Risks of gene flow from transgenic herbicide-resistant canola (Brassica napus) to weedy relatives in southern Australian cropping systems

1999 ◽  
Vol 50 (2) ◽  
pp. 115 ◽  
Author(s):  
Mary A. Rieger ◽  
Chris Preston ◽  
Stephen B. Powles
Keyword(s):  
Gene Flow ◽  
Cropping Systems ◽  
Cropping System ◽  
Experimental Information ◽  
Raphanus Raphanistrum ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Glufosinate Ammonium ◽  
Transgenic Canola ◽  
Genes Encoding

It is likely that transgenic canola expressing genes encoding resistance to glyphosate and glufosinate ammonium will be introduced into the Australian cropping system in the next few years. One risk associated with the introduction of such cultivars is the release of herbicide resistance genes into weedy relatives of canola. This review examines the currently available experimental information regarding the possibility of gene flow from canola to weedy relatives. Three species are identified as having the potential to outcross with canola, Brassica juncea, B. rapa, and Raphanus raphanistrum. Two of these species are not yet widespread weeds of the southern Australian cropping zone. In contrast, R. raphanistrum is already a major weed in Australia with existing resistance to ALS-inhibiting herbicides. Information is urgently needed to determine whether successful hybrids between B. napus and R. raphanistrum can be produced under Australian conditions. Major deficiencies in the existing information are identified in relation to some other important weed species within the southern Australian cropping zone. Further studies are required to determine the out-crossing potential of canola to B. tournefortii, Diplotaxis tenuifolia, Sisymbrium officinale, and S. orientale if transgenic canola is to be safely and responsibly introduced into Australia.

scholarly journals A decade of herbicide-resistant crops in Canada

2006 ◽  
Vol 86 (4) ◽  
pp. 1243-1264 ◽  
Author(s):  
H. J. Beckie ◽  
K. N. Harker ◽  
L. M. Hall ◽  
S. I. Warwick ◽  
A. Légère ◽  
...  
Keyword(s):  
Gene Flow ◽  
Weed Management ◽  
Selection Pressure ◽  
Cropping System ◽  
Fundamental Principle ◽  
Transgenic Crop ◽  
Economic Returns ◽  
Weed Species ◽  
Eastern Canada ◽  
Herbicide Resistant

This review examines some agronomic, economic, and environmental impacts of herbicide-resistant (HR) canola, soybean, corn, and wheat in Canada after 10 yr of growing HR cultivars. The rapid adoption of HR canola and soybean suggests a net economic benefit to farmers. HR crops often have improved weed management, greater yields or economic returns, and similar or reduced environmental impact compared with their non-HR crop counterparts. There are no marked changes in volunteer weed problems associated with these crops, except in zero-tillage systems when glyphosate is used alone to control canola volunteers. Although gene flow from glyphosate-HR canola to wild populations of bird’s rape (Brassica rapa L.) in eastern Canada has been measured, enrichment of hybrid plants in such populations should only occur when and where herbicide selection pressure is applied. Weed shifts as a consequence of HR canola have been documented, but a reduction in weed species diversity has not been demonstrated. However, reliance on HR crops in rotations using the same mode-of-action herbicide and/or multiple in-crop herbicide applications over time can result in intense selection pressure for weed resistance and consequently, greater herbicide use in the future to control HR weed biotypes. History has repeatedly shown that cropping system diversity is the pillar of sustainable agriculture; stewardship of HR crops must adhere to this fundamental principle. Key words: Canola, Brassica napus, corn, Zea mays, soybean, Glycine max, wheat, Triticum aestivum, gene flow, herbicide resistance, transgenic crop, volunteer crop

scholarly journals Weeds Hosting the Soybean Cyst Nematode (Heterodera glycines Ichinohe): Management Implications in Agroecological Systems

Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 146
Author(s):  
Leonardo F. Rocha ◽  
Karla L. Gage ◽  
Mirian F. Pimentel ◽  
Jason P. Bond ◽  
Ahmad M. Fakhoury
Keyword(s):  
Weed Management ◽  
Soybean Cyst Nematode ◽  
Heterodera Glycines ◽  
Integrated Management ◽  
Cropping System ◽  
Cyst Nematode ◽  
Weed Species ◽  
Initial Inoculum ◽  
Herbicide Resistant ◽  
Sites Of Action

The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is a major soybean-yield-limiting soil-borne pathogen, especially in the Midwestern US. Weed management is recommended for SCN integrated management, since some weed species have been reported to be hosts for SCN. The increase in the occurrence of resistance to herbicides complicates weed management and may further direct ecological–evolutionary (eco–evo) feedbacks in plant–pathogen complexes, including interactions between host plants and SCN. In this review, we summarize weed species reported to be hosts of SCN in the US and outline potential weed–SCN management interactions. Plants from 23 families have been reported to host SCN, with Fabaceae including most host species. Out of 116 weeds hosts, 14 species have known herbicide-resistant biotypes to 8 herbicide sites of action. Factors influencing the ability of weeds to host SCN are environmental and edaphic conditions, SCN initial inoculum, weed population levels, and variations in susceptibility of weed biotypes to SCN within a population. The association of SCN on weeds with relatively little fitness cost incurred by the latter may decrease the competitive ability of the crop and increase weed reproduction when SCN is present, feeding back into the probability of selecting for herbicide-resistant weed biotypes. Therefore, proper management of weed hosts of SCN should be a focus of integrated pest management (IPM) strategies to prevent further eco–evo feedbacks in the cropping system.

Transfer of resistance alleles from herbicide-resistant to susceptible grass weeds via pollen-mediated gene flow

2021 ◽  
pp. 1-51
Author(s):  
Amit J. Jhala ◽  
Hugh J. Beckie ◽  
Carol Mallory-Smith ◽  
Marie Jasieniuk ◽  
Roberto Busi ◽  
...  
Keyword(s):  
Gene Flow ◽  
Herbicide Resistance ◽  
Creeping Bentgrass ◽  
Agricultural Landscapes ◽  
Italian Ryegrass ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Wild Oats ◽  
Rigid Ryegrass ◽  
Grass Weed

Abstract The objective of this paper was to review the reproductive biology, herbicide-resistant (HR) biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from HR to susceptible grass weeds including barnyardgrass, creeping bentgrass, Italian ryegrass, johnsongrass, rigid (annual) ryegrass, and wild oats. The widespread occurrence of HR grass weeds is at least partly due to PMGF, particularly in obligate outcrossing species such as rigid ryegrass. Creeping bentgrass, a wind-pollinated turfgrass species, can efficiently disseminate herbicide resistance alleles via PMGF and movement of seeds and stolons. The genus Agrostis contains about 200 species, many of which are sexually compatible and produce naturally occurring hybrids as well as producing hybrids with species in the genus Polypogon. The self-incompatibility, extremely high outcrossing rate, and wind pollination in Italian ryegrass clearly point to PMGF as a major mechanism by which herbicide resistance alleles can spread across agricultural landscapes, resulting in abundant genetic variation within populations and low genetic differentiation among populations. Italian ryegrass can readily hybridize with perennial ryegrass and rigid ryegrass due to their similarity in chromosome numbers (2n=14), resulting in interspecific gene exchange. Johnsongrass, barnyardgrass, and wild oats are self-pollinated species, so the potential for PMGF is relatively low and limited to short distances; however, seeds can easily shatter upon maturity before crop harvest, leading to wider dispersal. The occurrence of PMGF in reviewed grass weed species, even at a low rate is greater than that of spontaneous mutations conferring herbicide resistance in weeds and thus can contribute to the spread of herbicide resistance alleles. This review indicates that the transfer of herbicide resistance alleles occurs under field conditions at varying levels depending on the grass weed species.

scholarly journals Assessing weeds at risk of evolving glyphosate resistance in Australian sub-tropical glyphosate-resistant cotton systems

2011 ◽  
Vol 62 (11) ◽  
pp. 1002 ◽  
Author(s):  
Jeff Werth ◽  
David Thornby ◽  
Steve Walker
Keyword(s):  
High Risk ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Cropping System ◽  
Glyphosate Resistance ◽  
Management Approach ◽  
Weed Species ◽  
Summer Fallow ◽  
Very High

Glyphosate resistance will have a major impact on current cropping practices in glyphosate-resistant cotton systems. A framework for a risk assessment for weed species and management practices used in cropping systems with glyphosate-resistant cotton will aid decision making for resistance management. We developed this framework and then assessed the biological characteristics of 65 species and management practices from 50 cotton growers. This enabled us to predict the species most likely to evolve resistance, and the situations in which resistance is most likely to occur. Species with the highest resistance risk were Brachiaria eruciformis, Conyza bonariensis, Urochloa panicoides, Chloris virgata, Sonchus oleraceus and Echinochloa colona. The summer fallow and non-irrigated glyphosate-resistant cotton were the highest risk phases in the cropping system. When weed species and management practices were combined, C. bonariensis in summer fallow and other winter crops were at very high risk. S. oleraceus had very high risk in summer and winter fallow, as did C. virgata and E. colona in summer fallow. This study enables growers to identify potential resistance risks in the species present and management practices used on their farm, which will to facilitate a more targeted weed management approach to prevent development of glyphosate resistance.

Multiple herbicide-resistant wild radish (Raphanus raphanistrum) populations dominate Western Australian cropping fields

2015 ◽  
Vol 66 (10) ◽  
pp. 1079 ◽  
Author(s):  
Mechelle J. Owen ◽  
Neree J. Martinez ◽  
Stephen B. Powles
Keyword(s):  
Weed Management ◽  
Cropping Systems ◽  
Acetolactate Synthase ◽  
Raphanus Raphanistrum ◽  
Management Options ◽  
Herbicide Resistant ◽  
Wide Range ◽  
Random Survey ◽  
Imidazolinone Herbicides ◽  
Western Australian

Raphanus raphanistrum is a problematic weed, which has become increasingly difficult to control in Australian cropping regions. In 2010, a random survey was conducted across 14 million ha of the Western Australian grain belt to establish the frequency of herbicide resistance in R. raphanistrum and to monitor the change in resistance levels by comparing results with a previous survey in 2003. Screening R. raphanistrum populations with herbicides commonly used to control this weed revealed that most populations (84%) contained individual plants resistant to the acetolactate synthase-inhibiting herbicide chlorsulfuron, whereas 49% of populations also had plants resistant to the imidazolinone herbicides. Resistance to other mode of action herbicides (2,4-D (76%) and diflufenican (49%)) was also common. Glyphosate, atrazine and pyrasulfotole + bromoxynil remained effective on most R. raphanistrum populations. These results demonstrate that resistance to some herbicides has increased significantly since 2003 when the values were 54% for chlorsulfuron and 60% for 2,4-D; therefore, a wide range of weed management options that target all phases of the cropping program are needed to sustain these cropping systems in the future.

scholarly journals Intercropping maize and succession crops alters the weed community in common bean under no-tillage

2020 ◽  
Vol 50 ◽  
Author(s):  
Victor D'Amico-Damião ◽  
Arthur Arrobas Martins Barroso ◽  
Pedro Luis da Costa Aguiar Alves ◽  
Leandro Borges Lemos
Keyword(s):  
Common Bean ◽  
Pearl Millet ◽  
Crop Rotation ◽  
Cropping Systems ◽  
Cropping System ◽  
Weed Species ◽  
Calculated Density ◽  
Commelina Benghalensis ◽  
The Common ◽  
Selection Of

ABSTRACT Crop rotation is critical in the management of herbicide-resistant weed species. This study aimed to evaluate the effect of intercropping systems of maize with brachiaria or crotalaria on qualitative and quantitative parameters of the weed seedbank, along the succession of pearl millet, maize and common bean. Moreover, the effect of these crop rotation systems on the selection of specific weed species of the seedbank was also evaluated. The experimental design was randomized blocks, with four replications. The treatments were represented by three cropping systems in succession: pearl millet, single maize, common bean; pearl millet, maize intercropped with brachiaria, common bean; pearl millet, maize intercropped with crotalaria, common bean. The following phytosociological indexes were calculated: density, frequency and relative importance, diversity and equitability. The grain yield of maize and common bean were also quantified. Twenty-three weed species were identified, divided into 12 families, highlighting the Poaceae one, with the most important being Alternanthera tenella, Commelina benghalensis, Eleusine indica and Phyllanthus tenellus. The cropping system with single maize presented a lower density and diversity of weeds, but with a high selection of E. indica. The intercropping systems in the previous crop, as a guarantee of a higher weed diversity, could be use as alternative tools, different from the herbicides, to control weeds and improve the common bean yield. Regarding the weed control in the common bean, Crotalaria spectabilis presented better results in the previous maize-intercropping system than Urochloa ruziziensis.

Risk Assessment of Weed Resistance in the Canadian Prairies

2008 ◽  
Vol 22 (4) ◽  
pp. 741-746 ◽  
Author(s):  
Hugh J. Beckie ◽  
Julia Y. Leeson ◽  
A. Gordon Thomas ◽  
Linda M. Hall ◽  
Clark A. Brenzil
Keyword(s):  
Management Practices ◽  
Cropping System ◽  
Acetolactate Synthase ◽  
Soil Disturbance ◽  
Weed Species ◽  
Forage Crops ◽  
Canadian Prairies ◽  
Herbicide Resistant ◽  
Herbicide Use ◽  
Weed Resistance

Agricultural practices, other than herbicide use, can affect the rate of evolution of herbicide resistance in weeds. This study examined associations of farm management practices with the occurrence of herbicide (acetyl-CoA carboxylase or acetolactate synthase inhibitor)-resistant weeds, based upon a multi-year (2001 to 2003) random survey of 370 fields/growers from the Canadian Prairies. Herbicide-resistant weeds occurred in one-quarter of the surveyed fields. The primary herbicide-resistant weed species was wild oat, with lesser occurrence of green foxtail, kochia, common chickweed, spiny sowthistle, and redroot pigweed. The risk of weed resistance was greatest in fields with cereal-based rotations and least in fields with forage crops, fallow, or where three or more crop types were grown. Weed resistance risk also was greatest in conservation-tillage systems and particularly low soil disturbance no-tillage, possibly due to greater herbicide use or weed seed bank turnover. Large farms (> 400 ha) had a greater risk of weed resistance than smaller farms, although the reason for this association was unclear. The results of this study identify cropping system diversity as the foundation of proactive weed resistance management.

scholarly journals Emerging Challenges for Weed Management in Herbicide-Resistant Crops

Agriculture ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 180 ◽  
Author(s):  
Karla L. Gage ◽  
Ronald F. Krausz ◽  
S. Alan Walters
Keyword(s):  
Weed Management ◽  
Selection Pressure ◽  
New Technologies ◽  
Cropping Systems ◽  
Critical Role ◽  
Cropping System ◽  
Herbicide Resistant ◽  
Increased Risk ◽  
Sites Of Action ◽  
Weed Resistance

Since weed management is such a critical component of agronomic crop production systems, herbicides are widely used to provide weed control to ensure that yields are maximized. In the last few years, herbicide-resistant (HR) crops, particularly those that are glyphosate-resistant, and more recently, those with dicamba (3,6-dichloro-2-methoxybenzoic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) resistance are changing the way many growers manage weeds. However, past reliance on glyphosate and mistakes made in stewardship of the glyphosate-resistant cropping system have directly led to the current weed resistance problems that now occur in many agronomic cropping systems, and new technologies must be well-stewarded. New herbicide-resistant trait technologies in soybean, such as dicamba-, 2,4-D-, and isoxaflutole- ((5-cyclopropyl-4-isoxazolyl)[2-(methylsulfonyl)-4-(trifluoromethyl)phenyl]methanone) resistance, are being combined with glyphosate- and glufosinate-resistance traits to manage herbicide-resistant weed populations. In cropping systems with glyphosate-resistant weed species, these new trait options may provide effective weed management tools, although there may be increased risk of off-target movement and susceptible plant damage with the use of some of these technologies. The use of diverse weed management practices to reduce the selection pressure for herbicide-resistant weed evolution is essential to preserve the utility of new traits. The use of herbicides with differing sites of action (SOAs), ideally in combination as mixtures, but also in rotation as part of a weed management program may slow the evolution of resistance in some cases. Increased selection pressure from the effects of some herbicide mixtures may lead to more cases of metabolic herbicide resistance. The most effective long-term approach for weed resistance management is the use of Integrated Weed Management (IWM) which may build the ecological complexity of the cropping system. Given the challenges in management of herbicide-resistant weeds, IWM will likely play a critical role in enhancing future food security for a growing global population.

scholarly journals Is Pasture Cropping a Valid Weed Management Tool?

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 135
Author(s):  
Ignacio M. Luna ◽  
César Fernández-Quintanilla ◽  
José Dorado
Keyword(s):  
Weed Management ◽  
Cropping Systems ◽  
Cropping System ◽  
Climatic Conditions ◽  
Winter Barley ◽  
Economic Feasibility ◽  
Management Tool ◽  
Severe Drought ◽  
Weed Species ◽  
Central Spain

The aim of the present work was to study the feasibility of pasture cropping under the Mediterranean conditions prevailing in central Spain and its potential as a weed management tool. Three cropping systems were assessed: conventionally grown winter barley and winter barley in pasture cropping with two perennial summer species, Cynodon dactylon and Eragrostis curvula. The results showed that the growth of these two species in a pasture cropping system was limited by the severe drought conditions and high temperatures present during the summer in some of the study years. Although there were no differences in the establishment of winter barley in any of the treatments assessed, pasture cropping reduced winter barley yields up to 50%–60% in years with low rainfall in spring. Regarding weed control, pasture cropping showed a significant suppression of the total weed density and number of weed species. As a conclusion, pasture cropping can be considered as a valid weed management tool. However, the economic feasibility of this system under the climatic conditions of central Spain (characterized by a high risk of severe summer droughts) is still not clear. The availability of supplemental irrigation may reduce competition between pastures and winter crops and ensure a profitable production of summer pastures.

The effects of soil tillage techniques on weed flora in high input barley systems in northern Spain

2020 ◽  
Vol 100 (3) ◽  
pp. 245-252
Author(s):  
M.I. Santín-Montanyá ◽  
A. Sombrero Sacristán
Keyword(s):  
Cropping Systems ◽  
Light Availability ◽  
Cropping System ◽  
Weather Conditions ◽  
Soil Tillage ◽  
Species Number ◽  
Weed Species ◽  
Northern Spain ◽  
Bromus Diandrus ◽  
Weed Density

In barley cropping systems of northern Spain, agronomic practices and weather conditions are key components of weed control efficacy. We compared the short-term effects of conventional tillage with minimum tillage (MT) and zero tillage (ZT), in barley monoculture and barley rotation systems. Weed density and weed species number were measured at tillering and flowering barley stages. We found that tillage system can influence weed density and weed species establishment due to, in part, the available light for weed seeds. The results obtained indicate that the MT system facilitates the prevalence of the grass weed Bromus diandrus Roth (50.37%) and the annual dicots Galium aparine (L.) and Buglossoides arvensis (L.) I.M. Johnst. abundant were high in the MT system too, 43.71% and 43.97% respectively. The germination of these species showed a high dependence on light availability. We saw that barley-monoculture plots had a large infestation of Bromus (71.29%) and barley-rotated plots presented more infestation of Galium and Buglossoides (74.36% and 84.4%, respectively). After herbicide application, weed infestation in conservation systems was reduced in barley-rotated plots compared with barley-monoculture. If conservation systems avoided the presence of dominant weeds, the weight of each weed species was balanced within competitive relationships of the cropping systems. Our results confirmed that MT and ZT systems favour different weed species emergences in barley-rotated plots. The combination of MT and barley-rotated cropping system resulted in greater weed diversity and lower total weed density.

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