Stem Base Diseases Research Articles

Yield Losses and Control by Sedaxane and Fludioxonil of Soilborne Rhizoctonia, Microdochium, and Fusarium Species in Winter Wheat.

Soilborne Rhizoctonia, Microdochium, and Fusarium species are major causal agents of seedling and stem-base diseases of wheat. Currently, seed treatments are considered the most effective solution for their control. Rhizoctonia solani anastomosis groups (AGs) 2-1 and 5, R. cerealis, Microdochium, and Fusarium spp., were used in series of field experiments to determine their capability to cause soilborne and stem-base disease and to quantify their comparative losses in the establishment and yield of wheat. The effectiveness and response to seed treatment formulated with 10 g sedaxane and 5 g fludioxonil 100 kg-1 against these soilborne pathogens were also determined. Our results showed that damping-off caused by soilborne R. cerealis was associated with significant reductions in the emergence and establishment, resulting in stunted growth and low plant numbers. The pathogen also caused sharp eyespot associated with reductions in the ear partitioning index. R. solani AG 2-1 and AG 5 were weakly pathogenic and failed to cause significant damping-off, root rot, and stem-base disease in wheat. Fusarium graminearum and F. culmorum applied as soilborne inoculum failed to cause severe disease. Microdochium spp. caused brown foot rot disease and soilborne M. nivale reduced wheat emergence. Applications of sedaxane and fludioxonil increased plant emergence and reduced damping-off, early stem-base disease, and brown foot rot, thus providing protection against multiple soilborne pathogens. R. cerealis reduced the thousand grain weight by 3.6%, whereas seed treatment including fludioxonil and sedaxane against soilborne R. cerealis or M. nivale resulted in a 4% yield increase.

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.

Novel Multiplex and Loop-Mediated Isothermal Amplification Assays for Rapid Species and Mating-Type Identification of Oculimacula acuformis and O. yallundae (Causal Agents of Cereal Eyespot), and Application for Detection of Ascospore Dispersal and In Planta Use.

Eyespot, caused by the related fungal pathogens Oculimacula acuformis and O. yallundae, is an important cereal stem-base disease in temperate parts of the world. Both species are dispersed mainly by splash-dispersed conidia but are also known to undergo sexual reproduction, yielding apothecia containing ascospores. Field diagnosis of eyespot can be challenging, with other pathogens causing similar symptoms, which complicates eyespot management strategies. Differences between O. acuformis and O. yallundae (e.g., host pathogenicity and fungicide sensitivity) require that both be targeted for effective disease management. Here, we develop and apply two molecular methods for species-specific and mating-type (MAT1-1 or MAT1-2) discrimination of O. acuformis and O. yallundae isolates. First, a multiplex PCR-based diagnostic assay targeting the MAT idiomorph region was developed, allowing simultaneous determination of both species and mating type. This multiplex PCR assay was successfully applied to type a global collection of isolates. Second, the development of loop-mediated isothermal amplification (LAMP) assays targeting β-tubulin sequences, which allow fast (<9 min) species-specific discrimination of global O. acuformis and O. yallundae isolates, is described. The LAMP assay can detect very small amounts of target DNA (1 pg) and was successfully applied in planta. In addition, mating-type-specific LAMP assays were also developed for rapid (<12 min) genotyping of O. acuformis and O. yallundae isolates. Finally, the multiplex PCR-based diagnostic was applied, in conjunction with spore trapping in field experiments, to provide evidence of the wind dispersal of ascospores from a diseased crop. The results indicate an important role of the sexual cycle in the dispersal of eyespot.

The Effect of Foliar Fertilization with Micronutrients on the Incidence and Severity of Leaf and Stem-base Diseases in Winter Triticale (x Triticosecale Witmm.) and Winter Rye (Secale cereale L.)

Winter triticale (Triticale) cv. Dinaro and winter rye (Secale cereale L.) cv. Dankowskie Diament were grown in 2012 and 2013 in a field-plot experiment in Tomaszkowo near Olsztyn (NE Poland). The experiment consisted of 7 treatments: absolute control (without fertilizers or the growth stimulator), control-NPK fertilizer, NPK fertilizer + micronutrients applied alone or in combination (4 treatments), NPK fertilizer + Nano-Gro growth stimulator. The severity of disease symptoms on the leaves and stem-bases of triticale and rye was evaluated throughout the growing season. Symptoms of powdery mildew on the leaves of winter triticale and winter rye were noted only in the growing season of 2013, and disease severity remained at a low level. In the growing season of 2012, weather conditions were conducive to the spread of Septoria tritici blotch (STB) and brown rust on triticale (the highest values of infection index were 41.6 and 23.8%, respectively), and scald and brown rust on rye (29.0 and 38.1%, respectively). Foliar application of micronutrients influenced the rates of infections caused by Zymoseptoria tritici and Puccinia recondita f. sp. tritici on triticale leaves. Symptoms of eyespot and Fusarium foot and root rot were noted on the stem-bases of both cereal species, whereas symptoms of take-all disease and sharp eyespot were observed sporadically. Significant differences were found between treatments in the severity of infections caused by Gaeumannomyces graminis on the stem-bases of triticale, and by Tapesia spp. and Rhizoctonia spp. on the stem-bases of rye.

Population dynamics of Rhizoctonia, Oculimacula, and Microdochium species in soil, roots, and stems of English wheat crops

AbstractThis study aimed to elucidate the population dynamics of Rhizoctonia, Oculimacula, and Microdochium species, causing the stem base disease complex of sharp eyespot, eyespot, and brown foot rot in cereals. Pathogen DNA in soil, roots, and stem fractions, and disease expression were quantified in 102 English wheat fields in two seasons. Weather data for each site was collected to determine patterns that correlate with assessed diseases. Oculimacula spp. (66%) and R. solani AG 2‐1 (63%) were most frequently detected in soil, followed by R. cerealis (54%) and Microdochium spp. (33%). Oculimacula spp. (89%) and R. cerealis (56%) predominated on roots and soil but were not associated with root rot symptoms, suggesting that these species used soil and roots for survival and as inoculum source. M. nivale was more frequently detected than M. majus on stems up to GS 21–30 and co‐occurred on plant samples with O. acuformis. O. yallundae had higher DNA concentration than O. acuformis at the lower 5 cm basal region at GS 37–45. R. cerealis predominated in the upper 15 cm above the base beyond stem extension. Brown foot rot by Microdochium spp. was favoured by cool and wet autumns/winters and dominated in English wheat. Eyespot and sharp eyespot disease index by Oculimacula spp. and R. cerealis, respectively, correlated with wet/humid springs and summers. Results suggested that stem base pathogens generally coexisted; however, their abundance in time and space was influenced by favourable weather patterns and host development, with niche differentiation after stem extension.

Wheat stem base diseases and their causal agents

Wheat stem base disease is an important disease complex, caused by various pathogens that are characterized by variable life cycles and ecological requirements. Wheat stem bases with symptoms of different stem diseases were collected in 2012-2018. Causal agents and other fungi were identified by mycological and molecular genetic methods. A total of 6787 isolates of fungi were obtained and identified to the genera/species level. Out of the total number of isolates, 50% belonged to causal agents of stem base diseases, 10% were causal agents of leaf spots, and 8% were different saprotrophs. Fungi from the genera Fusarium (51%) and Oculimacula (35%) were the most dominant causal agents of stem base diseases. An increasing occurrence of Microdochium nivale and M. bolleyi (totally 15%) was noticed. The dominant species of Fusarium were F. culmorum, F. avenaceum and F. tricinctum; other species were detected only in some cases. An unexpectedly high proportion (31%) of fungi from different ecological niches were isolated from wheat stems with stem base disease symptoms. Phaeosphaeria (most likely P. pontiformis) was the dominant fungus among non-pathogenic fungi. Further studies are required to clarify the interactions between this fungus, wheat, and causal agents of stem base diseases.

Effects of soil tillage and crop rotation on the development of wheat stem base diseases

Wheat stem base disease (WSD) is an important disease complex which can be caused by various pathogens with variable life cycles, ecological requirements and sensitivities to fungicides. Agronomic practices are considered important tools to control this disease complex and influence the spectrum of fungal communities in infected wheat stems. The aim of the present study was to determine the impact of crop rotation schemes and soil tillage methods on the development of WSD and to elucidate the spectrum of causal agents of this disease. The development of WSD was assessed in a two-factorial (soil tillage practice and crop rotation) experiment. The incidence of WSD was evaluated at the BBCH growth stages 83–85. Causal agents of WSD and other fungi were identified using molecular methods. The soil tillage method did not influence the development of WSD, but the impact of crop rotation was significant, and the cropping system where oilseed rape, barley and faba beans were included decreased disease levels. Members of the genera Oculimacula and Fusarium were the most prevalent fungi associated with WSD. Moreover, fungi from other taxonomic groups were detected, with Phaeosphaeria spp. being prevalent. An increasing occurrence of Microdochium spp. was also observed. In conclusion, agronomic practices influenced the level of WSD, but no distinct impact on the fungal spectrum was identified. Further investigation is required to clarify the roles that pathogens and fungi from other taxonomic groups play in the fungal–wheat relationship.

Effect of Exogenous Application of Methyl Jasmonate on the Lipid and Carbohydrate Content and Composition of Winter Triticale ( Triticosecale Wittm.) Grain and the Severity of Fungal Infections in Triticale Plants and Grain.

Kernels of winter triticale ( Triticosecale Wittm. cv. Dinaro) were analyzed. In the autumn of 2015, the effect of methyl jasmonate (MJ) on the germination of triticale kernels and the development of triticale seedlings was analyzed in a laboratory before kernels were sown in experimental plots. Kernels harvested from plots in August 2016 were analyzed to determine their lipid and carbohydrate content and composition and the severity of fungal infections. Triticale grain was harvested at full maturity. The plots were sprayed with MJ at concentrations of 10-6 to 10-3 M in the stem elongation stage (200 L/ha) and in the early milk stage (300 L/ha). Other preventive treatments, fungicides, pesticides, or foliar fertilizers were not applied. Lipids of triticale kernels contained 20 fatty acids (FAs) with the highest proportion of linoleic acid. Methyl jasmonate did not exert a significant effect on the FA composition of kernel lipids treated with the plant hormone during the growing season. Statistical analysis did not reveal significant ( p < 0.05) differences in the total content of soluble carbohydrates in control kernels and in the kernels collected from triticale plants treated with MJ. Methyl jasmonate applied at a concentration of 10-3 M in BBCH stages 54 and 73 reduced the prevalence of stem base, leaf, and spike diseases. However, the severity of grain infections caused by mycotoxin-producing fungi increased in treatments where MJ was applied at a concentration of 10-5 M relative to the control treatment. The study describes the results noted in naturally infected plants and provides valuable inputs for agricultural practice, but further research is required to validate the presented findings.

Weather determines the occurrence of wheat stem base diseases in biogas cropping systems

Renewable energy produced at biogas plants has tremendously increased the demand for digestible biomass in central Europe over the last twenty years. As a consequence, new crop rotations combining conventional and recently introduced bioenergy crops are tested in long-term field trials. The aim of this work was to determine risks for soilborne wheat stem base diseases in new bioenergy crop rotations. Crop rotations tested consisted of maize, sorghum, cereals, grasslegume mixtures, and phacelia. Field trials with five rotations were established at four different sites in Germany, whereby winter wheat was grown at the end of each rotation. Field trials were set up in a block or strip plot design in 2005 and 2006. After eight years, stem base diseases of winter wheat were visually assessed during milk ripeness. ‘Random forests’, a non-parametric statistical method, was used to select the most important variables describing weather, soil productivity and rotation. Subsequently, disease incidences were modeled with generalized linear models. Disease incidence was high for Fusarium foot rot (47%), moderately high for eyespot (30%), and low for sharp eyespot (4%). An increasing number of days with high precipitation during six weeks after sowing, and less growing degree days from February through June led to higher eyespot incidence (R2 = 60%). Fusarium foot rot incidence was correlated to high mean precipitation during six weeks after sowing, and low number of growing degree days from February through June (R2 = 78%). In contrast to the eyespot model, year and region had additional explanatory power to the Fusarium foot rot model. Based on the results of this study we could show that annual weather patterns had a high impact on eyespot and Fusarium foot rot incidences, while the effect of rotation was low. Although unexplained site and year-specific effects require further investigations, weather patterns identified by applying an innovative variable selection method provide a valuable starting point for developing and improving forecasting models for Fusarium foot rot.

Resistance of winter wheat cultivars to eyespot and characterisation of causal agents of the disease

The reaction of ten winter wheat cultivars grown in the Czech Republic to inoculation with Oculimacula yallundae and Oculimacula acuformis was evaluated in a small plot trial. In a parallel field trial the natural occurrence of stem-base disease complex in six of the tested cultivars was assessed. Lower severity of eyespot (and/or stem-base diseases) was observed in cultivars possessing the resistance gene Pch1 (cvs Hermann, Annie, Princeps, Manager, and Rebell) in plots inoculated with Oculimacula spp. as well as in natural field conditions. A total of 468 wheat stem bases from the Czech Republic was screened by PCR to study the frequency of eyespot causal agents. The plants were colonised significantly more often by both species Oculimacula yallundae and O. acuformis together than separately.

RNAi as an emerging approach to control Fusarium head blight disease and mycotoxin contamination in cereals.

Fusarium graminearum is a major fungal pathogen of cereals worldwide, causing seedling, stem base and floral diseases, including Fusarium head blight (FHB). In addition to yield and quality losses, FHB contaminates cereal grain with mycotoxins, including deoxynivalenol, which are harmful to human, animal and ecosystem health. Currently, FHB control is only partially effective due to several intractable problems. RNA interference (RNAi) is a natural mechanism that regulates gene expression. RNAi has been exploited in the development of new genomic tools that allow the targeted silencing of genes of interest in many eukaryotes. Host‐induced gene silencing (HIGS) is a transgenic technology used to silence fungal genes in planta during attempted infection and thereby reduces disease levels. HIGS relies on the host plant's ability to produce mobile small interfering RNA molecules, generated from long double‐stranded RNA, which are complementary to targeted fungal genes. These molecules are transferred from the plant to invading fungi via an uncharacterised mechanism, to cause gene silencing. Here, we describe recent advances in RNAi‐mediated control of plant pathogenic fungi, highlighting the key advantages and disadvantages. We then discuss the developments and implications of combining HIGS with other methods of disease control. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

EFFECTS OF FARMING SYSTEM ON ROOT-ZONE FUNGAL POPULATIONS IN WHEAT

Effects of farming system on the composition of the root-zone microbiota and on the occurrence of root and stem-base diseases in winter wheat cv. Rywalka were analysed. The wheat was grown in organic, integrated and conventional systems of production and in monoculture over three years. Using classical methods, saprotrophic and pathogenic microorganisms, mainly fungi, were isolated from the root zone and identified on the basis of morphology and, where possible, designated as potential pathogens or antagonists. In roots, rhizoplane, and rhizosphere and non-rhizosphere soil the total frequencies of dominants (with frequency >5%) was 80.7- 98.7% and subdominants (with frequency 1–5%) was 0.5-14.5% and were similar in all production systems. Potential major soil-borne pathogens included Fusarium + Haematonectria. Potential pathogen antagonists included Chaetomium, Clonostachys, Gliomastix, Sarocladium and Trichoderma species. The low ratio of fungal pathogens : antagonists (Fusarium + Haematonectria : Clonostachys + Trichoderma spp.) in soil associated with lowest incidence of root and stem-base diseases, lower occurrence of Fusarium and Rhizoctonia in root and stem-base region and highest yield of grain in a conventional system for production of wheat cv. Rywalka confirms the cultivar’s suitability for high-input conventional farming. Benefits of microbiological approaches in the study of suitability of cultivar to a particular farming system is demonstrated.

Genetic Structure of Populations of the Wheat Sharp Eyespot Pathogen Rhizoctonia cerealis Anastomosis Group D Subgroup I in China.

Sharp eyespot on wheat is caused by Rhizoctonia cerealis anastomosis group D subgroup I (AG-DI) and is an economically important stem-base disease of wheat in temperate regions worldwide. However, the understanding about the field population structure of R. cerealis is limited. In this study, the genetic structure of four wheat-infecting populations in China was investigated using six microsatellite markers characterized from the transcriptome data of R. cerealis AG-DI. A total of 173 unique genotypes were identified among 235 fungal isolates. Departure from Hardy-Weinberg equilibrium, a significant degree of inbreeding, and a significant deficit in heterozygotes indicated a nonrandom mating pattern. Combining the low to intermediate degrees of gametic disequilibrium, although with high genotypic diversity and low to moderate clonal fractions, sexual reproduction probably existed, but the asexual reproduction should be the predominant reproductive mode. Structural analysis showed three gene pools among the four populations, which indicated the existence of three evolutionary origins of R. cerealis AG-DI. The long-distance movement of contaminated material, especially the infected seed, might have caused the moderate gene flow among these populations, which was consistent with the high differentiation among these populations. Overall, the genetic characteristics of the populations suggested a moderate evolutionary potential for R. cerealis AG-DI in China.

Long-term dynamics of causative agents of stem base diseases in winter wheat and reaction of Czech Oculimacula spp. and Microdochium spp. populations to prochloraz

Cereal stem base diseases occur in the Czech Republic every year. In Europe today, there is a trend towards more comprehensive strategies for growing and protecting crops with the aim of reducing risks to the environment and to health associated with pesticide residues. Precise knowledge as to the dynamics of causative agents of stem base disease may constitute an important part of the decision support system for cereal-growing strategies. Over 17 years (1999–2015), 482,219 plants were collected within the Czech Republic and visually inspected for stem base disease symptoms. An in vitro culture test was then conducted to determine the causative agents. During 2012–2015, the response of Oculimacula spp. and Microdochium spp. populations to prochloraz was tested. The most plants infected with Oculimacula spp. (>6 %) were detected in 2004, 2008, 2014 and 2015. The lowest infection rates were recorded in 2005, 2006, 2011 and 2012, when the level did not exceed 2 %. Microdochium spp. occurred most frequently in 2003, 2006 and 2013 (29–37 % incidence). Its lowest occurrence was recorded in 2014, when only 13 % of plants were infected. All isolates of Microdochium spp. were sensitive to prochloraz. Some isolates of Oculimacula spp. showed low to medium resistance (12 and 5, respectively, from 86 total isolates through the entire testing period). In all years, ED50 for the Oculimacula spp. population was ≤0.1 μg ml−1. ED50 for Microdochium spp. ranged between 0.01 and 0.06 μg ml−1.

The eyespot resistance genes Pch1 and Pch2 of wheat are not homoeoloci

Key messagePhenotyping and mapping data reveal that chromosome intervals containing eyespot resistance genesPch1 andPch2 on 7D and 7A, respectively, do not overlap, and thus, these genes are not homoeloci.Eyespot is a stem-base fungal disease of cereals growing in temperate regions. Two main resistances are currently available for use in wheat. Pch1 is a potent single major gene transferred to wheat from Aegilops ventricosa and located on the distal end of chromosome 7D. Pch2, a moderate resistance deriving from Cappelle Desprez, is located at the end of 7AL. The relative positions of Pch1 and Pch2 on 7D and 7A, respectively, suggest that they are homoeoloci. A single seed decent recombinant F7 population was used to refine the position of Pch2 on 7A. New markers designed to 7D also allowed the position of Pch1 to be further defined. We exploited the syntenic relationship between Brachypodium distachyon and wheat to develop 7A and 7D specific KASP markers tagging inter-varietal and interspecific SNPs and allow the comparison of the relative positions of Pch1 and Pch2 on 7D and 7A. Together, phenotyping and mapping data reveal that the intervals containing Pch1 and Pch2 do not overlap, and thus, they cannot be considered homoeloci. Using this information, we analysed two durum wheat lines carrying Pch1 on 7A to determine whether the Ae.ventricosa introgression extended into the region associated with Pch2. This identified that the introgression is distal to Pch2 on 7A, providing further evidence that the genes are not homoeoloci. However, it is feasible to use this material to pyramid Pch1 and Pch2 on 7A in a tetraploid background and also to increase the copy number of Pch1 in combination with Pch2 in a hexaploid background.

Changing fitness of a necrotrophic plant pathogen under increasing temperature.

Warmer temperatures associated with climate change are expected to have a direct impact on plant pathogens, challenging crops and altering plant disease profiles in the future. In this study, we have investigated the effect of increasing temperature on the pathogenic fitness of Fusarium pseudograminearum, an important necrotrophic plant pathogen associated with crown rot disease of wheat in Australia. Eleven wheat lines with different levels of crown rot resistance were artificially inoculated with F.pseudograminearum and maintained at four diurnal temperatures 15/15°C, 20/15°C, 25/15°C and 28/15°C in a controlled glasshouse. To quantify the success of F.pseudograminearum three fitness measures, these being disease severity, pathogen biomass in stem base and flag leaf node, and deoxynivalenol (DON) in stem base and flag leaf node of mature plants were used. F.pseudograminearum showed superior overall fitness at 15/15°C, and this was reduced with increasing temperature. Pathogen fitness was significantly influenced by the level of crown rot resistance of wheat lines, but the influence of line declined with increasing temperature. Lines that exhibited superior crown rot resistance in the field were generally associated with reduced overall pathogen fitness. However, the relative performance of the wheat lines was dependent on the measure of pathogen fitness, and lines that were associated with one reduced measure of pathogen fitness did not always reduce another. There was a strong correlation between DON in stem base tissue and disease severity, but length of browning was not a good predictor of Fusarium biomass in the stem base. We report that a combination of host resistance and rising temperature will reduce pathogen fitness under increasing temperature, but further studies combining the effect of rising CO2 are essential for more realistic assessments.

Wykorzystanie biostymulatora Nano-Gro i międzyplonu ścierniskowego jako czynnika fitosanitarnego w monokulturowej uprawie pszenicy ozimej

Summary One-factorial field experiment was conducted in 2010–2013. The aim of the study was to evaluate the usefulness of Nano-Gro biostimulant and stubble catch crop in reducing the occurrence of stem base diseases of winter wheat growing in continuous crop under traditional or reduced post-harvest and pre-sowing tillage and the influence of these factors on wheat productivity. The significantly higher infection of stems and roots of winter wheat growing in continuous crop as well as the decrease in grain yield by 12.3% were observed in relation to crop rotation. In plowing system the seed-dressing with Nano-Gro biostimulant and the combined use of that product with the annual plowing down stubble catch crop of white mustard significantly reduced the infection of stem base respectively by 28.7 and 21.9% compared with monoculture without regenerative practices. After tillage simplification stem base diseases reduction (by 17.5%) were found only after plowing down biomass of cat ch crop. The degree of the root system infection generally did not depend on tillage and regenerative practices but there was significant correlation between grain yield and index of root infection.

VLIV APLIKACE FUNGICIDŮ NA FUSARIÓZY OZIMÉ PŠENICE A DALŠÍ PŮVODCE STÉBLOLAMU

From 1999 to 2004 the occurence of fungi: Pseudocercosporella herpotrichoides (Fron.) and Fusarium spp. was evaluated in small plot field trials on seven varieties of winter wheat. The efficacy of fungicide protection against stem base diseases and influence on yields was monitored in field conditions in Velká Bystřice near Olomouc.For diagnostic of casual fungi two methods were used: 1. Method of coloring mycelium in stems, 2. Method of cultivation of mycelim on agar.Results from detection of casual fungi are following: Pseudocercosporella herpotrichoides (Fron.), Fusarium culmorum (W. G. Sm.) Sacc. and Fusarium graminearum Schwabe.For high efficacy of protection against roots and stem base disease the following fungicide variants should be applied: Sportak Alpha 1.5 l . ha−1 (BBCH 30)/Cerelux Plus 0.7 l . ha−1 (BBCH 51), Sportak HF 1 l . ha−1 (BBCH 30)/Cerelux Plus 0.7 l . ha−1, Alert S 1.0 l . ha−1 (BBCH 30/Cerelux Plus 0.7 l . ha−1 (BBCH 51). The application of fungicides positively influenced yields. Yield increased at average by10–20 % after the aplication but the rise in yields was not in total correlation with the efficacy. These results can be possibly used in the system of integral control of winter wheat against stem base disease in wheat.

Antagonistic yeasts competes for iron with winter wheat stem base pathogens

Aureobasidium pullulans and Sporobolomyces roseus are a saprotrophic yeasts fungi commonly found on the leaves of winter wheat and on wheat kernels. The objective of this study was to compare the inhibitory effects of two species of yeasts fungi, Aureobasidium pullulans var. pullulans (de Bary) G. Arnaud and Sporobolomyces roseus Kluyver & van Niel, on the causal agents of stem base diseases, Rhizoctonia cerealis v. d. Hoeven, Gaeumannomyces graminis (Sacc.) Arx & D. Olivier, Helgardia herpotrichoides (Fron) Crous & W. Gams, Fusarium oxysporum (Schlecht) Snyd. et Hans.) and Fusarium culmorum (W. G. Smith). A. pullulans showed stronger inhibitory activity than S. roseus. Among the 70 A. pullulans isolates tested in the study, 25 were capable of suppressing the colony growth of R. cerealis under in vitro conditions. This is the first study to show that A. pullulans competes for iron with stem base pathogens, in particular with fast-growing R. cerealis and F. culmorum. Under greenhouse conditions, A. pullulans protected winter wheat seedlings against infection caused by F. culmorum, from two to four times compared with the control, and its protective effect was determined by the infection susceptibility of wheat cultivars and the time interval between the application of A. pullulans and inoculation with F. culmorum.

Mining the Watkins collection of wheat landraces for novel sources of eyespot resistance

Eyespot is an economically important stem base disease of wheat caused by the soilborne fungal pathogens Oculimacula yallundae and Oculimacula acuformis. The most effective method of controlling the disease is host resistance. However, there are only three genetically characterized resistances in wheat varieties and further sources of resistance are required. Previous studies have identified resistances in wild relatives, but use of these resistances has been limited by linkage drag with deleterious traits exacerbated by low rates of recombination. Therefore, the identification of novel resistances in hexaploid wheat germplasm is desirable. The Watkins collection currently consists of 1056 hexaploid wheat landraces that represent global wheat diversity at the time of its collection in the 1920s and 1930s. As such, it may contain beneficial agronomic traits such as eyespot resistance. The Watkins collection was screened for resistance to O. yallundae based on a glasshouse test of all 1056 accessions and a polytunnel test of 44 accessions selected from a previous field trial. Resistant lines identified in these tests were retested against both O. yallundae and O. acuformis. This identified 17 accessions with resistance to one or both of the pathogen species. From these, two accessions (1190094.1 and 1190736.3) provided a high level of resistance to both pathogen species. An F4 population derived from accession 1190736.3 indicated that the resistance to O. acuformis in this accession is conferred by a single gene and therefore would be suitable for introgression into elite wheat varieties to provide an alternative source of eyespot resistance.