Search

Bread wheat (Triticum aestivum L.) is severely affected by stripe rust caused by Puccinia striiformis Westend. f. sp. tritici (Pst). This study was conducted to investigate pathogenicity of Pst isolates to bread wheat landraces grown in Ethiopia, establish stripe rust yield loss models and estimate variability in bread wheat quantitative traits. A greenhouse pot experiment was setup to assess seedling stage responses of landraces to Pst and a field study was conducted for adult plant stage evaluation. Among dominant isolates of Pst, Kubsa was the most virulent. Apart from the detection of resistance at the seedling stage study, a broad range of adult‐stage resistance was also observed which can confer durable resistance. Among single‐point models, the onset of severe infection at the development of heading stage causes significant yield loss by stripe rust. The integral yield loss model predicted a strong negative linear relationship between agronomic traits and stripe rust. Hierarchical analysis revealed the presence of three distinct clusters of bread wheat landraces, each forming different stripe rust resistance groups. With the exception of the harvest index and the growth stage parameter of days to heading, all agronomic traits were significantly different for the various landraces. This suggests the presence of diverse genetic resources, which might have also led to different responses to the stripe rust in these materials. This work clarifies the many ways in which landraces of bread wheat react to Pst infection, revealing a range of resistance mechanisms that can be used for efficient disease management. Core Ideas: Pathogenicity of Puccinia striiformis f. sp. tritici isolates to bread wheat landraces grown in Ethiopia was tested.The study identify bread wheat landraces possessing effective resistance genes.The onset of severe stripe rust infection at the development of heading stage causes significant yield losses.Three distinct clusters of bread wheat landraces forming distinct stripe rust resistance groups were identified. [ABSTRACT FROM AUTHOR]

Bread wheat is one of the key food grains in Ethiopia. However, its production and productivity are affected by stripe rust. The objective of this study was to investigate and develop integrated management options for stripe rust using varieties and fungicide application frequency in the study area. A field experiment was conducted at Enarj Enawuga district in the Metaya Kebele farmer training center during the 2022 main cropping season. There were sixteen total treatment combinations [four bread wheat varieties (Ogolcho, Lemu, Hidase, and Local as check), and four Tilt 250 EC fungicide application frequencies (nil, 1, 2, and 3 times)]. The design of the experiment was laid out in a randomized complete block design with factorial arrangements within three replications. Both disease and yield-related data were collected and analyzed using SAS 9.4 software. The disease and yield parameters showed a significant (p < 0.01) difference, and all treated plots had higher yield and lower disease severity than untreated plots. On the untreated plots, the final mean stripe rust severity was 18.53%, 22.57%, 36.73%, and 57.63% on Ogolcho, Lemu, Hidase, and local varieties, respectively. The maximum disease control was recorded from Ogolcho variety (61.31%) with a three-time application of Tilt 250EC. Grain yield and thousand kernel weight increment were obtained at 79.72% and 17.37% from Ogolcho, 100% and 23.44% from Lemu, 94.85% and 34.54% from Hidase, and 102.85% and 49.56% from local varieties treated by three times of Tilt 250EC, respectively. A higher yield reduction and AUDPC (114 DAS) were recorded from untreated plots of local (50.70%, 2,031.49% days−1), and Hidase (48.68%, 1,020.6% days−1) varieties, receptively. The 15-day interval application frequency of Propiconazole increased the grain yield of all tested varieties and reduced stripe rust severity. The Ogolcho variety treated three times yielded the maximum net benefit (216,750 Birr/ha) with an accepted marginal rate of return (22,810%). Therefore, based on the results obtained, producers use the Ogolcho variety with three-time application of propiconazole fungicide for optimum wheat production and could be recommended to manage stripe rust in the study area. [ABSTRACT FROM AUTHOR]

Yellow rust disease caused by Puccinia striiformis f. sp. tritici is one of the major threats to wheat production in Ethiopia. In this paper, the impact of yellow rust on the physical qualities of bread wheat was studied. For this purpose, combinations of four bread wheat varieties (Digalu, Hidase, Danda'a, and Honkolo) and two fungicides (Nativo SC 300 and Tilt® 250E.C.) were tested at two different hotspot areas (Albazar and Alicho) in the Silte Zone, Southern Ethiopia, under natural epidemics of the disease during the 2018 growing season. A randomized complete block design in factorial arrangement with three replications was used to set up the experiment. A significant (p <.01) increase in hectoliters weight and wet gluten content were observed due to the application of Nativo SC 300; however, grain protein content did not respond significantly (p >.01) at both locations. Wheat varieties with high yellow rust severity exhibited maximum values of area under the disease progress curve and physical quality loss percentage (%). The highly susceptible wheat variety Digalu exhibited the highest values of hectoliter weight losses (%), and the actual losses ranged from 5.5% to 29.5%. Except for grain protein content, there was a significant negative correlation between the values of terminal rust severity, average coefficient infection, and area under the disease progress curve and that of hectoliters weight and wet gluten content, with correlation coefficients ranging from −0.85** to −0.33**. It is possible to improve the physiochemical properties of bread wheat through the application of foliar fungicides by selecting the appropriate genotypes that have an acceptable level of resistance to yellow rust. [ABSTRACT FROM AUTHOR]

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a severe disease in wheat worldwide, including Ethiopia, causing up to 100% wheat yield loss in the worst season. The use of resistant cultivars is considered to be the most effective and durable management technique for controlling the disease. Therefore, the present study targeted the genetic architecture of adult plant resistance to yellow rust in 178 wheat association panels. The panel was phenotyped for yellow rust adult-plant resistance at three locations. Phonological, yield, yieldrelated, and agro-morphological traits were recorded. The association panel was fingerprinted using the genotyping-by-sequencing (GBS) platform, and a total of 6,788 polymorphic single nucleotide polymorphisms (SNPs) were used for genome-wide association analysis to identify effective yellow rust resistance genes. The marker-trait association analysis was conducted using the Genome Association and Prediction Integrated Tool (GAPIT). The broad-sense heritability for the considered traits ranged from 74.52% to 88.64%, implying the presence of promising yellow rust resistance alleles in the association panel that could be deployed to improve wheat resistance to the disease. The overall linkage disequilibrium (LD) declined within an average physical distance of 31.44 Mbp at r2 = 0.2. Marker-trait association (MTA) analysis identified 148 loci significantly (p = 0.001) associated with yellow rust adult-plant resistance. Most of the detected resistance quantitative trait loci (QTLs) were located on the same chromosomes as previously reported QTLs for yellow rust resistance and mapped on chromosomes 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 3D, 4A, 4B, 4D, 5A, 5B, 6A, 6B, 7A, and 7D. However, 12 of the discovered MTAs were not previously documented in the wheat literature, suggesting that they could represent novel loci for stripe rust resistance. Zooming into the QTL regions in IWGSC RefSeq Annotation v1 identified crucial disease resistance-associated genes that are key in plants' defense mechanisms against pathogen infections. The detected QTLs will be helpful for marker-assisted breeding of wheat to increase resistance to stripe rust. Generally, the present study identified putative QTLs for field resistance to yellow rust and some important agronomic traits. Most of the discovered QTLs have been reported previously, indicating the potential to improve wheat resistance to yellow rust by deploying the QTLs discovered by marker-assisted selection. [ABSTRACT FROM AUTHOR]

Very high (spatial and temporal) resolution satellite (VHRS) and high-resolution unmanned aerial vehicle (UAV) imagery provides the opportunity to develop new crop disease detection methods at early growth stages with utility for early warning systems. The capability of multispectral UAV, SkySat and Pleiades imagery as a high throughput phenotyping (HTP) and rapid disease detection tool for wheat rusts is assessed. In a randomized trial with and without fungicide control, six bread wheat varieties with differing rust resistance were monitored using UAV and VHRS. In total, 18 spectral features served as predictors for stem and yellow rust disease progression and associated yield loss. Several spectral features demonstrated strong predictive power for the detection of combined wheat rust diseases and the estimation of varieties' response to disease stress and grain yield. Visible spectral (VIS) bands (Green, Red) were more useful at booting, shifting to VIS–NIR (near-infrared) vegetation indices (e.g., NDVI, RVI) at heading. The top-performing spectral features for disease progression and grain yield were the Red band and UAV-derived RVI and NDVI. Our findings provide valuable insight into the upscaling capability of multispectral sensors for disease detection, demonstrating the possibility of upscaling disease detection from plot to regional scales at early growth stages. [ABSTRACT FROM AUTHOR]

The Ethiopian highlands are suitable environment for wheat production and conducive for perpetuating of several wheat diseases including rusts. In 2022 during belg, early and late meher seasons, monitoring was conducted to determine distribution and extent of major wheat diseases. The survey result showed that yellow rust, fusarium head blight followed bacterial black chaff and stem rust diseases were the most economically important wheat production limiting constraints in the surveyed areas respectively. The dominant wheat cultivars grown in the assessed fields were Hidassie, Lemmu, Danda’a, Wane, Shaki, Israel, Kubsa, Deka, Digalu and unknown with coverage frequency of 13%, 3%, 11%, 8%, 3%, 3%, 19%, 13%, 3%, 24% respectively. Over all assessed fields maximum disease severities were recorded and wheat fields were infected by yellow rust at tillering to heading; bacterial black chaff during booting to dough growth stage and fusarium head blight at flowering to dough wheat growth stage with higher epidemics on popular varieties. Therefore, wheat foliar mainly rusts, fusarium head blight and bacterial diseases are economically important constraints to wheat production currently in Ethiopia particularly in Arsi and West Arsi potential wheat growing areas. The wheat cultivars that grown during growing seasons was susceptible to yellow rust that needs frequent application and replacement of recently released wheat cultivars besides future interventions to be taken to reduce its epidemics. [ABSTRACT FROM AUTHOR]

Twenty three advanced bread wheat genotypes have been evaluated against two released bread wheat varieties in 2018-19 and 2019-20 in nine diverse environments of Ethiopia. The experiment was laid out using alpha lattice design with three replications. Ten stability models were employed in order to assess stability and performance of 23 advanced bread wheat genotypes. Combined analysis of variance for grain yield has revealed that the environments, the genotypes and GEI effects were significantly different (p<0.001). In the present study, Environments, GEI and Genotypic effects accounted for 88.6%, 8.3% and 3.1% of the total grain yield variation, respectively. Twelve bread wheat genotypes, ETBW 9136, ETBW 9139, ETBW 9065, ETBW 9080, ETBW 9172, ETBW 9396, ETBW 9452, ETBW 9641, ETBW 9642, ETBW 9646, ETBW 9647 and ETBW 9648 produced grain yield that raged from 5.4 to 5.8 t ha-1, indicating their superior yielding potential. ETBW 9136, ETBW 9139, ETBW 9172, ETBW 9396, ETBW 9452, ETBW 9641, ETBW 9642 and ETBW 9646 were the most stable bread wheat genotypes as confirmed by five to ten stability models. However, ETBW 9452, ETBW 9641, ETBW 9642, ETBW 9646, ETBW 9647 and ETBW 9648 were susceptible to either stem rust or yellow rust or both. Providentially, ETBW 9136, ETBW 9139, ETBW 9172 and ETBW 9396 were superior yielding, stable, resistant and moderately resistant to wheat rusts. Thus, these four genotypes were the most promising advanced bread wheat genotypes to be verified and released in low to mid altitude areas of Ethiopia. [ABSTRACT FROM AUTHOR]

Field trials were conducted to evaluate wheat varieties and fungicides against yellow rust of wheat. Four wheat varieties (Digalu, Hidase, Danda'a, Honkolo) and two fungicides (Nativo SC 300, Tilt 250EC) were tested at two hotspot areas (Albazar and Alicho) of Southern Ethiopia. The experiment was laid out in a randomized complete block design in a factorial arrangement with three replications. Nativo SC 300 resulted in a significant (p < 0.05) grain yield increment of 51%, 178.4% and 528.5% at Albazar and 85%, 206.1% and 586.2% at Alicho on the treated plot of Danda'a, Hidase and Digalu, respectively. There was a significant negative correlation between disease parameters and grain yield. Based on cost-benefit analysis, application of fungicides was cost effective in controlling the disease. The resistant variety Honkolo and Nativo SC 300 can be used for management of yellow rust and improve yield of wheat. [ABSTRACT FROM AUTHOR]

A multiplications evaluation was conducted with twenty-eight advanced bread wheat genotypes and two standard checks for two consecutive years 2017 and 2018 at Kulumsa, Asasa, Robe Arsi, Bekoji, Areka, Shambu, Holeta, Adet, Enawari, Awalgera, and Debra Zeit, Ethiopia. The objective of the paper was to describe the agronomic and quality related traits of newly developed bread wheat varieties "Boru" for optimum moisture areas of Ethiopia. Boru is a commercial name given for a newly released variety with the pedigree name SAUAL/MUTUS/6/CNO79//PF70354/MUS/3/PASTOR/4/BAV92*2/5/FH6-1-7/7/CNO79//PF. 70354/MUS/3/PASTOR/4/BAV92*2/5/FH6-1-7 which originated from CIMMYT germplasms. Boru is adapted within the range of altitude 2050 to 2780 masl with annual rainfall amount receiving from 620 to 1290 mm. Boru showed superior overall agronomic performances over the standard check Wane and Hidasse and it had a 9% and 14% yield advantage respectively. The new variety had a bold seed size than the two checks. Boru variety showed relative resistance to stem, yellow and leaf rust as compared to wheat varieties under production at the medium to high land wheat-growing agroecologies. Boru offers new hope for resource-poor farmers in rust-prone areas of Ethiopia. It's expected to replace the variety 'Ogolcho' in medium areas, and 'Hidasse' in high land areas of Ethiopia. In addition, the Boru variety is known for its higher protein content (14.37%) than standard check Wane (12.14%) and local check Hidasse (12.3%). [ABSTRACT FROM AUTHOR]

Ethiopia is not self-sufficient to meet its increasing wheat demand from domestic production partly due to a lack of improved seeds. Efforts are undertaken to fill the gap through off-season production of wheat using supplemental irrigation and modern cultivars adapted to arid areas. This study was carried out to evaluate the genetic variability and adaptability of 15 Ethiopian bread wheat genotypes at different agroecologies in Wolaita and Dawuro zones, Ethiopia. The field experiment was conducted at three locations using a randomized complete block design with three replications during the 2019/2020 main cropping season. Analysis of variance based on 11 morphological agronomic traits and two major wheat diseases revealed that there were highly significant differences (P < 0.01) among the genotypes for all the traits studied at each location and combined over locations. The top three cultivars viz. Alidoro, Galema, and Honqolo exhibited higher average grain yield (GY) of 4.54 t/ha, 4.36 t/ha, and 4.0 t/ha, respectively, combined over locations. Eight of the traits (72.73%) exhibited moderate (30–60%) to high broad-sense heritability (h b 2 > 60%) values. High h b 2 associated with high genetic advance as percent of mean was observed for the severity of both stem and yellow rust diseases combined over locations. GY was significantly related to aboveground biomass at all locations. This study depicted that cultivar Alidoro had wider adaptability for grain yield and resistance to wheat rusts. [ABSTRACT FROM AUTHOR]

Multi-environment trials were carried out at 11 locations in different wheat growing zones of Ethiopia during 2017-18 and 2018-19 to identify high yielding, stable, biotic and abiotic stresses resistant varieties with improved quality traits for commercial release. Twenty-eight advanced bread wheat genotypes have been evaluated against two released bread wheat varieties. The experiment was laid out using alpha lattice design with three replications. Nine stability models were employed in order to assess stability and performance of 28 advanced bread wheat genotypes across 18 diverse environments. Combined analysis of variance for grain yield has revealed that the environments, the genotypes and GEI effects were significantly different (p<0.001). Environments, GEI and Genotypic effects accounted for 71.99%, 22.97% and 5.03% of the total grain yield variation, respectively. Significant GEI showed variable performance of genotypes across environments. Eight advanced bread wheat genotypes namely ETBW8595, ETBW8668, ETBW8751, ETBW8991, ETBW8996, ETBW9547, ETBW9553 and ETBW9554 produced grain yield of more than 5.0 t ha-1, indicating their superior yielding potential. ETBW8595, ETBW8668, ETBW8751, ETBW8991 and ETBW9554 were found the most stable bread wheat genotypes as confirmed by five to eight stability models. ETBW8751, ETBW8991 and ETBW9554 were highest yielding, stable, adaptable, resistant and moderately resistant to prevailing stem and yellow rust diseases. Thus, these three genotypes were the most promising advanced bread wheat genotypes to be verified and released in Ethiopia. These promising bread wheat genotypes can be included in multipurpose bread wheat crossing blocks in order to correct shortcomings of commercial varieties. [ABSTRACT FROM AUTHOR]

Durum wheat is an important cereal grown in Ethiopia, a country which is also its center for genetic diversity. Yellow (stripe) rust caused by Puccinia striiformis fsp tritici is one of the most devastating diseases threatening Ethiopian wheat production. To identify sources of genetic resistance and combat this pathogen, we conducted a genome wide association study of yellow rust resistance on 300 durum wheat accessions comprising 261 landraces and 39 cultivars. The accessions were evaluated for their field resistance using a modified Cobb scale at Meraro, Kulumsa and Chefe Donsa in the 2015 and 2016 main growing seasons. Analysis of the 35K Axiom Array genotyping data of the panel resulted in a total of 8,797 polymorphic SNPs of which 7,093 were used in subsequent analyses. Population structure analysis suggested two groups in which the cultivars clearly stood out separately from the landraces. Eleven SNPs significantly associated with yellow rust resistance were identified on four chromosomes (1A, 1B, 2B, and 5A) which defined at least five genomic loci. Six of the SNPs were consistently identified on chromosome 1B singly at each and combined overall environments which explained 62.6–64.0% of the phenotypic variation (R2). Resistant allele frequency ranged from 14.0–71.0%; Zooming in to the identified resistance loci revealed the presence of disease resistance related genes involved in the plant defense system such as the ABC transporter gene family, disease resistance protein RPM1 (NBS-LRR class), Receptor kinases and Protein kinases. This study has provided SNPs for tracking the loci associated with yellow rust resistance and a diversity panel which can be used for association study of other agriculturally important traits in durum wheat. [ABSTRACT FROM AUTHOR]

Wheat rusts are the key biological constraint to wheat production in Ethiopia—one of Africa's largest wheat producing countries. The fungal diseases cause economic losses and threaten livelihoods of smallholder farmers. While it is known that wheat rust epidemics have occurred in Ethiopia, to date no systematic long-term analysis of past outbreaks has been available. We present results from one of the most comprehensive surveillance campaigns of wheat rusts in Africa. More than 13,000 fields have been surveyed during the last 13 years. Using a combination of spatial data-analysis and visualization, statistical tools, and empirical modelling, we identify trends in the distribution of wheat stem rust (Sr), stripe rust (Yr) and leaf rust (Lr). Results show very high infection levels (mean incidence for Yr: 44%; Sr: 34%; Lr: 18%). These recurrent rust outbreaks lead to substantial economic losses, which we estimate to be of the order of 10s of millions of US-D annually. On the widely adopted wheat variety, Digalu, there is a marked increase in disease prevalence following the incursion of new rust races into Ethiopia, which indicates a pronounced boom-and-bust cycle of major gene resistance. Using spatial analyses, we identify hotspots of disease risk for all three rusts, show a linear correlation between altitude and disease prevalence, and find a pronounced north-south trend in stem rust prevalence. Temporal analyses show a sigmoidal increase in disease levels during the wheat season and strong inter-annual variations. While a simple logistic curve performs satisfactorily in predicting stem rust in some years, it cannot account for the complex outbreak patterns in other years and fails to predict the occurrence of stripe and leaf rust. The empirical insights into wheat rust epidemiology in Ethiopia presented here provide a basis for improving future surveillance and to inform the development of mechanistic models to predict disease spread. [ABSTRACT FROM AUTHOR]

Background: Triticale (X-Triticosecale Wittmack) is a hybrid of wheat (Triticum sp.) and rye (Secale sp.) It combines yield potential and grain quality of wheat with the diseases and environmental tolerance including adaptability to marginal soils, diseases resistance and low-input requirements of rye. The crop has demonstrated high yield potential under marginal growing conditions and could a very attractive alternative for raising cereal production in the globe, involves Ethiopia. Objective: To evaluate and release stable high yielding and disease resistant/tolerant Triticale variety for the western highland of Oromia and other similar agro-ecologies. Material and Methods: Twelve triticale genotypes including the standard check "Moti" were evaluated across two locations for three years (2015-2017). Eventually, two promising genotypes, "Acc 2012 MS #51 and Acc.2012 MS #59" were selected and promoted to variety verification trail with the standard check "Moti" during the 2018/19 cropping season. The national variety release technical committee evaluated the two candidate varieties both at Gedo and Shambu on research stations and farmers' fields. Results: Among the two evaluated varieties, 'Kombolcha' is well adapted to altitudes ranging between 2244 and 2784 meters above sea level and characterized by amber seed color, longer panicle and gave high seed yield (6184.8 kg ha-1) and stable performance across years and locations. It has about 13% yield advantage over the standard check variety, "Moti". The variety is also resistant to major diseases such as steam rust (Pucinia graminis f.sp. tritici), yellow rust (Puccinia striiformis f.sp. tritici) and Septoria tritici (Mycosphaerella graminicola). Conclusions: "Kombolcha" (Acc. 2012 MS #51) is released for the highlands of western Oromia and similar agro-ecologies for its stable and high grain yield, and resistant to major diseases. Therefore, farmers in western highlands of Oromia and similar agro ecologies particularly those inhabiting marginal and acid prone areas can produce "Kombolcha" variety with its full management recommendation. [ABSTRACT FROM AUTHOR]

Stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) is one the most important diseases of wheat in Ethiopia and worldwide. To identify resistance genes, 90 bread wheat lines and 10 cultivars were tested at the seedling stage against one Pst race from Ethiopia and six races from China as well as evaluated for the stripe rust response in an inoculated field nursery at Yangling, Shaanxi province and in a naturally infected field in Jiangyou, Sichuan, China. Resistance genes were postulated using molecular assays for Yr9, Yr17, Yr18, Yr26, Yr29, Yr36, Yr44 and Yr62. Of the 100 entries tested, 16 had all stage resistance to all races. Molecular markers were positive for Yr9 in five genotypes, Yr17 in 21 genotypes, Yr18 in 27 genotypes, Yr26 in ten genotypes, Yr29 in 22 genotypes, Yr36 in 12 genotypes, Yr44 in 30 genotypes, and Yr62 in 51 genotypes. No line had Yr5, Yr8, Yr10 or Yr15. Complete or all stage resistance was observed in genotypes carrying gene combinations Yr9 + Yr18 + Yr44 + Yr62, Yr29 + Yr62 + Yr26 and Yr9 + Yr17 + Yr26 + Yr44 + Yr62. The results are helpful for developing wheat cultivars with effective and more durable resistance to stripe rust both in China and Ethiopia. [ABSTRACT FROM AUTHOR]

Field experiment was carried at Burji, Bonke and Chencha during the 2018 cropping season to evaluate the effects of host resistance and fungicide application on yellow and stem rusts and grain yield (GY) of bread wheat. Five wheat varieties and four different fungicides were included as treatment and laid out in factorial arrangement in randomized complete block design with three replications. Significant (p ≤ 0.01) difference was observed in the magnitude of the parameters of disease and crop measured between treatments. Results showed that the mean terminal severities of yellow and stem rusts were highest at Chencha than at Burji and Bonke. Yellow and stem rust terminal severities as low as 46.41%, 40.69%, 29.22%, 28.24% and 21.74% and 43.67%, 42.54%, 40.93%, 16.07% and 17.15% were recorded on Hidase, Kubsa, Ogolcho, Wane and Shorima varieties, respectively, due to the integrated use of Tilt 250 EC, Rex® Dou and Natura 250 EW foliar applications across the three locations. Crosswise assessment revealed that the lowest area under the disease progress curve (AUDPC) of yellow rust of 15.73%, 14.93%, 10.42%, 8.79% and 7.67%-days was recorded on Hidase, Kubsa, Ogolcho, Wane and Shorima varieties, respectively, and that of stem rust of 18.96%, 17.33%, 16.36%, 6.80% and 6.37%-days was registered on Kubsa, Ogolcho, Hidase, Shorima and Wane varieties, respectively, as a result of combined use of Tilt 250 EC, Rex® Dou and Natura 250 EW foliar applications. The combined effect of variety and fungicide application in addition to environmental variability exhibited pronounced effects on the epidemic development of yellow and stem rusts through their effects on disease progress rate and spike infection. Rex® Dou and Natura 250 EW fungicides in combination with all the evaluated varieties proved to be effective against the rust management and gave the higher values of yield parameters and monitory advantage over the unsprayed plots. GY loss of up to 69.64% was recorded on unsprayed plots of Ogolcho as compared to fungicide sprayed plots of other varieties evaluated. Thus, Rex® Dou and Natura 250 EW fungicides in combination with wheat variety having a different level of resistance to wheat rusts could be suggested to the farmers in the study areas and elsewhere with similar agro-ecological conditions for efficient management and optimization of the GY. Further studies have to be sought in similar and other agro-ecologies elsewhere in Ethiopia for at least two consecutive years over locations to come up with a solid recommendation. [ABSTRACT FROM AUTHOR]

Stripe rust caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat worldwide. In Ethiopia, grain yield loss in wheat cultivars ranges from 30 to 69%. The use of resistant cultivars is the most economical and environmentally friendly method of controlling the disease. Gene postulation which is based on the gene-for-gene interaction between the host line and the pathogen races is commonly used to determine resistance genes in wheat cultivars. In the present study Yr genes in 22 bread wheat cultivars were studied by testing them, together with the 24 differential lines, with 20 Pst races that were collected from Ethiopia, France and Germany. These cultivars were postulated to have different combinations of stripe rust resistance genes Yr2, Yr3a, Yr4a, Yr6, Yr7, Yr8, Yr9, Yr27, Yr32 and YrSU. Among these genes, Yr2, Yr6, Yr7, Yr8, Yr9, Yr27 and Yr32 could not provide adequate control. This indicates the need for searching more effective resistance genes to be incorporated in Ethiopian bread wheat cultivars. Bread wheat cultivars Wabe and Tusie were resistant to all 20 races, similar to the differential lines with Yr5, Yr15 and Yr26. In addition, due to the absence of matching response spectra to the tested differential genotypes, the Yr gene(s) in bread wheat cultivar Suf-Omer could not be determined. However, the molecular experiments mapped Yr genes in cvs Wabe and Tusie on chromosome 7BL and 3BL in cv. Suf-Omer, showing that the resistance in these cultivars are governed by genes different from Yr5 (2BL), Yr15 (1BL), and Yr26 (1BS). [ABSTRACT FROM AUTHOR]

The effect of stripe rust (Puccinia striiformis) on yield and yield components of three common wheat cultivars was studied in 2002 and 2003 in Bale highlands, Ethiopia. The objectives were to quantify amount of loss in yield and yield components incurred by stripe rust on common wheat, and assess the relationship between stripe rust and yield. Different severity levels were created by varying triademefon spray intervals. Stripe rust significantly affected grain yield, kernels per spike (NKPS) and thousand kernels weight (TKW) of the susceptible Wabe cultivar. Losses of 3819 kg ha-1 (71%) grain yield, 21.5 (35%) NKPS and 13.9 g (37%) TKW occurred on Wabe. Each unit increase in stripe rust severity resulted in yield reduction of 41 - 47 kg ha-1 at Agarfa. The study indicated that stripe rust causes intolerable high yield loss in common wheat production and the importance of using resistant cultivars and applying fungicide on susceptible cultivars. [ABSTRACT FROM AUTHOR]

The article presents information on a study conducted on the genetic diversity of Puccinia striiformis f. sp. tritici, a pathogen that causes stripe rust of wheat in Ethiopia. To study the population structure of the pathogen, 107 single-pustule isolates were collected from four different regions in Ethiopia. These isolates were tested on 24 differential genotypes with known resistance genes. Significant differences were found regarding genes and genetic diversity within the populations.

Stripe rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is one of the most important diseases of wheat worldwide. To understand the worldwide distribution of its molecular groups, as well as the diversity, differentiation, and migration of the Pst populations, 567 isolates collected from nine countries (China, Pakistan, Italy, Egypt, Ethiopia, Canada, Mexico, Ecuador, and the U.S.) in 2010-2018 were genotyped using 14 codominant simple sequence repeat markers. A total of 433, including 333 new multi-locus genotypes (MLGs), were identified, which were clustered into ten molecular groups (MGs). The MGs and country-wise populations differed in genetic diversity, heterozygosity, and correlation coefficient between the marker and virulence data. Many isolates from different countries, especially the isolates from Mexico, Ecuador, and the U.S., were found to be identical or closely related MLGs, and some of the MGs were present in all countries, indicating Pst migrations among different countries. The analysis of molecular variance revealed 78% variation among isolates, 12% variation among countries, and 10% variation within countries. Only low levels of differentiation were found by the pairwise comparisons of country populations. Of the 10 MGs, 5 were found to be involved in sexual and/or somatic recombination. Identical and closely related MLGs identified from different countries indicated international migrations. The study provides information on the distributions of various Pst genetic groups in different countries and evidence for the global migrations, which should be useful in understanding the pathogen evolution and in stressing the need for continual monitoring of the disease and pathogen populations at the global scale.

Wheat production in Ethiopia faces numerous climate related constraints that entail development and dissemination of wheat germplasms with yield stabilizing traits under climate related challenges such as frost, drought, and yellow rust. The adoption of the germplasms will however depend on the effective demand of wheat growers. This study investigates the preferences and willingness to pay (WTP) for frost and yellow rust resistance, grain yield, grain color, plant height, and length of maturity traits of wheat in Ethiopia. A choice experiment method was used to generate 8181 observations from a random sample of 303 smallholder farm households. We report mean WTP values, preference heterogeneity and attribute non-attendance patterns based on different formulations of the mixed logit model. The results revealed that farmers are willing to pay for yellow rust resistance, frost resistance, increase in grain yield, and white grain color (cf. brown). Farmers showed disinterest in increase in length of maturity and black grain color (cf. brown). Farmers have high WTP for yellow rust resistance and frost resistance traits, which is nearly 10 times the value they are willing to pay for increase in grain yield of 100 kg per hectare. Similarly, farmers are willing to pay for harvesting wheat yield a month earlier a price four times the value they attach to increase in grain yield of 100 kg per hectare. The weight farmers attach to climate related traits of wheat show the importance farmers implicitly give to the climatic factors they must consider in their wheat production. Therefore, carefully developed wheat varieties would improve the effectiveness of the climate change adaptation strategies of smallholder farmers. • Wheat production in rural Ethiopia faces various climate related challenges such as yellow and stem rust diseases. • Implicit prices for traits and heterogeneities in preferences were estimated using mixed logit model. • Frost and rust resistance and early maturity are the most preferred wheat traits that drive farmers' variety selection. • Farmers are willingness to pay much higher for yellow rust and frost resistance than for an increase in grain yield. [ABSTRACT FROM AUTHOR]

Leaf (brown) rust (LR) and stripe (yellow) rust (YR), caused by Puccinia triticina and P. striiformis f. sp. tritici , respectively, significantly reduce wheat production worldwide. Disease-resistant wheat varieties offer farmers one of the most effective ways to manage these diseases. The common wheat ( Triticum aestivum L.) Arableu#1, developed by the International Maize and Wheat Improvement Center and released as Deka in Ethiopia, shows susceptibility to both LR and YR at the seedling stage but a high level of adult plant resistance (APR) to the diseases in the field. We used 142 F 5 recombinant inbred lines (RILs) derived from Apav#1 × Arableu#1 to identify quantitative trait loci (QTLs) for APR to LR and YR. A total of 4,298 genotyping-by-sequencing markers were used to construct a genetic linkage map. The study identified four LR resistance QTLs and six YR resistance QTLs in the population. Among these, QLr.cim-1BL.1/QYr.cim-1BL.1 was located in the same location as Lr46/Yr29 , a known pleiotropic resistance gene. QLr.cim-1BL.2 and QYr.cim-1BL.2 were also located on wheat chromosome 1BL at 37 cM from Lr46/Yr29 and may represent a new segment for pleiotropic resistance to both rusts. QLr.cim-7BL is likely Lr68 given its association with the tightly linked molecular marker cs7BLNLRR . In addition, QLr.cim-3DS , QYr.cim-2AL , QYr.cim-4BL , QYr.cim-5AL , and QYr.cim-7DS are probably new resistance loci based on comparisons with published QTLs for resistance to LR and YR. Our results showed the diversity of minor resistance QTLs in Arableu#1 and their role in conferring near-immune levels of APR to both LR and YR, when combined with the pleiotropic APR gene Lr46 / Yr29 .