VERIFICATION OF THE MECHANISM OF GLYPHOSATE RESISTANCE IN ITALIAN RYEGRASS BIOTYPES

ABSTRACT The intense use of glyphosate for weed control led to the emergence of several cases of resistance to this herbicide. Weeds can survive the application of herbicides due to several factors, which may or may not be related to the herbicide site of action. The objectives of this study were to quantify the accumulation of shikimate in ryegrass biotypes in response to glyphosate application; investigate possible mutations on the EPSPs gene in susceptible and resistant biotypes; and evaluate the response of ryegrass biotypes to the application of glyphosate after treatment with a metabolism inhibitor of cyt P450 monooxygenase. The seeds of ryegrass biotypes with suspected resistance came from the municipality of São Valentim, RS (SVA 1 and SVA 4) and Passo Fundo, RS (PFU 5) and the seeds of the susceptible biotype (SVA 2), from São Valentim. The results demonstrated that, SVA biotype 2 accumulated more shikimate than any of the resistant biotypes, regardless of the herbicide dose used. The EPSPs gene showed no point mutation previously associated with the resistance to glyphosate, and the evaluated biotypes show no metabolism of glyphosate by the cyt P450 complex concerning inhibition by piperonyl butoxide (PBO) and malathion.

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Strategies to manage the evolution of glyphosate resistance in New Zealand

New Zealand Plant Protection ◽

10.30843/nzpp.2016.69.5944 ◽

2016 ◽

Vol 69 ◽

pp. 252-257 ◽

Cited By ~ 2

Author(s):

K.C. Harrington ◽

T.K. James ◽

M.D. Parker ◽

H. Ghanizadeh

Keyword(s):

New Zealand ◽

Weed Control ◽

Lolium Perenne ◽

Perennial Ryegrass ◽

Lolium Multiflorum ◽

Resistance Management ◽

Glyphosate Resistance ◽

Italian Ryegrass ◽

Fruit Crops ◽

Sustainable Farming

The first cases of weeds developing resistance to glyphosate within New Zealand have recently been reported and investigated Both perennial ryegrass (Lolium perenne) and Italian ryegrass (Lolium multiflorum) populations have become resistant to glyphosate in several Marlborough vineyards due to many years of weed control using mainly just glyphosate Glyphosate is currently being used in many situations throughout New Zealand that could easily lead to further resistance developing such as in other perennial fruit crops on roadsides railways amenity areas waste areas fence lines and headlands of crops Following wide consultation as part of a Sustainable Farming Fund project strategies for resistance management in three systems (vineyard and orchards amenity and waste areas and crops and pastures) are suggested Adoption of these strategies will allow glyphosate to continue as a useful herbicide in New Zealand

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A Multistate Study of the Association Between Glyphosate Resistance and EPSPS Gene Amplification in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽

10.1614/ws-d-14-00149.1 ◽

2015 ◽

Vol 63 (3) ◽

pp. 569-577 ◽

Cited By ~ 31

Author(s):

Laura A. Chatham ◽

Kevin W. Bradley ◽

Greg R. Kruger ◽

James R. Martin ◽

Micheal D. K. Owen ◽

...

Keyword(s):

Gene Amplification ◽

Copy Number ◽

Quantitative Relationship ◽

Glyphosate Resistance ◽

Epsps Gene ◽

Number Magnitude ◽

Site Of Action ◽

Amaranthus Tuberculatus ◽

Polymerase Chain ◽

The Relationship

Waterhemp is an increasingly problematic weed in the U.S. Midwest, having now evolved resistances to herbicides from six different site-of-action groups. Glyphosate-resistant waterhemp in the Midwest is especially concerning given the economic importance of glyphosate in corn and soybean production. Amplification of the target-site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was found to be the mechanism of glyphosate resistance in Palmer amaranth, a species closely related to waterhemp. Here, the relationship between glyphosate resistance and EPSPS gene amplification in waterhemp was investigated. Glyphosate dose response studies were performed at field sites with glyphosate-resistant waterhemp in Illinois, Kansas, Kentucky, Missouri, and Nebraska, and relative EPSPS copy number of survivors was determined via quantitative real-time polymerase chain reaction (qPCR). Waterhemp control increased with increasing glyphosate rate at all locations, but no population was completely controlled even at the highest rate (3,360 g ae ha−1). EPSPS gene amplification was present in plants from four of five locations (Illinois, Kansas, Missouri, and Nebraska) and the proportion of plants with elevated copy number was generally higher in survivors from glyphosate-treated plots than in plants from the untreated control plots. Copy number magnitude varied by site, but an overall trend of increasing copy number with increasing rate was observed in populations with gene amplification, suggesting that waterhemp plants with more EPSPS copies are more resistant. Survivors from the Kentucky population did not have elevated EPSPS copy number. Instead, resistance in this population was attributed to the EPSPS Pro106Ser mutation. Results herein show a quantitative relationship between glyphosate resistance and EPSPS gene amplification in some waterhemp populations, while highlighting that other mechanisms also confer glyphosate resistance in waterhemp.

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Evolved Glyphosate Resistance in Plants: Biochemical and Genetic Basis of Resistance

Weed Technology ◽

10.1614/wt-04-142r.1 ◽

2006 ◽

Vol 20 (2) ◽

pp. 282-289 ◽

Cited By ~ 153

Author(s):

Stephen B. Powles ◽

Christopher Preston

Keyword(s):

Amino Acid ◽

Resistance Mechanism ◽

Nuclear Gene ◽

Glyphosate Resistance ◽

The United States ◽

Resistance Mechanisms ◽

Italian Ryegrass ◽

Weed Species ◽

Epsps Gene ◽

Rigid Ryegrass

Resistance to the herbicide glyphosate is currently known in at least eight weed species from many countries. Some populations of goosegrass from Malaysia, rigid ryegrass from Australia, and Italian ryegrass from Chile exhibit target site–based resistance to glyphosate through changes at amino acid 106 of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene. Mutations change amino acid 106 from proline to either serine or threonine, conferring an EPSPS weakly resistant to glyphosate. The moderate level of resistance is sufficient for commercial failure of the herbicide to control these plants in the field. Conversely, a nontarget site resistance mechanism has been documented in glyphosate-resistant populations of horseweed and rigid ryegrass from the United States and Australia, respectively. In these resistant plants, there is reduced translocation of glyphosate to meristematic tissues. Both of these mechanisms are inherited as a single, nuclear gene trait. Although at present only two glyphosate-resistance mechanisms are known, it is likely that other mechanisms will become evident. The already very large and still increasing reliance on glyphosate in many parts of the world will inevitably result in more glyphosate-resistant weeds, placing the sustainability of this precious herbicide resource at risk.

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Postemergence Control of Italian Ryegrass in Hazelnut Orchards

Weed Technology ◽

10.1017/wet.2021.41 ◽

2021 ◽

pp. 1-22

Author(s):

Marcelo L. Moretti

Keyword(s):

Weed Control ◽

Weed Management ◽

Field Studies ◽

Early Spring ◽

Italian Ryegrass ◽

Specific Response ◽

Record Keeping ◽

Effective Option ◽

Contrast Analysis ◽

Herbicide Use

Abstract Italian ryegrass has become a problematic weed in hazelnut orchards of Oregon because of the presence of herbicide-resistant populations. Resistant and multiple-resistant Italian ryegrass populations are now the predominant biotypes in Oregon; there is no information on which herbicides effectively control Italian ryegrass in hazelnut orchards. Six field studies were conducted in commercial orchards to evaluate Italian ryegrass control with POST herbicides. Treatments included flazasulfuron, glufosinate, glyphosate, paraquat, rimsulfuron, and sethoxydim applied alone or in selected mixtures during early spring when plants were in the vegetative stage. Treatment efficacy was dependent on the experimental site. The observed range of weed control 28 d after treatment was 13 to 76 % for glyphosate, 1 to 72% for paraquat, 58 to 88% for glufosinate, 16 to 97 % for flazasulfuron, 8 to 94% for rimsulfuron, and 25 to 91% for sethoxydim. Herbicides in mixtures improved control of Italian ryegrass compared to single active ingredients based on contrast analysis. Herbicides in mixture increased control by 27% compared to glyphosate, 18% to rimsulfuron, 15% to flazasulfuron, 19% to sethoxydim, and 12% compared to glufosinate when averaged across all sites, but mixture not always improved ground coverage of biomass reduction. This complex site-specific response highlights the importance of record-keeping for efficient herbicide use. Glufosinate is an effective option to manage Italian ryegrass. However, the glufosinate-resistant biotypes documented in Oregon may jeopardize this practice. Non-chemical weed control options are needed for sustainable weed management in hazelnuts.

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A double EPSPS gene mutation endowing glyphosate resistance shows a remarkably high resistance cost

Plant Cell & Environment ◽

10.1111/pce.13067 ◽

2017 ◽

Vol 40 (12) ◽

pp. 3031-3042 ◽

Cited By ~ 24

Author(s):

Heping Han ◽

Martin M. Vila-Aiub ◽

Adam Jalaludin ◽

Qin Yu ◽

Stephen B. Powles

Keyword(s):

Gene Mutation ◽

High Resistance ◽

Glyphosate Resistance ◽

Epsps Gene ◽

Resistance Cost

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Integration of residual herbicides with cover crop termination in soybean

Weed Technology ◽

10.1017/wet.2019.111 ◽

2019 ◽

Vol 34 (1) ◽

pp. 11-18 ◽

Cited By ~ 2

Author(s):

Derek M. Whalen ◽

Lovreet S. Shergill ◽

Lyle P. Kinne ◽

Mandy D. Bish ◽

Kevin W. Bradley

Keyword(s):

Weed Control ◽

Cover Crops ◽

Cover Crop ◽

Biomass Accumulation ◽

Field Studies ◽

Italian Ryegrass ◽

Cereal Rye ◽

Herbicide Treatments ◽

Residual Herbicide ◽

Herbicide Programs

AbstractCover crops have increased in popularity in midwestern U.S. corn and soybean systems in recent years. However, little research has been conducted to evaluate how cover crops and residual herbicides are effectively integrated together for weed control in a soybean production system. Field studies were conducted in 2016 and 2017 to evaluate summer annual weed control and to determine the effect of cover crop biomass on residual herbicide reaching the soil. The herbicide treatments consisted of preplant (PP) applications of glyphosate plus 2,4-D with or without sulfentrazone plus chlorimuron at two different timings, 21 and 7 d prior to soybean planting (DPP). Cover crops evaluated included winter vetch, cereal rye, Italian ryegrass, oat, Austrian winter pea, winter wheat, and a winter vetch plus cereal rye mixture. Herbicide treatments were applied to tilled and nontilled soil without cover crop for comparison. The tillage treatment resulted in low weed biomass at all collection intervals after both application timings, which corresponded to tilled soil having the highest sulfentrazone concentration (171 ng g−1) compared with all cover crop treatments. When applied PP, herbicide treatments applied 21 DPP with sulfentrazone had greater weed (93%) and waterhemp (89%) control than when applied 7 DPP (60% and 69%, respectively). When applied POST, herbicide treatments with a residual herbicide resulted in greater weed and waterhemp control at 7 DPP (83% and 77%, respectively) than at 21 DPP (74% and 61%, respectively). Herbicide programs that included a residual herbicide had the highest soybean yields (≥3,403 kg ha−1). Results from this study indicate that residual herbicides can be effectively integrated either PP or POST in conjunction with cover crop termination applications, but termination timing and biomass accumulation will affect the amount of sulfentrazone reaching the soil.

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Non‐target‐site mechanism of glyphosate resistance in Italian ryegrass ( Lolium multiflorum )

Weed Biology and Management ◽

10.1111/wbm.12156 ◽

2018 ◽

Vol 18 (3) ◽

pp. 127-135 ◽

Cited By ~ 4

Author(s):

Kohei Kurata ◽

Yuki Niinomi ◽

Yoshiko Shimono ◽

Masahiro Miyashita ◽

Tohru Tominaga

Keyword(s):

Lolium Multiflorum ◽

Glyphosate Resistance ◽

Target Site ◽

Italian Ryegrass

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Reduced Herbicide Antagonism of Grass Weed Control through Spray Application Technique

Agronomy ◽

10.3390/agronomy10081131 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1131 ◽

Cited By ~ 1

Author(s):

Luke H. Merritt ◽

Jason Connor Ferguson ◽

Ashli E. Brown-Johnson ◽

Daniel B. Reynolds ◽

Te-Ming Tseng ◽

...

Keyword(s):

Weed Control ◽

Environmental Sustainability ◽

Field Studies ◽

Italian Ryegrass ◽

Spray Application ◽

The Third ◽

Application Method ◽

Application Methods ◽

Over The Top ◽

Grass Weed

Dicamba and 2,4-D tolerance traits were introduced to soybean and cotton, allowing for over the top applications of these herbicides. Avoiding antagonism of glyphosate and clethodim by dicamba or 2,4-D is necessary to achieve optimum weed control. Three field studies were conducted in fallow fields with broadleaf signalgrass (Urochloa platyphylla) and Italian ryegrass (Lolium perenne ssp. multiflorum) pressure. A tractor-mounted dual boom sprayer was modified to spray one of three application methods: (1) two herbicides tanked-mixed (TMX); (2) two herbicides in separate tanks mixed in the boom line (MIL); and (3) two herbicides in separate tanks applied through separate booms simultaneously (SPB). One study compared the three application methods with sethoxydim applied with bentazon, the second compared clethodim applied with dicamba or 2,4-D, and the third compared glyphosate applied with dicamba or 2,4-D. In most cases over all three trials, there was a 7–15% increase in efficacy when using the SPB application method. Antagonism of all the herbicide combinations above was observed when applied using the TMX and MIL methods. In some cases, antagonism was avoided when using the SPB method. The separate boom application method increased efficacy, which allowed herbicides to be used more effectively, resulting in improved economic and environmental sustainability of herbicide applications.

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Herbicide-Resistant Canola (Brassica napus) Response and Weed Control with Postemergence Herbicides

Weed Technology ◽

10.1614/wt-05-061r.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 551-557 ◽

Cited By ~ 7

Author(s):

Timothy L. Grey ◽

Paul L. Raymer ◽

David C. Bridges

Keyword(s):

Weed Control ◽

Field Studies ◽

Italian Ryegrass ◽

Wild Radish ◽

Application Timing ◽

Herbicide Resistant ◽

Naturally Occurring ◽

And Control ◽

Postemergence Herbicides ◽

Significant Injury

Field studies were conducted to evaluate weed control in herbicide-resistant canola in Georgia. The resistant canola cultivars and respective herbicides were ‘Pioneer 45A76’ and imazamox, ‘Hyola 357RR’ and glyphosate, and ‘2573 Invigor’ and glufosinate. Weed seed of Italian ryegrass and wild radish were sown simultaneously in October with canola and control of these species was evaluated along with other naturally occurring weeds. Herbicide treatments for the respective herbicide-resistant canola cultivar were imazamox at 0.035 and 0.071 kg ai/ha, glyphosate at 0.84 and 1.64 kg ae/ha, and glufosinate at 0.5 and 1.0 kg ai/ha. Herbicides were applied at one– two-leaf (LF) and three–four-LF canola stages. There was no significant injury to any canola cultivar as a result of herbicide rate or timing of application. By midseason (February), imazamox effectively controlled wild radish, henbit, and shepherd's-purse at both rates and at both timings. When applied to three–four-LF canola, the higher rates of glyphosate and glufosinate were required to provide 75% or greater control of Italian ryegrass, wild garlic, and henbit. Glufosinate did not adequately control wild radish at either rate or application timing. Greenhouse experiments provided similar results.

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