scholarly journals Fate and adaptive plasticity of heterogeneous resistant population of Echinochloa colona in response to glyphosate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Md Asaduzzaman ◽  
Eric Koetz ◽  
Hanwen Wu ◽  
Michael Hopwood ◽  
Adam Shephard
Keyword(s):  
Management Practices ◽  
Growth Period ◽  
Adaptive Plasticity ◽  
Plant Mortality ◽  
Heterogeneous Populations ◽  
Herbicide Resistant ◽  
Application Rates ◽  
Resistant Population

AbstractUnderstanding the fate of heterogenous herbicide resistant weed populations in response to management practices can help towards overcoming the resistance issues. We selected one pair of susceptible (S) and resistant (R) phenotypes (2B21-R vs 2B21-S and 2B37-R vs 2B37-S) separately from two glyphosate resistant heterogeneous populations (2B21 and 2B37) of Echinochloa colona and their fate and adaptive plasticity were evaluated after glyphosate application. Our study revealed the glyphosate concentration required to cause a 50% plant mortality (LD50) was 1187, 200, 3064, and 192 g a. e. ha−1 for the four phenotypes 2B21-R, 2B21-S, 2B37-R, and 2B37-S respectively. Both S phenotypes accumulated more biomass than the R phenotypes at the lower application rates (34 and 67.5 g a. e. ha−1) of glyphosate. However, the R phenotypes generally produced more biomass at rates of glyphosate higher than 100 g a. e. ha−1 throughout the growth period. Plants from the R phenotypes of 2B21 and 2B37 generated 32% and 38% fewer spikesplant−1 than their respective S counterparts in the absence of glyphosate respectively. The spike and seed numbersplant-1 significantly higher in R than S phenotypes at increased rates of glyphosate and these relationships were significant. Our research suggests that glyphosate-resistant E. colona plants will be less fit than susceptible plants (from the same population) in the absence of glyphosate. But in the presence of glyphosate, the R plants may eventually dominate in the field. The use of glyphosate is widespread in field, would favour the selection towards resistant individuals.

Herbicide-Resistant Weeds: Management Tactics and Practices

2006 ◽  
Vol 20 (3) ◽  
pp. 793-814 ◽  
Author(s):  
Hugh J. Beckie
Keyword(s):  
Herbicide Resistance ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Integrated Weed Management ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Application Rates ◽  
Selection For ◽  
Reactive Management

In input-intensive cropping systems around the world, farmers rarely proactively manage weeds to prevent or delay the selection for herbicide resistance. Farmers usually increase the adoption of integrated weed management practices only after herbicide resistance has evolved, although herbicides continue to be the dominant method of weed control. Intergroup herbicide resistance in various weed species has been the main impetus for changes in management practices and adoption of cropping systems that reduce selection for resistance. The effectiveness and adoption of herbicide and nonherbicide tactics and practices for the proactive and reactive management of herbicide-resistant (HR) weeds are reviewed. Herbicide tactics include sequences and rotations, mixtures, application rates, site-specific application, and use of HR crops. Nonherbicide weed-management practices or nonselective herbicides applied preplant or in crop, integrated with less-frequent selective herbicide use in diversified cropping systems, have mitigated the evolution, spread, and economic impact of HR weeds.

Efficacy of Halauxifen-Methyl on Glyphosate-Resistant Horseweed (Erigeron canadensis)

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 758-763 ◽  
Author(s):  
Cara L. McCauley ◽  
William G. Johnson ◽  
Bryan G. Young
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Field Experiments ◽  
Foliar Application ◽  
Management Systems ◽  
Herbicide Resistant ◽  
Synthetic Auxin ◽  
Comparable Level ◽  
Erigeron Canadensis ◽  
Application Rates

AbstractHalauxifen-methyl is a new synthetic auxin herbicide for control of broadleaf weeds, including preplant applications for corn (Zea maysL.) or soybean [Glycine max(L.) Merr.]. The objective of this study was to investigate the efficacy of halauxifen-methyl in comparison to the current auxin standards, 2,4-D and dicamba, on glyphosate-resistant (GR) horseweed (Erigeron canadensisL.) at different plant heights. In field experiments, a foliar application of halauxifen-methyl at the recommended use rate of 5 g ae ha−1resulted in 81% control. Dicamba applied at 280 g ae ha−1provided a comparable level of efficacy of 80%, while 2,4-D at 560 g ae ha−1resulted in 49% control. The addition of glyphosate improved GRE. canadensiscontrol with 2,4-D more than with halauxifen-methyl or dicamba, possibly due to the higher level of control observed with halauxifen-methyl or dicamba alone. Even though applied at 50 to 100 times lower application rates, the efficacy of halauxifen-methyl onE. canadensiswas similar to dicamba and greater than 2,4-D. Thus, halauxifen-methyl should be an effective tool for management of GRE. canadensisbefore planting both conventional and herbicide-resistant soybean varieties, and it precludes the extended preplant application interval required for dicamba in some soybean management systems.

Physiological assessment of non–target site restistance in multiple-resistant junglerice (Echinochloa colona)

Weed Science ◽  
2019 ◽  
Vol 67 (6) ◽  
pp. 622-632 ◽  
Author(s):  
Christopher E. Rouse ◽  
Nilda Roma-Burgos ◽  
Bianca Assis Barbosa Martins
Keyword(s):  
Management Practices ◽  
Enzyme Inhibitors ◽  
Treatment Resistance ◽  
Target Site ◽  
Metabolic Enzyme ◽  
Herbicide Resistant ◽  
Whole Plant ◽  
Detoxification Mechanism ◽  
Target Site Resistance ◽  
Resistance To Herbicides

AbstractHerbicide-resistant Echinochloa species are among the most problematic weeds in agricultural crops globally. Recurring herbicide selection pressure in the absence of diverse management practices has resulted in greater than 20% of sampled Echinochloa populations from rice (Oryza sativa L.) fields demonstrating multiple resistance to herbicides in Arkansas, USA. We assessed the resistance profile and potential mechanisms of resistance in a multiple herbicide–resistant junglerice [Echinochloa colona (L.) Link] (ECO-R) population. Whole-plant and laboratory bioassays were conducted to identify the potential mechanisms of non–target site resistance in this population. ECO-R was highly resistant to propanil (>37,800 g ha−1) and quinclorac (>17,920 g ha−1) and had elevated tolerance to cyhalofop (R/S = 1.9) and glufosinate (R/S = 1.2) compared to the susceptible standard. The addition of glufosinate (590 g ha−1) to cyhalofop (314 g ha−1), propanil (4,500 g ha−1), or quinclorac (560 g ha−1) controlled ECO-R 100%. However, cyhalofop applied with propanil (48% control) or quinclorac (15% control) was antagonistic. The application of the known metabolic enzyme inhibitors malathion, carbaryl, and piperonyl butoxide increased control of ECO-R with propanil (>75%) but not with other herbicides. Neither absorption nor translocation of [14C]cyhalofop or propanil was different between ECO-R and ECO-S. [14C]Quinclorac absorption was also similar between ECO-R and ECO-S; however, translocation of quinclorac into tissues above the treated leaf of ECO-R was >20% higher than that in ECO-S. The abundance of metabolites was higher (∼10%) in the treated leaves of ECO-R than in ECO-S beginning 48 h after treatment. The activity of β-cyanoalanine synthase, which detoxifies hydrogen cyanide, was not different between ECO-R and ECO-S following quinclorac treatment. Resistance to propanil was due to herbicide detoxification by metabolic enzymes. Resistance to quinclorac was due to a detoxification mechanism yet to be understood. The reduction in sensitivity to cyhalofop and glufosinate might be a secondary effect of the mechanisms conferring high resistance to propanil and quinclorac.

Herbicide Timing and Rate Effects on Weed Management in Three Herbicide-Resistant Canola Systems

2004 ◽  
Vol 18 (4) ◽  
pp. 1006-1012 ◽  
Author(s):  
K. Neil Harker ◽  
George W. Clayton ◽  
John T. O'Donovan ◽  
Robert E. Blackshaw ◽  
F. Craig Stevenson
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Management Practices ◽  
Integrated Weed Management ◽  
Weed Biomass ◽  
Herbicide Resistant ◽  
Leaf Stage ◽  
Rate Effects ◽  
Herbicide Timing ◽  
Weed Removal

Herbicide-resistant canola dominates the canola market in Canada. A multiyear field experiment was conducted at three locations to investigate the effect of time of weed removal (two-, four-, or six-leaf canola) and herbicide rate (50 or 100% recommended) in three herbicide-resistant canola systems. Weeds were controlled in glufosinate-resistant canola (GLU) with glufosinate, in glyphosate-resistant canola (GLY) with glyphosate, and in imidazolinone-resistant canola (IMI) with a 50:50 mixture of imazamox and imazethapyr. Canola yields were similar among the three canola cultivar–herbicide systems. Yields were not influenced by 50 vs. 100% herbicide rates. Timing of weed removal had the greatest effect on canola yield, with weed removal at the four-leaf stage giving the highest yields in most cases. Percent dockage was often greater for GLU and IMI than for GLY. In comparison with the other treatments, dockage levels doubled for GLU after application at 50% herbicide rates. The consistency of monocot weed control was usually greater for GLY than for GLU or IMI systems. However, weed biomass data revealed no differences in dicot weed control consistency between IMI and GLY systems. Greater dockage and weed biomass variability after weed removal at the six-leaf stage or after low herbicide rates suggests higher weed seed production, which could constrain the adoption of integrated weed management practices in subsequent years.

Adoption of Best Management Practices for Herbicide-Resistant Weeds in Midsouthern United States Cotton, Rice, and Soybean

2013 ◽  
Vol 27 (4) ◽  
pp. 788-797 ◽  
Author(s):  
Dilpreet S. Riar ◽  
Jason K. Norsworthy ◽  
Lawrence E. Steckel ◽  
Daniel O. Stephenson ◽  
Thomas W. Eubank ◽  
...  
Keyword(s):  
Cover Crops ◽  
Best Management Practices ◽  
Management Practices ◽  
Cultural Practices ◽  
Direct Mail ◽  
Rice Seed ◽  
Planting Dates ◽  
Row Crops ◽  
Herbicide Resistant ◽  
Best Management

In fall 2011, cotton and soybean consultants from Arkansas, Louisiana, Mississippi, and Tennessee were surveyed through direct mail and on-farm visits, and rice consultants from Arkansas and Mississippi were surveyed through direct mail to assess the importance and level of implementation of herbicide resistance best management practices (HR-BMPs) for herbicide-resistant weeds. Proper herbicide timing, clean start with no weeds at planting, application of multiple effective herbicide modes of action, use of full labeled herbicide rates, and prevention of crop weed seed production with importance rating of ≥ 4.6 out of 5.0 were perceived as the most important HR-BMPs in all crops. Purchase of certified rice seed was on 90% of scouted hectares. In contrast, least important HR-BMPs as perceived by consultants with importance ratings of ≤ 4.0 in cotton, ≤ 3.7 in rice, and ≤ 3.8 in soybean were cultural practices such as manual removal of weeds; tillage including disking, cultivation, or deep tillage; narrow (≤ 50 cm)-row crops, cover crops, and altered planting dates. Narrow crop rows and cover crops in cotton; altered planting dates in cotton and soybean; and cleaning of farm equipment and manual weeding in rice and soybean is currently employed on ≤ 20% of scouted hectares. Extra costs, time constraints, adverse weather conditions, lack of labor and equipment, profitability, herbicide-related concerns, and complacency were perceived as key obstacles for adoption of most HR-BMPs. With limited adoption of most cultural practices that reduce risks of herbicide-resistant weeds, there are opportunities to educate growers concerning the proactive need and long-term benefits of adopting HR-BMPs to ensure sustainable weed management and profitable crop production.

scholarly journals Comparative Water and Nutrient Application Rates among Ornamental Operations in Maryland

HortScience ◽  
2018 ◽  
Vol 53 (9) ◽  
pp. 1364-1371 ◽  
Author(s):  
John C. Majsztrik ◽  
Andrew G. Ristvey ◽  
David S. Ross ◽  
John D. Lea-Cox
Keyword(s):  
Production Management ◽  
Management Practices ◽  
Nutrient Management ◽  
Production Systems ◽  
The State ◽  
Plant Production ◽  
Irrigation Application ◽  
Application Rates ◽  
Field Nursery ◽  
Container Nursery

Quantifying the range of fertilizer and irrigation application rates applied by the ornamental nursery and greenhouse industry is challenging as a result of the variety of species, production systems, and cultural management techniques that are used. To gain a better understanding of nutrient and water use by the ornamental industry in Maryland, 491 potential operations (including multiple addresses and contacts) in the state were mailed a packet of information asking for their voluntary participation. Of the 491 potential operations, it was determined that 348 operations were currently in operation. Of those 348 operations, 48 (14% of the operations in the state) participated in a site visit and an in-depth interview, and a detailed site analysis of the water and nutrient management practices was performed on a production management unit (MU) basis. The authors define an MU as a group of plants that is managed similarly, particularly in regard to nutrient and irrigation application. Greenhouse operations reported, on average, 198, 122, and 196 kg/ha/year of nitrogen (N), phosphorus (P, as P2O5), and potassium (K, as K2O) fertilizer used, respectively, for 27 operations, representing 188 MUs. Twenty-seven outdoor container nursery operations had a total of 162 MUs, with an average of 964, 390, and 556 kg/ha/year of N, P2O5, and K2O fertilizer used, respectively. Field nursery (soil-based) operations were represented by 17 operations, producing 96 MUs, with an average of 67, 20, and 25 kg/ha/year of N, P2O5, and K2O fertilizer used, respectively. Irrigation volume per application was greatest in container nursery operations, followed by greenhouse and field nursery operations. Data were also analyzed by creating quartiles, which represent the median of the lowest 25%, the middle 50%, and highest 75% of values. It is likely that the greatest quartile application rates reported by growers could be substantially reduced with little to no effect on plant production time or quality. These data also provide baseline information to determine changes in fertilization practices over time. They were also used as inputs for water and nutrient management models developed as part of this study. These data may also be useful for informing nutrient application rates used in the Chesapeake Bay nutrient modeling process.

Competitiveness of Herbicide-Resistant Waterhemp (Amaranthus tuberculatus) with Soybean

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 729-737 ◽  
Author(s):  
Thomas R. Butts ◽  
Bruno C. Vieira ◽  
Débora O. Latorre ◽  
Rodrigo Werle ◽  
Greg R. Kruger
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Biomass Accumulation ◽  
Stem Diameter ◽  
The Other ◽  
Harvest Time ◽  
Herbicide Resistant ◽  
Amaranthus Tuberculatus ◽  
Soybean Plants

AbstractWaterhemp [Amaranthus tuberculatus(Moq.) J. D. Sauer] is a troublesome weed occurring in cropping systems throughout the U.S. Midwest with an ability to rapidly evolve herbicide resistance that could be associated with competitive disadvantages. Little research has investigated the competitiveness of differentA. tuberculatuspopulations under similar environmental conditions. The objectives of this study were to evaluate: (1) the interspecific competitiveness of three herbicide-resistantA. tuberculatuspopulations (2,4-D and atrazine resistant [2A-R], glyphosate and protoporphyrinogen oxidase [PPO]-inhibitor resistant [GP-R], and 2,4-D, atrazine, glyphosate, and PPO-inhibitor susceptible [2AGP-S]) with soybean [Glycine max(L.) Merr.]; and (2) the density-dependent response of eachA. tuberculatuspopulation within a constant soybean population in a greenhouse environment.Amaranthus tuberculatuscompetitiveness with soybean was evaluated across five target weed densities of 0, 2, 4, 8, and 16 plants pot−1(equivalent to 0, 20, 40, 80, and 160 plants m−2) with 3 soybean plants pot−1(equivalent to 300,000 plants ha−1). At the R1 soybean harvest time, no difference in soybean biomass was observed acrossA. tuberculatuspopulations. AtA. tuberculatusdensities <8 plants pot−1, the 2AGP-S population had the greatest biomass and stem diameter per plant. At the R7 harvest time, the 2AGP-S population caused the greatest loss in soybean biomass and number of pods compared with the other populations at densities of <16 plants pot−1. The 2AGP-S population had greater early-season biomass accumulation and stem diameter compared with the otherA. tuberculatuspopulations, which resulted in greater late-season reduction in soybean biomass and number of pods. This research indicates there may be evidence of interspecific competitive fitness cost associated with the evolution of 2,4-D, atrazine, glyphosate, and PPO-inhibitor resistance inA. tuberculatus. Focus should be placed on effectively using cultural weed management practices to enhance crop competitiveness, especially early in the season, to increase suppression of herbicide-resistantA. tuberculatus.

scholarly journals Changes in Herbicide Use after Adoption of HR Canola in Western Canada

2011 ◽  
Vol 25 (3) ◽  
pp. 492-500 ◽  
Author(s):  
S. J. Smyth ◽  
M. Gusta ◽  
K. Belcher ◽  
P. W. B. Phillips ◽  
D. Castle
Keyword(s):  
Environmental Impact ◽  
Active Ingredient ◽  
Weed Management ◽  
Management Practices ◽  
Soil Management ◽  
Western Canada ◽  
Herbicide Resistant ◽  
Production Technologies ◽  
Time Required ◽  
Herbicide Use

This article examines the changes in herbicide use in relation to canola production in Western Canada, comparing 1995 and 2006. The commercialization and widespread adoption of herbicide-resistant (HR) canola has changed weed management practices in Western Canada. Before the introduction of HR canola, weeds were controlled by herbicides and tillage as the leading herbicides at that time required tillage to allow for soil incorporation of the herbicide. Much of the tillage associated with HR canola production has been eliminated as 64% of producers are now using zero or minimum tillage as their preferred form of crop and soil management. Additionally, there have been significant changes regarding the use and application of herbicides for weed control in canola. This research shows that when comparing canola production in 1995 and 2006, the environmental impact of herbicides applied to canola decreased 53%, producer exposure to chemicals decreased 56%, and quantity of active ingredient applied decreased 1.3 million kg. The cumulative environmental impact was reduced almost 50% with the use of HR herbicides. If HR canola had not been developed and Canadian canola farmers continued to use previous production technologies, the amount of active ingredient applied to control weeds in 2007 would have been 60% above what was actually applied.

Size of subsoil clods affects soil-water availability in sand–clay mixtures

Soil Research ◽  
2016 ◽  
Vol 54 (3) ◽  
pp. 276 ◽  
Author(s):  
Giacomo Betti ◽  
Cameron D. Grant ◽  
Robert S. Murray ◽  
G. Jock Churchman
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Best Management Practices ◽  
Water Availability ◽  
Water Retention ◽  
Management Practices ◽  
Crop Yields ◽  
Root Zone ◽  
Soil Water Availability ◽  
Application Rates

Clay delving in strongly texture-contrast soils brings up subsoil clay in clumps ranging from large clods to tiny aggregates depending on the equipment used and the extent of secondary cultivation. Clay delving usually increases crop yields but not universally; this has generated questions about best management practices. It was postulated that the size distribution of the subsoil clumps created by delving might influence soil-water availability (and hence crop yield) because, although the clay increases water retention in the root-zone, it can also cause poor soil aeration, high soil strength and greatly reduced hydraulic conductivity. We prepared laboratory mixtures of sand and clay-rich subsoil in amounts considered practical (10% and 20% by weight) and excessive (40% and 60% by weight) with different subsoil clod sizes (<2, 6, 20 and 45 mm), for which we measured water retention, soil resistance, and saturated hydraulic conductivity. We calculated soil water availability by traditional means (plant-available water, PAW) and by the integral water capacity (IWC). We found that PAW increased with subsoil clay, particularly when smaller aggregates were used (≤6 mm). However, when the potential restrictions on PAW were taken into account, the benefits of adding clay reached a peak at ~40%, beyond which IWC declined towards that of pure subsoil clay. Furthermore, the smaller the aggregates the less effective they were at increasing IWC, particularly in the practical range of application rates (<20% by weight). We conclude that excessive post-delving cultivation may not be warranted and may explain some of the variability found in crop yields after delving.

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