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Harms T.E.,Rural Water Branch | Konschuh M.N.,Crop Diversification Center South
Agricultural Water Management | Year: 2010

Current agronomic practices for potato production in the irrigated areas of southern Alberta involve a hill/furrow configuration that was adopted from elsewhere, and designed to shed rainfall away from the hill and into the furrow. However, the principal intent of supplemental irrigation is to capture as much of the applied water into the hill, where the potato tubers and roots are located, and minimize water accumulating in the furrow. A three-year project began in 2006 to quantify the potential irrigation water savings of altered hill shapes for potato production. The three treatments (standard hill, flat-topped hill, and double-planted wide-bed) were arranged in a randomized strip plot design replicated four times. Soil water in each treatment was generally kept between 60 and 90% of available. A fourth treatment, triple-planted wide bed, was added to the project in 2008. The irrigation requirements to maintain the treatments were 487, 442, and 449 mm for the standard hill, flat-topped hill, and double-planted bed, respectively, in 2006 and 442, 408 and 411 mm for the same treatments in 2007. This translates into approximately 10% less irrigation water required for the flat-topped hill shape compared to the standard hill shape. The flat-topped hill shape required 5.0% more irrigation than the standard hill in 2008, but the double and triple-planted wide beds required 8.0 and 9.9%, respectively, less irrigation water than the standard. Although not always statistically significant, water use efficiency was greater in all years for the altered bed shapes compared to the standard hill geometry. Greater water use efficiency can be interpreted as more of the applied water infiltrated into the hill, where the potato plant could use it for transpiration and tuber development. Total yield was greater in 2006 for both the flat-topped hill (72.3 Mg ha -1) and wide-bed hill (69.2 Mg ha -1) compared to the standard hill (61.4 Mg ha -1); however, the treatments were not significantly different. Significantly greater marketable yield was realized from the flat-topped hill treatment in 2006. This treatment also had a significantly greater number of marketable size tubers. In 2007, there were no significant differences in total yield; however, the standard and flat-topped treatments had a significantly greater number and yield of tubers in the 113-170 g size category. Significant differences in total yield were found in 2008. The triple-planted wide bed had significantly greater yield in the smaller size categories compared to the standard treatment and significantly greater total tuber numbers than the other treatments, but the increase was in the smaller size categories, less than 170 g. There were no significant differences among the treatments in yield or total number of tubers in the size categories greater than 171 g in 2008. © 2010 Elsevier B.V. All rights reserved.

Hwang S.-F.,Crop Diversification Center North | Howard R.J.,Crop Diversification Center South | Strelkov S.E.,University of Alberta | Gossen B.D.,Agriculture and Agri Food Canada | Peng G.,Agriculture and Agri Food Canada
Canadian Journal of Plant Pathology | Year: 2014

Clubroot, caused by Plasmodiophora brassicae, has emerged as a serious disease threatening the canola production industry in western Canada. This review summarizes results from studies, conducted since 2007, on the development of effective strategies for the management of clubroot in canola. Several options have been proposed for the control of this disease in infested fields, including liming the soil to increase soil pH, crop rotation with non-hosts and bait crops, manipulating the sowing date, sanitization of farm equipment, and the deployment of resistant cultivars, all aimed at reducing the severity of infection. Research began by assessing existing clubroot treatments, originally developed for the cole crop vegetable industry, for their applicability to canola production systems. Although these treatments provide good levels of clubroot reduction for the intensive production of short-season brassica vegetables, most are not economically feasible for the large-scale production of canola, which requires protection over a greater field acreage. Genetic resistance to P. brassicae has been shown to be a practical option for the management of clubroot on canola, but resistance stewardship, coupled with crop rotation and appropriate cultural practices, will be required to maintain the performance and durability of genetic resistance. Pathogen resting spores can be disseminated on infested soil carried on both machinery and seed. Efforts to minimize spread of the pathogen between canola fields have focused largely on the sanitization of field equipment and seed. © 2014 © 2014 The Canadian Phytopathological Society.

Hwang S.-F.,Crop Diversification Center North | Strelkov S.E.,University of Alberta | Feng J.,Crop Diversification Center North | Gossen B.D.,Agriculture and Agri Food Canada | Howard R.J.,Crop Diversification Center South
Molecular Plant Pathology | Year: 2012

Plasmodiophora brassicae causes clubroot disease in cruciferous plants, and is an emerging threat to Canadian canola (Brassica napus) production. This review focuses on recent studies into the pathogenic diversity of P. brassicae populations, mechanisms of pathogenesis and resistance, and the development of diagnostic tests for pathogen detection and quantification. Taxonomy: Plasmodiophora brassicae is a soil-borne, obligate parasite within the class Phytomyxea (plasmodiophorids) of the protist supergroup Rhizaria. Disease symptoms: Clubroot development is characterized by the formation of club-shaped galls on the roots of affected plants. Above-ground symptoms include wilting, stunting, yellowing and premature senescence. Disease cycle: Plasmodiophora brassicae first infects the root hairs, producing motile zoospores that invade the cortical tissue. Secondary plasmodia form within the root cortex and, by triggering the expression of genes involved in the production of auxins, cytokinins and other plant growth regulators, divert a substantial proportion of plant resources into hypertrophic growth of the root tissues, resulting in the formation of galls. The secondary plasmodia are cleaved into millions of resting spores and the root galls quickly disintegrate, releasing long-lived resting spores into the soil. A serine protease, PRO1, has been shown to trigger resting spore germination. Physiological specialization: Physiological specialization occurs in populations of P. brassicae, and various host differential sets, consisting of different collections of Brassica genotypes, are used to distinguish among pathotypes of the parasite. Detection and quantification: As P. brassicae cannot be cultured, bioassays with bait plants were traditionally used to detect the pathogen in the soil. More recent innovations for the detection and quantification of P. brassicae include the use of antibodies, quantitative polymerase chain reaction (qPCR) and qPCR in conjunction with signature fatty acid analysis, all of which are more sensitive than bioassays. Resistance in canola: Clubroot-resistant canola hybrids, recently introduced into the Canadian market, represent an important new tool for clubroot management in this crop. Genetic resistance must be carefully managed, however, as it has been quickly overcome in other regions. At least three resistance genes and one or two quantitative trait loci are involved in conferring resistance to P. brassicae. Root hair infection still occurs in resistant cultivars, but secondary plasmodia often remain immature and unable to produce resting spores. Fewer cell wall breakages occur in resistant hosts, and spread of the plasmodium through cortical tissue is restricted. More information on the genetics of clubroot resistance in canola is needed to ensure more effective resistance stewardship. © 2011 The Authors. Molecular Plant Pathology © 2011 BSPP and Blackwell Publishing Ltd.

Bennett D.R.,Alberta Agriculture and Rural Development | Harms T.E.,Crop Diversification Center South
Canadian Water Resources Journal | Year: 2011

Water supplies available for irrigation in southern Alberta are limited. A study was conducted in southern Alberta to develop crop yield and evapotranspiration (ET c) relationships for major irrigated crops based on current maximum potential crop yield data and improved methods for determination of crop evapotranspiration. Production functions for crop yield and the field water supply, which includes irrigation at 80% efficiency, effective precipitation, and stored soil moisture depletion, were subsequently determined. These empirical relationships may be used by water managers, economists, and producers to examine the economic implications of crop yield reductions from water stress due to limited water supplies, less than optimum (deficit) irrigation management, or variation in evaporative demand from year to year in different agro-climatic areas of southern Alberta. Potential yield estimates for different scenarios may be used with relevant economic information to determine optimum water use for irrigation. © 2011 Canadian Water Resources Association.

Dosdall L.M.,University of Alberta | Carcamo H.,Agriculture and Agri Food Canada | Olfert O.,Agriculture and Agri Food Canada | Meers S.,Crop Diversification Center South | And 2 more authors.
Biological Invasions | Year: 2011

Agroecosystems in the western Canadian provinces of Alberta, Saskatchewan, and Manitoba have been invaded by several alien herbivorous insects from several orders and families. These species have caused very substantial reductions in yield and quality of the dominant crops grown in this region, including cereals (primarily wheat, Triticum aestivum L., barley, Hordeum vulgare L., and oats Avena sativa L.), oilseeds (primarily canola, Brassica napus L. and Brassica rapa L., and mustard, Sinapis alba L. and Brassica juncea (L.) Czern.), and pulses (primarily field pea, Pisum sativum L., lentil, Lens culinaris Medik., and chickpea, Cicer arietinum L.). In this study, we used literature searches to identify the major species of insect pests of field crops in western Canada and determine those species indigenous to the region versus species that have invaded from other continents. We summarize invasion patterns of the alien species, and some estimated economic costs of the invasions. We document the invasion and dispersal patterns of the cereal leaf beetle, Oulema melanopus L. (Coleoptera: Chrysomelidae), for the first time in all three provinces. We also report the co-occurrence of its exotic parasitoid, Tetrastichus julis (Walker) (Hymenoptera: Eulophidae), and implications for classical biological control. We present results of field studies describing the dispersal patterns of a second recent invader, the pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae). The implications of invasions in this region are discussed in terms of economic and ecological effects, and challenges posed for pest mitigation. © 2011 Springer Science+Business Media B.V.

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