Incidence Of Black Point Research Articles

Mutagenesis-Derived Resistance to Black Point in Wheat.

Black point, a severe global wheat disease, necessitates deploying resistant cultivars for effective control. However, susceptibility remains prevalent among most wheat cultivars. Identifying new sources of resistance and understanding their mechanisms are crucial for breeding resistant cultivars. This study pinpointed black point resistance in an ethyl methane sulfonate (EMS)-mutagenized wheat population of Wanyuanbai 1 (WYB) and analyzed resistant mutants using RNA-Seq. The findings revealed the following: (i) wyb-18, among 10,008 EMS-mutagenized lines, exhibited robust resistance with significantly lower black point incidence under artificial Bipolaris sorokiniana inoculation in 2020 and 2021 (average incidence of 5.2% over 2 years), markedly reduced compared with WYB (50.9%). (ii) wyb-18 kernels displayed black point symptoms at 12 days after inoculation (dai), 3 days later than WYB. At 15 dai, wyb-18 kernels had isolated black spots, unlike WYB kernels, where the entire embryo turned black. (iii) wyb-18 showed heightened antioxidant enzyme activity, including peroxidase, catalase, and superoxide dismutase. (iv) Analysis of 543 differentially expressed genes between wyb-18 and WYB at 9 dai identified enrichment in the MAPK signaling pathway through KEGG analysis. Ten genes in this pathway exhibited upregulated expression, while one was downregulated in wyb-18. Among these genes, PR1, WRKY11, SAPK5, and TraesCS1A02G326800 (chitin recognition protein) consistently showed upregulation in wyb-18, making them potential candidates for black point resistance. These results offer valuable germplasm resources for breeding and novel insights into the mechanisms of black point resistance.

Incidence of black point (Alternaria sp.) in elite advanced bread wheat (Triticum aestivum) lines

Eighty four elite advanced bread wheat lines were evaluated for resistance to black point during the crop season 2015-2016 at the Norman E. Borlaug Experimental Station in the Yaqui Valley, Mexico. Sowing dates were November 12, 19 and 26, 2015. Harvest and threshing were done manually in ten spikes per line, and the evaluation by visual inspection, counting healthy and infected grains to calculate the percentage of infection. The range of infection for the first sowing date was 0 to 19.8 %, with an average of 1.9; thirty nine lines did not show infected grains; for the second date it was 0 to 32.7 %, with an average of 4.8; twenty seven lines did not show infected grains; while for the third date, it was 0 to 44.9 % with an average of 6.8, and eighteen lines did not show infected grains. Eight lines did not show infected grains in the three dates. Lines with the highest average percentage of infection were: WHEAR/KUKUNA/3/C80.1/3* BATAVIA//2*WBLL1*2/4/WBLL1/KUKUNA//TACUPETOF2001/3/UP2338*2/VIVITSI with 20.8, and WAXWING*2/ KRONSTADF2004/3/TRCH/SRTU//KACHU/4/SAUAL/YANAC//SAUAL with 20.5%. Within the infection categories based on the average of the three dates, thirty lines were within the 0.1-2.5 % infection category, fourteen within 2.6-5.0 %, twenty three within 5.1-10.0 %, and nine lines within 10.1-30.0 %. The infection average of the group was 4.5 % with a range of 0 to 20.8 %, but some lines showed high percentage of infection in the dates, like WHEAR/KUKUNA/3/C80.1/3*BATAVIA//2*WBLL1*2/4/WBLL1/KUKUNA//TACUPETOF2001/3/UP2338*2/ VIVITSI, WAXWING*2/KRONSTADF2004/3/TRCH/SRTU//KACHU/4/SAUAL/YANAC//SAUAL, and BAV92//IRENA/ KAUZ/3/HUITES/4/DOLL/5/SERI.1B//KAUZ/HEVO/3/AMAD*2/4/KIRITATI with 44.9, 44.7, and 37.1 %, respectively, in the third date.

Incidence of Black Point on Wheat Seeds in Different Location of Uttarakhand, India

An experiment was conducted to determine the incidence of black point disease in wheat varieties with different locations caused by A. alternata fungal pathogens of wheat grain. Fresh seeds of popularly cultivated wheat varieties, preferably viz., GW 366, GW 496, Lok 1, and GW 1, were collected after harvesting season from the farmers’ fields of wheat growing areas of middle Uttarakhand viz., Sahaspur, Roorkee, Haridwar, and Dehradun. At least 50 samples were collected from each of the districts. Five primary samples were collected and mixed from the harvested seed lot to have composite samples. Working samples were prepared from composite samples by repeated halving method. The black point disease incidence might be due to the inherent boldness of the seeds. Florets remain more open in bold-seeded varieties, enhancing the chances of more seed infection during seed development. Moreover, low night temperatures during the flowering period, severe dew at the seed maturation stage, frequent and heavy crop irrigation, and excessive application of nitrogenous fertilizers may lead to a higher incidence of the black point disease. Besides, infected seeds reveal seed rot, necrosis, and shriveling. High humidity due to prolonged rainfall or heavy dew deposition during seed maturation favors the black point. As our research findings varied, GW366 is significantly the highest incidence of black point disease.

Natural incidence of black point (Alternaria sp.) in a group of elite advanced bread wheat (Triticum aestivum) lines

One hundred and sixty eight elite advanced bread wheat lines were evaluated for resistance to black point during the crop season 2014-2015 at the Norman E. Borlaug Experimental Station in the Yaqui Valley, Mexico. Sowing dates were November 19 and 28, and December 8, 2014. Harvest and threshing were done manually in ten spikes per line, and the evaluation by visual inspection, counting healthy and infected grains to calculate the percentage of infection. The range of infection for the first sowing date was 0 to 34.6%, with an average of 2.7; sixty lines did not show infected grains; for the second date it was 0 to 43.6%, with an average of 3.1%; fifty lines did not show infected grains; while for the third date, it was 0 to 14.7%, and seventy one lines did not show infected grains. Five lines did not show infected grains in the three dates. Lines with the highest average percentage of infection were: WAXWING/KRONSTADF2004//2*FRNCLN with 18.6%, PFAU/MILAN/5/CHEN/AEGILOPS SQUARROSA (TAUS)//BCN/3/VEE#7/BOW/4/PASTOR/6/WHEAR/4/ SNI/TRAP#1/3/KAUZ*2/TRAP//KAUZ/5/C80.1/3*BATAVIA//2*WBLL1/7/C80.1/3*BATAVIA//2*WBLL1/5/REH/HARE//2*BCN/3/CROC_1/AE.SQUARROSA (213)//PGO/4/HUITES with 16.0, and WBLL1*2/BRAMBLING//SAAR/ 2*WAXWING/4/PBW343*2/KUKUNA//KRONSTAD F2004/3/PBW343*2/KUKUNA with 15.4%. Within the infection categories based on the average of the three dates, one hundred and twelve lines were within the 0.1-2.5% infection category, thirty one within 2.6-5.0%, thirteen within 5.1-10.0%, and seven lines within 10.1-30.0%. The infection average of the group was 2.3% with a range of 0 to 18.6%, but some lines showed high percentage of infection in the dates, like PFAU/MILAN/5/CHEN/AEGILOPSSQUARROSA(TAUS)//BCN/3/VEE#7/BOW/4/PASTOR/6/WHEAR/4/ SNI/TRAP#1/3/KAUZ*2/TRAP//KAUZ/5/C80.1/3*BATAVIA//2*WBLL1/7/C80.1/3*BATAVIA//2*WBLL1/5/REH/HARE//2*BCN/3/CROC_1/AE.SQUARROSA (213)//PGO/4/HUITES which showed 43.6% in the second date.

Fungal plant pathogens observed on perennial cereal crops in New York during 2017–2018

AbstractPerennial grain crops are emerging as a promising addition to sustainable agricultural systems because of their low-input requirements and delivery of ecosystem services. However, adoption of these crops is expected to bring novel management challenges, including those related to plant diseases. In New York, fungal pathogens of annual grains have a significant impact on crop yield and value and are generally controlled through a combination of host resistances, cultural practices and chemical fungicides. Without the availability of crop rotation and soil tillage practices, disease control in perennial grain systems may be problematic, and little is known about perennial grain crop susceptibility to local plant pathogen populations. During 2017 and 2018, ongoing field trials of two perennial grain crops recently introduced in New York, intermediate wheatgrass (IWG; Thinopyrum intermedium) and perennial cereal rye (PCR; Secale cereale), were assessed for the presence of putative fungal pathogens on actively growing plants, overwintered crop residue and harvested grain. A total of nine potential host–pathogen combinations were recorded based on symptomology, pathogen morphology and DNA sequences. Common annual crop pathogens were recovered most frequently, but, at one site, Phyllachora graminis, causal fungus of tar spot and a pathogen not previously reported on crops in New York, was found on IWG. Residue colonization by an important toxigenic pathogen (Fusarium graminearum) was high in both crops, though mycotoxin levels in associated grain were low, indicating either the hosts or environment were unsuitable for disease development. Seed-borne fungal communities differed across crops and locations, and black point, a condition caused by Alternaria and Bipolaris fungi and indicative of compromised grain quality, was prevalent in PCR under some conditions. Growing PCR with intercropped red clover (Trifolium pratense L.) resulted in less Stagonospora colonization of stem residue, and PCR grown with an oat (Avena sativa L.) nurse crop had a reduced incidence of black point. These alternative cultural practices may prove useful for managing disease in perennial grains. Our results suggest that the incorporation of perennial crops into the agricultural landscape will lead to familiar plant disease problems requiring new solutions as well as new problems that may require significant research investments.

Advances in genetic studies of black point disease in wheat

Black point disease seriously affects wheat production around the world. Because the incidence of black point is influenced by both pathogens and the environments, selecting resistant wheat lines and then breeding resistant cultivars under natural field conditions are not reliable, and assessment of disease resistance through inoculation of pathogens under controlled environments is time-consuming and laborious. One effective method to develop wheat cultivars resistant to black point is through molecular marker-assisted selection (MAS). Wheat resistance against black point is determined by quantitative trait loci (QTL) with broad-sense heritabilities of black point incidence in a range of 0.52–0.78. One hundred and ten loci for black point resistance have been identified on all wheat chromosomes. Among them, homoeologous groups 2 and 5 chromosomes contain the most loci, with 21 and 19, respectively, and homoeologous group 6 chromosomes have the fewest loci (11). The A, B, and D genomes contain 34, 41, and 35 loci, respectively. Although many loci for black point resistance have been reported, the effects of major loci are not clear. Further, because of the lack of molecular markers and resistant germplasms screened by pathogen inoculation under controlled conditions, breeding wheat cultivars resistant to black point is still difficult. In this review, these major problems were examined, and suggestions on identifying pathogens and using accurate assessment technology are proposed. It will be conducive to develop molecular markers closely linked to major loci and create resistant germplasms through MAS, which will promote the progress in resistance breeding and the control of black point in wheat.

Effect of black point on seed germination parameters in popular wheat cultivars of Northern India

Black point of wheat is a commonly occurring disease in all wheat growing regions of the world. It is characterized by the dark discoloration of the embryo side of the seed. Yellowing of leaves in early season and foliar blights on mature crop are common symptoms causing losses up to 20%. Therefore, present study was carried out on seeds of ten popularly cultivated wheat varieties of north India viz. HD 2967, HD 3086, PBW 502, PBW550, PBW 677, PBW 723, PBW725, WH 711, WH 1105 and DBW 17. Maximum incidence of black point was observed on seeds of var. HD 3086 and DBW 17 while it was minimum on var. PBW 502. The most prevalent fungal pathogens associated with diseased seeds are Alternaria triticina, Bipolaris sorokiniana and Fusarium graminearum. Association of black point in seeds reduced the germination and vigour index of all the varieties under study. Maximum decrease in seed germination was recorded in var. HD2967 followed by DBW 17. Pathogens harboring black point affected seeds induced seed rot and seedling mortality thus reducing seed germination and ultimately poor crop stand under field conditions.

Assessing Genetic Resistance in Wheat to Black Point Caused by Six Fungal Species in the Yellow and Huai Wheat Area of China.

The most effective and environmentally sustainable method for controlling black point disease of wheat (Triticum aestivum L.) is to plant resistant cultivars. To identify sources of resistance to black point, 165 selected cultivars/lines were inoculated with isolates of six fungal species (Bipolaris sorokiniana, Alternaria alternata, Fusarium equiseti, Exserohilum rostratum, Epicoccum sorghinum, and Curvularia spicifera) known to cause black point in wheat using spore suspensions under controlled field conditions in 2016 and 2017. Inoculation of the isolates significantly increased the incidence of black point in the cultivars/lines compared with those grown under natural field conditions (NFC). The disease incidence of plants inoculated with B. sorokiniana and E. rostratum was 15.5% and 18.8% in 2016, and 20.4% and 23.0% in 2017, whereas those under NFC were 5.7% (2016) and 1.5% (2017), respectively. Furthermore, disease symptoms varied with pathogen. Among the 165 cultivars/lines tested, 3.6%, 50.9%, 60.0%, 1.8%, 47.3%, and 58.8% were resistant to B. sorokiniana, A. alternata, F. equiseti, E. rostratum, E. sorghinum, and C. spicifera, respectively. In addition, we identified one line ('SN530070') resistant to black point caused by all six pathogens. This is the first study to assess resistance to wheat black point caused by six fungal species under controlled conditions. The black point-resistant cultivars/lines could be useful in breeding and also in research on the mechanisms of resistance to black point.

Black point in spring durum wheat under different environmental conditions

The study of cereal seed mycocenosis is relevant in solving problems determining the production of healthy, environmentally friendly agricultural products. Black point of wheat grain is a disorder characterised by a brown-black discolouration at the embryo end of the kernel. It is found in all regions of durum wheat cultivation and it results in significant economic loss annually. We studied seven varieties of spring durum wheat that were grown in 2014-2019. The weather conditions of the growing season have a significant impact on the development of black point of durum wheat in the forest-steppe zone of the Altai Territory of Russia (South-Western Siberia). The defeat of seeds by a black point varied from 2.3% to 28.0% on average for varieties. To obtain high-quality grain that is not affected by this disease, phytosanitary measures are required that reduce the infection of seeds with phytopathogens and limit the development of the disease during the growing season. Analysis of the pathogenic composition of fungal microorganisms in seeds of spring durum wheat, formed in different vegetations, revealed the presence of representatives of Fusarium, Alternaria, Helminthosporium, Penicillium and Aspergillum with a predominance of the first 3 genera. We found the negative effect of Fusarium fungi on seed germination. In the field conditions of the forest-steppe of the Altai Territory, the development of a black point in durum wheat grain is determined by the colonization of seeds with Bipolaris sorokiniana. No correlation was found between the incidence of black point and the infection of seeds by Fusarium and Alternaria.

Key periods and effects of meteorological factors affecting incidence of wheat black point in the Yellow and Huai wheat area of China

To determine the key periods and effects of meteorological factors affecting the incidence of black point, the correlations between 14 meteorological variables and incidence of black point were analyzed using 23 susceptible wheat genotypes planted at three locations in two years in the Yellow and Huai Wheat Area of China. The results showed that the incidence of black point and meteorological factors varied considerably across locations and years. There was a significantly negative correlation between temperature-related variables (daily average temperature, days with temperature > 30 °C, etc.) and black point incidence at 26–40 days after heading. Humidity-related variables (daily relative humidity, rainfall days, etc.) except precipitation were positively correlated with black point incidence at 1–20 days after heading. When the daily average temperature decreased by 1 °C at 31–35 days after heading, the incidence of black point increased by approximately 5.5%, and when the daily relative humidity increased by 10% at 11–15 days after heading, the incidence increased by approximately 9.4%. There was a significant negative correlation between daily sunshine duration and black point incidence at 1–15 days and 26–40 days after heading. In conclusion, the key periods and meteorological factors affecting black point incidence are a humid environment at 1–15 days, lower temperature at 26–40 days, and a short period of sunshine after heading. These results provide important information for the control of black point in wheat.

The correlation between wheat black point and agronomic traits in the North China Plain

Black point is an economically serious disease in cereals that affects crop yield and value, the incidence of which is known to vary with environmental conditions and fungal load. However, little is known about the genotypic differences in susceptibility towards the disease. We studied the correlations between 35 agronomic traits and the incidence of black point, using 48 representative wheat genotypes selected from a total of 403 genotypes. These 48 genotypes were inoculated with fungi and cultivated under field conditions during 2016–2018 in the North China Plain. The results showed that the incidence of black point varied across genotypes, fungal isolates, and years. First, we screened 28, 23, 19, and 23 genotypes susceptible or resistant to black point caused by Bipolaris sorokiniana, Alternaria alternata, Fusarium equiseti, and under natural field conditions, respectively. The correlations between black point incidence and agronomic traits were analyzed using the screened wheat genotypes. We found a positive correlation between incidence and filling stage (r = 0.652) and a negative correlation between incidence and freezing resistance (r = −0.613) during the three years. In addition, black point incidence was correlated with thousand grain weight, heading date, seedling habits, awn length, and glume opening; however, these associations varied across years and different fungal isolates. Black point incidence was not strongly associated with most of the agronomic traits studied, thus indicating that this disease was greatly affected by environmental factors. However, black point incidence was likely to be lower in genotypes with adequate freezing resistance and short filling stage. These results provide some markers of agronomic traits for breeders to improve the selection efficiency of high-yielding wheat varieties that are resistant to black point.

Biological control of pathogens associated with kernel black point disease of wheat

Pathogens associated with wheat kernel black-point disease were recovered from symptomatic grains and identified as Cochliobolus sativus, Alternaria alternata and Fusarium graminearum. A total of twenty-five microbial isolates obtained from the surface of healthy grains of wheat were screened for antagonism against the isolated pathogens. The most effective antagonistic isolates were Bacillus megaterium (B5), B. amyloliquefaciens (B28), Trichoderma harzianum (T37) and Epicoccum sp. (E52). In pots, treating of wheat grains with strains B5, B28, T37 and E52 significantly improved germination and seedling growth naturally infected with the black-point pathogens. Bacillus amyloliquefaciens (strain B28) was the most efficient biocontrol agent in terms of germination, length of roots and shoots which increased by 103.2, 55.3 and 43.91%, respectively. In field trials, the antagonistic isolates improved germination and tillering of black-pointed wheat grains. Spraying wheat plants with the antagonistic isolates significantly decreased the incidence of leaf-spots and kernel black-point down to 18.7 and 2.86, respectively, with B. amyloliquefaciens (B28). In addition, grain yield was significantly increased. Strain B28 (B. amyloliquefaciens) increased the weight of 1000-kernels by 16.77% and was as effective as the fungicide Sumi-8.

Effects of rain shelter or simulated rain during grain filling and maturation on subsequent wheat grain quality in the UK

SUMMARYThe effects of simulated additional rain (ear wetting, 25 mm) or of rain shelter imposed at different periods after anthesis on grain quality at maturity and the dynamics of grain filling and desiccation were investigated in UK field-grown crops of wheat (Triticum aestivumL., cvar Tybalt) in 2011 and in 2012 when June–August rainfall was 255·0 and 214·6 mm, respectively, and above the decadal mean (157·4 mm). Grain filling and desiccation were quantified well by broken-stick regressions and Gompertz curves, respectively. Rain shelter for 56 (2011) or 70 days (2012) after anthesis, and to a lesser extent during late maturation only, resulted in more rapid desiccation and hence progress to harvest maturity whereas ear wetting had negligible effects, even when applied four times. Grain-filling duration was also affected as above in 2011, but with no significant effect in 2012. In both years, there were strong positive associations between final grain dry weight and duration of filling. The treatments affected all grain quality traits in 2011: nitrogen (N) and sulphur (S) concentrations, N : S ratio, sodium dodecyl sulphate (SDS) sedimentation volume, Hagberg Falling Number (HFN), and the incidence of blackpoint. Only N concentration and blackpoint were affected significantly by treatments in 2012. Rain shelter throughout grain filling reduced N concentration, whereas rain shelter reduced the incidence of blackpoint and ear wetting increased it. In 2011, rain shelter throughout reduced S concentration, increased N : S ratio and reduced SDS. Treatment effects on HFN were not consistent within or between years. Nevertheless, a comparison between the extreme treatment means in 2012 indicated damage from late rain combined with ear wetting resulted in a reduction ofc. 0·7 s in HFN/mm August rainfall, while that between samples taken immediately after ear wetting at harvest maturity or 7 days later suggested recovery from damage to HFN upon re-dryingin planta. Hence, the incidence of blackpoint was the only grain quality trait affected consistently by the diverse treatments. The remaining aspects of grain quality were comparatively resilient to rain incident upon developing and maturing ears of cvar Tybalt. No consistent temporal patterns of sensitivity to shelter or ear wetting were detected for any aspect of grain quality.

Screening wheat genotypes for resistance to black point and the effects of diseased kernels on seed germination

This study was carried out to identify wheat genotypes with high levels of resistance towards black point disease. In total, 403 genotypes were tested between the years 2010 and 2012 in the North China Plain (NCP). The effect of different percentages of diseased kernels on seed germination and seedling growth (root length, shoot length, dry root weight and dry shoot weight) was assessed using three highly susceptible genotypes. Black point incidence varied greatly among wheat genotypes, the lowest and the highest values were 0.3% and 66.7%, respectively. Among the 403 wheat genotypes studied, 37.5% were classified as resistant (151 genotypes), 62.5% were classified as susceptible (252 genotypes) and 36 wheat genotypes were highly resistant to black point disease. The average broad-sense heritability for black point disease resistance of 403 wheat genotypes was 58.6%, suggesting that black point was stronger affected by genetic factors compared to environmental factors. Furthermore, black point decreased the percentage of germinated seeds and inhibited seedling growth. The results provided information on germplasm resources for disease-resistant cultivar breeding as well as a reference for determining the suitable sowing rate in wheat production in the NCP.

Pathogenicity, Symptom Development, and Mycotoxin Formation in Wheat by Fusarium Species Frequently Isolated from Sugar Beet

Crop rotations with putative non-host crops such as sugar beet are often recommended to reduce Fusarium head blight (FHB) in cereals. However, recent observations have shown pathogenic, endophytic, and saprotrophic colonization of sugar beet with various Fusarium spp. Therefore, strains of seven species frequently isolated from sugar beet were tested for pathogenicity on wheat. Species-specific symptoms on heads and kernels were evaluated and the grains were analyzed for 20 mycotoxins with liquid chromatography-tandem mass spectrometry. Fusarium graminearum, F. culmorum, and F. cerealis from sugar beet caused typical FHB symptoms and mycotoxin contamination with deoxynivalenol and nivalenol, while a high incidence of black point was observed in heads inoculated with F. tricinctum or F. equiseti. Black point kernels revealed 3.4 to 14.5 times higher mycotoxin concentrations than symptomless grains, containing enniatin B1 at 38,000 μg/kg, moniliformin at 4,900 μg/kg, and 2-amino-14,16-dimethyloctadecan-3-ol at 5,500 μg/kg, as well as monoacetoxyscirpenol at 2,600 μg/kg and nivalenol at 3,800 μg/kg. Monitoring of these latter two species in the field is hampered by the lack of typical head symptoms after infection. In further experiments, the impact of sugar beet residues on FHB severity and the correlation between mycotoxin contamination of cereal lots and the amount of black point have to be evaluated.

Relative susceptibility to blackpoint in durum wheat varieties of Argentina

Blackpoint incidence was assessed on grain from six durum wheat (Triticum durum Desf.) varieties grown during crop season 2004-05 at four sites, in the traditional durum wheat growing region of Argentina. Broad differences in... | Find, read and cite all the research you need on Tech Science Press

Modelling of wheat black point incidence based on meteorological variables in the southern Argentinean Pampas region

Studies were undertaken during 3 growing seasons at several locations on the Argentinean Pampas to investigate the relationships between environmental factors and black point incidence, and to develop predictive models. The strongest associations were observed throughout the critical period starting at 543 degree-days from heading to 861 degree-days (base temperature = 0°C). After a selection process, the best regression equation was: PI % = –6.50 + 0.07 DPrDDTd + 0.23 DRH, where PI is predicted disease incidence, DPrDDTd is a product of days with precipitation and the total degree-day accumulation of mean daily temperatures greater than 17°C (DDTd), and DRH is the total days with relative humidity above 62%. The equation accounted for 87% of the total variance in the disease incidence. Using logistic regression techniques, a model including precipitation frequency and DDTd could satisfactorily explain the probability of occurrence of severe, moderate, and light epidemics.

Preliminary Studies on the Natural Incidence of Wheat Blackpoint under Different Nitrogen Fertilization Levels and Tillage Systems in Argentina

Preliminary Studies on the Natural Incidence of Wheat Blackpoint under Different Nitrogen Fertilization Levels and Tillage Systems in Argentina

Kernel discoloration and downgrading in spring wheat varieties in western Canada

Kernel discolorations of wheat (Triticum spp.), as observed in black point, smudge, penetrated smudge, red smudge, and fusarium-damaged kernels, are important downgrading factors in western Canada. To determine varietal differences in the incidence of kernel discoloration and its effect on kernel grading, grain samples were taken from four Canada Western Amber Durum wheat varieties (one unregistered and three registered varieties) and six Canada Western Red Spring common wheat cultivars in 24 environments (during 4 years at six sites) in western Canada. The incidence of kernel discoloration resulted in kernel downgrading in 15 environments. In these environments, smudge damage was the major downgrading factor, followed by fusarium-damaged kernels. Penetrated smudge and red smudge were observed only in durum wheat varieties in the black-soil zone. The incidence of black point was generally not high enough to cause downgrading. For durum wheat, the unregistered variety DT 369 had the highest occurrence of downgrading, which was mainly associated with smudge damage. 'Plenty' had the lowest occurrence of smudge downgrading, but the highest fusarium downgrading. 'Saunders' and 'Garnet' had the least downgrading frequency of the common wheat cultivars.

Effects of foliar fungicides on kernel black point of wheat in southern Saskatchewan

This study was undertaken to determine the effect of fungicides on the incidence of black point in wheat (Triticum spp.) in southern Saskatchewan, Canada. Experiment 1 was conducted at Swift Current and Indian Head for 3 years. Folicur 3.6F (tebuconazole) and Bravo 500 (chlorothalonil) were applied at different growth stages from stem elongation to head emergence. Three spring common wheat (Triticum aestivum) and three durum wheat (Triticum turgidum var. durum) genotypes were used in this study. Experiment 2 was conducted at Indian Head for 3 years. Folicur 3.6F was applied from stem elongation to early milk stage for a durum cultivar. The incidence of black point was very low at Swift Current. Severe black point incidence occurred at Indian Head in 1999, which could be related to low temperature and high rainfall during the grain filling stage. Durum wheat cultivars had higher black point incidence than the common wheat cultivars. Fungicide applications from stem elongation to flag emergence could increase black point infection and it was, in many cases, associated with an increase in kernel mass. Fungicide applications at or after head emergence could reduce the incidence of black point, although this was not consistent.