In Ontario, Canada, the prevalence and severity of powdery mildew (PM) disease caused by Blumeria graminis on wheat has been escalating. Continual monitoring of the effectiveness of PM-resistance genes (Pm) and the pathogen virulence spectrum in the field is essential for breeding durable resistance to control the disease. In 2021 and 2022, a total of 74 single-colony isolates of B. graminis were purified from field samples from 40 randomly selected wheat fields and greenhouses in Ontario, then tested for virulence on 24 single-Pm gene wheat lines. Compared to a previous survey in 2018-2019, the virulence frequencies to most Pm genes have increased over the years, including Pm1a, Pm1b, Pm1c, Pm2, Pm3a, Pm3f, Pm5a, Pm5d, Pm17, Pm30, Pm34, Pm35, Pm43, MlAG12 and NCAG13. Nevertheless, Pm12, Pm16, Pm21 and Pm37 each remained effective against all isolates. Nine genes (Pm1a, Pm1b, Pm1c, Pm3d, Pm4b, Pm25, Pm29, MlAG12 and NCAG13) were generally effective, with resistance to more than 80% of the isolates. The remaining 11 genes were ineffective, having susceptible reactions to 37-97% of the isolates. DNA sequences of 116 isolates (2018-2022) for the fragments of alternative oxidase (AOX), protein kinase A (PKA), protein phosphatase type 2A (PPA) and beta-tubulin (bTUB) genes resulted in only four informative segregating single nucleotide polymorphisms (SNPs). The linkage disequilibrium analyses of these four SNPs suggested frequent genetic recombination. Additionally, network analyses of virulence phenotype data showed no genetic subdivision, suggesting B. graminis in the sampled area is likely a panmictic population.

This article presents a graphical method to visually analyze the trait-yield association (TYA) patterns based on data from multi-location, multi-year crop variety trials, exemplified using oat data from trials conducted across Canada from 2017 to 2022. Each year a new set of 60-66 oat (Avena sativa L.) breeding lines were tested in replicated yield trials at 9-11 locations, and data for yield, key agronomic and quality traits, and crown rust scores were collected at all or some of the locations. Pearson correlation coefficient was calculated between yield and each trait for each trial. The correlation coefficients from different locations and years were arranged in a TYA x trial (TYT) two-way table. This table was subjected to singular value decomposition, and the resulting first two principal components were used to generate a TYT biplot. The TYT biplot revealed three oat mega-environments (MEs) in Canada, consistent with the conclusion from previous ME analyses, indicating that each ME had its characteristic TYA patterns. It was found that yield was consistently and positively correlated with crown rust (Puccinia coronata var. avenae) resistance, test weight, kernel weight, and groat content in ME1 (the crown rust-prone regions of Ontario); yield was correlated positively with plant height but negatively with oil content in ME2 (the northern regions of eastern Canada). Interestingly, crown rust resistance was found to contribute negatively to yield in ME2. No strong and consistent TYAs were found in ME3 (the Canadian prairies). Different types of TYAs have different uses in genotypic selection. A trait-yield association x trial (TYT) biplot was introduced to reveal trait-yield association patterns.TYT biplots revealed different oat mega-environments in Canada, each with unique trait-yield association patterns.Trait-yield association patterns can be used to guide visual selection.Crown rust resistance was shown to be counterproductive in the non-rust regions.Different types of trait-yield associations have different uses in genotypic selection.

High biomass and nutrient acquisition are desirable for oat (Avena sativa L.) as a cover crop. However, our understanding of oat genotypes suitable for cover crops and associated traits is limited. The objectives of this experiment on growing oat as a cover crop, after winter wheat (Triticum aestivum L.) harvest, were to determine biomass production, nutrient uptake of a set of oat genotypes, and to identify phenotypic traits that can be used as indicators to select cultivars suitable for cover crops. The results showed that the top biomass-producing genotypes took up larger amounts of soil nutrients, up to 142 kg N ha(-1) and 17 kg P ha(-1) in 2016, and 43.5 kg N ha(-1) and 8.3 kg P ha(-1) in 2017. The biomass production was significantly related to plant height and leaf area index (LAI) in both years, and to the normalized difference vegetation index (NDVI) in 2017. Both NDVI and LAI were closely related to the total amounts of N and P uptake. The poor association between biomass and NDVI in 2016 was due to vigorous growth of volunteer wheat and weeds as well as severe rust (Puccinia coronata f. sp. avenae Eriks.) infestation. Our results suggest that it is important to choose oat varieties as cover crops. Leaf area index can be used as a nondestructive indicator for final biomass and nutrient acquisition, while both NDVI and LAI are important traits for choosing oats as soil conservation cover crops.

Effective nitrogen (N) management strategies are important for ensuring a balance between optimizing plant growth and minimizing disease damage. A field experiment was conducted for three years to (i) assess the effects of N fertilizer application on the growth and seed yield of canola and severities of Sclerotinia stem rot (SSR), and (ii) to determine a reasonable N-rate for optimizing plant growth and minimizing the loss from SSR in eastern Canada. The experiment was designed with factorial combinations of eight N treatments and two canola hybrids. All N treatments reduced canola emergence with increasing preplant N application rates above 100 kg ha −1 , but had a positive impact on plant height, fresh weight, dry weight, and seed yield. The development of SSR showed differential responses to N application rates. Of all the treatments, the split application (50 kg N ha −1 at preplant plus 100 kg N ha −1 side-dressed at the 6-leaf stage) increased canola growth and often produced the highest or similar seed yields to those of equivalent N rate applied as preplant. At the 150 kg ha −1 N rate, no severe development of SSR was observed in either preplant-only or split application. Overall, this study demonstrates that the split-N management strategy (50 + 100 kg ha −1 ) maintained a balance between enhancing plant growth and mitigating the negative impacts of SSR on canola.

Powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is a major disease of wheat (Triticum aestivum) in Ontario, which can cause 20% yield loss. The development of resistant commercial wheat cultivars is the most economical means of controlling this disease, but only if the resistance genes used are incompatible with the virulence phenotypes present in the pathogen population. The virulence structure of Bgt in Ontario was examined in 2018 and 2019. Of the 42 single colony isolates collected in Ontario greenhouses and commercial fields, 40 virulence phenotypes, assigned VP1 to VP40, were identified on a set of 24 single-gene differential genotypes. Of the 24 resistance genes possessed by the differential genotypes, eight genes including Pm1a, Pm1b, Pm1c, Pm12, Pm16, Pm21, Pm37, and MlAG12 were effective against all of the Bgt isolates. Four genes including Pm3d, Pm29, Pm34, and NCAG13 were mostly effective with resistance reactions to more than 80% of the isolates. There were no significant differences in numbers of virulence genes per isolate between the two years, or between the greenhouse and field origins. The virulence frequencies of Bgt isolates for these effective and mostly effective genes were also not significantly affected by the year of collection and their origins, suggesting that the Bgt population is relatively stable. The effective genes identified in this study may be deployed singly or used for gene pyramiding in wheat breeding programs for developing powdery mildew-resistant cultivars in Ontario.

Twenty oat fields located in the major production areas in Ontario were surveyed for diseases in 2019. Of the 11 diseases observed, crown rust, halo blight, barley yellow dwarf and loose smut were most prevalent, having moderate to severe levels of infection in 12, 4, 2 and 2 fields, respectively. Fusarium head blight (FHB) was observed in all surveyed fields with low severities. Fusarium poae and F. sporotrichioides were the predominant species isolated from the FHB-infected kernels. INTRODUCTION AND METHODS: A survey to document diseases in Ontario oat crops was conducted during the fourth week of July 2019 when plants were at the soft dough stage of development. Twenty fields were chosen at random in central and eastern regions where most oat crops were grown in Ontario. Foliar disease severity was determined on 10 flag and penultimate leaves sampled at each of three random sites per field, using a rating scale of 0 (no disease) to 9 (severely diseased). Disease diagnosis was based on visual symptoms. Average severity scores of <1, <3, <6 and >= 6 were considered as trace, slight, moderate and severe disease levels, respectively. The severity of ergot, loose smut and take-all was based on the percentage of plants infected at each of the three random sites per field. FHB was rated for incidence [% infected panicles (heads)] and severity (% infected spikelets in the affected panicles) based on approximately 200 panicles at each of the three sites per field. An FHB index [(% incidence x % severity)/100] was determined for each field. The percentage of infected plants or FHB index values of <5, <10, <20 and >= 20% were considered as slight, moderate, severe and very severe disease levels, respectively. Determination of the causal species of FHB was based on 50 infected panicles collected from each affected field. The panicles were air-dried at room temperature and subsequently threshed. Fifty discoloured kernels per sample were chosen at random, surface sterilized in 1% NaOCl for 60 seconds and plated in 9 cm diameter petri dishes on modified potato dextrose agar (10 g dextrose per litre amended with 50 ppm of streptomycin sulphate). The plates were incubated for 10-14 days at [GRAPHICS] 22-25 degrees C and a 14-hour photoperiod using fluorescent and long wavelength ultraviolet tubes. Fusarium species isolated from kernels were identified by microscopic examination using standard taxonomic keys. RESULTS AND COMMENTS: Eleven diseases were identified (Table 1). Crown rust (Puccinia coronata f. sp. avenae), halo blight (Pseudomonas syringae pv. coronafaciens), and barley yellow dwarf (BYDV) were the most prevalent foliar diseases and were found in 15, 18 and 17 fields at average severities of 4.0, 1.8 and 1.7, respectively. Moderate to severe levels of infection from these diseases were observed in 12, 4 and 2 fields, respectively. Yield reductions due to these diseases were estimated to be <10% in affected fields. Other foliar diseases observed were pyrenophora leaf blotch (Pyrenophora avenae), spot blotch (Cochliobolus sativus), stagonospora leaf blotch (Stagonospora avenae f. sp. avenaria), and stem rust (Puccinia graminis f. sp. tritici); they were observed in 17, 14, 18 and 5 fields at mean severities of 1.1, 1.1, 1.0 and 1.0, respectively. Moderate or severe levels of these diseases were not found and none would have resulted in measurable damage to the crop. Ergot (Claviceps purpurea), loose smut (Ustilago nuda) and take-all root rot (Gaeumannomyces graminis var. avenae) were observed in 20, 20 and 16 fields at incidence levels of 0.5, 1.1 and 0.8%, respectively (Table 1). Moderate to severe levels of infection from ergot and take-all were not observed, while moderate levels of loose smut were found in two fields. Yield reductions due to loose smut were estimated at <5% in affected fields. Fusarium head blight occurred in all of the surveyed fields at a mean FHB index of 0.1% (range 0.01-0.5%) (Table 1). Moderate to severe FHB infection was not observed. Yield and quality reductions due to FHB were estimated at <1%. Five Fusarium species were isolated from putatively infected kernels (Table 2). Fusarium poae and F. sporotrichioides predominated and occurred in 90 and 80% of the affected fields, isolated from 29.8 and 17.1% of infected kernels, and represented 58.1 and 33.3% of the pathogen population, respectively. Fusarium equiseti and F. graminearum were less common, occurring in 45-55% of fields and 1.9-2.4% of kernels, and representing 3.7-4.7% of the pathogen population. Fusarium acuminatum was least common, occurring in 5% of fields and 0.1% of kernels, and representing 0.2% of the pathogen population. The 11 diseases observed on oat in Ontario in 2019 were the same as those recorded in 2018 (Xue and Chen 2019). Overall, the incidence and severity of these diseases were generally lower in 2019 than in 2018. Less frequent rain events in June and July in 2019 compared with 2018 in Central and Eastern Ontario were likely responsible for the decreased disease severities observed.

Twenty-four barley fields located in the major production areas in Ontario were surveyed for diseases in 2019. Of the 14 diseases observed, net blotch, loose smut and take-all were the most prevalent, having moderate to severe levels of infection in seven, three and two fields, respectively. Fusarium head blight (FHB) was observed in 23 fields with low severities. Fusarium poae and F. sporotrichioides were the predominant species isolated from the FHB infected kernels. INTRODUCTION AND METHODS: A survey for barley diseases was conducted in Ontario during the fourth week of July 2019 when plants were at the soft dough stage of development. Twenty-four fields consisting of nine 2-row and 15 6-row barley were chosen at random in the central and eastern regions where most of the barley crops were grown in Ontario. Foliar disease severity was determined on 10 flag and penultimate leaves sampled at each of three random sites per field, using a rating scale of 0 (no disease) to 9 (severely diseased). Diagnosis was based on visual symptoms. Average severity scores of <1, <3, <6 and >= 6 were considered as trace, slight, moderate and severe disease levels, respectively. The severity of covered smut, ergot, leaf stripe, loose smut, and take-all was rated as the percentage of plants infected at each of the three random sites per field. FHB was rated for incidence (% infected spikes) and severity (% infected spikelets in the affected spikes) based on approximately 200 spikes at each of the three sites per field. An FHB index [(% incidence x % severity)/100] was determined for each field. The percentage of infected plants or FHB index values of <5, <10, <20 and >= 20% were considered as slight, moderate, severe and very severe disease levels, respectively. Determination of the causal species of FHB was based on 50 infected spikes collected from each affected field. The spikes were air-dried at room temperature and [GRAPHICS] subsequently threshed. Fifty discoloured kernels per sample were chosen at random, surface sterilized in 1% NaOCI for 60 seconds and plated in 9 cm diameter petri dishes on modified potato dextrose agar (10 g dextrose per litre amended with 50 ppm of streptomycin sulphate). The plates were incubated for 10-14 days at 22-25 degrees C and a 14-hour photoperiod using fluorescent and long wavelength ultraviolet tubes. Fusarium species isolated from kernels were identified by microscopic examination using standard taxonomic keys. RESULTS AND COMMENTS: A total of 14 diseases or disease complexes were observed (Table 1). Net blotch (Pyrenophora teres), barley yellow dwarf virus (BYDV) and spot blotch (Cochliobolus sativus) were the most common foliar diseases, and were found in 22, 22 and 21 fields at average severities of 1.9, 1.1 and 1.1 respectively. Moderate to severe levels of infection with barley yellow dwarf were not observed and moderate to severe levels of net blotch and spot blotch were observed in seven and one fields, respectively. Yield reductions due to these diseases were estimated to have averaged <5% in affected fields. Other foliar diseases observed included leaf rust (Puccinia hordei), powdery mildew (Blumeria graminis f.sp. hordei), scald (Rhynchosporium secalis), septoria complex including speckled leaf blotch (Septoria passerinii) and leaf blotch (Stagonospora nodorum), and stem rust (Puccinia graminis f. sp. tritici or f. sp. secalis). These were observed in 4, 1, 5, 13 and 5 fields at mean severities of 1.0, 1.0, 1.4, 1.0 and 1.4, respectively. All of these diseases occurred at trace to slight levels, except for one field with moderate levels of stem rust. None of these diseases would have resulted in substantive damage to the crop. Covered smut (Ustilago hordei), ergot (Claviceps purpurea), leaf stripe (Pyrenophora graminea), loose smut (Ustilago nuda) and take-all (Gaeumannomyces graminis) were all commonly observed. These were found in 24, 24, 24, 23 and 22 fields at mean incidences of 0.5, 0.5, 0.5, 1.9 and 1.6%, respectively. Severe infections of these diseases were not observed, but moderate levels of loose smut and take-all were found in three and two fields, respectively. Yield reductions due to loose smut and take-all were estimated at <5% in affected fields. FHB was observed in 23 fields at a mean FHB index of 0.1% (range 0.01% to 1.0%) (Table 1). Moderate to severe FHB infection was not observed. Yield and quality reductions due to FHB were estimated at <1%. Seven Fusarium species were isolated from putatively infected kernels (Table 2). Fusarium poae and F. sporotrichioides predominated and occurred in 100 and 87% of the affected fields, isolated from 27.7 and 14.0% of infected kernels, and represented 57.6 and 29.2% of the pathogen population, respectively. Fusarium equiseti and F. graminearum were less common, occurring in 48-57% of fields and 2.1-3.9% of kernels, and representing 4.38.2% of the pathogen population. Fusarium acuminatum, F. oxysporum and F. verticillioides were least common, occurring in 4-9% of fields and 0.1-0.2% of kernels, and collectively representing <1% of the pathogen population. The 14 diseases observed on barley in Ontario in 2019 were the same as those recorded in 2018 (Xue and Chen 2019). Overall, the incidence and severity of these diseases were generally lower in 2019 than in 2018. Less frequent rain events in June and July in 2019 compared with 2018 in Central and Eastern Ontario were likely responsible for the decreased disease severities observed.

Crown rust, caused by Puccinia coronata f. sp. avenae (Pca), is the most important disease and yield limiting factor of oat production in eastern Canada. In this study 101 oat genotypes composed of 51 cultivars and 50 breeding lines from eight oat breeding programs across Canada were evaluated for seedling reactions to six common Pca races, as well as reactions to a bulk inoculum of Pca in greenhouse trials and for adult plant resistance (APR) to natural populations of Pca in field trials in 2014 and 2015. Sixty-six genotypes showed resistant reactions to at least one of the six races; of these, 22 were resistant to all six races. These 22 genotypes also showed resistance to the bulk inoculum at the seeding stage and to the natural populations of Pca at the adult plant stage, suggesting that these current and future oat varieties have effective resistance against the common races and Pca populations in the region. Eleven genotypes, including 12ANS03, AAC Bullet, CFA1213, CFA1306, Idaho, OA1301-1w-3, OA1369-5, OA1370-2, OA1371-2, OA1383-2, and Oscar, were susceptible as seedlings but resistant as adult plants. APR is proven to be long lasting and provides broad-spectrum resistance to Pca populations. The 11 oat genotypes identified with APR in the present study are more desirable as sources of resistance for breeding programs developing durable crown rust resistant cultivars for eastern Canada.

Thirty-eight spring wheat fields located in the major production areas in Ontario were surveyed for diseases in 2019. Of the 12 diseases observed, leaf rust and septoria/stagonospora leaf blotch were most prevalent and each had moderate to severe levels of infection in three fields. Fusarium head blight (FHB) was observed in 37 fields with low severities. Fusarium graminearum was the predominant species isolated from the FHB infected kernels.

Abstract Fusarium spp. associated with fusarium head blight (FHB) on cereals in Ontario was monitored in this study. Nine species were recovered from 24 300 putatively infected kernels collected from 486 affected spring wheat fields from 2001 to 2017, 11 species from 13 250 kernels from 265 barley fields from 2005 to 2017, and nine species from 8800 kernels from 176 oat fields from 2008 to 2017. Fusarium avenaceum, F. equiseti, F. graminearum, F. poae and F. sporotrichioides were the most commonly isolated species, occurring in 23–66% of the infected fields and 1.3–27.0% of the infected kernels. In spring wheat, F. graminearum was predominant, occurring in 88% of fields and in 60.4% of kernels, and represented 90% of the pathogen population. In barley, F. poae and F. graminearum were equally dominant, occurring in 77% and 64% of fields, 17.6% and 17.0% of kernels, and represented 42% and 40% of the pathogen population, respectively. In oat, F. poae was predominant, occurring in 93% of fields and 23.5% of kernels, and represented 68% of the pathogen population. Growth seasons characterized as an FHB epidemic occurred in 11 of 17 years surveyed in spring wheat, 3 of 13 years surveyed in barley, and no epidemic years were observed over the 10-year period in oat. There were no significant differences in frequency of isolation of the Fusarium species, except for F. graminearum which increased by 60% in wheat and by 210% in barley in the FHB epidemic years compared with the non-epidemic years, suggesting that F. graminearum was responsible for the FHB epidemics in Ontario.

We developed 178 recombinant inbred lines from a southern-by-spring oat population designated as "TxH." These lines were genotyped to generate a high-quality linkage map that resolved 6,902 markers into 21 linkage groups that matched closely with the latest hexaploid oat consensus map. Three major quantitative trait loci (QTLs) affecting heading date were found in locations that are consistent with known QTLs and candidate genes, and two other QTLs affecting heading date were found in novel locations. Five QTLs affecting plant height were found. Both sets of QTLs are responsible for transgressive segregation observed for these two traits. Four QTLs affecting resistance to crown rust, caused by the pathogen Puccinia coronata f. sp. avenae, were identified. Two of these QTLs are consistent with known clusters of rust resistance genes, while two may represent new locations of novel rust resistance genes. A complete set of SNP sequences suitable for generating markers for molecular selection is provided.

Thirty-three oat crops in Central and Eastern Ontario were surveyed for diseases in 2018.Of the 11 diseases observed, barley yellow dwarf, crown rust, take-all, and stagonospora leaf blotch were most prevalent, having moderate to severe levels of infection in 8, 6, 6, and 5 fields, respectively. Fusarium head blight (FHB) was observed in 32 fields with low severities. Fusarium poae was the predominant species isolated from the FHB infected kernels.

Twenty-nine spring wheat fields in Central and Eastern Ontario were surveyed for diseases in 2018. Of the 13 diseases observed, take-all, septoria glume blotch, and septoria/stagonospora leaf blotch were most prevalent, having moderate to severe levels of infection in 9, 5, and 3 fields, respectively. Fusarium head blight (FHB) was observed in 25 fields with low severities. Fusarium graminearum and F. poae were the predominant species isolated from the FHB-infected kernels.

Crown rust, caused by Puccinia coronata var. avenae f. sp. avenae (Urban & Markova) (Pca), is an economically significant problem in oat in Canada. The growing of crown rust resistant oat cultivars has been an important management practice. The development of oat cultivars with effective resistance requires knowledge of the virulence genes present in the pathogen population. This study's objective was to determine the presence and frequency of virulence to 24 oat lines with single Pc genes in isolates of Pca collected in Canada during 2010 to 2015. A total of 692 distinct races were identified, of which 603 were from the eastern Prairie region (EPR) and 89 from eastern Canada. None of the 24 Pc resistance genes studied was effective against all of the Pca isolates from the EPR. The frequency of virulence increased on 15 of the Pc differential lines in the EPR between 2010 and 2015, with the most dramatic increase from 0% to 67% being to Pc91. The most effective resistance genes were Pc94, Pc50, Pc96, Pc97, Pc98 and Pc101. Virulence to Pc58, Pc94, Pc98 and Pc101 was not observed in Pca isolates from eastern Canada. The race structure of the Pca population in Canada was highly variable, with more than 80% of the races identified each year represented by one Pca isolate. The race structure of the Pca populations in eastern Canada and the EPR were distinct, as 80% of the races identified from Pca isolates collected in eastern Canada were not detected in the EPR. The results of this study indicate that the Pca populations in the EPR and eastern Canada continue to evolve in their virulence dynamics, creating a challenge to breed oat lines with effective and stable resistance.

Fusarium head blight (FHB) is the most important disease of wheat in Canada. FHB reduces grain yield and quality and results in seed contamination with Fusarium spp. that is associated with reduced seed vigor and poor stand establishment in wheat. The effect of seed treatments with six strains representing three species Trichoderma, selected based on their superior antagonistic ability on mycelium growth of F. graminearum in dual culture assays, on wheat seed lots contaminated with Fusariurn spp. (28-43%) was examined in field trials in 2008, 2009, and 2011. None of the six strains of Trichoderma spp. showed a significant seed treatment effect for all parameters measured each year, but over the three years, all six strains significantly reduced root rot severity and increased yield, three stains (Trich12, TrichC70 and TrichPine) increased emergence and four strains (Trich06, TrichC39, TrichC70, and TrichMM7) increased plant dry weight, compared with the untreated control. TrichC70 was the only strain that showed a significant improvement to all four parameters, increasing emergence by 10.9%, dry weight by 51.7%, and yield by 11.0% and reducing root rot severity by 51.7%. These effects were less but not significantly different from that of the registered fungicide Vitaflo-280 (carbathiin + thiram) used as the positive control in the field trials. The results indicate that Trichoderma stain TrichC70 may be used as an alternative to fungicide seed treatments to alleviate the detrimental effect of the seed-borne phase of FHB in wheat. Crown Copyright (C) 2017 Published by Elsevier Ltd. All rights reserved.

Fusarium head blight is a common disease of oat and resistant cultivars are not available in Canada. The effect of nitrogen (N) fertilization on the incidence of seed-borne Fusarium spp. was evaluated under natural field conditions in three locations (Ottawa, ON; Melfort, SK; and Normandin, QC) in Canada in 2013 and 2014. At each site, oat cultivars CDC Morrison, AAC Nicolas, and AAC Noranda were used under four levels of N fertilization (0, 50,100, and 150 kg N ha(-1) ). Of the seven Fusarium spp. recovered, F. poae, F. equiseti, F. graminearum, F. sporotrichioides, and F. avenaceum were the most common species and were isolated from 9.6%, 1.3%, 1.1%, 1.0%, and 0.3% of the harvested grain, representing 72%, 10%, 8%, 7%, and 3% of the pathogen population, respectively. The remaining species, F. acuminatum and F. oxysporum, were each recovered from a single seed only. A significant N treatment effect (P < 0.05) was observed in four of the six location-years in which the highest N treatment of 150 kg N ha(-1) resulted in greater incidence of the predominant species (F. poae) and total Fusarium spp. than the untreated control (0 kg N ha(-1) ). Among the commonly recovered species, only seed-borne infection by F. graminearum increased significantly with the levels of N treatments applied. A highly significant effect of location, year, and location x year interaction (P < 0.01) was observed, suggesting that the field and weather conditions have a stronger influence on incidence of seed-borne Fusarium spp. than the N treatments.

Xue, A. G., Chen, Y., Marchand, G., Guo, W., Ren, C., Savard, M. and McElroy, A. R. B. 2015. Timing of inoculation and Fusarium species affect the severity of Fusarium head blight on oat. Can. J. Plant Sci. 95: 517–524. The influence of timing of inoculation and pathogenicity of four Fusarium spp. (F. culmorum, F. graminearum, F. sporotrichioides, and F. avenaceum) causing Fusarium head blight (FHB) were examined on 12 oat genotypes under controlled environmental conditions in two separate sets of experiments. In the first set, early inoculations with F. graminearum at or before the complete emergence of ears resulted in little or no visible FHB symptoms but deoxynivalenol (DON) contents ranging from 0.4 to 2.6 ppm were detected in the harvested grain. Severe levels of FHB were observed on these genotypes with infected spikelets ranging from 30 to 74% and DON concentrations, from 6.6 to 10.0 ppm, when plants were inoculated at or after the 50% anthesis stage. Inoculation at 50% anthesis was considered the...

Phytophthora root rot (PRR), caused by the oomycete Phytophthora sojae, is a devastating disease of soybean worldwide, and has been present in Canada since the 1950s. Major resistance to P. sojae (Rps) genes have been deployed by soybean breeders to mitigate yield losses, which has caused shifts in the pathogen population to more complex pathotypes and the emergence of new races. This study reports on a survey of races and pathotypes of P. sojae throughout 203 commercial soybean fields and two PRR nurseries in the province of Ontario, Canada, and is the first extensive survey to be conducted in Canada since the late 1980s. A total of 22 races and one intermediate reaction type (IRT) were detected from 262 isolates from commercial soybean fields. Race 25 was the predominant race, comprising 43 isolates and representing 16% of the pathogen population. Races 3, 4, 5, 6, 7, 9, 28 and 45 were frequently detected, each representing 5-11% of the pathogen population. A total of 16 races and two IRTs were detected in 96 isolates from the two PRR nurseries. Race 3 was the most abundant, representing 23% of isolates, while races 5, 6, 7, 8, 9, 14, 25 and 28 each represented 5-10% of total isolates. New races and more complex pathotypes have emerged since the last Canadian survey, and this will have implications for the future deployment of Rps genes or other forms of resistance to P. sojae. ResumeLe pourridie phytophthoreen des racines (PPR) du soja, cause par l'agent pathogene de la classe des oomycetes Phytophthora sojae, ravage le soja cultive a l'echelle de la planete, et est present au Canada depuis les annees 1950. Des genes de resistance verticale a P. sojae (Rps) ont ete deployes par les selectionneurs de soja afin de mitiger les pertes de rendement, ce qui a engendre des changements au sein des populations de l'agent pathogene, vers des profils de virulence plus complexe et l'emergence de nouvelles races. Dans le cadre de cette etude, un releve des races et pathovars de P. sojae a ete effectue a l'echelle de 203 champs de soja en production commerciale et deux pepinieres d'etudes de cette maladie dans la province de l'Ontario, Canada, et represente le premier releve de cette envergure dans cette region du Canada depuis la fin des annees 1980. Au total, 22 races et un type de reaction intermediaire (TRI) ont ete identifies parmi 262 isolats provenant de champs de soja en production commerciale. La race 25 s'est averee predominante, representant 43 isolats ou 16% du total de la population de l'agent pathogene. Les races 3, 4, 5, 6, 7, 9, 28 et 45 ont ete frequemment identifiees, chacune representant 5 a 11% du total. Un total de 16 races et deux TRIs furent identifies au sein de 96 isolats provenant des deux pepinieres d'etudes de la maladie. La race 3 etait la plus abondante, representant 23% des isolats, alors que les races 5, 6, 7, 8, 9, 14, 25 et 28 representaient chacune entre 5 et 10% des isolats. De nouvelles races, ainsi que des pathovars plus complexes, ont fait leur apparition depuis le dernier releve au Canada, ce qui aura des consequences pour le futur deploiement de genes Rps ou d'autres formes de resistance au PPR.

•CLO-1 (Clonostachys rosea strain ACM941) controls Fusarium head blight in wheat.•CLO-1 biofungicide was to large extent as effective as conventional fungicides.•CLO-1 biofungicide was most effective on moderately resistant cultivars.

Fusarium head blight (FHB) is a destructive disease of oats in Canada. To assist the development of FHB-resistant cultivars, the influence of timing of inoculation and pathogenicity of four Fusarium spp. causing FHB were examined on 12 oat genotypes under controlled environmental conditions. Early inoculations with F. graminearum at or before the complete emergence of ears resulted in little or no visible FHB symptoms but deoxynivalenol (DON) contents ranging from 0.9 to 3.7 ppm were detected in the harvested grain. Severe levels of FHB were observed on these genotypes with infected spikelets (IS) ranging from 40 to 75% and DON concentrations, from 6.3 to 10.2 ppm, when plants were inoculated at or after the 50 % anthesis stage. Inoculation at the 50 % anthesis was considered the most appropriate timing as it allowed sufficient time for disease development and assessment prior to physiological maturity of the plant. Of the four Fusarium spp., F. culmorum and F. graminearum were equally highly pathogenic, having areas under the disease progress curve (AUDPC) of 45.3 and 47.3, and DON content in the harvested grain of 10.4 and 14.3 ppm, respectively. Fusarium sporotrichioides resulted in the lowest AUDPC (31.2) and was significantly less pathogenic than the two highly pathogenic species. Fusarium avenaceum was intermediate and the resulting AUDPC (36.7) was not significantly different from those of either the highly pathogenic or the weakly pathogenic species. The oat genotype and Fusarium spp. interaction was not significant, suggesting that breeding for resistance to F. graminearum may also confer enhanced resistance to other Fusarium spp. Introduction Oat (Avena sativa L.) is a common crop grown for both feed and food in Canada. In 2012, Canada produced over 2.6 million tonnes of oats, making it the third largest producer of oats next to the European Union and Russia (Statistics Canada 2013). Oats contain high amounts of valuable nutrients such as dietary fiber, ß-glucans, proteins, unsaturated fatty acids antioxidants, proteins, dietary fiber, vitamins, and minerals (Behall et al. 1997; Sobotka et al. 2012; Tsopmo et al. 2010; Wood 1990). Due to their beneficial effects on human health, the use of oats and oat products for human food has been increasing in recent years (North American Millers’ Association and the National Oat Improvement Committee 2008; Peterson 1992). During the past 20 years, there has been an increase in the incidence of Fusarium head blight (FHB) on oats grown in the Canadian Prairies (McCallum et al. 1999; Tekauz et al. 2004, 2008, 2011) and in the eastern provinces of Ontario and Québec (Couture and Lévesque 1995; Couture et al. 1996; Tamburic-Ilincic 2010; Xue and Chen 2010, 2014) where the majority of oats is grown in Canada. As a result, seed harvested from these regions may contain a considerable portion of Fusarium-infected kernels resulting from infection by several Fusarium spp. (Clear et al. 1996, 2000; Tamburic-Ilincic 2010; Tekauz et al. 2008, 2011). A number of research reports have demonstrated that FHB lowers grain yield and quality; the fungi also produce deoxynivalenol (DON), zearalenone and HT-2 mycotoxins in the kernels, which are harmful to livestock and pose a safety concern in human food (Bottalico and Perrone 2002; Clear et al. 2000; Parikka et al. 2008; Placinta et al. 1999; Tamburic-Ilincic 2010). Consequently, there has been an increase in disease awareness and the development of management strategies to mitigate the adverse effects of FHB on oats (Gavrilova et al. 2008; Mitchell Fetch et al. 2008; Tekauz et al. 2008; Yan et al. 2008, 2010). Several Fusarium species including F. acuminatum Ellis and Everhart, F. avenaceum (Corda: Fr.) Sacc., F. culmorum (W.G. Smith) Sacc., F. equiseti (Corda) Sacc., F. graminearum Schwabe (teleomorph Gibberella zeae (Schwein.) Petch.), F. poae (Peck) Wollenw., and F. sporotrichioides Sherb. have been frequently isolated from Fusarium-infected kernels (Clear et al. 1996; Tamburic-Ilincic 2010; Tekauz et al. 2008, 2011; Xue and Chen 2010, 2014). Among these species, F. graminearum is the principal causal agent of FHB in Canada (Clear et al. 1996, 2000; Tekauz et al. 2008, 2011). Studies on the pathogenicity of these Fusarium species to wheat and barley revealed that only F. graminearum and F. culmorum were highly pathogenic, and the other species were intermediate or weakly pathogenic (Stack et al. 1997; Wong et al. 1995; Xue et al. 2004, 2006). There has been no study on the comparative pathogenicity of Fusarium species causing head blight of oats. Although FHB severity can be reduced or controlled by foliar fungicide applications, the use of genetic resistance is considered one of the most practical and environmentally safe measures for disease management (Mitchell Fetch et al. 2008; Tekauz et al. 2004, 2008; Yan et al. 2008, 2010). High levels of resistance to FHB have been identified in oat germplasm and considerable breeding has been conducted to develop resistant cultivars and lines (Gavrilova et al. 2008; Mitchell Fetch et al. 2008; Tekauz et al. 2008; Yan et al. 2010). The reactions of oat lines to FHB have commonly been evaluated by field screening, which depends on the natural occurrence of Fusarium spp. or artificial inoculation in a FHB nursery (Mitchell Fetch et al. 2008; Yan et al. 2010). These methods do not account for the effect of the timing of inoculation on oat reactions to FHB, differences in pathogenicity of Fusarium spp., and any possible Fusarium species by oat genotype interactions. As a result, breeders have frequently encountered inconsistent disease reactions in their breeding lines, leading to significant loss of time and resources (Yan et al. 2010). The objectives of this research were to determine the effect of timing of inoculation on oat variety reactions to FHB and to compare the pathogenicity of four commonly observed Fusarium spp. in causing FHB under controlled environmental conditions. Materials and methods Plant materials and growth conditions Twelve oat cultivars and lines originated from diverse sources and having shown different levels of resistance to FHB based on field evaluations (A. McElroy, personal communication) were used (Table 1). Seeds were planted in 15-cm diameter pots containing a mixture of loam soil, sand and composted cow manure (1:1:1, v/v/v), and were maintained at 23-25 °C during the day and at 18-20 °C during the night in a greenhouse. Supplemental light was provided by 300-W metal halide lamps to ensure a 16-h photoperiod and a minimum intensity of 360 mol m s. Plants were thinned to three plants per pot. Five weeks after planting, the plants were supplied with a 1 % solution of 20-20-20 (N-P-K) fertilizer. Due to genotypic differences in maturity, seeds were planted serially over a two-week period, so that all genotypes were at the same growth stage when they were inoculated. Pathogen species and inoculum production To determine the inoculation timing effect on the FHB reactions of the 12 oat genotypes, three isolates of F. graminearum, DAOM 178148, DAOM 212678, and DAOM 232369, were used. Four Fusarium spp. including F. avenaceum, F. culmorum, F. graminearum, and F. sporotrichioides were used to examine the species effect on the varietal reactions to FHB in the 12 oat genotypes. These Fusarium spp. are either reported to cause FHB on oat or frequently isolated from Fusarium-infected kernels in Canada (Clear et al. 1996, 2000; Tamburic-Ilincic 2010; Tekauz et al. 2008, 2011; Xue and Chen 2010, 2014). One isolate from each of the four Fusarium spp. was used: DAOM 232349, DAOM 232360, DAOM 232372, and DAOM 232384, representing F. avenaceum, F. culmorum, F. graminearum, and F. sporotrichioides, respectively. The Fusarium isolates used in the present study were obtained from the Canadian Collection of Fungal Cultures at Agriculture and Agri-Food Canada’s Eastern Cereal and Oilseed Research Centre (ECORC-AAFC), Ottawa, Canada. DAOM stands for Department of Agriculture, Ottawa, Mycology and is an internationally recognized acronym for the national mycological herbarium of Canada. Table 1. Origins of 12 oat genotypes used for studies on the influence of timing of inoculation and Fusarium spp. on the development of Fusarium head blight and deoxynivalenol contamination in harvested grains.