scholarly journals Quantifying the Effects of Wheat Residue on Severity of Stagonospora nodorum Blotch and Yield in Winter Wheat

2015 ◽  
Vol 105 (11) ◽  
pp. 1417-1426 ◽  
Author(s):  
L. K. Mehra ◽  
C. Cowger ◽  
R. Weisz ◽  
P. S. Ojiambo
Keyword(s):  
North Carolina ◽  
Winter Wheat ◽  
Disease Severity ◽  
Block Design ◽  
Soil Surface ◽  
Kernel Weight ◽  
Stagonospora Nodorum ◽  
Wheat Crop ◽  
Stagonospora Nodorum Blotch ◽  
Initial Inoculum

Stagonospora nodorum blotch (SNB), caused by the fungus Parastagonospora nodorum, is a major disease of wheat (Triticum aestivum). Residue from a previously infected wheat crop can be an important source of initial inoculum, but the effects of infected residue on disease severity and yield have not previously been quantified. Experiments were conducted in Raleigh and Salisbury, North Carolina, in 2012, 2013, and 2014 using the moderately susceptible winter wheat cultivar DG Shirley. In 2014, the highly susceptible cultivar DG 9012 was added to the experiment and the study was conducted at an additional site in Tyner, North Carolina. Four (2012) or six (2013 and 2014) wheat residue treatments were applied in the field in a randomized complete block design with five replicates. Treatments in 2012 were 0, 30, 60, and 90% residue coverage of the soil surface, while 10 and 20% residue treatments were added in 2013 and 2014. Across site-years, disease severity ranged from 0 to 50% and increased nonlinearly (P < 0.05) as residue level increased, with a rapid rise to an upper limit and showing little change in severity above 20 to 30% soil surface coverage. Residue coverage had a significant (P < 0.05) effect on disease severity in all site-years. The effect of residue coverage on yield was only significant (P < 0.05) for DG Shirley at Raleigh and Salisbury in 2012 and for DG 9012 at Salisbury in 2014. Similarly, residue coverage significantly (P < 0.05) affected thousand-kernel weight only of DG 9012 in 2014 at Raleigh and Salisbury. Our results showed that when wheat residue was sparse, small additions to residue density produced greater increases in SNB than when residue was abundant. SNB only led to effects on yield and test weight in the most disease-conducive environments, suggesting that the economic threshold for the disease may be higher than previously assumed and warrants review.

scholarly journals Effect of Inoculation with Selected Isolates of Stagonospora nodorum on Field Evaluations of Host Resistance in Winter Wheat

Plant Disease ◽  
2003 ◽  
Vol 87 (10) ◽  
pp. 1213-1220 ◽  
Author(s):  
D. E. Fraser ◽  
J. P. Murphy ◽  
S. Leath ◽  
D. A. Van Sanford
Keyword(s):  
North Carolina ◽  
Genetic Variation ◽  
Winter Wheat ◽  
Host Resistance ◽  
Growth Stage ◽  
Field Experiments ◽  
Natural Infection ◽  
Stagonospora Nodorum ◽  
Test Field ◽  
Stagonospora Nodorum Blotch

Although Stagonospora nodorum blotch occurs annually in North Carolina, selection for resistance in wheat (Triticum aestivum) breeding nurseries is hampered by the infrequent occurrence of heavy and timely disease pressure. The objective of this study was to compare estimates of host resistance in a population of 147 random winter wheat lines evaluated in epidemics produced by natural infection versus epidemics supplemented by inoculation with selected isolates. Two isolates were chosen from a set of 43 collected in North Carolina based on their aggressiveness on four wheat cultivars in a controlled environment test. Field experiments utilized a split-plot design with three replications. The main plots were inoculation treatments and the subplots were the 147 wheat genotypes. The inoculation treatments were (i) selected isolate A (more aggressive) alone, (ii) selected isolate B (less aggressive) alone, (iii) a combination of isolates A plus B, and (iv) natural infection. Selected isolate treatments were applied at Feekes growth stage 9 to 10.1, and disease intensity was measured two or three times at 14-day intervals postinoculation. The study was conducted at one location in the 1996-97 season and two locations in the 1997-98 season. High levels of natural infection occurred, and no differences were observed among the four inoculation treatments for mean disease intensity in any of the three environments. Within environments, genotype-by-inoculation treatment variance was significant in the two environments inoculated with selected isolates at growth stage 9 but not in the environment inoculated at growth stage 10.1. Magnitudes of genetic variation and heritability for Stagonospora nodorum blotch resistance were not consistently associated with main plot treatments, and inoculation with selected isolates masked genetic variation for resistance in two treatments in one environment. Genotype rank correlations for Stagonospora nodorum blotch resistance between inoculation treatments varied from zero to 0.69 within environments, but only a single correlation between inoculation treatments in different environments was observed. Estimates of host resistance in epidemics supplemented with selected isolates did not consistently agree with estimates in epidemics produced by natural infection. Our results did not support the routine use of supplemental inoculation of wheat breeding nurseries with selected isolates of S. nodorum as a means of increasing genetic gain for host resistance.

scholarly journals Influence of Soil Background on Spectral Reflectance of Winter Wheat Crop Canopy

2019 ◽  
Vol 11 (16) ◽  
pp. 1932 ◽  
Author(s):  
Elena Prudnikova ◽  
Igor Savin ◽  
Gretelerika Vindeker ◽  
Praskovia Grubina ◽  
Ekaterina Shishkonakova ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Soil Type ◽  
Spectral Reflectance ◽  
Vegetation Index ◽  
Vegetation Indices ◽  
Soil Surface ◽  
Wheat Crop ◽  
Crop Canopy ◽  
Winter Wheat Crop ◽  
Type Factor

The spectral reflectance of crop canopy is a spectral mixture, which includes soil background as one of the components. However, as soil is characterized by substantial spatial variability and temporal dynamics, its contribution to the spectral reflectance of crops will also vary. The aim of the research was to determine the impact of soil background on spectral reflectance of crop canopy in visible and near-infrared parts of the spectrum at different stages of crop development and how the soil type factor and the dynamics of soil surface affect vegetation indices calculated for crop assessment. The study was conducted on three test plots with winter wheat located in the Tula region of Russia and occupied by three contrasting types of soil. During field trips, information was collected on the spectral reflectance of winter wheat crop canopy, winter wheat leaves, weeds and open soil surface for three phenological phases (tillering, shooting stage, milky ripeness). The assessment of the soil contribution to the spectral reflectance of winter wheat crop canopy was based on a linear spectral mixture model constructed from field data. This showed that the soil background effect is most pronounced in the regions of 350–500 nm and 620–690 nm. In the shooting stage, the contribution of the soil prevails in the 620–690 nm range of the spectrum and the phase of milky ripeness in the region of 350–500 nm. The minimum contribution at all stages of winter wheat development was observed at wavelengths longer than 750 nm. The degree of soil influence varies with soil type. Analysis of variance showed that normalized difference vegetation index (NDVI) was least affected by soil type factor, the influence of which was about 30%–50%, depending on the stage of winter wheat development. The influence of soil type on soil-adjusted vegetation index (SAVI) and enhanced vegetation index (EVI2) was approximately equal and varied from 60% (shooting phase) to 80% (tillering phase). According to the discriminant analysis, the ability of vegetation indices calculated for winter wheat crop canopy to distinguish between winter wheat crops growing on different soil types changed from the classification accuracy of 94.1% (EVI2) in the tillering stage to 75% (EVI2 and SAVI) in the shooting stage to 82.6% in the milky ripeness stage (EVI2, SAVI, NDVI). The range of the sensitivity of the vegetation indices to the soil background depended on soil type. The indices showed the greatest sensitivity on gray forest soil when the wheat was in the phase of milky ripeness, and on leached chernozem when the wheat was in the tillering phase. The observed patterns can be used to develop vegetation indices, invariant to second-type soil variations caused by soil type factor, which can be applied for the remote assessment of the state of winter wheat crops.

scholarly journals Evaluation and Association Mapping of Resistance to Tan Spot and Stagonospora Nodorum Blotch in Adapted Winter Wheat Germplasm

Plant Disease ◽  
2015 ◽  
Vol 99 (10) ◽  
pp. 1333-1341 ◽  
Author(s):  
Zhaohui Liu ◽  
Ibrahim El-Basyoni ◽  
Gayan Kariyawasam ◽  
Guorong Zhang ◽  
Allan Fritz ◽  
...  
Keyword(s):  
United States ◽  
Winter Wheat ◽  
Association Mapping ◽  
Great Plains ◽  
The United States ◽  
Tan Spot ◽  
Stagonospora Nodorum ◽  
Northern Great Plains ◽  
Stagonospora Nodorum Blotch ◽  
Pyrenophora Tritici Repentis

Tan spot and Stagonospora nodorum blotch (SNB), often occurring together, are two economically significant diseases of wheat in the Northern Great Plains of the United States. They are caused by the fungi Pyrenophora tritici-repentis and Parastagonospora nodorum, respectively, both of which produce multiple necrotrophic effectors (NE) to cause disease. In this work, 120 hard red winter wheat (HRWW) cultivars or elite lines, mostly from the United States, were evaluated in the greenhouse for their reactions to the two diseases as well as NE produced by the two pathogens. One P. nodorum isolate (Sn4) and four Pyrenophora tritici-repentis isolates (Pti2, 331-9, DW5, and AR CrossB10) were used separately in the disease evaluations. NE sensitivity evaluation included ToxA, Ptr ToxB, SnTox1, and SnTox3. The numbers of lines that were rated highly resistant to individual isolates ranged from 11 (9%) to 30 (25%) but only six lines (5%) were highly resistant to all isolates, indicating limited sources of resistance to both diseases in the U.S. adapted HRWW germplasm. Sensitivity to ToxA was identified in 83 (69%) of the lines and significantly correlated with disease caused by Sn4 and Pti2, whereas sensitivity to other NE was present at much lower frequency and had no significant association with disease. As expected, association mapping located ToxA and SnTox3 sensitivity to chromosome arm 5BL and 5BS, respectively. A total of 24 potential quantitative trait loci was identified with −log (P value) > 3.0 on 12 chromosomes, some of which are novel. This work provides valuable information and tools for HRWW production and breeding in the Northern Great Plains.

scholarly journals Differential Seed Infection of Wheat Cultivars by Stagonospora nodorum

Plant Disease ◽  
2000 ◽  
Vol 84 (7) ◽  
pp. 749-752 ◽  
Author(s):  
Denis A. Shah ◽  
Gary C. Bergstrom ◽  
Mark E. Sorrells
Keyword(s):  
New York ◽  
Winter Wheat ◽  
Agar Medium ◽  
Stagonospora Nodorum ◽  
Seed Infection ◽  
Wheat Cultivars ◽  
Production Environment ◽  
Flag Leaves ◽  
Initial Inoculum ◽  
Relative Susceptibility

Seed of soft white winter wheat collected from New York regional cultivar trials in 1995 and 1996 were assayed on an agar medium selective for Stagonospora nodorum. Incidence of seed infection varied with production environment. Relative incidence of seed infection differed significantly among cultivars and was consistent across environments. The flag leaves and ears of 12 cultivars were inoculated quantitatively at flowering in a glasshouse. Cultivars did not differ significantly in disease on the flag leaves. Incidence of seed infection for all cultivars was above 60%, but was significantly lower in Delaware and Houser than in other cultivars. Results confirm that wheat cultivars differ in their relative susceptibility to seed infection by S. nodorum. Resistance in wheat to seed infection by S. nodorum may be a useful mechanism for reducing initial inoculum in areas where infected seed is considered the primary inoculum source for Stagonospora nodorum blotch.

scholarly journals Yield increases due to fungicide control of leaf blotch diseases in wheat and barley as a basis for IPM decision-making in the Nordic-Baltic region

2020 ◽  
Vol 158 (2) ◽  
pp. 315-333 ◽  
Author(s):  
Marja Jalli ◽  
Janne Kaseva ◽  
Björn Andersson ◽  
Andrea Ficke ◽  
Lise Nistrup-Jørgensen ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Spring Barley ◽  
Tan Spot ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Stagonospora Nodorum ◽  
Net Blotch ◽  
Baltic Region ◽  
Stagonospora Nodorum Blotch ◽  
Leaf Blotch

Abstract Fungal plant diseases driven by weather factors are common in European wheat and barley crops. Among these, septoria tritici blotch (Zymoseptoria tritici), tan spot (Pyrenophora tritici-repentis), and stagonospora nodorum blotch (Parastagonospora nodorum) are common in the Nordic-Baltic region at variable incidence and severity both in spring and winter wheat fields. In spring barley, net blotch (Pyrenophora teres), scald (Rhynchosporium graminicola, syn. Rhynchosporium commune) and ramularia leaf spot (Ramularia collo-cygni) are common yield limiting foliar diseases. We analysed data from 449 field trials from 2007 to 2017 in wheat and barley crops in the Nordic-Baltic region and explored the differences in severity of leaf blotch diseases between countries and years, and the impact of the diseases on yield. In the experiments, septoria tritici blotch dominated in winter wheat in Denmark and southern Sweden; while in Lithuania, both septoria tritici blotch and tan spot were common. In spring wheat, stagonospora nodorum blotch dominated in Norway and tan spot in Finland. Net blotch and ramularia leaf blotch were the most severe barley diseases over large areas, while scald occurred more locally and had less yield impact in all countries. Leaf blotch diseases, with severity >50% at DC 73–77, caused an average yield loss of 1072 kg/ha in winter wheat and 1114 kg/ha in spring barley across all countries over 5 years. These data verify a large regional and yearly variation in disease severity, distribution and impact on yield, emphasizing the need to adapt fungicide applications to the actual need based on locally adapted risk assessment systems.

scholarly journals Genome-wide association analysis permits characterization of Stagonospora nodorum blotch (SNB) resistance in hard winter wheat

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rami AlTameemi ◽  
Harsimardeep S. Gill ◽  
Shaukat Ali ◽  
Girma Ayana ◽  
Jyotirmoy Halder ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Genome Wide Association Study ◽  
Seedling Stage ◽  
Genome Wide Association ◽  
Stagonospora Nodorum ◽  
Complex Nature ◽  
Breeding Programs ◽  
Stagonospora Nodorum Blotch ◽  
Genome Wide ◽  
A Genome

AbstractStagonospora nodorum blotch (SNB) is an economically important wheat disease caused by the necrotrophic fungus Parastagonospora nodorum. SNB resistance in wheat is controlled by several quantitative trait loci (QTLs). Thus, identifying novel resistance/susceptibility QTLs is crucial for continuous improvement of the SNB resistance. Here, the hard winter wheat association mapping panel (HWWAMP) comprising accessions from breeding programs in the Great Plains region of the US, was evaluated for SNB resistance and necrotrophic effectors (NEs) sensitivity at the seedling stage. A genome-wide association study (GWAS) was performed to identify single‐nucleotide polymorphism (SNP) markers associated with SNB resistance and effectors sensitivity. We found seven significant associations for SNB resistance/susceptibility distributed over chromosomes 1B, 2AL, 2DS, 4AL, 5BL, 6BS, and 7AL. Two new QTLs for SNB resistance/susceptibility at the seedling stage were identified on chromosomes 6BS and 7AL, whereas five QTLs previously reported in diverse germplasms were validated. Allele stacking analysis at seven QTLs explained the additive and complex nature of SNB resistance. We identified accessions (‘Pioneer-2180’ and ‘Shocker’) with favorable alleles at five of the seven identified loci, exhibiting a high level of resistance against SNB. Further, GWAS for sensitivity to NEs uncovered significant associations for SnToxA and SnTox3, co-locating with previously identified host sensitivity genes (Tsn1 and Snn3). Candidate region analysis for SNB resistance revealed 35 genes of putative interest with plant defense response-related functions. The QTLs identified and validated in this study could be easily employed in breeding programs using the associated markers to enhance the SNB resistance in hard winter wheat.

scholarly journals Novel Necrotrophic Effectors from Stagonospora nodorum and Corresponding Host Sensitivities in Winter Wheat Germplasm in the Southeastern United States

2012 ◽  
Vol 102 (5) ◽  
pp. 498-505 ◽  
Author(s):  
A. D. Crook ◽  
T. L. Friesen ◽  
Z. H. Liu ◽  
P. S. Ojiambo ◽  
C. Cowger
Keyword(s):  
United States ◽  
Winter Wheat ◽  
Block Design ◽  
Southeastern United States ◽  
The United States ◽  
Stagonospora Nodorum ◽  
Wheat Cultivars ◽  
Breeding Programs ◽  
Culture Filtrates ◽  
Necrotrophic Effectors

Stagonospora nodorum blotch (SNB), caused by the necrotrophic fungus Stagonospora nodorum (teleomorph: Phaeosphaeria nodorum), is among the most common diseases of winter wheat in the United States. New opportunities in resistance breeding have arisen from the recent discovery of several necrotrophic effectors (NEs, also known as host-selective toxins) produced by S. nodorum, along with their corresponding host sensitivity (Snn) genes. Thirty-nine isolates of S. nodorum collected from wheat debris or grain from seven states in the southeastern United States were used to investigate the production of NEs in the region. Twenty-nine cultivars with varying levels of resistance to SNB, representing 10 eastern-U.S. breeding programs, were infiltrated with culture filtrates from the S. nodorum isolates in a randomized complete block design. Three single-NE Pichia pastoris controls, two S. nodorum isolate controls, and six Snn-differential wheat controls were also used. Cultivar–isolate interactions were visually evaluated for sensitivity at 7 days after infiltration. Production of NEs was detected in isolates originating in each sampled state except Maryland. Of the 39 isolates, 17 produced NEs different from those previously characterized in the upper Great Plains region. These novel NEs likely correspond to unidentified Snn genes in Southeastern wheat cultivars, because NEs are thought to arise under selection pressure from genes for resistance to biotrophic pathogens of wheat cultivars that differ by geographic region. Only 3, 0, and 23% of the 39 isolates produced SnToxA, SnTox1, and SnTox3, respectively, by the culture-filtrate test. A Southern dot-blot test showed that 15, 74, and 39% of the isolates carried the genes for those NEs, respectively; those percentages were lower than those found previously in larger international samples. Only two cultivars appeared to contain known Snn genes, although half of the cultivars displayed sensitivity to culture filtrates containing unknown NEs. Effector sensitivity was more frequent in SNB-susceptible cultivars than in moderately resistant (MR) cultivars (P = 0.008), although some susceptible cultivars did not exhibit sensitivity to NEs produced by isolates in this study and some MR cultivars were sensitive to NEs of multiple isolates. Our results suggest that NE sensitivities influence but may not be the only determinant of cultivar resistance to S. nodorum. Specific knowledge of NE and Snn gene frequencies in this region can be used by wheat breeding programs to improve SNB resistance.

Postharvest Tillage Reduces Downy Brome (Bromus tectorumL.) Infestations in Winter Wheat

2014 ◽  
Vol 28 (2) ◽  
pp. 418-425 ◽  
Author(s):  
Frank L. Young ◽  
Alex G. Ogg ◽  
J. Richard Alldredge
Keyword(s):  
Winter Wheat ◽  
Pacific Northwest ◽  
Weed Management ◽  
Soil Surface ◽  
Wheat Crop ◽  
Downy Brome ◽  
No Till ◽  
The Pacific ◽  
Plant Densities ◽  
Summer Fallow

In the Pacific Northwest, downy brome continues to infest winter wheat, especially in low-rainfall areas where the winter wheat–summer fallow rotation is the dominant production system. In Washington, a study was conducted for 2 yr at two locations in the winter wheat–summer fallow region to determine the influence of four postharvest tillage treatments on vertical seed movement, seedbank depletion, and plant densities of downy brome. The four tillage implements included a disk, sweep plow, harrow, and skew treader. The study also included a no-till treatment for comparison. The sweep plow and disk led to the most vertical movement of downy brome seed compared with the no-till treatment. Approximately 75% of the fall postharvest seed in the no-till treatment was located either on the soil surface or in the 0- to 3-cm depth at both locations. In contrast, 75% of the seed in the disked treatment was located from 0 to 6 cm deep at both locations. The disk and sweep plow both decreased downy brome seed in the soil at the 0- to 3-cm depth compared with the harrow and no-till treatments. There was no difference in downy brome plant densities following postharvest tillage in the summer fallow due to any of the treatments. However, plant densities in the subsequent winter wheat crop were reduced by the disk and sweep plow compared with the no-till and skew-treader treatments. In general, seed densities as affected by the skew treader fell between the disk and the no-till treatments. The use of the sweep plow and the disk should be integrated into a weed management strategy for downy brome in the wheat–fallow region of the Pacific Northwest.

scholarly journals Weed Control and Winter Wheat Crop Yield With the Application of Herbicides, Nitrogen Fertilizers, and Their Mixtures With Humic Growth Regulators

2021 ◽  
Vol 74 ◽  
Author(s):  
Irina Korotkova ◽  
Mykola Marenych ◽  
Volodymyr Hanhur ◽  
Oksana Laslo ◽  
Oksana Chetveryk ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Ammonium Nitrate ◽  
Weed Control ◽  
Block Design ◽  
Nitrogen Fertilizers ◽  
Wheat Crop ◽  
Yield Increase ◽  
Physiologically Active Substances ◽  
Winter Wheat Cultivars ◽  
Winter Wheat Crop

Abstract The aim of the present study was to determine the efficacy of the application of mixtures containing various combinations of humic substances, with herbicides and nitrogen fertilizers, in weed control and optimizing the plant nutrition system. We also aimed to evaluate the influence of these substances on winter wheat productivity. Five Ukrainian winter wheat cultivars (‘Kryzhynka,’ ‘Smuhlyanka,’ ‘Slavna,’ ‘Kubus,’ and ‘Mulan’) were sown in a randomized complete block design, with three replications, in the years 2014–2019. The analysis of the effect of the compositions containing herbicides, with various physiologically active substances, in a mixture with humic preparations (Humifield, 4R Foliar concentrate) was performed by counting weeds per square meter in each experimental plot. The best performance in weed control, including perennial species, was obtained from using a mixture of Grodil Maxi herbicide with the humic preparation, Humifield. The crop treatment of this mixture resulted in a 23.6% reduction in weeds, compared to the treatment with the Grodil Maxi herbicide only. At the same time, the complex application of a number of herbicides in a mixture with the humic preparation, 4R Foliar concentrate led to the opposite effect. Various applications of mixtures of humates (4R Foliar concentrate, 5R SoilBoost) with nitrogen fertilizers (ammonium nitrate; carbamide-ammonium mixture) to optimize the winter wheat nutritional system and yield increases have been studied. The highest yield increase of 20%–22% was harvested in the plots treated with 5R SoilBoost and 4R Foliar concentrate plus ammonium nitrate. In addition, the efficacy of wheat crop foliar feeding with mixtures of humates, plus a carbamide-ammonia mixture, in different phases of vegetation has been established. A yield increase of 10.0%–21.4% resulting from the use of such compositions was obtained.

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