Net Blotch Disease Research Articles

Linear Discriminant Analysis for Predicting Net Blotch Severity in Spring Barley with Meteorological Data in Finland

Predictive information on plant diseases could help to reduce and optimize the usage of pesticides in agriculture. This research presents classification procedures with linear discriminant analysis to predict three possible severity levels of net blotch in spring barley in Finland. The weather data utilized for classification included mathematical transformations, namely features of outdoor temperature and air humidity with calculated dew point temperature values. Historical field observations of net blotch density were utilized as a target class for the identification of classifiers. The performance of classifiers was analyzed in sliding data windows of two weeks with selected, cumulative, summed feature values. According to classification results from 36 yearly data sets, the prediction of net blotch occurrence in spring barley in Finland can be considered as a linearly separable classification task. Furthermore, this can be achieved with linear discriminant analysis by combining the output probabilities of separate binary classifiers identified for each severity level of net blotch disease. In this case, perfect classification with a resolution of three different net blotch severity levels was achieved during the first 50 days from the beginning of the growing season. This strongly suggests that real-time classification based on a few weather variables measured on a daily basis can be applied to estimate the severity of net blotch in advance. This allows application of the principles of integrated pest management (IPM) and usage of pesticides only when there is a proven need.

Nitrogen fertilization management and seeding density differently affect net blotch incidence and grain yield in one two-row and one six-row cultivar of barley

A two-year field experiment was carried out on barley (Hordeum vulgare L.) to test the effect of cultivar, N fertilization management and seeding density on crop growth, net blotch (NB) disease occurrence and yield. The three variables were factorially combined in a split-split-plot design as follows: 1) two barley cultivars, one two-row (H. v. distichum, cv Callas) and one six-row (H. v. hexastichum, cv Azzurro); 2) four N application schedules differing for rates and/or timing of N supply: unfertilized control; fertilized with 35kgha-1 of N at BBCH29 plus 30kgha-1 of N at BBCH31; fertilized with 70kgha-1 of N at BBCH29 plus 60kgha-1 of N at BBCH31; fertilized with 130kgha-1 of N simultaneously at BBCH31; 3) four seeding densities: 100, 200, 400 and 800 viable seeds m2.The three variables affected crop growth and NB occurrence resulting in different grain yield and quality. Results varied with the seasonal trend, in particular with rainfall regime and air temperature, for their possible effect on soil N dynamics and the presence of NB, which resulted in different source capacity, and for their effect on grain setting and filling, i.e., the sink capacity. Both N fertilization and seeding density increased NB pressure, with seeding density affecting the disease even under unfavourable weather conditions for NB development. At the maximum N fertilization rate, delaying N application helped limit plant height and the related risk of lodging, as well as NB symptoms, resulting in greater hectolitre weight and protein content together with no appreciable decrease of grain yield, provided seeding density was close to optimal (i.e., 400 seeds m-2) or higher.

Deep Learning-Based Barley Disease Quantification for Sustainable Crop Production.

Net blotch disease caused by Drechslera teres is a major fungal disease that affects barley (Hordeum vulgare) plants and can result in significant crop losses. In this study, we developed a deep learning model to quantify net blotch disease symptoms on different days postinfection on seedling leaves using Cascade R-CNN (region-based convolutional neural network) and U-Net (a convolutional neural network) architectures. We used a dataset of barley leaf images with annotations of net blotch disease to train and evaluate the model. The model achieved an accuracy of 95% for Cascade R-CNN in net blotch disease detection and a Jaccard index score of 0.99, indicating high accuracy in disease quantification and location. The combination of Cascade R-CNN and U-Net architectures improved the detection of small and irregularly shaped lesions in the images at 4 days postinfection, leading to better disease quantification. To validate the model developed, we compared the results obtained by automated measurement with a classical method (necrosis diameter measurement) and a pathogen detection by real-time PCR. The proposed deep learning model could be used in automated systems for disease quantification and to screen the efficacy of potential biocontrol agents to protect against disease.

Do Growers Using Solo Fungicides Affect the Durability of Disease Control of Growers Using Mixtures and Alternations? The Case of Spot-Form Net Blotch in Western Australia.

Growers often use alternations or mixtures of fungicides to slow down the development of resistance to fungicides. However, within a landscape, some growers will implement such resistance management methods, whereas others do not, and may even apply solo components of the resistance management program. We investigated whether growers using solo components of resistant management programs affect the durability of disease control in fields of those who implement fungicide resistance management. We developed a spatially implicit semidiscrete epidemiological model for the development of fungicide resistance. The model simulates the development of epidemics of spot-form net blotch disease, caused by the pathogen Pyrenophora teres f. maculata. The landscape comprises three types of fields, grouped according to their treatment program, with spore dispersal between fields early in the cropping season. In one field type, a fungicide resistance management method is implemented, whereas in the two others, it is not, with one of these field types using a component of the fungicide resistance management program. The output of the model suggests that the use of component fungicides does affect the durability of disease control for growers using resistance management programs. The magnitude of the effect depends on the characteristics of the pathosystem, the degree of inoculum mixing between fields, and the resistance management program being used. Additionally, although increasing the amount of the solo component in the landscape generally decreases the lifespan within which the resistance management program provides effective control, situations exist where the lifespan may be minimized at intermediate levels of the solo component fungicide. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Virulence Spectra of Hungarian Pyrenophora teres f. teres Isolates Collected from Experimental Fields Show Continuous Variation without Specific Isolate × Barley Differential Interactions.

Pyrenophora teres f. teres (Ptt), the causal agent of net form net blotch (NFNB) disease, is an important and widespread pathogen of barley. This study aimed to quantify and characterize the virulence of Ptt isolates collected from experimental fields of barley in Hungary. Infection responses across 20 barley differentials were obtained from seedling assays of 34 Ptt isolates collected from three Hungarian breeding stations between 2008 and 2018. Twenty-eight Ptt pathotypes were identified. Correspondence analysis followed by hierarchical clustering on the principal components and host-by-pathogen GGE biplots suggested a continuous range of virulence and an absence of specific isolate × barley differential interactions. The isolates were classified into four isolate groups (IG) using agglomerative hierarchical clustering. One IG could be distinguished from other IGs based on avirulence/virulence on one to five barley differentials. Several barley differentials expressed strong resistance against multiple Ptt isolates and may be useful in the development of NFNB-resistant barley cultivars in Hungary. Our results emphasize that the previously developed international barley differential set needs to be improved and adapted to the Hungarian Ptt population. This is the first report on the pathogenic variations of Ptt in Hungary.

Sensitivity of Argentine Pyrenophora teres f. teres isolates to different fungicide mixtures

Net blotch disease, caused by Pyrenophora teres f. teres (Ptt), is one of the most serious diseases of barley in Argentina. The in vitro sensitivity profile of Ptt to different fungicide mixtures currently used in Argentina was determined in isolates from different localities. Mycelial growth inhibition was measured, and the 50% inhibitory concentration (EC50) was estimated by simple logarithmic regression. In addition, the in vivo sensitivity of Ptt to the application of fluxapyroxad 5% + epoxiconazole 5% + pyraclostrobin 8.1% (FEP) was evaluated in greenhouse and field trials. The EC50 values ranged from 0.004 to 0.527 µg/mL, indicating that the fungicide mixtures tested were highly fungitoxic to all Ptt isolates tested. The in vivo and field fungicide efficacy averaged 99.9% and 79.5%, confirming a correlation between in vitro and in vivo sensitivity. The fungicide mixtures evaluated here were all highly fungitoxic and efficient for managing net blotch.

Innovative approach to diagnosing the development of net blotch in winter barley

The article demonstrates the possibility of applying intelligent digital technologies to forecast the development of net blotch disease in winter barley caused by Pyrenophora teres. The obtained intelligent solution in the form of a binary decision tree has the ability to determine scenarios of net blotch development into three classes: depressive, moderate, and epiphytotic. To effectively train the model during the period from 2021 to 2023, field and laboratory experiments were conducted on the research sites of the Federal Research Center of Biological Plant Protection. The experiments collected data on the degree of leaf damage, the type of resistance of the variety, the growth phase at which primary infection occurred, and the average relative air humidity during the vegetation period in which infection occurred. The total sample size was 249 observations. The trained model demonstrated high classification accuracy on both the training and test sets, with an accuracy rate exceeding 0.96 and 0.92, respectively. The study shows that the innovative method discussed in the article for forecasting the development of net blotch in winter barley can be successfully integrated into the overall strategy of phytosanitary diagnostics of grain crops, including barley.

Immunological assessment of winter barley cultivars against leaf net blotch

Immunological assessment of winter barley varieties sown in the south of Russia in relation to leaf net blotch infestation for further use in agricultural production has been carried out. Barley net blotch is dominant in the pathologic complex of barley diseases worldwide. The pathophysiological processes of infection development depend on the type of resistance of the variety. Net blotch on resistant varieties is noted as small dark rounded spots. Infection often occurs as a result of mechanical damage to the leaf plate. The symptoms of net blotch disease on a susceptible variety have a characteristic reticulate pattern with pronounced necrosis and extensive chlorosis. One of the main ways to protect crops from the disease is the cultivation of resistant varieties. The study was conducted during the growing seasons of 2020–2022 on artificial infectious background in the sprouting phase phase of the vegetation experiment and in the adult plant on the natural infectious background in field conditions. 10 varieties of winter barley of domestic and foreign selection were selected. Immunological assessment in the sprouting phase revealed two varieties resistant to leaf net blotch, score: Vivat (1.7) and Kvant (1.6); the varieties Artel (3.8), Fox-1 (2.3) of domestic selection and Carioca (2.7) of foreign selection showed moderate resistance. Field moderate resistance was detected in four winter barley varieties, %: Vivat (18.3), Kvant (26.6), Marusya (19.9), Fox-1 (24.9). Immunological assessment of barley varieties recommended for sowing in the south of Russia is one of the main components in the strategy of increasing the efficiency of plant protection measures and improving the ecological component of crops.

Field Evaluation of Fungicides and Host Plant Resistance Against Spot Form of Net Blotch (Pyrenophora Teres F. Maculata) Disease of Barley in South Tigray, Ethiopia

Field Evaluation of Fungicides and Host Plant Resistance Against Spot Form of Net Blotch (Pyrenophora Teres F. Maculata) Disease of Barley in South Tigray, Ethiopia

Identification of novel and stable genomic regions associated with barley resistance to spot form net blotch disease under different temperature conditions during the reproductive stage

AbstractSpot form net blotch (SFNB) is one of the most important barley diseases in the world; abiotic stresses caused by climate change are also a problem for cultivation of cereals, including barley, on a global level. Identifying stable genomic regions associated with resistance to SFNB in different temperature conditions at the reproductive stage can accelerate the process of producing new cultivars resistant to this disease. In this study, 103 F8 lines, resulting from the cross of cultivars Kavir and Badia, were cultivated in three years on three different dates. After artificial inoculation with Pyrenophora teres f. maculata Gonbad Kavous isolate, the plants were evaluated at the adult stage. The planting dates were chosen so that during early, conventional and delayed planting dates, the reproductive stage of the lines coincided with cold, non‐thermal and heat stress conditions, respectively. A genome‐wide composite interval mapping method was used to identify quantitative trait loci (QTLs) controlling SFNB and estimate the effect of each of them. In the cold, non‐thermal and heat stress conditions at the reproductive stage, three (three major), four (two major) and six (one major) stable resistance QTLs against SFNB were detected, respectively. The stable QTLs of resistance including QRPtma‐2H, QRPtma‐3H and QRPtma‐7H were located on chromosomes 2H, 3H and 7H, respectively. After flanking markers confirm the resistance of QTLs to SFNB, the SCoT7‐C, ISJ17‐B and Bmac0144k markers can be used in the screening resistance of cultivars under non‐thermal and heat stress conditions. Moreover, the Bmac0282b and Ebmatc0016 markers can be used for screening resistance of cultivars under cold stress conditions in marker‐assisted selection projects.

Digital solutions in the system of intelligent crop monitoring

The paper is dedicated to the intelligent diagnosis of net blotch disease in winter barley using computer vision methods. The authors propose a solution that allows diagnosing and segmenting the disease on plant leaves without the involvement of a human expert. The proposed approach demonstrates high modeling quality results, confirmed by visual analysis.

Effectiveness of fungicides with different modes of action against net blotch disease of two-rowed spring barley

Net blotch disease caused by Pyrenophora teres is one of the most damaging fungal diseases of barley crop. This study screened comparatively the effectiveness of eleven fungicide products applied to malting barley (Hordeum vulgare L. conv. distichum Alef.) cultivar ‘Daciana’ in conditions from Transylvania. After fungicide treatment, the net blotch disease index decreased an average of 70.37-78.04% relative to untreated control. Fungicide application ensured an average of 28.66% grain yield increase, 7.51% thousand grains weight increase and 4.36% grain starch content increase relative to untreated control. Top performance was obtained by using products that contained demethylation inhibitors targeting sterol biosynthesis in combination with other active substances with a different mode of action particularly targeting mitochondrial respiration. It is a difficult task to achieve top performance on all dimensions: strict disease suppression, high quantity and quality grain yields. Preventing the occurrence of pathogen resistance to fungicide and minimizing negative effect on crop as well as remanence in the plant, are the main challenges for fungicide use and should receive further attention.

Determination of The Seedling Reactions of Some Two-Rowed Barley Landraces Maintained at Osman Tosun Gene Bank to Pyrenophora Teres F. Teres

Seedling stage reactions of thirty-eight 2-rowed barley landraces representing different areas of Turkey obtained from Osman Tosun Gene Bank to two Pyrenophora teres f. teres isolates were evaluated. In addition, barley cultivars Bülbül 89 and Avcı 2002 were included. Landraces exhibited different reactions to the disease and their reactions ranged from resistant- moderately resistant to susceptible. Landrace number 33 obtained from Diyarbakır was found the most resistant to the disease compared to all other landraces whereas landrace number 10 obtained from Bilecik-Söğüt, and cultivar Bülbül 89 were the most susceptible. The majority of the landraces were classified between the Moderately Resistant-Moderately Susceptible to Moderately Susceptible-Susceptible. Landrace number 33 exhibited Resistant-Moderately Resistant reactions to both isolates. This landrace from Diyarbakır could be used as the seed source and in the breeding studies for obtaining barley cultivars resistant to the net form of net blotch disease.

Investigating InVitro Mating Preference Between or Within the Two Forms of Pyrenophora teres and Its Hybrids.

Net blotch diseases result in significant yield losses to barley industries worldwide. They occur as net-form and spot-form net blotch caused by Pyrenophora teres f. teres and P. teres f. maculata, respectively. Hybridization between the forms was proposed to be rare, but recent identifications of field hybrids has renewed interest in the frequency and mechanisms underlying hybridization. This study investigates the mating preference of P. teres f. teres, P. teres f. maculata, and laboratory-produced hybrids invitro, using 24 different isolates and four different experimental setups. Two crosses in our study produced ascospores during two intervals separated by a 32- to 35-day period of no ascospore production. For these crosses, P. teres f. teres isolates mated with isolates of the same form during the early ascospore production interval, and produced hybrids during the later interval. P. teres f. maculata isolates did not mate with isolates of the same form, but instead hybridized with P. teres f. teres isolates. Analyses based on DArTseq markers confirmed that laboratory-produced hybrids, when given the choice to mate with both P. teres f. teres and P. teres f. maculata, mated with P. teres f. teres isolates. These results unravel a novel concept that P. teres f. teres seems to have a greater reproduction vigor than P. teres f. maculata, which could lead to increased prevalence of hybrid incidences invivo.

Virulence of Icelandic Pyrenophora teres f. teres populations and resistance of Icelandic spring barley lines

The causal agent of the barley net blotch disease, Pyrenophora teres, is known for its high level of diversity due to sexual reproduction. Different pathotypes, defined by a virulence combination, even within the same fields are frequently found and virulence between locations can vary considerably. Evaluation of virulence patterns of a pathogen population is essential for breeding resistant cultivars suitable for specific locations. To identify virulence patterns in Icelandic Pyrenophora teres f. teres (Ptt) isolates, twenty single spore isolates of Ptt were collected from seven locations in Iceland and analysed with AFLP markers. Principle Coordinate Analysis (PCoA) revealed Icelandic Ptt isolates clustering away from reference isolates from Austria, Finland, Sweden, Switzerland, UK, and USA. Hierarchical clustering grouped the Icelandic isolates into three distinct groups. Furthermore, the virulence of these twenty isolates was tested on 16 barley differential lines and revealed high variation in their virulence. Twenty-one barley cultivars commonly used in Iceland showed high susceptibility towards inoculation with Icelandic Ptt isolates.

Population Structure of Pyrenophora teres f. teres Barley Pathogens from Different Continents.

Net form net blotch disease, caused by Pyrenophora teres f. teres, results in significant yield losses to barley industries. Up-to-date knowledge of the genetic diversity and structure of pathogen populations is critical for elucidating the disease epidemiology and unraveling pathogen survival and dispersal mechanisms. Thus, this study investigated long-distance dispersal and adaptation by analyzing the genetic structure of 250 P. teres f. teres isolates collected from Australia, Canada, Hungary, and Republic of South Africa (RSA), and historical isolates from Canada, Denmark, Japan, and Sweden. The population genetic structure detected by discriminant analysis of principal components, with the use of 5,890 Diversity Arrays Technology markers, revealed the presence of four clusters. Two of these contained isolates from all regions, and all isolates from RSA were grouped in these two. Australia and Hungary showed three clusters each. One of the Australian clusters contained only Australian isolates. One of the Hungarian clusters contained only Hungarian isolates and one Danish isolate. STRUCTURE analysis indicated that some isolates from Australia and Hungary shared recent ancestry with RSA, Canada, and historical isolates and were thus admixed. Subdivisions of the neighbor joining network indicated that isolates from distinct countries were closely related, suggesting that multiple introduction events conferred genetic heterogeneity in these countries. Through a neighbor joining analysis and amplification with form-specific DNA markers, we detected two hybrid isolates, CBS 281.31 from Japan and H-919 from Hungary, collected in 1931 and 2018, respectively. These results provide a foundation for exploring improved management of disease incursions and pathogen control through strategic deployment of resistance.

An optimized sporulation method for the wheat fungal pathogen Pyrenophora tritici-repentis

BackgroundThe necrotrophic fungal pathogen Pyrenophora tritici-repentis (Ptr) causes tan (syn. yellow) spot of wheat and accounts for significant yield losses worldwide. Understanding the molecular mechanisms of this economically important crop disease is crucial to counteract the yield and quality losses of wheat globally. Substantial progress has been made to comprehend the race structure of this phytopathogen based on its production of necrotrophic effectors and genomic resources of Ptr. However, one limitation for studying Ptr in a laboratory environment is the difficulty to isolate high spore numbers from vegetative growth with mycelial contamination common. These limitations reduce the experimental tractability of Ptr.ResultsHere, we optimized a multitude of parameters and report a sporulation method for Ptr that yields robust, high quality and pure spores. Our methodology encompasses simple and reproducible plugging and harvesting techniques, resulting in spore yields up to 1500 fold more than the current sporulation methods and was tested on multiple isolates and races of Ptr as well as an additional seven modern Australian Ptr isolates. Moreover, this method also increased purity and spore harvest numbers for two closely related fungal pathogens (Pyrenophora teres f. maculata and f. teres) that cause net blotch diseases in barley (Hordeum vulgare), highlighting the usability of this optimized sporulation protocol for the wider research community.ConclusionsLarge-scale spore infection and virulence assays are essential for the screening of wheat and barley cultivars and combined with the genetic mapping of these populations allows pinpointing and exploiting sources of host genetic resistance. We anticipate that improvements in spore numbers and purity will further advance research to increase our understanding of the pathogenicity mechanisms of these important fungal pathogens.

Sexual recombination and genetic diversity in Iranian populations of Pyrenophora teres

AbstractPyrenophora teres is an economically important pathogen of barley worldwide causing net blotch diseases. In this study, the frequency and mating‐type alleles's distribution as well as genetic diversity of P. teres were assessed on micro‐spatial scale and also on macro‐geographical scale to find out whether a sexual cycle is possible within its Iranian populations. A multiplex PCR assay was developed for simultaneous identification and recognition of P. teres f. teres and P. teres f. maculata and to screen their mating‐type alleles. 118 isolates of P. teres were procured from barley fields of East Azerbaijan province during 2017–2018. Among 89 isolates of P. teres f. teres examined, 39 isolates were found as MAT1‐1 and 50 isolates were found to be MAT1‐2. Among 29 isolates of P. teres f. maculata examined, 17 isolates were found as MAT1‐1 and 12 isolates were found to be MAT1‐2 with the dominancy belonging to MAT1‐1. Nearly same mating‐type alleles distribution within and between various populations of P. teres f. teres (1:1 ratio; χ2 = 1.36) and P. teres f. maculata (1:1 ratio; χ2 = 0.862) was observed. Genetic diversity assessment of 118 P. teres isolates was carried out through inter‐simple sequence repeat (ISSR) analysis and results revealed that there was 70.83% and 63.89% polymorphism among the isolates of P. teres f. teres and P. teres f. maculata, respectively. No relation was observed between the isolates and their mating as well as geographical type. Among collected isolates (89 P. teres f. teres and 29 P. teres f. maculata isolates), the gene diversity was generally similar (h = 0.280 and h = 0.238 for P. teres f. teres and P. teres f. maculata, respectively). Based on our findings and referring to the prior data on the structure of P. teres population, we conclude that in the majority of tested areas, this fungal species might have the potential to undergo regular sexual recombination cycles.

The Use of an Alternative Differential Set for Determination of Pyrenophora teres f. maculata Pathotypes

Pyrenophora teres f. maculata incites spot form of barley net blotch disease. For determination of Pyrenophora teres f. maculata pathotypes, a differential set consisted of 22 international cultivars and genotypes and a susceptible Turkish barley variety Bülbül 89 were tested using 45 isolates obtained from different regions of Turkey. Nineteen pathotypes were determined out of 45 isolates used. It appears that this differential set could be useful for determination of P. teres f. maculata pathotypes.

Evaluation of Different Fungicides Efficacy Against Net Blotch (<i>Pyrenophorateres</i>) and Leaf Rust (<i>Pucciniahordei</i>) Diseases of Barley, South-Eastern Ethiopia

Barley (Hordeum vulgare L.) is one of the most important staple food crops in the highlands of Ethiopia. However, the production and productivity of barley are constrained by various a biotic and biotic stresses. Among the biotic stresses, barley net blotch and leaf rust are the most destructive diseases of barley. The field experiment was conducted at three locations (Sinana, Robe and Goba) for two consecutive years (2017 and 2018) crop growing seasons. The objective of this study was to evaluate the effectiveness of different fungicides for the management of barley net blotch and leaf rust diseases. Treatments were composed of one highly susceptible barley variety (Guta) to major barley diseases and seven systemic foliar fungicides (Tilt250EC (PropiconazoleEC), RexDuo (Epoxiconazole+Thiophanatemethyl), AmistarXtra280SC (Azoxystrodin+Cyproconazole), OperaMax (F500 (85G/L)) (Pyraclostrobin+Epoxiconazole), Natura250EC (Tebuconazole250EC), Nativo300SC (Tebuconazole50%+Trifloxystrobin75WG), Artea330EC (Propiconazole+Cyproconazole) and untreated plot (control) were arranged in a randomized complete block design with three replications. The present study revealed that Tilt 250 EC and Artea 330 EC fungicides provided significant grain yield increment over untreated plot (control) across the three sites. The highest grain yield obtained from plots treated by Tilt 250 EC (2778.9 kgha-1) and Artea 330 EC (2538.9 kgha-1), which was 40% and 35% higher than the untreated control, respectively. The most effective among all tested fungicides, Artea 330 EC and Tilt 250 EC applied at the rate of 0.5 litre per hectare which reached 98.63% and 94.54% efficacy in controlling barley rust disease, respectively. Likewise, Tilt 250 EC and Artea 330 EC also relatively reduced net blotch disease severity to the lowest level. Likely, Tilt 250 EC and Artea 330 EC revealed that 11.4 quintal ha-1 and 9 quintal ha-1 yield advantage over untreated plot (control). The highest net benefit obtained from the application of Tilt 250 EC followed by Artea 330 EC fungicides as compared to the untreated plot. The application of Tilt 250 EC and Artea 330 EC fungicides gave maximum economic profitability with an attractive acceptable return to control leaf rust and a net blotch of barley. One time application of Tilt 250 EC and Artea 330 EC fungicides is the most effective in controlling barley leaf rust and net blotch diseases at the time of disease appearance.