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Barbara J Howlett - One of the best experts on this subject based on the ideXlab platform.
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crop isolation not extended rotation length reduces blackleg leptosphaeria maculans severity of Canola brassica napus in south eastern australia
Animal Production Science, 2004Co-Authors: S J Marcroft, S J Sprague, S J Pymer, P A Salisbury, Barbara J HowlettAbstract:Due to the large increase of Canola production in Australia, current blackleg cultural control recommendations (extended rotation length and isolation distance from Canola stubble) are not adhered to by farmers in many Canola-producing regions. Canola crops are increasingly being sown in short rotation and, in many instances, adjacent to paddocks containing Canola stubble. In this study, the level of disease in commercial Canola crops was determined for different rotations and distances from Canola stubble. There was a strong relationship between the presence of Canola stubble from the previous year (6-month-old stubble) and distance to current Canola crops, but no relationship between the presence of older (18–42 month old) stubble and distance to current Canola crops. Blackleg severity was highest where Canola crops had been sown adjacent to 6-month-old Canola stubble, with the level of blackleg severity decreasing markedly in the first 100 m. Disease severity then generally declined up to 500 m. Plants 500–1000 m from 6-month-old stubble had similar levels of blackleg infection. Blackleg severity was similar between Canola crops sown into 18-month-old Canola stubble (short rotation) and crops sown into paddocks that had no history of Canola for at least the previous 3 years (long rotation). Based on these findings, we recommend that Canola crops should be sown at distances greater than 100 m and preferably 500 m from last season's Canola stubble, rather than extending rotation length between crops.
S J Marcroft - One of the best experts on this subject based on the ideXlab platform.
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Incidence and severity of blackleg caused by Leptosphaeria spp. in juncea Canola (Brassica juncea L.) in Australia
Australasian Plant Pathology, 2015Co-Authors: V. L. Elliott, P A Salisbury, R. M. Norton, R. K. Khangura, S J MarcroftAbstract:Juncea Canola ( Brassica juncea L.) is being developed throughout the worlds Canola growing countries as a drought tolerant, shatter resistant and highly blackleg resistant option to Canola ( Brassica napus L.). Juncea Canola was grown commercially in Australia for the first time in 2007. This study determined the incidence and severity of blackleg infection in juncea Canola prior to commercial release throughout south-eastern Australia in 2006 and 2007, and then again 5 years after commercialisation (2010–2013) to determine if blackleg severity had increased. Blackleg was found at all 127 sites surveyed throughout Victoria, New South Wales, South Australia and Western Australia. The severity of blackleg infection differed among sites and among the juncea Canola cultivars and breeding lines suggesting that differences in resistance may be present. This is the first report that L. maculans isolates virulent on B. juncea are already widespread throughout the Australian Canola growing regions and contradicts the widespread opinion that B. juncea is immune to blackleg. This also demonstrates that blackleg infection was already occurring in juncea Canola prior to commercialisation of this crop in Australia and that disease management strategies similar to those used in Canola cultivation will need to be implemented.
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crop isolation not extended rotation length reduces blackleg leptosphaeria maculans severity of Canola brassica napus in south eastern australia
Animal Production Science, 2004Co-Authors: S J Marcroft, S J Sprague, S J Pymer, P A Salisbury, Barbara J HowlettAbstract:Due to the large increase of Canola production in Australia, current blackleg cultural control recommendations (extended rotation length and isolation distance from Canola stubble) are not adhered to by farmers in many Canola-producing regions. Canola crops are increasingly being sown in short rotation and, in many instances, adjacent to paddocks containing Canola stubble. In this study, the level of disease in commercial Canola crops was determined for different rotations and distances from Canola stubble. There was a strong relationship between the presence of Canola stubble from the previous year (6-month-old stubble) and distance to current Canola crops, but no relationship between the presence of older (18–42 month old) stubble and distance to current Canola crops. Blackleg severity was highest where Canola crops had been sown adjacent to 6-month-old Canola stubble, with the level of blackleg severity decreasing markedly in the first 100 m. Disease severity then generally declined up to 500 m. Plants 500–1000 m from 6-month-old stubble had similar levels of blackleg infection. Blackleg severity was similar between Canola crops sown into 18-month-old Canola stubble (short rotation) and crops sown into paddocks that had no history of Canola for at least the previous 3 years (long rotation). Based on these findings, we recommend that Canola crops should be sown at distances greater than 100 m and preferably 500 m from last season's Canola stubble, rather than extending rotation length between crops.
Marc St-arnaud - One of the best experts on this subject based on the ideXlab platform.
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Canola Root–Associated Microbiomes in the Canadian Prairies
Frontiers in Microbiology, 2018Co-Authors: Chih-ying Lay, Terrence Bell, Chantal Hamel, K Neil Harker, Ramona Mohr, Charles Greer, Etienne Yergeau, Marc St-arnaudAbstract:Canola is one of the most economically important crops in Canada, and the root and rhizosphere microbiomes of a Canola plant likely impact its growth and nutrient uptake. The aim of this study was to determine whether Canola has a core root microbiome (i.e., set of microbes that are consistently selected in the root environment), and whether this is distinct from the core microbiomes of other crops that are commonly grown in the Canadian Prairies, pea, and wheat. We also assessed whether selected agronomic treatments can modify the Canola microbiome, and whether this was associated to enhanced yield. We used a field experiment with a randomized complete block design, which was repeated at three locations across the Canola-growing zone of Canada. Roots and rhizosphere soil were harvested at the flowering stage of Canola. We separately isolated total extractable DNA from plant roots and from adjacent rhizosphere soil, and constructed MiSeq amplicon libraries for each of 60 samples, targeting bacterial, and archaeal 16S rRNA genes and the fungal ITS region. We determined that the microbiome of the roots and rhizosphere of Canola was consistently different from those of wheat and pea. These microbiomes comprise several putative plant-growth-promoting rhizobacteria, including Amycolatopsis sp., Serratia proteamaculans, Pedobacter sp., Arthrobacter sp., Stenotrophomonas sp., Fusarium merismoides, and Fusicolla sp., which correlated positively with Canola yield. Crop species had a significant influence on bacterial and fungal assemblages, especially within the roots, while higher nutrient input or seeding density did not significantly alter the global composition of bacterial, fungal, or archaeal assemblages associated with Canola roots. However, the relative abundance of Olpidium brassicae, a known pathogen of members of the Brassicaceae, was significantly reduced in the roots of Canola planted at higher seeding density. Our results suggest that seeding density and plant nutrition management modified the abundance of other bacterial and fungal taxa forming the core microbiomes of Canola that are expected to impact crop growth. This work helps us to understand the microbial assemblages associated with Canola grown under common agronomic practices and indicates microorganisms that can potentially benefit or reduce the yield of Canola.
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Canola Root-Associated Microbiomes in the Canadian Prairies.
Frontiers in microbiology, 2018Co-Authors: Chih-ying Lay, Chantal Hamel, K Neil Harker, Etienne Yergeau, Terrence H. Bell, Charles W. Greer, Ramona M. Mohr, Marc St-arnaudAbstract:Canola is one of the most economically important crops in Canada, and the root and rhizosphere microbiomes of a Canola plant likely impact its growth and nutrient uptake. The aim of this study was to determine whether Canola has a core root microbiome (i.e., set of microbes that are consistently selected in the root environment), and whether this is distinct from the core microbiomes of other crops that are commonly grown in the Canadian Prairies, pea, and wheat. We also assessed whether selected agronomic treatments can modify the Canola microbiome, and whether this was associated to enhanced yield. We used a field experiment with a randomized complete block design, which was repeated at three locations across the Canola-growing zone of Canada. Roots and rhizosphere soil were harvested at the flowering stage of Canola. We separately isolated total extractable DNA from plant roots and from adjacent rhizosphere soil, and constructed MiSeq amplicon libraries for each of 60 samples, targeting bacterial, and archaeal 16S rRNA genes and the fungal ITS region. We determined that the microbiome of the roots and rhizosphere of Canola was consistently different from those of wheat and pea. These microbiomes comprise several putative plant-growth-promoting rhizobacteria, including Amycolatopsis sp., Serratia proteamaculans, Pedobacter sp., Arthrobacter sp., Stenotrophomonas sp., Fusarium merismoides, and Fusicolla sp., which correlated positively with Canola yield. Crop species had a significant influence on bacterial and fungal assemblages, especially within the roots, while higher nutrient input or seeding density did not significantly alter the global composition of bacterial, fungal, or archaeal assemblages associated with Canola roots. However, the relative abundance of Olpidium brassicae, a known pathogen of members of the Brassicaceae, was significantly reduced in the roots of Canola planted at higher seeding density. Our results suggest that seeding density and plant nutrition management modified the abundance of other bacterial and fungal taxa forming the core microbiomes of Canola that are expected to impact crop growth. This work helps us to understand the microbial assemblages associated with Canola grown under common agronomic practices and indicates microorganisms that can potentially benefit or reduce the yield of Canola.
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Image_2_Canola Root–Associated Microbiomes in the Canadian Prairies.TIFF
2018Co-Authors: Chih-ying Lay, Neil K Harker, Chantal Hamel, Ramona Mohr, Etienne Yergeau, Terrence H. Bell, Charles W. Greer, Marc St-arnaudAbstract:Canola is one of the most economically important crops in Canada, and the root and rhizosphere microbiomes of a Canola plant likely impact its growth and nutrient uptake. The aim of this study was to determine whether Canola has a core root microbiome (i.e., set of microbes that are consistently selected in the root environment), and whether this is distinct from the core microbiomes of other crops that are commonly grown in the Canadian Prairies, pea, and wheat. We also assessed whether selected agronomic treatments can modify the Canola microbiome, and whether this was associated to enhanced yield. We used a field experiment with a randomized complete block design, which was repeated at three locations across the Canola-growing zone of Canada. Roots and rhizosphere soil were harvested at the flowering stage of Canola. We separately isolated total extractable DNA from plant roots and from adjacent rhizosphere soil, and constructed MiSeq amplicon libraries for each of 60 samples, targeting bacterial, and archaeal 16S rRNA genes and the fungal ITS region. We determined that the microbiome of the roots and rhizosphere of Canola was consistently different from those of wheat and pea. These microbiomes comprise several putative plant-growth-promoting rhizobacteria, including Amycolatopsis sp., Serratia proteamaculans, Pedobacter sp., Arthrobacter sp., Stenotrophomonas sp., Fusarium merismoides, and Fusicolla sp., which correlated positively with Canola yield. Crop species had a significant influence on bacterial and fungal assemblages, especially within the roots, while higher nutrient input or seeding density did not significantly alter the global composition of bacterial, fungal, or archaeal assemblages associated with Canola roots. However, the relative abundance of Olpidium brassicae, a known pathogen of members of the Brassicaceae, was significantly reduced in the roots of Canola planted at higher seeding density. Our results suggest that seeding density and plant nutrition management modified the abundance of other bacterial and fungal taxa forming the core microbiomes of Canola that are expected to impact crop growth. This work helps us to understand the microbial assemblages associated with Canola grown under common agronomic practices and indicates microorganisms that can potentially benefit or reduce the yield of Canola.
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Table_1_Canola Root–Associated Microbiomes in the Canadian Prairies.DOCX
2018Co-Authors: Chih-ying Lay, Neil K Harker, Chantal Hamel, Ramona Mohr, Etienne Yergeau, Terrence H. Bell, Charles W. Greer, Marc St-arnaudAbstract:Canola is one of the most economically important crops in Canada, and the root and rhizosphere microbiomes of a Canola plant likely impact its growth and nutrient uptake. The aim of this study was to determine whether Canola has a core root microbiome (i.e., set of microbes that are consistently selected in the root environment), and whether this is distinct from the core microbiomes of other crops that are commonly grown in the Canadian Prairies, pea, and wheat. We also assessed whether selected agronomic treatments can modify the Canola microbiome, and whether this was associated to enhanced yield. We used a field experiment with a randomized complete block design, which was repeated at three locations across the Canola-growing zone of Canada. Roots and rhizosphere soil were harvested at the flowering stage of Canola. We separately isolated total extractable DNA from plant roots and from adjacent rhizosphere soil, and constructed MiSeq amplicon libraries for each of 60 samples, targeting bacterial, and archaeal 16S rRNA genes and the fungal ITS region. We determined that the microbiome of the roots and rhizosphere of Canola was consistently different from those of wheat and pea. These microbiomes comprise several putative plant-growth-promoting rhizobacteria, including Amycolatopsis sp., Serratia proteamaculans, Pedobacter sp., Arthrobacter sp., Stenotrophomonas sp., Fusarium merismoides, and Fusicolla sp., which correlated positively with Canola yield. Crop species had a significant influence on bacterial and fungal assemblages, especially within the roots, while higher nutrient input or seeding density did not significantly alter the global composition of bacterial, fungal, or archaeal assemblages associated with Canola roots. However, the relative abundance of Olpidium brassicae, a known pathogen of members of the Brassicaceae, was significantly reduced in the roots of Canola planted at higher seeding density. Our results suggest that seeding density and plant nutrition management modified the abundance of other bacterial and fungal taxa forming the core microbiomes of Canola that are expected to impact crop growth. This work helps us to understand the microbial assemblages associated with Canola grown under common agronomic practices and indicates microorganisms that can potentially benefit or reduce the yield of Canola.
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Data_Sheet_1_Canola Root–Associated Microbiomes in the Canadian Prairies.DOCX
2018Co-Authors: Chih-ying Lay, Neil K Harker, Chantal Hamel, Ramona Mohr, Etienne Yergeau, Terrence H. Bell, Charles W. Greer, Marc St-arnaudAbstract:Canola is one of the most economically important crops in Canada, and the root and rhizosphere microbiomes of a Canola plant likely impact its growth and nutrient uptake. The aim of this study was to determine whether Canola has a core root microbiome (i.e., set of microbes that are consistently selected in the root environment), and whether this is distinct from the core microbiomes of other crops that are commonly grown in the Canadian Prairies, pea, and wheat. We also assessed whether selected agronomic treatments can modify the Canola microbiome, and whether this was associated to enhanced yield. We used a field experiment with a randomized complete block design, which was repeated at three locations across the Canola-growing zone of Canada. Roots and rhizosphere soil were harvested at the flowering stage of Canola. We separately isolated total extractable DNA from plant roots and from adjacent rhizosphere soil, and constructed MiSeq amplicon libraries for each of 60 samples, targeting bacterial, and archaeal 16S rRNA genes and the fungal ITS region. We determined that the microbiome of the roots and rhizosphere of Canola was consistently different from those of wheat and pea. These microbiomes comprise several putative plant-growth-promoting rhizobacteria, including Amycolatopsis sp., Serratia proteamaculans, Pedobacter sp., Arthrobacter sp., Stenotrophomonas sp., Fusarium merismoides, and Fusicolla sp., which correlated positively with Canola yield. Crop species had a significant influence on bacterial and fungal assemblages, especially within the roots, while higher nutrient input or seeding density did not significantly alter the global composition of bacterial, fungal, or archaeal assemblages associated with Canola roots. However, the relative abundance of Olpidium brassicae, a known pathogen of members of the Brassicaceae, was significantly reduced in the roots of Canola planted at higher seeding density. Our results suggest that seeding density and plant nutrition management modified the abundance of other bacterial and fungal taxa forming the core microbiomes of Canola that are expected to impact crop growth. This work helps us to understand the microbial assemblages associated with Canola grown under common agronomic practices and indicates microorganisms that can potentially benefit or reduce the yield of Canola.
S J Sprague - One of the best experts on this subject based on the ideXlab platform.
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integrating dual purpose wheat and Canola into high rainfall livestock systems in south eastern australia 1 crop forage and grain yield
Crop & Pasture Science, 2015Co-Authors: S J Sprague, J A Kirkegaard, H Dove, J M Graham, S E Mcdonald, W M KelmanAbstract:The development of guidelines for successful dual-purpose (graze and grain) use of wheat and Canola in Australia’s high-rainfall zones (HRZ) has mostly emerged from separate wheat- and Canola-focused research. Less attention has been placed on the benefits of integrating dual-purpose wheat and Canola into pasture-based grazing enterprises. We conducted a farming systems experiment during 2010–11 to evaluate the benefits of integrating wheat and Canola as dual-purpose crops into a pasture-based grazing system in Australia’s south-eastern tablelands. We compared forage production and grain yield in three separate crop–livestock systems in which the sheep grazed long-season wheat, winter Canola or a combination of these. Initial growth rates were higher in early-autumn-sown Canola than wheat in 2010, but were much lower although similar in both crops in 2011. Significant forage was available from both Canola (3.1–3.4 t ha–1) and wheat (2.3–2.4 t ha–1) at the onset of grazing, but winter growth rates of wheat were higher than those of Canola, leading to increased sheep grazing days (SGD). In the favourable 2010 season, dual-purpose wheat and Canola separately provided 2393 and 2095 SGD ha–1, and yielded 5.0 and 1.9 t ha–1 grain, respectively, with an apparent nitrogen limitation in Canola. In the drier season of 2011, grazing was reduced to 1455 and 735 SGD ha–1 in wheat and Canola, respectively. Wheat yield was reduced from 5.9 to 5.4 t ha–1 grain by grazing, whereas Canola yield was unaffected (3.6 t ha–1). In both years, grazing did not affect harvest index or oil content of Canola, but harvest index was higher in grazed wheat crops. The yield of wheat and Canola crops grazed in sequence did not differ from yield in treatments where animals grazed only a single crop, but the total overall grazing window when crops were grazed sequentially increased by 1054 and 618 SGD ha–1 in wheat, and by 1352 and 1338 SGD ha–1 in Canola in 2010 and 2011, respectively. The major benefits of including crops that can be grazed sequentially were the widening of the grazing window and other operational windows (sowing, harvest), along with the rotational benefits for wheat by including Canola in the system. Additional benefits to pastures may include eliminating the need to re-sow, because a more productive pasture composition is maintained under lower grazing pressure while stock are on crops, and reduced weed invasion. The commercial availability of new, herbicide-tolerant winter Canola varieties provides significant opportunities to underpin the performance of dual-purpose crop sequences on mixed farms in the high-rainfall zone.
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crop isolation not extended rotation length reduces blackleg leptosphaeria maculans severity of Canola brassica napus in south eastern australia
Animal Production Science, 2004Co-Authors: S J Marcroft, S J Sprague, S J Pymer, P A Salisbury, Barbara J HowlettAbstract:Due to the large increase of Canola production in Australia, current blackleg cultural control recommendations (extended rotation length and isolation distance from Canola stubble) are not adhered to by farmers in many Canola-producing regions. Canola crops are increasingly being sown in short rotation and, in many instances, adjacent to paddocks containing Canola stubble. In this study, the level of disease in commercial Canola crops was determined for different rotations and distances from Canola stubble. There was a strong relationship between the presence of Canola stubble from the previous year (6-month-old stubble) and distance to current Canola crops, but no relationship between the presence of older (18–42 month old) stubble and distance to current Canola crops. Blackleg severity was highest where Canola crops had been sown adjacent to 6-month-old Canola stubble, with the level of blackleg severity decreasing markedly in the first 100 m. Disease severity then generally declined up to 500 m. Plants 500–1000 m from 6-month-old stubble had similar levels of blackleg infection. Blackleg severity was similar between Canola crops sown into 18-month-old Canola stubble (short rotation) and crops sown into paddocks that had no history of Canola for at least the previous 3 years (long rotation). Based on these findings, we recommend that Canola crops should be sown at distances greater than 100 m and preferably 500 m from last season's Canola stubble, rather than extending rotation length between crops.
Robert E. Blackshaw - One of the best experts on this subject based on the ideXlab platform.
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rotational effects of legumes and non legumes on hybrid Canola and malting barley
Agronomy Journal, 2014Co-Authors: John T Odonovan, Eric N. Johnson, Robert E. Blackshaw, C A Grant, Neil K Harker, G P Lafond, Kelly T Turkington, Newton Z Lupwayi, Craig F Stevenson, Debra L MclarenAbstract:High costs of fertilizer in western Canada have generated interest in alternative N sources. Legumes produce N through fixation, and may increase soil residual and mineralizable N, thus reducing the need for fertilizer N in subsequent crops. Hybrid Canola (Brassica napus L.) has a high N requirement for optimum yield, but knowledge of rotational effects of legumes on Canola is limited. The objective was to determine the effects of legume and non-legume preceding crops on yield and quality of Canola grown the follow ing year and malting barley (Hordeum vulgare L.) grown after Canola. Field pea ( Pisum sativum L.), lentil (Lens culinaris Medik.), faba bean (Vicia faba L.), Canola, and wheat (Triticum aestivum L.) harvested for grain, and faba bean grown as a green manure were direct-seeded at seven locations in 2009. Canola was seeded in 2010 and barley in 2011, with fertilizer N applied at 0, 30, 60, 90, and 120 kg ha –1 . On average, all legumes, except faba bean for seed, produced higher Canola and barley yields than when wheat was the preceding crop. Faba bean green manure produced the highest yields, while Canola on Canola produced the lowest Canola yield. The legumes had little negative effect on Canola oil or barley protein concentration. Yields of both crops increased with increasing N rate, but Canola oil concentration decreased, and barley protein increased. The results indicate that growing legumes for seed before hybrid Canola can improve Canola and subsequent barley yield without negatively affecting Canola oil or malting barley protein.
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crop sequence effects on root maggot diptera anthomyiidae delia spp infestations in Canola
Journal of Economic Entomology, 2012Co-Authors: L M Dosdall, Robert E. Blackshaw, Yantai Gan, John T Odonovan, K. N. Harker, H R Kutcher, Eric N. JohnsonAbstract:Strong market demand for Canola, Brassica napus L., has prompted some western Canadian producers to increase the frequency of this crop in rotations with other crop species, but the impact of this practice on Canola insect pests has not been determined. Here, we investigate 12 cropping sequences involving Canola over a 3-yr period (2008–2010 inclusive) at five locations across western Canada. Cropping sequences varied from continuous production of two herbicide-tolerant Canola varieties, to production in two of 3 yr, to Canola production in one of the 3 yr. Treatments analyzed were the frequency and timing of Canola within the rotational sequence. Damage by larvae of root maggots (Diptera: Anthomyiidae: Delia spp.) to Canola taproots increased as the study progressed, particularly in 2010 after Canola had been grown continuously for 3 yr. Yield declined with continuous Canola production, and differences were greatest in 2010. At mean Canola crop prices for 2010, the yield reduction from continuous production amounted to economic losses of approximately Can$282–$377/ha. Crop quality, in terms of oil and protein concentrations of harvested seed, was affected more by crop variety than cropping sequence. Crop sequence effects for root maggot damage, yield, and seed quality were relatively stable in the presence of environmental (location) variation. Results of our study suggest that continuous Canola production could be unsustainable over the long-term even though market forces currently provide incentive for this practice.
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Weed Suppression by Canola and Mustard Cultivars
Weed Technology, 2008Co-Authors: Hugh J. Beckie, Eric N. Johnson, Robert E. Blackshaw, Yantai GanAbstract:Competitive crops or cultivars can be an important component of integrated weed management systems. A study was conducted from 2003 to 2006 at four sites across semiarid prairie ecoregions in western Canada to investigate the weed-suppression ability of Canola and mustard cultivars. Four open-pollinated Canola cultivars, four hybrid Canola cultivars, two Canola-quality mustard cultivars, two oriental mustard cultivars, and two yellow mustard cultivars were grown in competition with indigenous weed communities. Yellow mustard was best able to suppress weed growth, followed in decreasing order of weed competitiveness by oriental mustard and hybrid Canola, open-pollinated Canola, and Canola-quality mustard. Competitive response of cultivars, assessed by weed biomass suppression, was negatively correlated with time to crop emergence and positively correlated with early-season crop biomass accumulation (prior to bolting) and plant height. Nomenclature: Canola, Brassica napus L., oriental mustard or Canola-qual...
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control of volunteer Canola with herbicides effects of plant growth stage and cold acclimation
Weed Technology, 2006Co-Authors: Anne Légère, Hugh J. Beckie, Eric N. Johnson, Craig F Stevenson, Marie-josée Simard, Robert E. BlackshawAbstract:Phenoxy herbicides are frequently used to control volunteer Canola populations. However, there have been claims that poor control could be due to cold acclimation of Canola plants in the spring. The objective of this study was to determine whether cold acclimation or growth stage affected the response of Canola volunteers to herbicides. In a growth room experiment, Canola plants were prehardened and cold acclimated or were grown at 20/12 C and treated with one of six 2,4-D doses. Cold acclimation as achieved by this experiment affected upper and lower asymptotes of the dose–response curve but not the herbicide dose required to reduce Canola weight by 50% relative to the nontreated control (GR50), indicating limited cold-related effects on Canola tolerance to 2,4-D. Field experiments, conducted in the provinces of Quebec and Saskatchewan, examined the effects of Canola growth stage on the efficacy of 2,4-D, MCPA, and carfentrazone. Comparisons of the estimates from the dose–response curves confirmed that h...
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Persistence of Glyphosate-Resistant Canola in Western Canadian Cropping Systems
Agronomy Journal, 2006Co-Authors: K. N. Harker, Eric N. Johnson, Robert E. Blackshaw, Yantai Gan, George W. Clayton, John T. O'donovan, F. A. Holm, Ken L. Sapsford, R. B. Irvine, R. C. Van AckerAbstract:Canola (Brassica napus L.) is the most important oilseed crop in western Canada. Its prevalence across the Canadian Prairies influences the occurrence and impact of Canola volunteers as weeds. Here we determined the persistence of Canola seed in cropping systems so effective volunteer management strategies can be developed. In mid-to late-October of 2000, approximately 770 seeds m -2 of glyphosate [N-(phosphonomethyl)glycine]-resistant (GR) Canola were scattered on plot areas at seven western Canadian sites. From 2001 to 2003 the plots were seeded to a wheat (Triticum aestivum L.)-field pea (Pisum sativum L.)-barley (Hordeum vulgare L.) rotation or a fallow-field pea-fallow rotation in five different seeding systems involving seeding dates and soil disturbance levels, and monitored four times each year for Canola plant density. Crop seeding date did not consistently influence volunteer Canola density. With some exceptions, higher levels of soil disturbance led to higher volunteer Canola densities. The vast majority of Canola seedlings were recruited in the year following seed dispersal (2001). Across all locations, rotations, and seeding systems, and averaged over preplanting (PREP) and in-crop prespray (PRES) intervals, Canola densities were 6.2, 0.7, and 0.0 plants m -2 in 2001, 2002, and 2003, respectively. Canola volunteers were usually most abundant at PREP and PRES intervals; total recruitment at those intervals averaged across all seeding systems in the continuous cropping rotation was 3% (25 plants m -2 ). Preventing seed production in new Canola volunteers in 2001 reduced Canola densities in subsequent years (2002 and 2003) below those required to mitigate weed-crop competition influences in most crops.