the farms of the Krasnodar Territory is capable of almost completely restraining the development of the pathogenic complex on winter wheat seeds. The maximum biological efficiency at the level of 100% was shown by the preparations in protection against dust and kernel smut, while it was at the level of 96.5% in protection against fusarium root rot.