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Summary: This study describes the seedbank persistence of glyphosate‐resistant (GR) Kochia scoparia at two sites in western Canada and examines if GRK. scoparia from western Canada and mid‐western United States (USA) differ from their susceptible counterparts in seed germination and early growth characteristics at low‐temperature regimes. Site or depth of seed burial (surface, 2.5 cm, 10 cm) did not affect seed viability over time and time to 50% and 90% loss of viability averaged 210 and 232 days respectively. Glyphosate‐resistant K. scoparia generally germinated later and had lower cumulative germination than glyphosate‐susceptible (GS) K. scoparia from Saskatchewan, Canada; and Kansas, USA; but not Colorado, USA. Similarly, time to 10% first leaf of GSK. scoparia from Saskatchewan and Kansas tended to be sooner than that of GRK. scoparia, with a greater percentage of GS vs. GR seedlings of populations from all regions having attained first leaf by the end of the experiment. The short seedbank longevity and delayed and reduced germination and time to first leaf of GRK. scoparia may potentially be exploited to maximise management efficacy through delayed preseeding weed control or alternatively by early seeding date to enhance crop competitiveness. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 6-yr study was conducted across western Canada to evaluate the residual effects of preceding crops (PCs) and past N rate management on the economics of subsequent wheat (Triticum aestivum L.) and canola (Brassica napus L.). Field pea (Pisum sativum L.), lentil (Lens culinaris Medik.), canola and wheat harvested for grain, and faba bean (Vicia faba L.) grown and harvested for grain or as a green manure were direct seeded in 2009. Canola was seeded in 2010, barley in 2011, and canola again in 2012 with fertilizer N applied at varying rates for each crop. Spring wheat grown in 2013 and canola in 2014, both without N application, were used to determine residual PC and residual N effects. The positive benefit of legume PCs on the annual crop net revenue (NR) of wheat and canola crops diminished over time. Residual N from previously applied N had positive effects on annual wheat NR in 2013, but only the highest application rate contributed significantly to canola NR in 2014. The NR was greatest with an annual fertilization program based on regional production capacity, but under the dry conditions of the Canadian prairies excess N remaining in the soil after crop production could remain in the soil as residual N to be used by following crops. While generally insufficient to optimize crop production, residual N can reduce the economic risk from over-application of fertilizer if N is not utilized by the crop due to adverse growing conditions in the year of fertilizer application. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of a ferulic acid esterase ( FAE) and a non- FAE-producing inoculant applied alone or in combination with exogenous fibrolytic enzymes ( EFE) on the fermentation and nutritive value of mixed grain (barley, oats and spring triticale) silage. The mixed crop was ensiled in laboratory mini-silos either untreated ( CON), or treated with a FAE inoculant ( FAE), a non- FAE inoculant ( NFAE) or NFAE + EFE. Inoculated silages were lower ( P < 0·01) in water-soluble carbohydrate, whereas NFAE and NFAE + EFE silages had higher ( P < 0·001) DM loss than other silages. FAE and NFAE silage had higher neutral detergent fibre ( NDF), but were lower in NFAE + EFE than other silages ( P < 0·001). Copy numbers of 16S rRNA associated with Lactobacillus buchneri were higher ( P < 0·001) in NFAE and NFAE + EFE silages than in others, resulting in higher ( P < 0·001) acetic acid in these silages. NFAE + EFE silage had lower ( P < 0·001) in vitro gas production and NDF digestibility ( NDFD) than other silages. FAE silage had higher ( P < 0·01) in situ NDFD than CON and NFAE + EFE silages. Inoculation of mixed small-grain silage with NFAE-producing inoculants combining EFE reduced NDFD. [ABSTRACT FROM AUTHOR]

During the period from 2000 to 2013, average canola yields from Canadian farms increased from 1330 to 2025 kg ha-1, or 54kgha-1 year-1. The objective of this review was to propose likely reasons behind this increase by examining genotypic, environmental and agronomic factors. During this period, hybrid canola cultivars with herbicide tolerance (HY-HT) expanded from 80% to >95% of the area sown to canola. Genetic gain from switching from openpollinated cultivars to HY-HT cultivars was estimated to account for 32 kg ha-1 year-1. When some key environmental factors were examined, there were no significant linear changes in growing season temperature, although the linear increase in April and May precipitation was significant and likely responsible for an increase of 12 kg ha-1 year-1. When coupled with the yield increase from changes in atmospheric CO2 (3 kg ha-1 year-1), the environment was estimated to account for ∼15 kg ha-1 year-1. Ignoring all main-factor interactions, changes due to management accounted for the remainder, or 7kgha-1 year-1. The expanded use of HY-HT varieties has resulted in better weed control, and an increase in the use of minimum tillage, leading to greater water-use efficiency and higher yield. It is likely that many of the effects of changes in management were hidden in the interaction with genotype and environment main effects. It is difficult to estimate these interactions without designing experiments to do so. The design and implementation of experiments to understand the interaction among main factors should be a priority. Future yield targets of 25 Mt canola by 2025 will require an increase in yield per ha beyond the current rate, or an increase in the land seeded to canola, or a combination of the two factors. Continued progress with canola yield depends on active plant-breeding programs, agronomic research using new varieties, favourable environmental conditions, and high world commodity prices. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Remote Sensing is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Strong market demand for canola, Brassica napus L., has prompted some wester 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. [ABSTRACT FROM AUTHOR]

The article discusses research on the effects of the depth and speed of seeding on a no-till canola seed. The researchers examined the seeding process and the influence of cultivar to the level of maturity, yield, and seed quality of a glyphosate-resistant canola seed. The study explored the canola emergence density with regard to environmental factors and precipitation levels. Also noted is the biotic and abiotic stress with regard to the level of tolerance of a canola seed.

The article discusses the results of experiments that determined if high level of crop inputs could increase canola seed yield and oil concentration over yield levels during the experiment period. Herbicides, insecticides and fertilizers were applied during planting as required for optimal production. Results indicate that canola oil concentration varied among cultivars but consistently low when nitrogen rates were high, although in some cases normal seeding rates led to high oil concentration.

Farmers are interested in more cost-efficient and environmentally sound fertilization programs in field crops. A multi-site study on the Canadian prairies was conducted to determine the effect ofpolymer-coated urea (Environmentally Smart Nitrogen, ESN) compared with urea on weed management and barley (Hordeurn vulgare L.) yield and quality. Treatments included a semi-dwarf and tall barley cultivar, polymer-coated urea (ESN) and urea, 100 and 150% of soil test N fertilizer rates, and 50 and 100% of registered herbicide rates. Treatments were applied to the same plots in four consecutive years. Barley yield was greater with semi-dwarfcompared with tall barley in 13 of 20 site-years but weed biomass was greater in 7 of 18 site-years with the semi-dwarfcultivar. The 150% N fertilizer rate increased yield ofboth cultivars in 9 of 20 site-years and of the semi-dwarf cultivar in four additional site-years. Barley yield was often similar with ESN and urea but ESN increased barley yield in three site-years at both N rates, two additional site-years at the 150% N rate, and one further site-year with semi-dwarfbarley. Barley grain protein concentration was greater with ESN than with urea in 8 of 20 site-years. Information gained in this study will be used to advise growers on improved barley production practices. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizer is a major input cost in canola (Brassica napus L.) production and farmers are interested in improving N use efficiencies. A multi-site study in western Canada was conducted to determine the merits of polymer-coated urea (Environmentally Smart Nitrogen, ESN) compared with urea on weed management and yield of hybrid and open-pollinated (OP) canola. Treatments included a hybrid and OP canola cultivar, ESN and urea, 100 and 150% of soil test N fertilizer rates, and 50 and 100% of registered in-crop herbicide rates. Canola was grown in rotation with barley (Hordeum vulgare L.) in a no-till system and both crops of the rotation were present each year. Fertilizer and herbicide rate treatments were applied to the same plots in four consecutive years to determine annual and cumulative effects. Hybrid compared with OP canola reduced weed tissue N concentration in 40% of the cases and reduced weed biomass in 80% of the cases. Additionally, weed tissue N concentration was lower with ESN than with urea in 70% of the cases, indicating that crop-weed competition for soil N might be reduced if ESN were used. Canola yield was greater for the hybrid cultivar in 15 of 20 site-years. Both cultivars expressed a positive yield response to the 150% N fertilizer rate in 10 of 20 site- years. This yield response occurred in three additional site-years with hybrid canola, indicating that hybrid cultivars have a higher N demand under favorable growing conditions. Canola yield was similar with ESN and urea in 14 of 20 site-years. The ESN compared with urea increased canola yield in 4 site-years and in one additional site-year for hybrid canola, indicating that ESN may be advantageous in some situations. Canola seed oil concentration was similar with ESN and urea in 19 of 20 site-years. Information gained in this study will be used to develop improved fertilization strategies for canola production on the semiarid Canadian prairies. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Entomologist is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Site-Specific Herbicide Management (SSHM) in Precision Agriculture (PA) requires weed detection in crop fields for directed herbicide application instead of spraying entire fields. This has significant economic and environmental advantages for improved agricultural practices that are essential given forecast increases in global population and food production needs. In this study, a new hybrid segmentation - Artificial Neural Network (HS-ANN) method was compared to standard Maximum Likelihood Classification (MLC) for improving crop/weed species discrimination in SSHM/PA. Very high spatial resolution (1.25 mm) ground-based hyperspectral image data were acquired over field plots of canola, pea, and wheat crops seeded with two weed species (redroot pigweed, wild oat) in southern Alberta, Canada. The very high spatial and spectral resolution image data required development of a simple yet efficient vegetation index (Modified Chlorophyll Absorption in Reflectance Index (MCARI)) threshold segmentation to separate vegetation from soil for classification. The HS-ANN consistently outperformed MLC in both single date and multi-temporal classifications. Higher class accuracies were obtained with multi-temporally trained ANNS (84 to 92 percent overall), with improvements up to 31 percent over MLC. With advancements in imaging technology and computer processing speed, this HS-ANN method may constitute a viable farm option for real-time detection and mapping of weed species for SSHM in agriculture. [ABSTRACT FROM AUTHOR]

Flea beetles ( Phyllotreta striolata (Fabricius), Phyllotreta cruciferae (Goeze) and Psylliodes punctulata Melsheimer) (Coleoptera: Chrysomelidae) are chronic threats to canola seedling establishment throughout the Northern Great Plains of North America. We conducted field studies in AB, Canada, from 2001 to 2004 at Lethbridge, Lacombe and Beaverlodge in the southern, central and northern regions of the province, respectively, to assess the impacts of seeding date (fall, April, May), and canola species ( Brassica rapa L., Brassica napus L.) on flea beetle damage to canola. Flea beetle damage was generally low at Lacombe but reached economic threshold levels at other sites. Although our results were not consistent in all years, seeding date had opposite effects on flea beetle damage to canola seedlings at the southern and northern sites. In the south, both canola species planted in April escaped flea beetle damage unlike the May-seeded plots, which required insecticide spraying in 2003. The numbers of flea beetles on sticky cards sampled during the seedling stage of canola were also lower in early-planted plots than in those planted in May. In the north, flea beetle damage was lower in the May-planted plots compared with those planted earlier. To maximize yields, canola growers need to plant as early as possible in all agro-ecoregions; our study showed that crops in the central and northern regions will be at greater risk of flea beetle damage than in southern regions. [ABSTRACT FROM AUTHOR]

Pitfall traps were used to monitor populations of ground beetles (Coleoptera: Carabidae) in plots of corn grown in continuous cultivation during a 4-yr period (2000-2003). Treatments included transgenic corn expressing a Bt Cry protein with efficacy specific against Lepidoptera (Bt), conventional corn grown with insecticide application (I), and the same conventional cultivar grown without insecticide application (NI). Mixed-model analyses of variance were performed on pitfall captures of beetles combined across weeks to give seasonal sums. Effects of corn treatment were not detected (P>0.05) on total beetle abundance or species richness in any year. Effects of corn treatment on individual taxa were detected (P < 0.05) for 3 of the 39 species-by-year combinations examined. Effects of near significance (P < 0.08) were detected for an additional two species. In 2001, captures ofAmarafarcta Leconte and Harpalus amputatus Say were lower in Bt plots than in I or NI plots. In 2003, captures of Amara apricaria (Paykull) and Amara carinata (Leconte) were higher in Bt plots than in I or NI plots. Also in 2003, captures of Poecilus scitulus Leconte were higher in I plots than in Bt or NI plots. These patterns were not repeated among years. Results of this study indicate that cultivation of Lepidoptera-specific Bt corn in southern Alberta does not appreciably affect ground beetle populations. [ABSTRACT FROM AUTHOR]

The vegetative growth response of Erodium cicutarium (L.) L'Her. ex Ait. to various day:night temperature regimes was studied under controlled environment conditions. Dry matter production was greatest with day temperatures of 18 to 34°C combined with night temperatures of 12 to 18°C. A high night temperature of 24°C was very detrimental, reducing dry matter production to 15 to 25% of that attained at 12°C. The optimum mean daily temperature for growth of E, cicutarium is predicted to be in the range 17 to 20°C. Little growth is predicted at mean daily temperatures below 5°C and above 30°C. Partitioning of biomass in leaves, stems and roots was markedly affected by day and night temperatures. Stem weight ratio was greatest at day temperatures of 18 to 34°C and night temperatures of 18 to 24°C. Maximum leaf weight ratio occurred at day and night temperatures of 10 to 18°C. Root biomass was little affected by day temperatures, but was greatest at a night temperature of 12°C, declining substantially as night temperature increased from 12 to 24°C. Results are discussed in terms of the potential for E. cicutarium to become an increasingly troublesome weed in crops of the Canadian prairies and in terms of possible management strategies for its control. [ABSTRACT FROM AUTHOR]

Copyright of Weed Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil surface cover (crop residue and fall-seeded cover crops) during the nongrowing season is an important tenet of sustainable agriculture, reducing wind and water erosion risk and enhancing soil water conservation. Expansion of irrigated row crop production, namely, potato (Solanum tuberosum L.), dry bean (Phaseolus vulgaris L.), and sugar beet (Beta vulgaris L.), in southern Alberta in the late 1990s prompted a 12-year (2000 to 2011) study to evaluate rotations and soil management systems for improved soil quality. The study compared conservation (CONS) and conventional (CONV) management systems in three- to six-year rotations. Conservation management included cover crops; reduced tillage; feedlot manure compost addition; and solid-seeded, narrow-row dry bean production. Beginning in the third year of the study (2002), surface residue cover was estimated each spring prior to tillage or seeding. Averaged over 10 years (2002 to 2011), residue cover was significantly higher on CONS (15.6%) versus CONV (7.1%) management. Cover was significantly higher where wheat (Triticum aestivum L.) was the previous crop (33.7%) compared to narrow-row dry bean (9.7%), which was significantly higher than potato and sugar beet (6.5% to 6.7%), which were in turn significantly higher than wide-row bean (3.6%). Inclusion of a fall rye (Secale cereale L.) cover crop after potato or dry bean increased residue cover close to or more than 30%, the threshold required to reduce wind erosion risk. Long-term replacement of cereals with lower residue-producing crops (e.g., potato, dry bean, and sugar beet) on irrigated rotations in southern Alberta should be considered judiciously in light of potential negative effects on surface residue cover. [ABSTRACT FROM AUTHOR]

Cover crops grown on summer fallow in semiarid environments can be used to provide soil erosion protection and enhance soil nutrients. The economic benefits and costs of fallow cover crop systems were evaluated using fall and spring rye (Secale cereale L.) cover crops with minimum and zero tillage, and using sweet clover (Melilotus officinalis (L.) Lam.) established in companion crops of field peas (Pisum sativum L.), mustard (Brassica juncea (L.) Coss.), or flax (Linum usitatissimum L.) and terminated in the fallow year by four methods. Spring wheat (Triticum aestivum L.) followed the fallow or partial fallow year. The fall rye?minimum tillage system had average returns similar to the no cover?zero tillage, and lower but not significantly different returns from the no cover?minimum tillage system. The lower companion crop yields in which sweet clover was underseeded, reduced the economic benefit of the sweet clover cover crop. Mustard was the most profitable companion crop. Harvesting the sweet clover as hay increased net returns over soil incorporation. For the sweet clover system to be competitive with conventional fallow, reducing the negative effect of sweet clover on companion crop yield is required. [ABSTRACT FROM AUTHOR]