Contributed Abstracts
        Oral Abstracts

Are certain field pea lines tolerant to mycosphaerella blight? B.D. Gossen, R.L. Conner, S.F. Hwang, and M.R. McDonald. Agriculture and Agri-Food Canada (AAFC), Saskatoon, SK  S7N 0X2 Canada; (R.L.C.) AAFC, Morden, MB  R6M 1Y5; (S.F.H.) Alberta Agriculture and Rural Development, Edmonton, AB  T5B 4K3; and (M.R.M.) University of Guelph, Guelph, ON  N1G 2W1 Canada.

Mycosphaerella blight, caused primarily by Mycosphaerella pinodes (Berk. & Blox.) Vestergr.,  frequently occurs at high levels on field pea (Pisum sativum L.) in western Canada. In previous studies, some commercial cultivars exhibited a pattern of disease response that indicates that they are tolerant to blight (susceptible to infection and symptom development, but disease has a smaller impact on yield than a susceptible cultivar). Trials to detect and quantify this reaction were conducted over nine station years at sites across the Canadian prairies from 2005−2007. The relationship between blight severity and yield was examined for nine field pea cultivars that represent a range of reaction to mycosphaerella blight. The experimental layout was a split-plot design; the main-plot treatments were cultivars, and the sub-plot treatments compared one application of foliar fungicide to reduce blight severity with a nontreated control. Fungicide application reduced blight severity for each cultivar but had little impact on yield, so there were no clear differences in tolerance among cultivars. Although tolerance may be present in some of these cultivars, this characteristic will be difficult to use in a breeding program due to the high variability associated with these assessments.

Understanding host- and non-host plant pathogen interactions using transcriptional analysis of wheat and barley infected with the barley smut pathogen Ustilago hordei. C. Penniket, D. Gaudet, M. Frick, G. Bakkeren, A. Laroche. Lethbridge Research Centre, Agriculture and Agri-Foods Canada, 5403 1^st Avenue South, Lethbridge, Alberta T1J 4B, Canada; (G.B.) Pacific Agri-Food Research Centre, Agriculture and Agri-Foods Canada, 4200 Highway #97, South, Summerland, British Columbia, V0H 1Z0, Canada.

Plant diseases can drastically reduce grain and biomass yield and quality of crops intended for food, animal feedstock or bioindustrial production. Understanding compatible and incompatible host and non-host interactions between plant pathogens and their hosts will provide new opportunities for developing broad-based disease resistance in crops. Covered smut of barley (Hordeum vulgare L.) caused by Ustilago hordei (Pers.) is an important disease of barley, especially susceptible hulless varieties. We have innoculated ‘Odessa’ (susceptible) and ‘Hannchen’ (resistant, containing the Uh1-R gene) barley with an appropriate race of U. hordei to study the host compatible and Uh-R gene incompatible interaction. ‘Neepawa’ wheat inoculated with U. hordei was employed to study the non-host incompatible interaction. Little is known about the molecular functions involved in these interactions. To address this, the Affymetrix GeneChip^® Wheat Genome Array was used to study global gene expression during these interactions.  Preliminary gene expression analysis has shown a very broad and general response of numerous stress and pathogen-related transcripts in the non-host variety and a more specific response limited to much fewer transcripts in the resistant variety. These results are providing candidate genes for identification of different signalling and metabolic pathways involved in pathogen defense and their further evaluation as potential broad based resistance factors.

Resistance to the Leaf Spotting Complex in the Wheat Line 86ISMN 2137. C.A. McCartney¹, G. Hughes¹, P. Singh², P. Hucl¹, and C. Pozniak¹. ¹Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada. ²CIMMYT, Apdo. Postal 6-641, 06600 Mexico, D.F., Mexico.

Leaf spotting diseases are a persistent problem of common (Triticum aestivum) and durum (Triticum turgidum subsp. durum) wheat in Saskatchewan. The main diseases of the Saskatchewan leaf spotting complex are tan spot (pathogen: Pyrenophora tritici-repentis), stagonospora nodorum blotch (pathogen: Phaeosphaeria nodorum), and septoria tritici blotch (pathogen: Mycosphaerella graminicola). The genetic basis of resistance to the wheat leaf spotting complex is being investigated in the cross Kenyon/86ISMN 2137. The population was assessed for reaction to the P. nodorum isolate Kelvington at the seedling stage. The data suggested two or more genes controlled reaction to this isolate. Microsatellite and Diversity Array Technology (DArT) marker data is being collected for QTL analysis of reaction to P. nodorum. Reaction to P. tritici-repentis and M. graminicola will be investigated at the seedling stage in the future. The population was evaluated for reaction to the leaf spot complex in a replicated field test in Saskatoon, 2008 and will be evaluated in additional field environments in 2009. This will determine whether genes detected in seedling tests will impact leaf spot reaction under field conditions.

Update on the chickpea ascochyta blight sentinel plant project.  F.L. Dokken, D. Risula, P.G. Pearse, Y. Gan, C. McDonald, B.D. Gossen, S. Banniza, B. Ta’ran, and M. Goodwin.  Saskatchewan Ministry of Agriculture, 3085 Albert Street, Regina, SK, S4S 0B1; (YG) Agriculture and Agri-Food Canada (AAFC)  Semi-Arid Prairie Agriculture Research Centre, Airport Road East, Swift Current, SK S9H 3X2; (BDG) AAFC Saskatoon Research Centre, 107 Science Place, Saskatoon, SK S7N 0X2; (SB & BT) University of Saskatchewan, Crop Development Centre, 51 Campus Drive, Saskatoon, SK S7N 5A8; (MG) Pulse Canada, 1212-220 Portage Avenue, Winnipeg, MB R3C 0A5.

The Chickpea Ascochyta Sentinel Plant Project was designed to develop an early-warning system for ascochyta blight of chickpea, to facilitate proper timing of the critical first fungicide application.  Objectives were to identify when Ascochyta rabiei (Pass.) Labrousse spores were first released and assess disease risk before commercial crops became infected.  Sentinel sites were selected in Saskatchewan chickpea production regions with a history of ascochyta blight, in fields with chickpea residue from the previous crop, providing a potential source of disease inoculum.  Every 3-4 days from mid-May to late-June, pre-grown susceptible ‘sentinel’ chickpea plants were placed 0m, 10m, or 100m from residue, and following 3-4 days of exposure, they were returned to the lab and incubated to promote symptom development.  Disease risk assessments were sent along with scouting and management information to agronomist and grower cooperators twice a week for the project duration.  Although primary inoculum was trapped on sentinel plants earlier in 2008 than 2007, commercial crop development was delayed due to dry, cool conditions.  Therefore, fungicide applications could have been postponed until crops were advanced enough to spray and conditions were more conducive for infection.  Cooperators are being surveyed to assess the economic impact and fungicide reduction resulting from using the early warning system and its accompanying extension materials.

Efficacy of selected biofungicides for control of clubroot on canola. G. Peng, B.D. Gossen, S.E. Strelkov, S.F. Hwang and M.R. McDonald. Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2, Canada; (S.E.S.) Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada; (S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Food, 17507 Fort Road, Edmonton, AB T5Y 6H3, Canada; (M.R.M.) Department of Plant Agriculture, University of Guelph, Guelph ON N1G 2W1, Canada.

Clubroot of canola, caused by the fungal pathogen Plasmodiophora brassicae, is an emerging threat to the canola industry in western Canada. Since its discovery near Edmonton in 2003, the disease has been found in more than 250 canola fields in Alberta. All commercial cultivars are susceptible, and currently there is a lack of effective/practical control options. In this study, biofungicides registered in Canada and the USA including Serenade, Pre-stop, Mycostop, Actinovate, SoilGard, Root Shield and Taegro, were tested initially at 5× label rates for control of the disease. Conidial suspensions (10⁶ spores/ml) of the fungal endophyte Heteroconium chaetospira, reported to control clubroot on Chinese cabbage in Japan, and two chemical fungicides, Allegro and Ranman (at label rates), were also evaluated. All treatments were applied as a soil drench at 50 ml/plant in a 4 cm × 20 cm root-trainer 72 h prior to (for microbial products/agent) or 1 h after (fungicides) pathogen inoculation. Control plants were drenched with water. Treated canola plants were kept in growth cabinets set at 23/18ºC (day/night, 14 h photoperiod) in a containment facility. Clubroot severity was assessed using a 0–3 scale based on the portion of root diseased and gall size. At the lower pathogen inoculum dose (10⁵ spores/ml), Serenade, Pre-stop, H. chaetospira, Allegro and Ranman were highly effective, reducing disease severity by 77–100% three weeks after pathogen inoculation. At the higher pathogen dose (10⁶ spores/ml), H. chaetospira was less effective while the other four treatments reduced disease severity by 56–100% when compared to pathogen controls. Serenade, Allegro, and Ranman consistently provided 85–100 % reduction of disease severity in repeated trials.

Lentil Anthracnose : Studies on the mating system of Colletotrichum truncatum. J. Menat, Y.D. Wei, and S. Banniza. Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada; (Y.D.W.) Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada.

Lentil anthracnose is a fungal disease responsible for severe yield losses in Canada. It is caused by Colletotrichum truncatum (Schwein.) Andrus & Moore, which is known to reproduce asexually via water-splashed conidia. Sexual reproduction has been demonstrated under laboratory conditions, but has not been observed in the field. In order to describe the mating system of C. truncatum, crosses among 21 isolates from Saskatchewan and Manitoba were performed. Sterile lentil stems were soaked in spore suspensions of each isolate individually and of all possible pairs of isolates to test for cross- and self-fertility. Stems were incubated under optimum conditions for perithecium formation. All isolates were self-sterile, suggesting that C. truncatum is heterothallic. Isolates fell into two mating compatibility groups, which is consistent with a bipolar self-incompatibility mating system. In this type of system, mating types are usually determined by a single locus with two alleles called MAT1 and MAT2. Experiments to determine if MAT2 is present in C. truncatum are being conducted. Information from this project will eventually provide direction for anthracnose management and anthracnose-resistance breeding in lentil.

Wind trajectories and cereal rust risk, western Canada, 2007. T.K. Turkington, B. McCallum, T. Fetch, K. Xi, K. Kumar, D. Gaudet, O.O. Olfert, R. Weiss and J. Soroka. Lacombe Research Centre/Beaverlodge Research Farm, Agriculture and Agri-Food Canada, 6000 C&E Trail, Lacombe, AB, T4L 1W1, Canada;  (B.Mc., T.F.), Cereal Research Centre, 195 Dafoe Road, Winnipeg MB, R3T2M9, Canada, MB;( K.X., K.K.), Alberta Agriculture and Rural Development, 6000 C&E Trail, Lacombe, AB, T4L 1W1, Canada; (D.G.), Lethbridge Research Centre, Box 3000, 5403 1st Avenue South, Lethbridge, Alberta, T1J 4B1, Canada; and (O.O.O., R.W., J.S.), Saskatoon Research Centre, 107 Science Place, Saskatoon, Saskatchewan, S7N 0X2.

Cereal rusts present a unique challenge for western Canadian cereal producers.  In contrast to cereal leaf spot diseases and fusarium head blight, most cereal rusts do not typically overwinter in western Canada and as a consequence crop rotation and volunteer control are not relevant management strategies.  In general, rusts of wheat and barley will overwinter on cereals and grasses in the southern USA and northern Mexico, although stripe rust can also overwinter in the Pacific Northwest (PNW) and California.  Urediniospores are blown northward by wind currents, affecting successive northerly winter and spring cereal crops.  Depending on availability, a resistant variety can be grown and this decision can be made the previous fall or winter.  However, production of susceptible varieties requires routine crop scouting and timely fungicide spray decisions, which can be difficult during a busy growing season.  An overview will be presented of preliminary efforts to identify wind trajectory events that may bring rust urediniospores into western Canada from epidemic areas in the central and PNW regions of the USA.  Identification of potential events as well as an assessment of epidemic severities from source locations can be used to assess the need for prompt targeted crop scouting for at risk regions of the Canadian prairies.

Wheat stripe rust in central Alberta. K. Xi, K. Kumar, T.K. Turkington, L. Vandermaar and M. Wilson. Field Crop Development Centre, Alberta Agriculture and Rural Development, 6000 C and E Trail, Lacombe, AB T4L 1W1, Canada; and (T.K.T.) Lacombe Research Centre, Agriculture and Agri-Food Canada, Lacombe, AB 6000 C and E Trail, T4L 1W1, Canada.

Stripe rust was observed in commercial winter wheat fields and reseasrch plots of central Alberta in the fall of 2007.  Stripe rust pustules were present in the winter wheat field plots at Lacombe until the middle of March, 2008.  Urediospores sampled from symptomed plants were able to germinate in the laboratory conditions.  Pustules developed after symptomless winter wheat plants from the field plots were incubated under conducive conditions in the growth chamber.  High levels of stripe rust were generally found in winter wheat compared with spring wheat in breeding nurseries.  The potential winter survival of this fungal pathogen is being monitored in central Alberta. The results from the 2007 and 2008 growing season showed that there were significant or nearly significant correlations in disease severity measured by wheat differentials among the test locations between central Alberta and the Pacific Northwest (PNW), suggesting that the pathogen populations of P. striiformis f.sp. tritici were similar between the two areas.  Samples of P. striiformis are being differentiated using wheat differentials in controled environmental conditions.  The structure of pathogen populations will also be determined using inter simple sequence repeat analysis.

Effects of pyraclostrobin on pasmo disease, yield, and fibre content of flax.   K. Y. Rashid.  Cereal Research Centre, Agriculture and Agri-Food Canada, Morden Research Station, Unit 100 – 101 Route 100, Morden, MB R6M 1Y5, Canada   

Pasmo caused by the fungus Septoria linicola (Speg.) Garassini (Sexual state Mycosphaerella linorum Naumov) is a common disease affecting flax (Linum usitatissimum L.) in all flax growing areas in Canada and worldwide.  Pasmo was present in 62-96% of the fields surveyed in western Canada between 1996 and 2007 with mean disease incidence ranging from 16 % to 35% infected plants and mean disease severity ranging from 10% to 25% of the stem and leaf area affected.  Commercial flax cultivars lack acceptable level of resistance to this pathogen.  The fungicide Pyraclostrobin (Headline, BASF Canada) was used in field trials at Morden, Manitoba as foliar applications at flowering time and/or late flowering.  Pasmo-infected straw was spread between the rows of all plots before flowering as the source of inoculum.  Pyraclostrobin proved to be effective in reducing disease severity on four flax cultivars by up to 60% and 70% on flax leaves and stems, respectively.  The fungicide applications resulted in up to 20% yield improvement in fungicide-treated plots over the untreated control plots but had no positive effects on the fibre content of the flax stems.  Further studies are underway to investigate the effects of reducing the S. linicola stem infections on the quality of the stem fibre.

Optimizing spray coverage on onion leaves: interaction of nozzle angle, water volume, and surfactant . Jennifer Allen, Mary Ruth McDonald, Kevin Vander Kooi and Kristy Grigg. Ontario Ministry of Agriculture, Food and Rural Affairs, Guelph, ON, N1G 4Y2 Canda; (MRM &KV) Department of Plant Agriculture, University of Guelph, Guelph, ON, N1G 2W1, Canada

Onion thrips (Thrips tabaci) are the vector of iris yellow spot virus in onions, and are the most important insect pest of onions in North America, largely because they are so difficult to control.  Improving the spray coverage of onion leaves may improve thrips control. Field trials were established in 2007 and 2008 to investigate how combinations of water volume, surfactant and nozzle angle affect spray coverage and efficacy of insecticides.  Water volumes of 400, 500 and 600 L*ha-¹, in combination with no surfactant or Sylgard 309 (0.375% siloylated polyetger), or Super Spreader (0.25% octyl phenoxypoly ethoxy ethanol) were applied at 120 psi with a tractor-mounted sprayer with AI TeeJet Air Induction Even Flat spray tips (AI9503 EVS for 400 and 500 L*ha-¹ , AI9504 EVS for 600 L*ha-¹ ,) at an angle of O ^o  or 22^o.  Spray coverage was assessed with water sensitive paper or fluorescent Tinopal CBS-X dye. The fluorescent dye was best for evaluating spray coverage.  Highest percent coverage of leaves (19.5%) was obtained with Sylgard in a volume of 500 L*ha-¹ , applied at a 22^o angle.  Thrips pressure was low in 2008. Some insecticides were more effective when applied with Sylgard as compared to water, although Sylgard plus water sometimes reduced thrips counts compared to water alone.  The most effective insecticide was Carzol (formetanate hydrochloride). Nozzle angle or surfactant did not improve efficacy of Carzol. Measures to optimize spray coverage and efficacy may be product specific.

Development of a new effective seed treatment (Agress®) in Alberta for management of seed-borne diseases in pulse crops. M.W. Harding, D.A. Sowa, R.J. Howard and M.E. Olson. Innovotech Inc. Suite 101 -- 2011 94 St., Edmonton, AB  T6N 1H1 Canada; (RJH.) Alberta Agriculture and Rural Development, Crop Diversification Centre South, 301 Horticultural Station Rd. E., Brooks, AB T1R 1E6 Canada.

The use of agricultural streptomycin as a seed-treatment on dry edible beans in Canada is uncertain. In response to this uncertainty, copper sulphate pentahydrate was registered in 2002 under the User-Requested Minor-Use Label Expansion program as a bactericidal seed treatment on dry edible beans. It is currently the only bactericidal seed-treatment product registered for use on dry beans in Canada. However, some concerns have been raised regarding efficacy and phytotoxicity of copper sulphate. The need for alternative and effective seed treatments is an important missing link in pulse seed production in Canada. A novel seed-treatment, Agress® for seed-borne bacterial and fungal diseases, has recently been developed in Alberta. Agress® contains a highly oxygenated form of silver that releases high-valency silver ions toxic to microorganisms at concentrations between 100-ppm and 1000-ppm. Agress® is well-suited to integrated pest management programs, is a low risk for development of pathogen resistance, and is effective at relatively low concentrations. These characteristics make Agress® a very cost-effective treatment with low environmental impact and high efficacy. Agress® is currently in regulatory review. The development and registration of Agress® will provide a viable replacement for agricultural streptomycin and copper sulfate, and an additional disease management option for pulse producers.

Understanding the population structure of  Leptosphaeria maculans in western Canada.  H.R. Kutcher. Agriculture and Agri-Food Canada (AAFC), Box 1240, Melfort, SK S0E 1A0

In western Canada the management of blackleg disease of canola, caused by Leptosphaeria maculans (Desmaz.) Ces. & De Not., depends in large measure on cultural practices and varietal resistance.  Future use of these strategies may be improved through knowledge of the race structure of the pathogen.  The objective of this study is to identify and quantify the races of the pathogen that exist at eight sites in western Canada.  A trap crop (cv. ‘Westar’) was seeded at each site and material collected that displayed blackleg symptoms on leaves or basal stems.  From this material, the pathogen was isolated and inoculum derived from single-spore isolates used to inoculate cotyledons of a differential set of Brassica lines or varieties known to carry specific resistance genes.  Avirulence genes carried by each isolate were determined.  Preliminary results indicate significant variation in five avirulence genes (AvrLm1, AvrLm2, AvrLm3, AvrLm4 and AvrLm9) among four of the collection sites: Camrose, AB, Melfort, SK and Carberry and Plum Coulee, MB.

Occurrence of Bacterial Canker in Greenhouse Tomatoes in Alberta. R.J. Howard, N.A. Savidov, S. Rajput, M. Mirza, P. Cote, and N. Butler.  Alberta Agriculture and Rural Development, Crop Diversification Centre South, 301 Horticultural Station Rd. E., Brooks, AB T1R 1E6, Canada; (M.M.) Alberta Agriculture and Rural Development, Crop Diversification Centre North, 17507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; and (S.R.) Alberta Research Council, Postal Bag 4000, Vegreville, AB T9C 1T4, Canada.

Stemphylium botryosum - a known known or a known unknown? S. Banniza, Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon SK S7N 5A8

Stemphylium botryosum Wallr. causes stemphylium blight on lentil, a disease characterized by initially small, light beige lesions on the upper leaves that enlarge and coalesce. The fungus spreads from these initial lesions to and entire branches become necrotic resulting in the characteristic blighted appearance of plants. Only terminal leaves remain on branches due to severe leaf drop. Flower abortion, a reduction in plant biomass, lower seed yield, a decrease in seed size, seed staining and low germination rates are further symptoms. Stemphylium blight is one of the most important diseases in lentil production in Bangladesh and north-eastern India where yield losses of 80% and higher have been recorded. In Canada, the disease has been regularly observed on lentil plants and seed at low levels, but appears to be on the increase in recent years. Limited research has demonstrated that the fungus can be active under a wide temperature range. Field observations also indicate that the air-borne spores of S. botryosum are less dependent on rain for germination as infection during the dry but relatively humid growing season of 2007 was surprisingly widespread. Information on actual yield loss in Canadian lentil fields due to this disease is still very limited and primarily anecdotal, and warrants further research.

Virus-Induced Gene Silencing-Based approach to the Functional Characterization of Genes Associated with Stripe Rust Resistance in Wheat. W. Liu^a,b, A. Laroche^a, Z. Kang^b, D. A. Gaudet^a .  ^aAgriculture and Agri-Food Canada, Lethbridge Research Centre, P. O. Box 3000, 5430-1st Avenue, South, Lethbridge, Alberta, T1J 4B1 Canada. ^bCollege of Plant Protection and Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwestern A&F University, Yangling, Shaanxi 712100, PR China.

Wheat stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici, is a destructive disease of wheat worldwide and the development of resistant cultivars is the most economical control method. The Yr10 gene in wheat, that encodes a cytoplastic NB-LRR protein containing nucleotive-binding sites (NBS) and lencine-rich repeats (LRR), imparts seedling resistance to stripe rust. Virus-induced gene silencing (VIGS) is a rapid and powerful tool to analyze the function of plant genes. Short target sequences with homology to host nuclear genes are cloned into a viral vector; following transfection, inoculated plants trigger the host’s sequence-specific RNA degradation, resulting in post transcriptional silencing of the gene under investigation. We have employed barley stripe mosaic virus (BSMV)-VIGS to study the function of different domains of the Yr10 gene, in the resistance response of wheat. A series of primer pairs have been designed based on the different domains of Yr10 and its pseudogene. The resulting fragments have been inserted into BSMV-VIGS vectors. Wheat infection by P. striiformis following transfection with vectors will be examined at morphological, cytological and molecular level. This study will demonstrate the efficacy of BSMV-VIGS, and permit the study of the different domains of Yr10 and its pseudogene in stripe rust resistance.

Barley net blotch quantitative trait loci – mapping, validation and their utilization. T.S. Grewal, B.G. Rossnagel, and G.J. Scoles. Crop Development Centre/Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK  S7N 5A8, Canada.

Net blotch, caused by Pyrenophora teres Drechs., is an important foliar barley disease in all barley growing regions of the world. Resistant cultivars are the most economic and eco-friendly control strategy. Quantitative trait loci (QTL) associated with net blotch resistance were mapped in a doubled-haploid barley population (CDC Dolly/TR251) using Diversity Arrays Technology (DArT®) markers. A major net-form net blotch (NFNB) seedling resistance QTL, designated QRpt6, was mapped to chromosome 6H for isolates WRS858 and WRS1607. QRpt6 was associated with adult-plant resistance in 2005 and 2006 field trials. A seedling resistance QTL (QRpts4) for the spot-form net blotch (SFNB) isolate WRS857 was detected on chromosome 4H as was a significant QTL (QRpt7) on chromosome 7H. Three QTL (QRpt6, QRpts4, QRpt7) were associated with resistance to both net blotch forms and lines with one or more of these demonstrated improved resistance. Simple sequence repeat (SSR) markers tightly linked to QRpt6 and QRpts4 were identified and validated in many unrelated barley populations. Since the major 6H QTL, QRpt6, may provide adequate NFNB field resistance in western Canada, the  Crop Development Centre barley breeding program plans to conduct MMAS for QRpt6 in combination with net blotch screening in field nurseries to pick up the additional resistance provided by the other QTL.

Compatible and Incompatible interactions Involving Puccinia stiiformis and Fielder and Moro wheat.
X. Wang^1,2, A. Laroche¹, Z. Kang², F. Leggett, and D. Gaudet¹1. Agriculture and Agri-Food Canada, Lethbridge Research Centre, P. O. Box 3000, 5430-1st Avenue, South, Lethbridge, Alberta, T1J 4B1 Canada 2. College of Plant Protection and Shaanxi Key Laboratory of Molecular Biology for Agriculture,

Autofluorescence in leaves, generation of Active Oxygen Species (AOS), and the hypersensitive response (HR) have been previously associated in plant defense responses to pathogens. These factors were studied in the interactions between Puccinia striiformis f. sp. tritici and susceptible wheat cultivar ‘Fielder’ and ‘Moro’, which possesses Yr10. Both varieties were inoculated with P. striiformis strain 29 and strain 84 which are virulent and avirulent on Yr10, respectively. The generation of H₂O₂ and the hypersensitive response (HR), were analyzed histochemically using 3,3-diamino-benzidine (DAB) and trypan blue, respectively. At the pre-penetration stage during appressorium formation, 2-4 days after inoculation (dai), H₂O₂ accumulation in guard cells was observed in both compatible and incompatible interactions. After approximately 6 dai and 14 dai, a marked increase of H₂O₂ generation at stoma was detected in both compatible and incompatible interactions involving ‘Moro’ compared to those in ‘Fielder’; the second increase of in H₂O₂ coincided with HR at 12-14 dai. The higher number and larger size of the fluorescing regions on the leaf appeared to be the only reliable indicator of the incompatible interactions involving Yr10 compared to the compatible interactions. Morphological of aspects of compatible and incompatible interactions in ‘Fielder’ and ‘Moro’ involving Yr10, will presented.

Genetic variation and population structure of the blackleg pathogen Leptosphaeria maculans and L. biglobosa of canola. Y. Chen^1,2 and W. G. D. Fernando¹ . ¹Department of Plant Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada. ² Cargill, Specialty Canola Oils, Aberdeen, SK, S0K 0A0, Canada.

Canola/rapseed (Brassica napus L.) important pathogen Leptosphaeria maculans (Desm.) Ces. & de Not or L. biglobosa can be identified into different pathogenicity groups based on interaction phenotype on the differential cultivars. More highly virulent pathogenicity isolates were recently found for the presence in Western Canada and North Dakota (ND), USA. Genetic diversity and population structure of blackleg disease populations collected from North America, Brazil, Australia and United Kingdom were investigated using the sequence-related amplified polymorphism (SRAP) marker technique. High number of polymorphic loci was found based on polymorphic fragments and high number of genotypes was detected in each of those populations, suggesting that L. maculans is extensive diverse in genetics. Each population consists of isolates with high number of unique genotypes. Phylogenic analysis indicated that all populations were clustered together. Indirect estimation of gene flow showed that high rate of gene flow existed among all populations. AMOVA revealed that a major genetic variance source came from the genetic variation among isolates within populations regardless of the origin and pathogenicity.

Brassica napus responses to oxalic acid stress. Y. Liang, S.E. Strelkov and N.N.V. Kav. Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6G 2P5

Oxalic acid (OA) plays an important role during pathogenesis by several plant pathogens including Sclerotinia sclerotiorum.  OA has been shown to chelate calcium, weakening plant cell walls, and modifying the pH in affected tissues, bringing it closer to the optimum for cell wall degrading enzymes.  However, the spectrum of molecular changes accompanying OA treatment is not completely understood.  To characterize the OA-mediated molecular changes in host plants, we performed a detailed analysis of the leaf proteome and oxidative/signaling responses in Brassica napus.  We observed that 18 proteins increased in abundance and 28 decreased as a result of OA treatment.  The proteins were classified into functional groups including carbohydrate metabolism, protein or RNA processing, photosynthesis, signal transduction, stress response, and redox homeostasis.  Signaling processes known to respond to jasmonic acid (JA), ethylene (ET) and abscisic acid (ABA) were affected by OA treatment, whereas those responding to SA were not affected.  Moreover, when OA-mediated modulation of enzymes involved in the generation and detoxification of free radicals was investigated, it was observed that catalase, peroxidase, SOD, and oxalic acid oxidase were unaffected whereas NADPH oxidase appeared to be affected by OA treatment.  Our findings are discussed within the context of the role of OA during the interaction between S. sclerotiorum and B. napus.

Poster Abstracts

Molecular Profiling of Fungal Functional Groups in the Rhizosphere of Short-Rotation Willow Plantations. A.H. Corredor, K. van Rees and V. Vujanovic. Department of Food and Bioproduct Sciences;and (K.V.) Department of Soil Science, University of Saskatchewan, College of Agriculture and Bioresources, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada.

In Saskatchewan, willow (Salix sp.) short-rotation intensive cultures (SRIC) have been established to investigate the potential of several Salix species to produce biomass for bioenergy. Additionally, willows have been studied for environmental purposes such as land reclamation and phytoremediation. Since soil biotic components are major stabilizing factors, it is relevant to assess the influence of fungal communities on the success of willow establishment in the Canadian prairies (SK, AB and MB). The ongoing project aims to investigate the dominant fungal communities and their functions in SRIC by comparing the fluctuation of fungal communities within the rhizosphere of healthy and diseased plants. The approaches used for taxonomical identification include both culture dependent and culture independent polymerase chain reaction (PCR) targeting the ITS (internal transcribed spacer), 18S and 28S regions. The PCR-denaturing gradient gel electrophoresis (PCR-DGGE) technique is also optimized to efficiently perform the comparisons between fungal communities. Initial results indicate that the presence of pathogenic agents could negatively affect plant development, whereas beneficial organisms seem to have a positive influence on plant establishment and healthy growth. The results also indicate a shift in the composition of fungal communities throughout the ages of the plantations, thus, suggesting the importance of fungal diversity on the plants performance for biomass production. The information obtained from this study will help to understand the role of microbial communities in willow plantations and contribute to further soil ecological studies related to sustainable willow SRIC production in western Canada.

Seed infection by Mycosphaerella pinodes does not affect foliar disease severity or seed yield of field pea. B.D. Gossen, R.L. Conner, S.F. Hwang, and M.R. McDonald. Agriculture and Agri-Food Canada (AAFC) Research Centre, Saskatoon, SK S7N 0X2, Canada; (R.L.C.) AAFC Research Centre, Morden, MB  R6M 1Y5, Canada; (S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Rural Development (ARD), Edmonton, AB, T5Y 6H3, Canada; (M.R.M.) University of Guelph, Guelph ON N1G 2W1, Canada.

A study was conducted to examine the impact of seed infection with Mycosphaerella pinodes (Berk. & Blox.) Vestergr. on subsequent levels of mycosphaerella blight of field pea (Pisum sativum L.). To provide seed lots for the study that differed only in levels of seed infection, seed of two cultivars, ‘Keoma’ – highly susceptible (S) and ‘Carneval’ – partially resistant (R), was produced at Saskatoon, SK in 2004. Adjacent plots were either inoculated to increase disease severity or sprayed with foliar fungicide. The incidence of M. pinodes in seed harvested from the inoculated plots was 47% for S and 26% for R, compared with 15% for S and 6% for R in the fungicide-treated plots. The trial was conducted over eight station years (four sites each in 2005 and 2006). High levels of infection consistently reduced seedling emergence and establishment. Little or no foliar disease developed at a site in Ontario where there was limited background inoculum from adjacent fields, regardless of treatment. At three sites where abundant air-borne inoculum was present (Vegreville AB, Saskatoon SK, Morden MB), seed infection had little impact on subsequent disease development and even less impact on seed yield. We conclude that seed infection is unlikely to affect foliar disease severity or seed yield in field pea production areas on the Canadian prairies.

Management of leaf spotting diseases of winter wheat in western Canada.  C.L. Kirkham, T.K. Turkington, D.L. McLaren, R.B. Irvine and H.R. Kutcher. (C.L.K. and H.R.K.) Agriculture and Agri-Food Canada (AAFC), Box 1240, Melfort, SK S0E 1A0; (T.K.T.) AAFC, 6000 C and E Trail, Lacombe, Alberta AB T4L 1W1; (D.L.M. and R.B.I.) AAFC, Box 1000A, R.R. #3, Brandon, MB R7A 5Y3.

A complex of leaf spotting diseases [tan spot (Pyrenophora tritici-repentis (Died.) Drechs.), Septoria complex (Septoria tritici Roberge in Desmaz. and Stagonospora nodorum (Berk.) Castellani & E.G. Germano), spot blotch (Cochliobolus sativus (Ito & Kuribayashi) Drechs. Ex Dastur) and powdery mildew (Blumeria graminis (DC.) E.O. Speer f.sp. tritici Ém. Marchal)] are frequently observed on winter wheat in western Canada. To determine the benefit of varietal improvement and fungicide treatment, field experiments were conducted at three sites in 2006 and 2007 (five site-years) in western Canada.  The varieties Osprey (susceptible) and McClintock (less susceptible) were used in combination with four fungicides in split-plot experiments with fungicide treatments as sub-plots. Leaf spot complex (LSC) severity of flag and penultimate leaves was assessed at the soft dough stage. Severity among sites-years ranged from trace to 21% of leaf area diseased.  At four site-years LSC severity was 4.7% lower on McClintock than Osprey, and was reduced from the check by fungicide treatments. However, interactions between varieties and fungicide treatments were observed at all site-years.  At the two site-years with the greatest LSC severity, yield improvements of 21 and 26%, averaged over varieties and fungicide treatments, were detected.  Varietal selection and fungicide use in some environments are beneficial components of an integrated leaf spot disease management program.

Seedborne transmission of Plasmodiophora brassicae Woronin; evaluation of importance and potential for detection. D. Rennie, V.P. Manolii, T.S. Cao, S.F. Hwang and S.E. Strelkov. Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5.

Plasmodiophora brassicae, causal agent of clubroot of crucifers, is a soilborne pathogen that can be spread from field to field by the movement of infested soil.  Less well understood is the potential for the dissemination of clubroot in seed lots contaminated with pathogen-infested soil tags or plant debris.  Therefore, we have been working on the development of PCR-based assays for the detection and quantification of P. brassicae on seeds.   Seed wash protocols allow for the elution of spores and subsequent isolation of pathogen DNA.  The DNA obtained in this manner can be subjected to routine PCR to establish the presence or absence of P. brassicae-inoculum, whilst the amount of inoculum can be quantified by real-time PCR.  The assays appear to be very sensitive, with a detection limit as low one pathogen resting spore per seed.  Artificially infested seeds were also sown and evaluated for disease development, with the plants showing a progressive decrease in disease index with decreasing levels of contamination.  Thus, the infestation of seedlots with P. brassicae may represent a secondary mechanism of pathogen spread.  The efficacy of fungicidal treatments in eradicating P. brassicae seedborne inoculum will also be examined.

Genetics of Stagonospora nodorum blotch resistance in the wheat population Altar Synthetic/Kenyon. E. Matlock, C. McCartney, G. Hughes and P. Singh. University of Saskatchewan, Plant Sciences, Agriculture Building, 51 Campus Dr, Saskatoon, SK S7N 5A8

Stagonospora nodorum blotch, causal agent Stagonospora nodorum, is part of the wheat leaf spotting complex and is a major disease in Saskatchewan and other wheat growing regions.  Breeding resistant varieties is desirable but requires an understanding of the genetic basis of resistance.  Resistance to Stagonospora nodorum isolate Kelvington was studied in the wheat population Altar Synthetic/Kenyon. This population consists of 96 F6:7 lines and was evaluated for disease reaction in a RCBD experiment with 3 replicates inoculated at the second leaf stage.  The second leaf was rated on a 1 to 5 scale at 7 days post inoculation.  Altar Synthetic was resistant (rating of 1.8) and Kenyon was highly susceptible (rating of 4.6).  Segregation for disease reaction in the population did not fit a single gene model and was skewed towards susceptibility.  Marker analysis has been initiated to determine the number of genes controlling disease reaction and to identify markers suitable for marker-assisted selection.

Biological control of fusarium root rot of pea with Trichoderma species.

K.F. Chang, S.F. Hwang, R. Bowness, G. Turnbull, S.E. Strelkov and D.J. Bing. Field Crop Development Centre, Alberta Agriculture and Rural Development (ARD), Lacombe, AB T4L 1W8, Canada; (S.F.H., G.T) Crop Diversification Centre North, ARD, Edmonton, AB T5Y 6H3, Canada; (S.E.S.) Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (D.J.B.) Agriculture and Agri-Food Canada (AAFC), Lacombe AB, Canada T6R 1W1.

 Fusarium root rot caused by Fusarium spp. is one of the most widespread and destructive diseases occurring on dry pea (Pisum sativum L.) in Alberta.  A total of 18 strains of Trichoderma spp., isolated from soil, were evaluated in vitro for antagonism against four isolates of F. avenaceum.  Trichoderma strains showed various degrees of overgrowth of F. avenaceum colonies in paired culture on Potato Dextrose Agar.  The efficacy of biocontrol by 18 strains of Trichoderma was also examined in greenhouse studies.  Seeds of the pea cultivar Cutlass were coated with a slurry of Trichoderma and grown in Fusarium- inoculated (two concentrations) and non-inoculated soilless mix.  The high concentration of Fusarium inoculum induced more severe root rot symptoms than the lower one. Without inoculum, all Trichoderma spp. isolates significantly increased seedling emergence and biomass compared to their inoculated counterparts and no symptoms of root infection appeared.  In inoculated treatments, all treatments exhibited root rot, but those treated with the Trichoderma isolates Bh-3, Tf-3, Els-15, Bh-2, E12, Bh-4 and B6 still had significantly higher emergence and biomass relative to all other isolates and the control treatment. The results suggest that certain Trichoderma strains have excellent potential for use in the management of fusarium root rot of pea. A field study to confirm the efficacy of Trichoderma in the control of fusarium root rot is planned for next season.

Genetic diversity of Fusarium species isolated from pea in Alberta, Canada. J.Feng¹, R. Hwang², K.F. Chang³, S.F. Hwang¹, S.E.Strelkov² and B.D.Gossen⁴. ¹Crop Diversification Centre North, Alberta Agriculture and Rural Development (AARD), Edmonton, AB, T5Y 6H3; ²Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada; ³Crop Development Centre, AARD, Lacombe, AB, T4L 1W1; ⁴Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2.

Fusarium root rot is a important disease of pea in Canada. Although most studies have focused on Fusarium solani as the primary organism responsible for root rot of pea, other species, including F. oxysporum, F. culmorum and F. avenaceum, have also been shown to produce the same symptoms. In this study, 80 isolates of the Fusarium complex, which produced brown to black discoloration of the root and stem base, yellowing of the basal foliage and stunted growth, were collected from four different locations in Alberta, Canada. To assess the genetic relatedness of these strains, the rDNA ITS region and a Type I chaperonin (cpn60) gene were sequenced and analyzed. Alignment of the ITS or cpn60 gene sequences from each strain and those from other Fusarium species revealed that all 80 strains were closely related to F. avenaceum. Genealogical analysis based on the cpn60 sequences resulted in clustering of all strains into a single group. However, alignment of the DNA sequences from the ITS region yielded a parsimonious tree containing four supported clades. There was no correlation between the clades and the geographic origin of the strains. The genetic relationship between pathogenic and non-pathogenic strains is under investigation. The data indicate that 1) F. avenaceum is the major pathogen responsible for pea root rot in Alberta, 2) strains with different geographic origins are closely related genetically, and 3) for phylogenetic analysis within Fusarium species, the ITS region provides more discriminating information than the cpn60 region.

Confocal microscopic studies of root-endophytic fungi in wheat. L. Abdellatif, S. Kaminskyj, S. Bouzid, and V. Vujanovic. (L.A and V.V) Department of Food and Bioproduct Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8; (S.K) Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon SK, S7N 5E2; (S.B) Department of Biology, University of Tunis, Tunis 1060, Tunisia

Colonization of plant tissues by fungus include several steps: host recognition, spore germination, penetration of the epidermis and tissue colonization. Plant and fungal colonization studies have been extensively explore with confocal microscope. In this study, wheat living root cells and γ-irradiated dead root cells were treated with endophytic fungi (ep1 and ep2). Using confocal microscope, colonization patterns between living and dead root cells were analyzed. Considerable variations were observed between the two types of root cells. In living root cells, ep1 showed inter and intra cellular colonization, whereas ep2 only showed intra cellular colonization. However, in the irradiated root cells, both ep1 and ep2 exhibited inter and intra cellular colonization. Overall, living root cells showed low frequency colonization when compared to dead root cells. Intracellular microfurcated and coiled-like structures were observed only in living cells. By contrast and interestingly so, intracellular micropellet structures were observed in both living and dead root cells. Hence, our confocal microscopic study revealed important variations between living and dead root cells, – showing presence of both symbiotic and non-symbiotic associations with living and dead root cells, respectively.

Clubroot incidence on Asian Brassica vegetables in relation to temperature and fungicide application. M.R. McDonald, K. K.c., S. M. Westerveld, and B. D. Gossen, Department of Plant Agriculture, University of Guelph, Guelph, ON, N1G 2W1, Canada; and (B. D. G.) Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, Saskatchewan S7N 0X2, Canada.

Clubroot of crucifers, caused by Plasmdiophora brassicae (Woronin), is an important disease of Brassica vegetables in Ontario and other parts of the world.  Field trials were established to determine if clubroot could be managed by a combination of fungicide application and seeding date.  Asian vegetables, Shanghai pak choy (Brassica rapa L. subsp. chinensis (Rupr.) var. communis Tsen and Lee) and Chinese flowering cabbage (B. rapa L. subsp. chinensis (Rupr.) var. utilis Tsen and Lee) were seeded into organic soil (pH 6.7, 69% organic matter) naturally infested with the clubroot pathogen at the Muck Crops Research Station, Ontario, Canada, in May, June, July, August and September, 2007 and 2008.  Ranman (34.5% cyazofamid, 3.2 kg ai/ha) was applied as a drench (46.1 g ai/100 L water, 300 ml/m) in a 15 cm band over the seed row within a week ( 2007) or 3 days (2008) of seeding.  Plants were harvested at weekly intervals and assessed for clubroot incidence and severity. Disease incidence was highest on crops seeded in June and July.  Ranman application was effective only on a few seeding dates.  Brassica vegetables seeded very early or late in the season escaped high levels of clubroot.  More research is required to determine the optimum rates, timing and volumes of water to increase the efficacy of Ranman for clubroot control on organic soils.

Characterization of food-spoilage pathogens from fresh produce in Alberta. M.W. Harding, N.M. Butler, K. den Brok, S. Rajput, and R.J. Howard. Alberta Agriculture and Rural Development, Crop Diversification Centre South, 301 Horticultural Station Rd. E., Brooks, AB T1R 1E6 Canada; (S.R.) Life Sciences Division - BioResource Technologies, Alberta Research Council, Postal Bag 4000, Vegreville, Alberta, T9C 1T4.

In order to better understand the dynamics of food spoilage, we collected samples of fresh produce from 10 farmers’ markets, and environmental samples from five farms. Sampling was done across southern and south-central Alberta between July-October 2007. The predominant microbial species were amplified in moist chambers and were collected and purified. Isolates from produce were identified to species (where possible) by PCR amplification of 16S rDNA and sequencing. Microbial isolates from farm production surfaces were identified to genus using Gram’s staining, morphology and metabolic assessments (if necessary). Thirty-one species of bacteria and 22 species of fungi were identified. Some isolates represented typical produce-spoilage genera (i.e. Pseudomonas, Pantoea, Fusarium, Penicillium), but many unique species, not typically associated with food spoilage, were also identified. There was no regional- or host-specificity observed among the isolates. Koch’s postulates were completed for each of 27 bacterial isolates and 27 fungal isolates. Approximately 93% of the isolates were recovered after re-inoculation of fresh produce. Of those recovered, 39% were independently responsible for spoilage and 33% were present in mixed populations where spoilage occurred. These results indicated that the spoilage process can involve complex mixtures of microbial species, some of which have not traditionally been identified as plant pathogens.

Assessment and characterization of viral dsRNAs in Fusarium pathogenic species from Canadain cereals. P. Daida and V. Vujanovic. Department of Food and Bioproduct Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada and (V.V.) AFIF Chair in Microbial Biotechnology and Bioproducts, Department of Food and Bioproducts Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada.

Double stranded RNAs (dsRNAs) eukaryiotic cell inhabitants are widespread throughout fungal kingdom. In plant pathogenic fungi, some viruses or viral elements cause important cell physiological changes, including the capability of toxin synthesis, cytological alteration and enzymatic activity associated with fungal virulence. Although most dsRNAs detected in fungi are assumed to be the genome of mycoviruses, the majority of dsRNAs exist as unencapsidated forms in the fungal cell cytoplasm. They are classified into eight families based on their molecular or physicochemical properties: Birnaviridae, Chrysoviridae, Reoviridae, Endornaviridae, Hypoviridae, Partiitviridae, Reoviridae and  Totoviridae. In this study we are assessing the presence of dsRNA-mycoviruses that occure in F. graminearu, F. avenaceum, F.culmorum and F. oxysporum pathogenic isolates originating from Canadian cereal fields. The extracted dsRNAs were analyzed using specific dsRNA primers; bands             were amplified, purified and sequenced. Sequence analyses will reveal virus identities in relation with Fusarium isolates that showed shifts in virulence on cereal hosts.

Effect of vesicular-arbuscular mycorrhizaal fungi on growth and development of seedling and root rot of Rhodiola rosea in Alberta, Canada. S.F. Hwang, H. Ahmed, K. Ampong-Nyarko, S.E. Strelkov, R.J. Howard, S. Lutz and G.D. Turnbull. Crop Diversification Centre North, Alberta Agriculture and Food, Edmonton, AB, T5Y 6H3, Canada; (S.E.S.) Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.

Rhodiola (Rhodiola rosea) is a plant with adaptogenic properties and is suitable for cultivation under environmental conditions in Alberta. Survey results indicated that Fusarium, Rhizoctonia, and Pythium species are associated with diseased rhodiola seedlings. Rhodiola requires about five years of growth before harvest, so plants are exposed and vulnerable to these soil borne pathogens for long periods.  These pathogens are a potential threat to the quality and quantity of production under field conditions. Experiments were conducted to determine the efficacy of vesicular-arbuscular mycorhizal fungi (VAM) in controlling seedling diseases associated with rhodiola roots under greenhouse conditions. Overall results indicated that Fusarium, Pythium and Rhizoctonia are all capable of reducing rhodiola biomass.  However, biomass was significantly higher when VAM was applied either in conjunction with these pathogens or in non-inoculated controls. This suggests that VAM could be used as a management tool for seedling root rot diseases in rhodiola.

Bunt in triticale. T. Despins, D.A. Gaudet, and  B. Puchalski. Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta.

Triticale (X Triticosecale Whittmack) is a manmade cross between durum wheat (Triticum durum) and rye (Secale creale). Triticale is normally immune to many of the common pathogens of wheat including common bunt caused by Tilletia spp.  This resistance likely originated from the immune rye parent. In the summer of 2008, we observed considerable levels (3%) of bunt species in T209, a triticale line entered in the 2008 Bunt Cooperative Trials. Standard light and fluorescence microscopy were employed compare infection of T209 triticale with that of the bunt-immune variety AC Ultima.

Assessment of Melanospora-like biotrophic mycoparasite using genus specific real-time PCR for biocontrol of phytopathogenic Fusarium strains in wheat mycorrhizosphere.  Y.K. Goh and V. Vujanovic. Department of Food and Bioproduct Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, Canada and (V.V.) AFIF Chair in Microbial Biotechnology and Bioproducts, Department of Food and Bioproducts Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, Canada.

Fusarium species are well-known causal agents of Fusarium root-rot, Fusarium head blight (FHB), and Fusarium damaged kernels (FDK) diseases in Saskatchewan and other provinces of Canada. Our goal is to develop quantitative real-time PCR techniques to determine and evaluate interactions between Fusarium-associated biotrophic mycoparasitic fungus (Melanospora-like SMCD 501) and two different Fusarium spp.- Fusarium graminearum Schwabe and Fusarium avenaceum (Fr.) Sacc.- in the wheat roots and surrounding mycorhizosphere. ITS1F/ITS4 (internal transcribed spacer), NS1/NS6 (nuclear-encoded small subunit - nrSSU) and LS1/LR5 (nuclear-encoded large subunit - nrLSU) sequences from two Melanospora-like biotrophic mycoparasitic fungal isolates (SMCD 500 and 501) and three different Fusarium species will be aligned, and consensus sequences will be verified. Four candidate primer sets from ITS regions, ten candidate primer sets from nrSSU regions, and ten candidate primer sets from nrLSU regions will be designed based on the non-conserved regions of the consensus sequences. Each primer set will be tested on genomic DNA of Melanospora-like isolates, as well as three different Fusarium species: F. graminearum Schwabe, F. avenaceum (Fr.) Sacc., and F. oxysporum Schlecht.:Fr. The primer set which is able to amplify Melanospora-like biotrophic mycoparasite genomic DNA only and which does not amplify Fusarium species genomic DNA will be selected and developed for assessing and quantifying the interactions between Melanospora-like biotrophic mycoparasite and two Fusarium species. It will also be used for comparison of the well-known necrotrophic Trichoderma mycoparasites.  

Effects of abiotic and biotic stress factors on chlamydospore formation by Fusarium graminearum and Fusarium sporotrichioides. Y.K. Goh, P. Daida and V. Vujanovic. Department of Food and Bioproduct Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada and (V.V.) AFIF Chair in Microbial Biotechnology and Bioproducts, Department of Food and Bioproducts Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada.

Chlamydospores are vital asexual resting cells, which allow most of the Fusarium strains to retain the longevity, thus ensuring survival of viable reproductive cells. This study suggested that both abiotic and biotic stressors are able to stimulate chlamydospores formation in F. graminearum and F. sporotrichioides. Two Fusarium pathogenic and mycotoxigenic taxa were exposed to abiotic - extreme temperature and different growth media and biotic - Bacillus amyloliquefaciens SMCD 518 and mycoparasite Acremonium strictum SMCD 504 stressors. In F. sporotrichioides, Minimal Conversion Media (MCM) with mannitol supplement (MCM- mannitol) induced high chlamydospore size/cell number in chain, and abundance/number of chains at optimal 21⁰C and extreme 37⁰C temperatures, respectively. F. graminearum showed low chlamydospore formation on MCM-mannitol, even when exposed to 37⁰C under prolonged 5-days incubation. There is a positive evidence of chlamydospore formation in the presence of bacteria and mycoparasite. Generally, F. sporotrichioides has higher chlamydospore abundance and production rapidity compared to F. graminearum.
 

Symposium Abstracts

Potential distribution and severity of clubroot of canola in western Canada. T.K. Turkington, O.O. Olfert, R. Weiss, H. Klein-Gebbinck, D. Kriticos, H.R. Kutcher, K.C. Falk, and S.E. Strelkov. (T.K.T., H.K.-G.) Lacombe Research Centre/Beaverlodge Research Farm, Agriculture and Agri-Food Canada, 6000 C&E Trail, Lacombe, AB, T4L 1W1, Canada; (O.O.O., R.W., H.R.K., K.C.F.) Saskatoon Research Centre, 107 Science Place, Saskatoon, Saskatchewan, S7N 0X2, Canada; (D.K.), CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia; and S.E.S., Dept. Agricultural, Food and Nutritional Science, University of Alberta, 410 Agriculture/Forestry Centre, Edmonton, AB, T6G 2P5, Canada.

Clubroot of canola caused by Plasmodiophora brassicae Woronin, was first reported in the St. Albert region of Alberta in 2003.  Since this initial report, clubroot of canola has been mainly reported in a broad region around Edmonton, Alberta, but also from  individual fields elsewhere in the province.  The computer simulation program, CLIMEX^TM (Hearne Scientific, Inc.) was used to develop models to predict potential distribution and severity of clubroot of canola in western Canada under current long-term climatic conditions as well as in above/below average precipitation scenarios. Initial predictions of clubroot disease occurrence and severity were consistent with observations on cruciferous vegetables in the lower mainland of British Columbia and central Canada, and canola  in Alberta Based on current conditions, the model predicted that clubroot of canola could expand to the moister regions of Alberta,  Saskatchewan and Manitoba. Under the scenario of 130% of normal rainfall during the growing season there was an expansion of the area where clubroot may occur at economic levels, while limited occurrence and impact was predicted with only 70% of growing season rainfall.  Further validation of the CLIMEX^TM model is underway, while efforts are being made to incorporate the impacts of  soil pH and soil texture. 

Management of clubroot in Brassica vegetables. M.R. McDonald, B. Kornatowska, K. Vander Kooi, K. K.c.,and B. D. Gossen. Department of Plant Agriculture, University of Guelph, Guelph, ON, N1G 2W1, Canada; and (B. D. G.) Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, Saskatchewan S7N 0X2, Canada.

Clubroot of crucifers, caused by Plasmdiophora brassicae (Woronin), is one of the most persistent and economically important diseases of Brassica vegetables.  The pathogen persists as resting spores which can survive many years in soil. Recommended cultural controls emphasize liming soil to raise the pH over 7.2 but also include preventing the spread of the disease, avoiding infested fields, choosing well drained soils, applying nitrate rather than ammonium fertilizers and adding calcium and boron to the soil.  These methods are not always successful, especially in heavily infested soils.  Calcium cyanamide (Perlka) has been tested in many regions and soil types.  The material must be incorporated several days before planting, as it is phytotoxic, but can effectively reduce clubroot infection. The fungicide fluazinam (Allegro) was recently registered in Canada.  Another fungicide, cyazofamid (Ranman), may be registered soon.   However, all of these products are relatively expensive, may require large volumes of water and often suppress, rather than control, disease.  Resistant cultivars of cabbage, cauliflower, and napa cabbage have recently been released. The resistance is usually race specific and can breakdown if not managed carefully.  PCR techniques have been developed to determine infestation levels in soils and the identification of effective  biofungicides may provide more management tools.  An integrated approach can allow for successful vegetable production in infested soils, but much remains to be done to develop economical and consistent control of this frustratingly persistent disease.

Soil treatments and amendments for management of clubroot on canola in Alberta, Canada. S.F. Hwang, S.E. Strelkov, G.D. Turnbull, V. Manolii, R.J. Howard, M. Hartman and P. Laflamme. Alberta Agriculture and Food, 17507 Fort Road, Edmonton, AB, Canada.

Clubroot, caused by Plasmodiophora brassicae Woronin, has appeared in many canola crops near Edmonton, Canada.  With a half-life of four years, this pathogen represents a long-term challenge to canola production in central Alberta.  Field plots were established in infested soils near Leduc and St. Albert, Alberta, to determine the effects of soil amendments and chemical soil treatments on crop damage due to clubroot.  Clubroot severity was significantly lower compared to the untreated control in soils treated with Terraclor 75% WP.  This treatment also resulted in reduced seedling mortality, increased plant cover and increased plant height in severely infested soils.  Yield increased with dosage level of Terrachlor, but was unaffected by the other chemical treatments. Percentage plant cover and height also responded positively to treatment with Ranman at 7.5 L/ha in less severely infested soils.  Amendment of infested soils with calcium carbonate, wood ash, or calcium cyanamide did not result in changes in clubroot severity, compared to the untreated control.  In severely infested soils, amendment with wood ash at 7.5 t/ha or with calcium carbonate at 5.0 or 7.5 t/ha resulted in greater plant height and crop cover compared to the untreated control. Yield was greater in plots treated with the high rate of wood ash, and the two highest rates of calcium carbonate, compared to all other soil amendments. Results indicate that Terraclor 75% WP and treatment with high levels of calcium carbonate or wood ash have the potential to reduce the effect of P. brassicae on canola.

 
        Workshop Abstract

        Issues in seed treatment K. Anderson. Bayer CropScience, 295 Henderson Drive. Regina, SK S4N 6C2. Canada.

 

 

 

 

 

 

 

 

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Contact  
Godfrey Chongo
CPS Saskatchewan Regional Representative

   © 2007 Canadian Phytopathological Society - Saskatchewan Regional Society
Update: September 30, 2007