Evolved Resistance to Glyphosate in Junglerice (Echinochloa colona) from the Tropical Ord River Region in Australia

2012 ◽  
Vol 26 (3) ◽  
pp. 480-484 ◽  
Author(s):  
Todd A. Gaines ◽  
Andrew Cripps ◽  
Stephen B. Powles
Keyword(s):  
Cropping Systems ◽  
Cropping System ◽  
Acetolactate Synthase ◽  
Glyphosate Resistance ◽  
Population Based ◽  
Perennial Crop ◽  
Susceptible Population ◽  
River Region ◽  
Resistant Population ◽  
Chemical Fallow

The objective of this study was to determine whether a junglerice population from the tropical Ord River region of northwest Australia was glyphosate resistant, and whether alternative herbicides labeled for junglerice control were still effective. Seed samples collected from the field site were initially screened with glyphosate in the glasshouse, and surviving individuals were self-pollinated for subsequent glyphosate dose-response studies. Glyphosate resistance was confirmed, as the suspected resistant population was found to be 8.6-fold more resistant to glyphosate than a susceptible population based on survival (LD50of 3.72 kg ha−1), and 5.6-fold more resistant based on biomass reduction (GR50of 1.16 kg ha−1). The glyphosate-resistant population was susceptible to label-recommended doses of all other herbicides assessed, including three acetyl-CoA carboxylase (ACC) –inhibiting herbicides (fluazifop-P, haloxyfop, and sethoxydim), two acetolactate synthase (ALS) –inhibiting herbicides (imazamox and sulfometuron), paraquat, and glufosinate. Glyphosate resistance has previously evolved in numerous species found in glyphosate-resistant cropping systems, no-till chemical fallow, fence line, and perennial crop situations. Here we report the evolution of glyphosate resistance in a cropping system that included annual tillage. The evolution of glyphosate resistance in junglerice from a tropical cropping system further demonstrates the need for improved glyphosate stewardship practices globally.

Inheritance of Glyphosate Resistance in Hairy Fleabane (Conyza bonariensis) from California

Weed Science ◽  
2014 ◽  
Vol 62 (2) ◽  
pp. 258-266 ◽  
Author(s):  
Miki Okada ◽  
Marie Jasieniuk
Keyword(s):  
Resistance Mechanism ◽  
Glyphosate Resistance ◽  
Population Based ◽  
Single Individual ◽  
Resistance Level ◽  
Backcross Population ◽  
Resistant Parent ◽  
Susceptible Population ◽  
Locus Model ◽  
Hairy Fleabane

Inheritance of glyphosate resistance was investigated in hairy fleabane populations from California as part of providing the information needed to predict and manage resistance and to gain insight into resistance mechanism (or mechanisms) present in the populations. Three glyphosate-resistant individuals grown from seed collected from distinct sites near Fresno, CA, were crossed to individuals from the same susceptible population to create reciprocal F1populations. A single individual from each of the F1populations was used to create a backcross population with a susceptible maternal parent, and an F2population. Based on dose response analyses, reciprocal F1populations were not statistically different from each other, more similar to the resistant parent, and statistically different from the susceptible parent, consistent with nuclear control of the trait and dominance to incomplete dominance of resistance over susceptibility in all three crosses. Glyphosate resistance in two of the three crosses segregated in the backcross and the F2populations as a single-locus trait. In the remaining cross, the resistant parent had approximately half the resistance level as the other two resistant parents, and the segregation of glyphosate resistance in backcross and F2populations conformed to a two-locus model with resistance alleles acting additively and at least two copies of the allele required for expression of resistance. This two-locus model of the segregation of glyphosate resistance has not been reported previously. Variation in the pattern of inheritance and the level of resistance indicate that multiple resistance mechanisms may be present in hairy fleabane populations in California.

A Waterhemp (Amaranthus tuberculatus) Population Resistant to 2,4-D

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Mark L. Bernards ◽  
Roberto J. Crespo ◽  
Greg R. Kruger ◽  
Roch Gaussoin ◽  
Patrick J. Tranel
Keyword(s):  
Dose Response ◽  
Dry Weight ◽  
Population Based ◽  
Susceptible Population ◽  
Herbicide Resistant ◽  
Synthetic Auxins ◽  
Resistant Population ◽  
Amaranthus Tuberculatus ◽  
Susceptible Populations ◽  
Dose Response Study

A waterhemp population from a native-grass seed production field in Nebraska was no longer effectively controlled by 2,4-D. Seed was collected from the site, and dose-response studies were conducted to determine if this population was herbicide resistant. In the greenhouse, plants from the putative resistant and a susceptible waterhemp population were treated with 0, 18, 35, 70, 140, 280, 560, 1,120, or 2,240 g ae ha−12,4-D. Visual injury estimates (I) were made 28 d after treatment (DAT), and plants were harvested and dry weights (GR) measured. The putative resistant population was approximately 10-fold more resistant to 2,4-D (R:S ratio) than the susceptible population based on both I50(50% visual injury) and GR50(50% reduction in dry weight) values. The R:S ratio increased to 19 and 111 as the data were extrapolated to I90and GR90estimates, respectively. GR50doses of 995 g ha−1for the resistant and 109 g ha−1for the susceptible populations were estimated. A field dose-response study was conducted at the suspected resistant site with 2,4-D doses of 0, 140, 280, 560, 1,120, 2,240, 4,480, 8,960, 17,920, and 35,840 g ha−1. At 28 DAT, visual injury estimates were 44% in plots treated with 35,840 g ha−1. Some plants treated with the highest rate recovered and produced seed. Plants from the resistant and susceptible populations were also treated with 0, 9, 18, 35, 70, 140, 280, 560, or 1,120 g ae ha−1dicamba in greenhouse bioassays. The 2,4-D resistant population was threefold less sensitive to dicamba based on I50estimates but less than twofold less sensitive based on GR50estimates. The synthetic auxins are the sixth mechanism-of-action herbicide group to which waterhemp has evolved resistance.

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.

Confirmation and Resistance Mechanisms in Glyphosate-Resistant Common Ragweed (Ambrosia artemisiifolia) in Arkansas

Weed Science ◽  
2009 ◽  
Vol 57 (6) ◽  
pp. 567-573 ◽  
Author(s):  
Chad E. Brewer ◽  
Lawrence R. Oliver
Keyword(s):  
Resistance Mechanism ◽  
Population Data ◽  
Glyphosate Resistance ◽  
Population Based ◽  
Resistance Mechanisms ◽  
Ambrosia Artemisiifolia ◽  
Target Site ◽  
Susceptible Population ◽  
Common Ragweed

Greenhouse studies were established in Fayetteville, AR, to investigate glyphosate resistance in Arkansas common ragweed populations. Common ragweed seed were collected from plants in Pope and Jackson counties in Arkansas. Plants grown from seed were sprayed with one of seven glyphosate rates. Populations in Pope and Jackson counties were 21-fold and 10-fold more tolerant to glyphosate, respectively, than a known susceptible population. Based on14C-glyphosate absorption and translocation studies, reduced glyphosate absorption or translocation was not the resistance mechanism in Arkansas glyphosate-resistant common ragweed. Shikimate accumulation did not differ among the known susceptible and the two resistant populations at 3 d after treatment (DAT). However, by 5 DAT, shikimate accumulation in the two resistant populations was lower than the known susceptible population. Data indicate that glyphosate-resistant common ragweed is present in at least two locations in Arkansas, and the resistance mechanism is not an insensitive target site or reduced glyphosate absorption or translocation.

scholarly journals Economic Analysis of Perennial Crop Systems in Dak Lak Province, Vietnam

2018 ◽  
Vol 11 (1) ◽  
pp. 81 ◽  
Author(s):  
Phan Thuy ◽  
Le Niem ◽  
Thi Ho ◽  
Philippe Burny ◽  
Philippe Lebailly
Keyword(s):  
Economic Efficiency ◽  
Cropping Systems ◽  
Group Discussion ◽  
National Level ◽  
Cropping System ◽  
Black Pepper ◽  
Interesting Case ◽  
Crop Failure ◽  
Perennial Crop ◽  
Factors Affecting

Dak Lak province, Central Highlands, Vietnam presents an interesting case in perennial crop systems, of which coffee and black pepper are the two premier commodities and contribute a large part to economic growth provincially and at the national level. In recent years, in addition to mono-cropping systems, intercropping systems for diversification have developed quickly. This paper focuses on (1) comparing the economic efficiency of mono-coffee systems (MCSes), mono-pepper systems (MPSes), and coffee and pepper intercropping (CPI) by analyzing startup cost, annual cost, and profits; and (2) identifying the main factors affecting farmers’ decisions to convert their crop systems. The study was carried out by investigating 90 perennial crop samples using the three perennial crop systems (MCSes, MPSes, and CPI) in 2017–2018. Additionally, in-depth interviews and focus group discussion (FGD) methods were applied to collect more information about the operations of each system. Another survey with 37 samples (new plantations) was carried out to compute the startup cost. The findings showed evidence that MCSes had the lowest startup and annual costs, whereas MPSes had the highest costs of the three perennial crop systems. MCSes used less manure or compost in the initial setup and overused chemical fertilizer in annual production. Similarly, MPSes had high pesticide-stimulant costs in the production process to sustain crop development. The study indicated that CPI not only had the highest economic efficiency, but also created the best family employment opportunities of the three systems. Additionally, the study found some social factors that strongly influenced farmers’ decisions to shift their cropping system: These included ethnicity, education, training, and crop failure, in addition to economic factors (profits).

Glyphosate Resistance in Tall Waterhemp (Amaranthus tuberculatus) from Mississippi is due to both Altered Target-Site and Nontarget-Site Mechanisms

Weed Science ◽  
2013 ◽  
Vol 61 (3) ◽  
pp. 374-383 ◽  
Author(s):  
Vijay K. Nandula ◽  
Jeffery D. Ray ◽  
Daniela N. Ribeiro ◽  
Z. Pan ◽  
Krishna N. Reddy
Keyword(s):  
Glyphosate Resistance ◽  
Target Site ◽  
Weed Species ◽  
Single Nucleotide ◽  
Susceptible Population ◽  
Single Leaf ◽  
Resistant Population ◽  
Amaranthus Tuberculatus ◽  
Population Sequence

A tall waterhemp population from Missisippi was suspected to be resistant to glyphosate. Glyphosate dose response experiments resulted in GR50(dose required to reduce plant growth by 50%) values of 1.28 and 0.28 kg ae ha−1glyphosate for the glyphosate-resistant (GR) and -susceptible (GS) populations, respectively, indicating a five-fold resistance. The absorption pattern of14C-glyphosate between the GR and GS populations was similar up to 24 h after treatment (HAT). Thereafter, the susceptible population absorbed more glyphosate (55 and 49% of applied) compared to the resistant population (41 and 40% of applied) by 48 and 72 HAT, respectively. Treatment of a single leaf in individual plants with glyphosate at 0.84 kg ha−1, in the form of 10 1-µl droplets, provided greater control (85 vs. 29%) and shoot fresh weight reduction (73 vs. 34% of nontreated control) of the GS plants compared to the GR plants, possibly indicating a reduced movement of glyphosate in the GR plants. The amount of14C-glyphosate that translocated out of the treated leaves of GR plants (20% of absorbed at 24 HAT and 23% of absorbed at 48 HAT) was significantly lower than the GS plants (31% of absorbed at 24 HAT and 32% of absorbed at 48 HAT). A potential difference in shikimate accumulation between GR and GS populations at different concentrations of glyphosate was also studied in vitro. The IC50(glyphosate concentration required to cause shikimate accumulation at 50% of peak levels measured) values for the GR and GS populations were 480 and 140 µM of glyphosate, respectively, resulting in more shikimate accumulation in the GS than the GR population. Sequence analysis of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), the target site of glyphosate, from GR and GS plants identified a consistent single nucleotide polymorphism (T/C, thymine/cytosine) between GR/GS plants, resulting in a proline to serine amino acid substitution at position 106 in the GR population. The GR and GS plants contained equal genomic copy number ofEPSPS, which was positively correlated withEPSPSgene expression. Thus, glyphosate resistance in the tall waterhemp population from Mississippi is due to both altered target site and nontarget site mechanisms. This is the first report of an alteredEPSPS-based resistance in a dicot weed species that has evolved resistance to glyphosate.

scholarly journals Is glyphosate-resistant ryegrass resistant to paraquat?

2017 ◽  
Vol 70 ◽  
pp. 323
Author(s):  
H. Ghanizadeh ◽  
K.C. Harrington
Keyword(s):  
New Zealand ◽  
Perennial Ryegrass ◽  
Glyphosate Resistance ◽  
Main Mechanism ◽  
Susceptible Population ◽  
Mechanism Of Resistance ◽  
First Case ◽  
Paraquat Resistance ◽  
Resistant Population ◽  
Translocation Mechanism

Sequestration of herbicide into vacuoles is considered to be the main mechanism of resistance to both glyphosate and paraquat worldwide. In New Zealand, the first case of glyphosate resistance was found in ryegrass (Lolium) species, and the restricted herbicide translocation was found to be the main mechanism of resistance in the studied populations, presumably through sequestration. Overseas researchers hypothesised that the mechanism responsible for glyphosate resistance could also cause resistance to paraquat. We examined this hypothesis by comparing a known glyphosate-resistant population of perennial ryegrass with a known susceptible population after spraying with different rates (25—800 g ai/ha) of paraquat. The glyphosate-resistant population responded similarly to the susceptible population at the different rates of paraquat application. This result suggests that the restricted glyphosate translocation mechanism does not necessarily lead to paraquat resistance. These results also suggest that paraquat could be useful for controlling ryegrass when glyphosate resistance has evolved and the application of paraquat is permitted.

Glyphosate-Resistant Rigid Ryegrass (Lolium rigidum) Populations in the Western Australian Grain Belt

2010 ◽  
Vol 24 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Mechelle J. Owen ◽  
Stephen B. Powles
Keyword(s):  
Cropping Systems ◽  
Acetolactate Synthase ◽  
Glyphosate Resistance ◽  
Weed Species ◽  
Resistance Evolution ◽  
Crop Field ◽  
Intensive Cropping ◽  
Low Levels ◽  
Rigid Ryegrass ◽  
Acetyl Coenzyme A Carboxylase

Glyphosate-resistance evolution in weeds is evident globally, especially in areas where transgenic glyphosate-resistant crops dominate. Resistance to glyphosate is currently known in 16 weed species, including rigid ryegrass in Australia. Following the first report of glyphosate resistance in 1998, there are now 78 documented glyphosate-resistant populations of rigid ryegrass in grain-growing regions of southern Australia. In some regions where glyphosate-resistance evolution has already occurred in rigid ryegrass, transgenic glyphosate-resistant canola was introduced in 2008, further highlighting the need to monitor glyphosate-resistance evolution in weeds. A rigid ryegrass population (WALR70) was collected in 2005 from a crop field in Esperance, Western Australia, after it had survived applications of glyphosate. Dose–response experiments confirmed resistance in the population, with the glyphosate rate resulting in 50% mortality (LD50) for WALR70 being 11 times greater than that for a susceptible biotype. The WALR70 population also had low levels of resistance to some acetyl coenzyme A carboxylase (ACCase)- and acetolactate synthase (ALS)-inhibiting herbicides (diclofop, fluazifop, clodinafop, tralkoxydim, chlorsulfuron, and imazethapyr), but was susceptible to other herbicide modes of action, such as atrazine, trifluralin, and paraquat. Two other rigid ryegrass populations assessed in this study were also confirmed to be resistant to glyphosate. The increasing number of glyphosate-resistant rigid ryegrass populations in Australia is of concern to growers because of the importance of glyphosate in intensive cropping systems and the introduction of glyphosate-resistant canola to this region.

Net nitrogen mineralization from a Gray Luvisol under diverse cropping systems in the Peace River region of Alberta

1996 ◽  
Vol 76 (2) ◽  
pp. 117-123 ◽  
Author(s):  
K. Broersma ◽  
N. G. Juma ◽  
J. A. Robertson
Keyword(s):  
N Mineralization ◽  
Cropping Systems ◽  
Cropping System ◽  
Red Clover ◽  
Growing Season ◽  
Soil Samples ◽  
Net N Mineralization ◽  
Mineralization Rate ◽  
River Region ◽  
Gray Luvisol

Proper management of crops on Gray Luvisols requires knowledge of net soil N mineralization during the growing season. Soil samples from a long-term field experiment at Beaverlodge, Alberta, were used to determine the kinetics of net N mineralization in soil samples from different crop rotations. The cropping systems established in 1968 consisted of (i) continuous barley (Hordeum vulgare L.) (CB); (ii) barley–forage (BF) [bromegrass (Bromus inermis Leyss.) and red clover (Trifolium pratense L.)]; (iii) continuous bromegrass (CG); and (iv) continuous legume (red clover) (CL.). The BF rotation was generally alternated every 3 yr, and each phase of the rotation (BF and BF) was present in every year. Soil samples from each cropping system were sampled to a depth of 15 cm in 1984. Net N mineralized during a 20-wk laboratory incubation at 30 °C and optimum moisture ranged from 32 to 207 mg kg−1 soil and followed the trend BF < CB = CG = BF < CL. The potentially mineralizable N (N0) ranged from 29 to 364 mg kg−1 soil; the mineralization rate constant (k) ranged from 0.04 to 0.26 wk−1; and the ratio of N0 to total N (active fraction) ranged from 1.1 to 11.4%. The net N mineralization rate of CL soil was 10-fold greater than that of the other cropping systems at the end of 20 wk of incubation. This suggests that the CL cropping system provides more N than other cropping systems during the growing season. Results support the observation that forages improve the N-supplying power of Gray Luvisols. Key words: Gray Luvisol, Typic Cryoboralf, N mineralization potential, cropping rotations, active N fraction

The effects of diverse cropping systems on aggregation of a Luvisolic soil in the Peace River region

1997 ◽  
Vol 77 (2) ◽  
pp. 323-329 ◽  
Author(s):  
K. Broersma ◽  
J. A. Robertson ◽  
D. S. Chanasyk
Keyword(s):  
Evaluation Method ◽  
Water Drop ◽  
Cropping Systems ◽  
Aggregate Stability ◽  
Cropping System ◽  
Red Clover ◽  
Forage Crops ◽  
Peace River ◽  
River Region ◽  
Wet Sieving

Aggregate distribution and stability of surface soil were determined for different cropping systems of a Luvisolic soil in the Peace River region of Alberta. Gray Luvisolic soils have inherent problems that include weak platy structured surface horizons which are underlain by compact sub-soils. The cropping systems consisted of (i) continuous barley (CB) (Hordeum vulgare L.); (ii) barley/forage (BF), 3 yr of barley followed by 3 yr of forage (mixture of bromegrass [Bromus inermis Leyss] and red clover [Trifolium pratense L.]); (iii) continuous grass (CG) (bromegrass); and (iv) continuous legume (CL) (red clover). The barley/forage rotation consisted of two phases, the barley phase (BF) and forage phase (BF). Each phase was present every year. Aggregate separation by dry-sieving with a rotary sieve indicated that the CL cropping system had fewer large aggregates and more small aggregates than the other cropping systems. The CG, BF and CB cropping systems had more larger aggregates and were similar to each other. Wet-sieving, by contrast, resulted in the CG cropping system having greater amounts of large aggregates while the CL, BF phases, and CB cropping systems were similar with more smaller aggregates. Wet-sieving of the different aggregate size fractions from the rotary dry-sieve indicated that the cropping system aggregate stability was in the order of: CG > CL > BF ≥ BF ≥ CB. The stability of the BF cropping system was greater than that of the BF as it had recently come out of the BF phase (3 yr of forage production). Aggregate stability for the cropping system soils was consistent among the evaluation method of wet-sieving and the McCalla water-drop method. Inclusion of forage crops are important in maintaining or improving soil structure of Luvisolic surface horizons. Key words: Luvisolic soil, cropping systems, aggregation, aggregate stability, Peace River region

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