Characterization of Zymoseptoria tritici populations in Belarus by morphologic and cultural features

Septoria leaf blotch caused by Zymoseptoria tritici is one of the most harmful diseases in Belarus. Isolates of the pathogen were obtained from northern, central and southern populations: in 2018–2019, whichvaried significantly among in the structure of colonies. The rate of fungal isolates forming yeast-like colonies decreased from 55.0 % in the North of Belarus to 6.7 % in the South, whereas incidence of filamentous isolates increased from 31.3 % to 80.0 %, respectively. In the northern population, phenotypic diversity was high, while in the southern population it was the lowest (Shannon’s index was 1.53 and 1.14, respectively).

Bioefficacy of microbial antagonists against Zymoseptoria tritici on wheat

From our previous research of bio-control agents of the wheat pathogen Zymoseptoria tritici as an alternative to chemical control, one strain of Bacillus amyloliquefaciens and one strain of Trichoderma harzianum showed high antagonistic potential in vitro and in vivo as a foliar treatment on potted plants under greenhouse. The present work aimed to evaluate the antagonistic potential of these two strains of microorganisms in seed treatment. The results obtained showed that the two antagonists can reduce the severity of the disease assessed at three growth stages of the two wheat cultivars. B. amyloliquefaciens I3 reduced the severity of septoria leaf blotch by 56% and 58% compared to the checks on Aguilal and Karim respectively at the flag leaf stage, while in the case of T. harzianum A, this rate was 54% on Aguilal and 55% on Karim. These results suggest that the antagonistic potential is due to a distant mechanism of action such as induced systemic resistance. The viability tests of the two antagonists on coated seeds stored at 4 °C showed that they were viable after twelve months of conservation and preserved their antagonistic potential against Z. tritici.

Genetic Protection of Soft Wheat from Diseases in the Southern Ural of Russia and Virulence Variability of Foliar Pathogens

The southern Ural is consistently among the 10 best regions in Russia for agricultural production, including wheat. Breeding in the Chelyabinsk Research Institute of Agriculture aims to develop wheat cultivars genetically protected from the main diseases (leaf and stem rust, septoria leaf blotch and tan spot). The genes for resistance to leaf rust, Lr1, Lr9, Lr10 and Lr26/Sr31, alone or in combination, are widespread in cultivars grown in the southern Ural. In 2012, a new wheat cultivar, Chelyaba 75, was proposed for commercial production in the southern Ural, being highly resistant to leaf rust with the highly effective genes LrSp and SrSp transferred from the cuckoo line with the genetic material Aegilops speltoides. Isolates virulent to cv. Chelyaba 75 were not found in Russian populations of Puccinia triticina. Additionally, for a long period, genes Lr29, Lr 41, Lr42, Lr45, Lr47, Lr50, Lr51, Lr53 and Lr57 were characterized by high efficiency. Virulence frequencies to other Lr genes vary annually, but no races with new virulence have been identified. The resistance of lines with the Sr31 and Sr24 genes indicates that the Puccinia graminis population does not contain genotypes with the potentially damaging race Ug99. Mixed septoria and tan spot infections occurred in the southern Ural, with the latter dominating. Races producing the exotoxin ToxA are widely distributed in Pyrenophora tritici-repentis populations. Two causal agents of septoria leaf blotch (Parastagonospora nodorum and P. avenae f. sp. tritici) occur in the region, with the first dominating. Aggressiveness of P. nodorum isolates to wheat cultivars was higher than that of P. avenae f. sp. tritici. All Parastagonospora isolates showed the presence of the SnTox3 marker. SnToxA and SnTox1 markers were found in P. nodorum isolates, usually separately, but in one isolate, these genes were found together. The analysis of the genetic diversity of wheat cultivars grown in the southern Ural, and the pathogenic complex present, indicate that pathogens continuously evolve under the influence of the host plant.

The septoria leaf blotch of wheat in Central Kazakhstan: prognosis, evaluation and monitoring with remotely sensed data

Fungal diseases represent a widely spread natural phenomenon affecting many of wild and domesticated plants. In nature, all plant species forms plant communities of a mixed character, and the spatial pattern of dominant species is usually irregular and spotted. Some species are impregnable to a certain infection, which provides a kind of natural barrier to the infection spread within the natural community. Under the agricultural environment, when the single plant species may occupy a huge area, the species-specific parasite takes a great advantage to develop focal outbreaks and fast spreading of the infection within the area. The concentration of vulnerable plants and the absence of natural barriers within the agricultural areas provokes outbreaks of fungal diseases, that may have highly harmful consequences and result in significant yield losses. One of the purposes of the satellite optical data is an operative, cost-effective diagnostic and, in combination with climatic datasets and crop rotation information, a prognosis of fungal disease appearance and severity. In this paper, we describe the system of prognostic and monitoring measures to control the fungal diseases of wheat in Central Kazakhstan with special attention to septoria leaf blotch. The prognostic procedure provides a map of the probability of septoria leaf blotch appearance. The prognosis takes into consideration the combination of three main variables: the model of ecological niche for Septoria, the presence of wheat residue, and Vegetation Condition Index counted for the late spring (May) of the current year. The new spectral index, introduced in this paper, is the core component of monitoring activity. The index is sensitive to septoria leaf blotch severity at middle to late (stages 8-11, accordingly Feekes growth stages) periods of wheat development. Several other indices (RETA, VSDI, vegetation indices) may be of help in providing information on the spatial unevenness of wheat crops that may indicate the presence of fungal infection.

The Effect of Foliar Fertilization with Micronutrients on Disease Severity and Mycotoxin Concentrations in the Grain of Winter Spelt (Triticum Aestivum spp. Spelta L.): A Case Study

The effect of mineral fertilization (NPK), foliar fertilization with micronutrients (Cu, Zn and Mn) and the NanoGro biostimulant on the severity of leaf, spike, stem base and root diseases in winter spelt cv. Schwabenkorn was evaluated in a field-plot experiment. A mycological analysis was performed and the content of Fusarium mycotoxins in grain was determined. Mineral fertilization (NPK), foliar fertilization with micronutrients and the NanoGro biostimulant exerted varied effects on the severity of Septoria leaf blotch and Septoria glume blotch, they promoted the spread of brown rust (excluding the NPK + NanoGro treatment) and inhibited the spread of black head mold (excluding the NPK treatment), eyespot and Fusarium foot and root rot (excluding the NPK + Mn treatment). Fertilization had no influence on grain yield or the content of Fusarium mycotoxins in grain. The concentrations of deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and fumonisins FB1 + FB2 did not exceed the maximum permissible levels (except for DON in NPK + Cu + Zn + Mn and NPK + NanoGro treatments). Throughout the experiment, ergosterol (ERG) concentrations were highest in the grain of unfertilized spelt plants.

Development and species composition of septariosis in crops of spring triticale varieties in Belarus

Septoria leaf and head blotch is the most economically significant disease of grain crops in Belarus, as it is annually observed in crops and is highly harmful. Spring triticale is a perspective crop in our country with a high yield potential and grain quality, which, as known, decreases due to diseases development. There is little information on the varieties disease susceptibility, development peculiarities and species composition of septoria blotch of spring triticale, which determined the relevance of our research subject. The paper presents the results of studies in 2015-2019 on susceptibility of spring triticale varieties Uzor, Doublet, Sadko to septoria leaf and head blotch, peculiarities of the disease development depending on weather conditions were revealed and the species composition of pathogens of septoria leaf blotch was determined. It has been determined that severity of septoria leaf blotch by the end of early – soft dough of grain stage reached 36.6 %. Based on calculation of area under the disease progress curve, no significant differences were found in severity of septoria leaf blotch depending on the variety. Severity of septoria head blotch reached 22.7 % by the end of growing season. Direct dependences of septoria leaf and head blotch development on the amount of precipitation have been established, and a close correlation between the severity of septoria head blotch and septoria leaf blotch has been revealed. The species composition of septoria leaf blotch is represented by the fungi Parastagonospora nodorum, Parastagonospora avenae f. sp. triticae and Zymoseptoria tritici. The dominant species was P. nodorum, its frequency reached 99.2 % depending on the variety and growth stage of spring triticale, the second most common fungus was P. avenae f. sp. triticae - up to 58.6 %. For the first time in our country, in-depth research has been carried out to study septoria leaf and head blotch of spring triticale, the results obtained will serve as the basis for development of a protection system.

Data mining of digital phytosanitary

methods of data mining were used to predict the Septoria leaf blotch of wheat. A system has been developed that allows parallel forecasting with the same data set using the methods of an artificial neural network, a decision tree, and a naive Bayesian classifier. The system allows you to interactively adjust the design parameters for each of the methods, see the results obtained and evaluate their effectiveness.

Peculiarities of action and retrospective analysis of fungicides efficacy for protection of soft winter wheat against leaf diseases

The data on the efficacy of 40 fungicides for protection of soft winter wheat against leaf diseases during 2010–2019 are demonstrated. Biological efficacy is calculated based upon the area under the curve of disease development. Biological and economical efficacy of those compounds has been analyzed depending on the number of components, as well as chemical classes of active agents in those compounds. The highest biological efficacy of one-component fungicides against powdery mildew has been recorded for those containing proquinazid, tebuconazole and metrafenone – 69.9–79.3 %. Among 23 two-component fungicides the higher efficacy (82.1–84.3 %) against powdery mildew has been recorded for the fungicides containing azole combined with morpholine. Biological efficacy against Septoria leaf blotch has varied from 64.7 to 88.0 % depending on fungicide composition. Among three-component fungicides the efficacy against powdery mildew has varied from 59.5 to 82.8 %, and against Septoria leaf blotch it has varied from 59.8 to 89.9 %. As a result of the diseases severity decrease due to the fungicide application the saved yield has reached 9.9 centner of grain per hectare.