Integrated Weed Management: The Rationale and Approach

A growing awareness of environmental issues in Canada has had a major influence on government policies. An initiative was launched by the government of Ontario to promote research toward the development of an integrated weed management (IWM) system. Research in IWM must take all aspects of the cropping system into consideration and evolve in a progressive manner. This approach must encompass the role of conservation tillage, knowledge of the critical period of weed interference, alternative methods of weed control, enhancement of crop competitiveness, modeling of crop-weed interference, influence of crop rotation and seed bank dynamics, and education and extension of the findings. The complexity involved in addressing these issues requires a multi-disciplinary approach.

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Key Aspects on the Biology, Ecology and Impacts of Johnsongrass [Sorghum halepense (L.) Pers] and the Role of Glyphosate and Non-Chemical Alternative Practices for the Management of This Weed in Europe

Agronomy ◽

10.3390/agronomy9110717 ◽

2019 ◽

Vol 9 (11) ◽

pp. 717 ◽

Cited By ~ 1

Author(s):

Travlos ◽

Montull ◽

Kukorelli ◽

Malidza ◽

Dogan ◽

...

Keyword(s):

Weed Management ◽

Control Plant ◽

Field Trials ◽

European Countries ◽

Alternative Methods ◽

Sorghum Halepense ◽

Current Status ◽

Integrated Weed Management ◽

Alternative Practices

Sorghum halepense (L.) Pers is a common and noxious worldwide weed of increasing distribution in many European countries. In the present review, information on the biology, ecology, agricultural, economic and environmental impact of johnsongrass is given, and the current status of this weed in Europe is discussed. Furthermore, special attention is given to the important role of field trials using glyphosate to control weeds in arable and perennial crops in many European countries. Some of the factors which affect control efficacy and should be taken into account are also discussed. Finally, several non-chemical alternative methods (cultural, mechanical, thermal, biological, etc.) for johnsongrass management are also presented. The adoption of integrated weed management (IWM) techniques such as glyphosate use, crop rotation, and deep tillage is strongly recommended to control plant species that originate from both seed and rhizomes.

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Role of Edamame (Glycine max) Seed Size in Early-Season Crop–Weed Interactions

Weed Science ◽

10.1017/wsc.2018.46 ◽

2018 ◽

Vol 66 (6) ◽

pp. 746-751 ◽

Cited By ~ 1

Author(s):

Laura E. Crawford ◽

Martin M. Williams

Keyword(s):

Glycine Max ◽

Seed Size ◽

Weed Management ◽

Soybean Seed ◽

Integrated Weed Management ◽

Early Season ◽

Weed Interference ◽

Large Seed ◽

Weed Emergence

AbstractEdamame [Glycine max(L.) Merr.] differs from grain-type soybean in several aspects, one being that edamame seeds are 65% to 100% larger than grain-type soybean seed. Crop seed size has implications for weed management in grain-type soybean; however, the extent to which this observation holds true for edamame is unknown. Because weed interference continues to be a barrier to domestic edamame production, the objective was to quantify the effect of edamame seed size on the crop’s ability to tolerate weed interference (CT) and the crop’s ability to suppress weeds (WSA). Five edamame cultivars plus one grain-type cultivar were each sorted to create “small” and “large” seed size classes. Seed lots were included in a split–split plot design, whereby an additional experimental factor was presence or absence of velvetleaf (Abutilon theophrastiMedik.). Crop and weed emergence and growth were monitored through 8 wk after emergence (WAE). Crop plants from large seed had higher tolerance toA. theophrastithan plants from small seed, as evidenced by crop height, area, and biomass. Edamame seed size had little effect on WSA; however, crop cultivars differentially reducedA. theophrastileaf area and biomass at 4 and 8 WAE. While both seed size and edamame cultivar influence early-season crop competitive ability, the magnitude of these factors on CT and WSA underscores the importance of considering them not as stand-alone tactics but rather as useful additions to a more comprehensive integrated weed management system.

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An Integrated Weed Management Approach to Managing Foxtail Barley (Hordeum jubatum) in Conservation Tillage Systems

Weed Technology ◽

10.1017/s0890037x00041841 ◽

1999 ◽

Vol 13 (2) ◽

pp. 347-353 ◽

Cited By ~ 19

Author(s):

Robert E. Blackshaw ◽

Greg Semach ◽

Xiangju Li ◽

John T. O'Donovan ◽

K. Neil Harker

Keyword(s):

Crop Yield ◽

Weed Management ◽

Conservation Tillage ◽

Wheat Yield ◽

Integrated Weed Management ◽

Management Approach ◽

Row Spacing ◽

Seeding Rate ◽

Tillage Systems ◽

Perennial Plants

A 4-yr field experiment was conducted to determine the merits of combining cultural and chemical controls to manage foxtail barley in reduced-tillage systems. Factors studied were crop row spacing, seeding rate, and application rate and timing of glyphosate within a spring wheat-flax cropping sequence. Glyphosate applied preseeding at 400 or 800 g/ha killed foxtail barley seedlings but only suppressed established perennial plants. Glyphosate applied postharvest at 800 g/ha killed 60 to 70% of established plants. Combinations of preseeding and postharvest glyphosate gave the greatest reductions in foxtail barley biomass and seed production and resulted in the greatest increases in crop yield. Including flax in the rotation allowed use of grass herbicides such as quizalofop or sethoxydim that effectively controlled foxtail barley seedlings and provided some suppression of perennial plants. An increase in wheat seeding rate from 75 to 115 kg/ha reduced foxtail barley growth and increased wheat yield in 3 of 4 yr. Increasing the flax seeding rate from 40 to 80 kg/ha or reducing wheat and flax row spacing from 30 to 20 cm provided little benefit in managing foxtail barley or increasing crop yield. A multiyear approach combining agronomic practices and timely use of herbicides should allow growers to effectively manage foxtail barley in annual cropping systems using conservation tillage.

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Seeding rate and row spacing affect flax yields and weed interference

Canadian Journal of Plant Science ◽

10.4141/cjps96-098 ◽

1996 ◽

Vol 76 (3) ◽

pp. 537-544 ◽

Cited By ~ 16

Author(s):

F. C. Stevenson ◽

A. T. Wright

Keyword(s):

Seed Yield ◽

Weed Management ◽

Management Practices ◽

The Other ◽

Integrated Weed Management ◽

Row Spacing ◽

Flax Seed ◽

Seeding Rate ◽

Weed Interference ◽

Interference Study

Seeding rate and row spacing are management practices that affect flax seed yield. Two experiments were conducted from 1988 to 1990 to determine the influence of flax seeding rates (300, 600, and 900 seeds m−2) and row spacings (9, 18, and 27 cm). One was a flax-weed interference study (three sites) and the other was a weed-free study (13 sites). In the presence of weeds, increasing seeding rate from 300 to 900 seeds m−2 improved flax seed yield by 180 kg ha−1, and reduced broadleaf weed yields by 300 kg ha−1 and grassy weed yields by 180 kg ha−1. In weed-free conditions, seed yield was not affected by seeding rate. Row spacing did not affect flax yield and had minor effects on weed yields when weeds were not controlled. When weeds were controlled, seed yield in the 9-cm row spacing was 9% (15% in the flax-weed interference study) greater than in the two wider row spacings. Seeding rate and row spacing independently influenced flax yield, and their effect was consistent among sites with weeds present, but was not consistent when weeds were controlled. Our results showed that flax seeding rate was an important component of integrated weed management. Key words: Flax, seeding rate, row spacing, weed interference

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Response of Barley Genotypes to Weed Interference in Australia

Agronomy ◽

10.3390/agronomy10010099 ◽

2020 ◽

Vol 10 (1) ◽

pp. 99 ◽

Cited By ~ 2

Author(s):

Gulshan Mahajan ◽

Lee Hickey ◽

Bhagirath Singh Chauhan

Keyword(s):

Negative Correlation ◽

Weed Management ◽

Field Experiments ◽

Yield Loss ◽

Production Systems ◽

Relative Yield ◽

Organic Production ◽

Integrated Weed Management ◽

Weed Interference ◽

Barley Genotypes

Weed-competitive genotypes could be an important tool in integrated weed management (IWM) practices. However, weed competitiveness is often not considered a priority for breeding high-yielding cultivars. Weed-competitive ability is often evaluated based on weed-suppressive ability (WSA) and weed-tolerance ability (WTA) parameters; however, there is little information on these aspects for barley genotypes in Australia. In this study, the effects of weed interference on eight barley genotypes were assessed. Two years of field experiments were performed in a split-plot design with three replications. Yield loss due to weed interference ranged from 43% to 78%. The weed yield amongst genotypes varied from 0.5 to 1.7 Mg ha−1. Relative yield loss due to weed interference was negatively correlated with WTA and WSA. A negative correlation was also found between WSA and weed seed production (r = −0.72). Similarly, a negative correlation was found between WTA and barley yield in the weedy environment (r = −0.91). The results suggest that a high tillering ability and plant height are desirable attributes for weed competitiveness in the barley genotypes. These results also demonstrated that among the eight barley genotypes, Commander exhibited superior WSA and WTA parameters and therefore, could be used in both low- and high-production systems for weed management. Westminster had a superior WSA parameter. Therefore, it could be used for weed management in organic production systems. These results also implied that genotypic ranking on the basis of WSA and WTA could be used as an important tool in strengthening IWM programs for barley.

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A “Stressed” Alfalfa-Based Cropping System Leads to the Selection of Quizalofop-Resistant Italian Ryegrass (Lolium perennessp.multiflorum)

Weed Science ◽

10.1614/ws-d-15-00193.1 ◽

2016 ◽

Vol 64 (4) ◽

pp. 683-694 ◽

Cited By ~ 1

Author(s):

Alberto Collavo ◽

Silvia Panozzo ◽

Antonio Allegri ◽

Maurizio Sattin

Keyword(s):

Ethyl Ester ◽

Seed Production ◽

Weed Management ◽

Cropping System ◽

Italian Ryegrass ◽

Integrated Weed Management ◽

Forage Production ◽

Weed Seed ◽

Quizalofop Ethyl ◽

Selection Of

Italian ryegrass populations investigated in this study were harvested in an alfalfa-based cropping system. In that system, the agronomic practices and chemical weed management, based on the use of aryloxyphenoxy-propionates herbicides (i.e., quizalofop ethyl ester), were optimized to obtain a dual seed–forage production. Five of seven populations tested were confirmed resistant to quizalofop ethyl ester with resistance indexes ranging from 4.5 to >209. Both target- and nontarget-site resistance mechanisms were most likely involved. Three allelic variants were detected (Ile-1781–Leu, Trp-2027–Cys, and Ile-2041–Asn) in four resistant populations, whereas no known mutations were found in one resistant population. The herbicide treatment on Italian ryegrass plants at different phenological stages suggested that to control regrowth, it is necessary to use two to fives times the herbicide dose suitable for younger plants. This situation is encountered in fields when Italian ryegrass plants need to be controlled to maximize the alfalfa seed production, and it is comparable to using a sublethal herbicide dose, leading to the selection of herbicide-resistant biotypes. In such a situation, the cropping system is not sustainable, and integrated weed management should be implemented to deplete the soil weed seed bank and prevent new weed seed production.

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Productivity and quality of canola and mustard cultivars under weed competition

Canadian Journal of Plant Science ◽

10.4141/cjps07152 ◽

2008 ◽

Vol 88 (2) ◽

pp. 367-372 ◽

Cited By ~ 9

Author(s):

H. J. Beckie ◽

E. N. Johnson ◽

R. E. Blackshaw ◽

Y. Gan

Keyword(s):

Brassica Juncea ◽

Seed Yield ◽

Weed Management ◽

Sinapis Alba ◽

Integrated Weed Management ◽

Weed Competition ◽

Weed Interference ◽

Canola Quality ◽

Oriental Mustard

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 Saskatchewan and Alberta to investigate the productivity and quality of canola (Brassica napusL.) and mustard cultivars under weed competition. Four open-pollinated canola cultivars, four hybrid canola cultivars, two canola-quality mustard and two oriental mustard cultivars [Brassica juncea (L.) Czern. & Coss.], and two yellow mustard (Sinapis alba L.) cultivars were grown under weedy and weed-free conditions. When combined across site-years, crop aboveground biomass at maturity and seed yield were reduced by weed interference, except for yellow and oriental mustard. However, seed oil and protein content of cultivars were not affected by weed competition. Among crop types, yellow and oriental mustard were best able to maintain biomass and seed yield under weed interference, followed in decreasing order of competitiveness by hybrid and open-pollinated canola, then canola-quality mustard. Key words: Brassica napus, Brassica juncea, Sinapis alba, weed competition

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Weed response and crop growth in winter wheat–lucerne intercropping: a comparison of conventional and reduced soil-tillage conditions in northern France

Crop and Pasture Science ◽

10.1071/cp16459 ◽

2017 ◽

Vol 68 (11) ◽

pp. 1070 ◽

Cited By ~ 4

Author(s):

E. Barilli ◽

M.-H. Jeuffroy ◽

J. Gall ◽

S. de Tourdonnet ◽

S. Médiène

Keyword(s):

Winter Wheat ◽

Weed Control ◽

Weed Management ◽

Conservation Tillage ◽

Group Analysis ◽

Soil Tillage ◽

Integrated Weed Management ◽

Living Mulch ◽

Wheat Production ◽

Weed Communities

Changing agricultural practices from conventional to conservation tillage generally leads to increased weed populations and herbicide use. To gain information about the possible use of lucerne (Medicago sativa L.) cover crop as an alternative and sustainable weed-control strategy for winter wheat (Triticum aestivum L.), an experiment was performed at Thiverval-Grignon, France, from 2008 to 2010. We compared conventional and reduced tillage as well as the presence and absence of living mulch (i.e. lucerne) on weeds and wheat production. Percentage soil coverage and aboveground biomass of wheat, lucerne and weeds were measured at the end of grain filling. Weed communities were analysed in terms of composition and diversity. During both seasons, wheat biomass did not significantly decrease in reduced-till trials compared with conventional ones (7.0 and 7.2 t ha–1, respectively, in 2008–09; 6.9 and 7.1 t ha–1 in 2009–10). Regardless of soil management, the percentage soil coverage by wheat significantly decreased when it was intercropped, although wheat biomass was not significantly reduced compared with the sole crop. To minimise cash-crop losses, we studied the competition between wheat, lucerne and weeds, testing various herbicide strategies. Early control of lucerne allowed better balance between weed control and wheat development. In addition, weed communities varied among treatments in terms of abundance and composition, being reduced but more varied in plots associated with lucerne. A functional group analysis showed that grasses benefited from reduced-till conditions, whereas problematic weeds such as annuals with creeping and climbing morphologies were substantially reduced. In addition, annual and perennial broad-leaf species with rosette morphology were also significantly decreased when lucerne was used as living mulch. Wheat production in reduced-till conditions intercropped with lucerne living mulch may be useful for integrated weed management, reducing the need for herbicides.

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Sustainability, conservation tillage and weeds in Canada

Canadian Journal of Plant Science ◽

10.4141/cjps96-115 ◽

1996 ◽

Vol 76 (4) ◽

pp. 651-659 ◽

Cited By ~ 22

Author(s):

D. A. Derksen ◽

R. E. Blackshaw ◽

S. M. Boyetchko

Keyword(s):

Biological Control ◽

Weed Management ◽

Conservation Tillage ◽

The United States ◽

Integrated Weed Management ◽

Biological Weed Control ◽

Plant Residues ◽

Tillage Systems ◽

Weed Communities ◽

Inundative Biological Control

The sustainability of conservation tillage is dependent on the extent of changes in weed community composition, the usage of herbicides, and the development of integrated weed management (IWM) strategies, including biological weed control. The objective of this paper is to review research on conservation tillage and weed management in light of these factors. Recent Canadian research has found that changes in weed communities due to the adoption of conservation tillage are not necessarily those expected and were not consistant by species, location, or year. Changes reflected the use of different selection pressures, such as different crop rotations and herbicides, within the studies to a greater extent than weed life cycle groupings. Therefore, research that determines the reasons for change or the lack of change in weed communities is required to provide the scientific basis for the development of IWM strategies. Documented herbicide usage in conservation tillage varies from less than to more than conventional-tillage systems. Potential to reduce herbicide usage in conservation-tillage systems exists. Furthermore, the herbicides used in western Canada are different from those causing ground water contamination in the United States, are less volatile, and are used at lower rates. The presence of surface crop residues in conservation tillage may provide a unique environment for classical and inundative biological control agents. Some insects, fungi, and bacteria have the potential to survive to a greater extent in undisturbed plant residues. Residue management and conservation tillage systems are evolving in Canada. Research must keep pace by providing weed management strategies that enchance the sustainability of these systems. Key words: Biological control, zero tillage, integrated weed management, residues, herbicides, rhizobacteria.

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Tillage, fertiliser and glyphosate timing effects on foxtail barley (Hordeum jubatum) management in wheat

Canadian Journal of Plant Science ◽

10.4141/p99-132 ◽

2000 ◽

Vol 80 (3) ◽

pp. 655-660 ◽

Cited By ~ 14

Author(s):

R. E. Blackshaw ◽

G. Semach ◽

X. Li ◽

J. T. O'Donovan ◽

K. N. Harker

Keyword(s):

Weed Management ◽

Production Systems ◽

Conservation Tillage ◽

Wheat Yield ◽

Soil Surface ◽

Integrated Weed Management ◽

Canadian Prairies ◽

Application Timing ◽

Hordeum Jubatum ◽

Timing Effects

Foxtail barley (Hordeum jubatum L.) is becoming a more severe weed problem as conservation tillage becomes widely adopted on the southern Canadian prairies. A 5-yr field study was conducted to determine the combined effects of tillage, N rate, N placement and application timing of glyphosate to manage foxtail barley in spring wheat. Wide-blade tillage conducted in fall and spring, compared to zero-till, reduced foxtail barley biomass and seed production in all yr and increased wheat yield in 4 of 5 yr. Foxtail barley was highly competitive with wheat for added N. N fertiliser placed mid-row in 10-cm-deep bands reduced foxtail barley growth in 2 of 5 yr and increased wheat yield in 3 of 5 yr compared with soil surface broadcast N. Wheat yield sometimes was similar when N was banded at 60 kg ha−1 or broadcast at 120 kg ha−1, indicating the large advantage of banding N in some situations. Glyphosate at 800 g ha−1 applied preharvest or postharvest gave similar levels of foxtail barley control in 2 of 3 yr. Results indicate that foxtail barley can be adequately managed in wheat production systems utilizing conservation tillage. Key words: Foxtail barley, Hordeum jubatum, glyphosate, integrated weed management, nitrogen placement, zero tillage

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