Control of Glyphosate-Resistant Common waterhemp (Amaranthus rudis) in Three New Herbicide-Resistant Soybean Varieties in Ontario

2017 ◽  
Vol 31 (6) ◽  
pp. 828-837 ◽  
Author(s):  
Mike G. Schryver ◽  
Nader Soltani ◽  
David C. Hooker ◽  
Darren E. Robinson ◽  
Patrick J. Tranel ◽  
...  
Keyword(s):  
Control System ◽  
Weed Control ◽  
Corn Belt ◽  
Us States ◽  
Common Waterhemp ◽  
Herbicide Resistant ◽  
Control Programs ◽  
The Us ◽  
Amaranthus Rudis ◽  
Excellent Control

Glyphosate-resistant (GR) common waterhemp (CW) is a localized weed in Ontario and one of the most problematic weeds in the US Corn Belt. First confirmed in Ontario in 2014, GR CW has now been confirmed in forty fields in three counties in Ontario as of 2015. Historically, the primary POST herbicides used for the control of CW in soybean were glyphosate, acifluorfen and fomesafen, but resistance to all three has been confirmed in many US states. Research was conducted in 2015 and 2016 to determine the control of GR CW with some of the new herbicide-resistant soybean technologies including glufosinate (LibertyLink), 2,4-D and glyphosate (Enlist), and isoxaflutole, mesotrione, and glufosinate (HPPD-resistant). Glyphosate-resistant CW was controlled (≥90%) all season with a two-pass weed control system across all herbicide-resistant soybean technologies evaluated. The two-pass weed control system in this research is defined as a PRE herbicide followed by a POST herbicide. At 12 WAA, the two-pass programs in LibertyLink, Enlist, and HPPD-resistant systems controlled GR CW up to 98, 98, and 92%, respectively, and reduced GR CW densities to 0 to 2% of the weedy control at 4 WAA. The two-pass programs provided greater GR CW control than PRE or POST herbicides alone. This study found that the use of two-pass weed control programs in glufosinate-resistant, glyphosate DMA/2,4-D choline-resistant and HPPD-resistant soybean can provide excellent control of GR CW, and can be valuable tools to reduce the selection intensity for herbicide-resistant weeds. Through the rotational use of different technologies, growers may be able to better manage their weed populations in reducing the risk of resistance when compared to the use of one herbicide repeatedly.

scholarly journals The Influence of Nozzle Type on Peanut Weed Control Programs

2017 ◽  
Vol 44 (2) ◽  
pp. 93-99 ◽  
Author(s):  
O.W. Carter ◽  
E.P. Prostko ◽  
J.W. Davis
Keyword(s):  
Weed Control ◽  
Palmer Amaranth ◽  
Annual Grass ◽  
Weed Species ◽  
Target Movement ◽  
Herbicide Resistant ◽  
Control Programs ◽  
The Past ◽  
Auxin Herbicides ◽  
Nozzle Type

ABSTRACT The increase in herbicide-resistant weeds over the past decade has led to the introduction of crops that are resistant to auxin herbicides. Strict application procedures are required for the use of auxin herbicides in auxin-resistant crops to minimize off-target movement. One requirement for application is the use of nozzles that will minimize drift by producing coarse droplets. Generally, an increase in droplet size can lead to a reduction in coverage and efficacy depending upon the herbicide and weed species. In studies conducted in 2015 and 2016, two of the potential required auxin nozzle types [(AIXR11002 (coarse) and TTI11002 (ultra-coarse)] were compared to a conventional flat-fan drift guard nozzles [DG11002 (medium)] for weed control in peanut herbicide systems. Nozzle type did not influence annual grass or Palmer amaranth control in non-crop tests. Results from in-crop tests indicated that annual grass control was 5% to 6% lower when herbicides were applied with the TTI nozzle when compared to the AIXR or DG nozzles. However, Palmer amaranth control and peanut yield was not influenced by coarse-droplet nozzles. Peanut growers using the coarse-droplet nozzles need to be aware of potential reduced grass control.

Biotypes of Palmer Amaranth (Amaranthus palmeri) and Common Waterhemp (Amaranthus rudis) are Resistant to Imazethapyr and Thifensulfuron

1995 ◽  
Vol 9 (1) ◽  
pp. 192-195 ◽  
Author(s):  
Michael J. Horak ◽  
Dallas E. Peterson
Keyword(s):  
Herbicide Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Typical Pattern ◽  
Resistance Development ◽  
Common Waterhemp ◽  
Herbicide Resistant ◽  
Amaranthus Rudis ◽  
History Of ◽  
History Of Use

Seeds of suspected herbicide-resistant Palmer amaranth and common waterhemp were collected in Clay County and Douglas County, KS, respectively. An experiment was established in a greenhouse to determine if these species had developed resistance to imazethapyr and thifensulfuron. Imazethapyr was applied pre- (PRE) and postemergence (POST) at 1×, 2×, 4×, and 8× the suggested use rate (70 g/ha), and thifensulfuron was applied POST at 1×, 2×, 4×, and 8× the suggested use rate (4.5 g/ha). Both species had developed resistance to all rates of these herbicides. The occurrence of resistance at the Clay County site (Palmer amaranth) fit the typical pattern for the development of herbicide resistance, i.e., multiple applications of the same class of herbicide for several years. However, the Douglas County (common waterhemp) site had a limited history of use of ALS-inhibiting herbicides and did not follow typical models of resistance development.

scholarly journals Tolpyralate Applied Alone and With Atrazine for Weed Control in Corn

2018 ◽  
Vol 10 (10) ◽  
pp. 32
Author(s):  
O. Adewale Osipitan ◽  
Jon E. Scott ◽  
Stevan Z. Knezevic
Keyword(s):  
Weed Control ◽  
Chenopodium Album ◽  
Field Studies ◽  
Weed Species ◽  
Common Waterhemp ◽  
Common Lambsquarters ◽  
Green Foxtail ◽  
Constant Rate ◽  
Amaranthus Rudis ◽  
Calculated Dose

Tolpyralate, an HPPD (4-hydroxyphenyl-pyruvate dioxygenase) inhibitor, is a relatively new herbicide for weed control in corn. Field studies were conducted in 2015 and 2016 to evaluate the effective dose of tolpyralate applied alone or mixed with atrazine for weed control in corn. The treatments included seven rates (0, 5, 20, 29, 40, 50 and 100 g ai ha-1) of tolpyralate applied alone or mixed with a constant rate (560 g ai ha-1) of atrazine. The evaluated weed species were common waterhemp (Amaranthus rudis Sauer), common lambsquarters (Chenopodium album L.), velvetleaf (Abutilon theophrasti Medik), henbit (Lamium amplexicaule L.) and green foxtail (Setaria viridis L.). Overall, POST-application of tolpyralate resulted in 58-94% visual weed control when applied alone; whereas, addition of atrazine provided 71-100% control of same species. Calculated dose of 19-31 g ai ha-1 (ED90) of tolpyralate applied alone provided 90% visual control of waterhemp, lambsquaters, henbit, and velvetleaf. Whereas, addition of atrazine resulted in significantly lower dose of 11-17 g ai ha-1 for the same level of control, suggesting synergy between the two herbicides.

The Impact of Herbicide-Resistant Weeds on Kansas Agriculture

1999 ◽  
Vol 13 (3) ◽  
pp. 632-635 ◽  
Author(s):  
Dallas E. Peterson
Keyword(s):  
Weed Control ◽  
Herbicide Resistance ◽  
Seed Bank ◽  
Control Program ◽  
Palmer Amaranth ◽  
Integrated System ◽  
Common Waterhemp ◽  
Herbicide Resistant ◽  
Modes Of Action ◽  
The Impact

Herbicides are important components of weed management programs for most Kansas farmers. Monocropping systems and repeated use of the same or similar herbicides in some areas of the state have resulted in the development of herbicide-resistant weeds. The development of herbicide-resistant weed populations can have an immediate and a long-term effect on the cost, implementation, and effectiveness of weed control programs. In Kansas, resistance to triazine herbicides has been confirmed in kochia (Kochia scoparia), redroot pigweed, common waterhemp (Amaranthus rudis), Palmer amaranth (Amaranthus palmeri), and downy brome (Bromus tectorum) populations, and resistance to acetolactate synthase (ALS)-inhibiting herbicides has been confirmed in kochia, Russian thistle (Salsola kali), common waterhemp, Palmer amaranth, common cocklebur (Xanthium strumarium), shattercane (Sorghum bicolor), and common sunflower (Helianthus annum). The frequency and distribution of herbicide resistance varies among species. Producers who experience herbicide resistance problems adjust their weed control program accordingly. Producers that have not encountered an herbicide resistance problem tend to continue with a successful herbicide program until it fails. The recommended management strategies for herbicide-resistant weed populations include an integrated system of crop rotation, rotation of herbicide modes of action, tank-mixes of herbicides with different modes of action, and cultivation. The greatest direct cost to the producer occurs during the first year of poor weed control. The first response to an herbicide failure often is to reapply the same herbicide that has worked well previously. By the time the producer realizes that the treatment is not going to work, it usually is too late for any other remedial action. Consequently, the farmer experiences reduced crop production from weed competition, high herbicide costs, and a tremendous increase in the seed bank. The increase in seed bank may cost the farmer the most in the long run because the increased weed pressure often requires an intensified control program for several years.

Herbicide Options for Control of Palmer Amaranth (Amaranthus palmeri) and Common Waterhemp (Amaranthus rudis) in Double-Crop Soybean

2019 ◽  
Vol 33 (1) ◽  
pp. 106-114 ◽  
Author(s):  
Marshall M. Hay ◽  
Douglas E. Shoup ◽  
Dallas E. Peterson
Keyword(s):  
Winter Wheat ◽  
Field Experiments ◽  
Cropping Systems ◽  
Palmer Amaranth ◽  
Common Waterhemp ◽  
Amaranthus Rudis ◽  
Excellent Control ◽  
Glyphosate Herbicide ◽  
Residual Herbicide ◽  
Herbicide Programs

AbstractDouble-crop soybean after winter wheat is a component of many cropping systems across eastern and central Kansas. Until recently, control of Palmer amaranth and common waterhemp has been both easy and economical with the use of sequential applications of glyphosate in glyphosate-resistant soybean. Many populations of Palmer amaranth and common waterhemp have become resistant to glyphosate. During 2015 and 2016, a total of five field experiments were conducted near Manhattan, Hutchinson, and Ottawa, KS, to assess various non-glyphosate herbicide programs at three different application timings for the control of Palmer amaranth and waterhemp in double-crop soybean after winter wheat. Spring-POST treatments of pyroxasulfone (119 g ai ha–1) and pendimethalin (1065 g ai ha–1) were applied to winter wheat to evaluate residual control of Palmer amaranth and waterhemp. Less than 40% control of Palmer amaranth and waterhemp was observed in both treatments 2 wk after planting (WAP) double-crop soybean. Preharvest treatments of 2,4-D (561 g ae ha–1) and flumioxazin (107 g ai ha–1) were also applied to the winter wheat to assess control of emerged Palmer amaranth and waterhemp. 2,4-D resulted in highly variable Palmer amaranth and waterhemp control, whereas flumioxazin resulted in control similar to PRE treatments that contained paraquat (841 g ai ha–1) plus residual herbicide(s). Excellent control of both species was observed 2 WAP with a PRE paraquat application; however, reduced control of Palmer amaranth and waterhemp was noted 8 WAP due to subsequent emergence. Results indicate that Palmer amaranth and waterhemp control was 85% or greater 8 WAP for PRE treatments that included a combination of paraquat plus residual herbicide(s). PRE treatments that did not include both paraquat and residual herbicide(s) did not provide acceptable control.

Establishing white clover (Trifolium repens) as a living mulch: weed control and herbicide tolerance

2021 ◽  
pp. 1-28
Author(s):  
Nicholas T. Basinger ◽  
Nicholas S. Hill
Keyword(s):  
Weed Control ◽  
White Clover ◽  
Cover Crops ◽  
Herbicide Tolerance ◽  
Single Application ◽  
Weed Species ◽  
Living Mulch ◽  
Herbicide Resistant ◽  
Research And Education ◽  
Weed Emergence

Abstract With the increasing focus on herbicide-resistant weeds and the lack of introduction of new modes of action, many producers have turned to annual cover crops as a tool for reducing weed populations. Recent studies have suggested that perennial cover crops such as white clover could be used as living mulch. However, white clover is slow to establish and is susceptible to competition from winter weeds. Therefore, the objective of this study was to determine clover tolerance and weed control in established stands of white clover to several herbicides. Studies were conducted in the fall and winter of 2018 to 2019 and 2019 to 2020 at the J. Phil Campbell Research and Education Center in Watkinsville, GA, and the Southeast Georgia Research and Education Center in Midville, GA. POST applications of imazethapyr, bentazon, or flumetsulam at low and high rates, or in combination with 2,4-D and 2,4-DB, were applied when clover reached 2 to 3 trifoliate stage. Six weeks after the initial POST application, a sequential application of bentazon and flumetsulam individually, and combinations of 2,4-D, 2,4-DB, and flumetsulam were applied over designated plots. Clover biomass was similar across all treatments except where it was reduced by sequential applications of 2,4-D + 2,4-DB + flumetsulam in the 2019 to 2020 season indicating that most treatments were safe for use on establishing living mulch clover. A single application of flumetsulam at the low rate or a single application of 2,4-D + 2,4-DB provided the greatest control of all weed species while minimizing clover injury when compared to the non-treated check. These herbicide options allow for control of problematic winter weeds during clover establishment, maximizing clover biomass and limiting canopy gaps that would allow for summer weed emergence.

scholarly journals Estimation of Cry3Bb1 resistance allele frequency in field populations of western corn rootworm using a genetic marker

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alan Willse ◽  
Lex Flagel ◽  
Graham Head
Keyword(s):  
Allele Frequency ◽  
Western Corn Rootworm ◽  
Allele Frequencies ◽  
Chromosome 8 ◽  
Corn Belt ◽  
Corn Rootworm ◽  
Resistance Allele ◽  
Response To Selection ◽  
The Us ◽  
Causal Allele

Abstract Following the discovery of western corn rootworm (WCR; Diabrotica virgifera virgifera) populations resistant to the Bacillus thuringiensis (Bt) protein Cry3Bb1, resistance was genetically mapped to a single locus on WCR chromosome 8 and linked SNP markers were shown to correlate with the frequency of resistance among field-collected populations from the US Corn Belt. The purpose of this paper is to further investigate the relationship between one of these resistance-linked markers and the causal resistance locus. Using data from laboratory bioassays and field experiments, we show that one allele of the resistance-linked marker increased in frequency in response to selection, but was not perfectly linked to the causal resistance allele. By coupling the response to selection data with a genetic model of the linkage between the marker and the causal allele, we developed a model that allowed marker allele frequencies to be mapped to causal allele frequencies. We then used this model to estimate the resistance allele frequency distribution in the US Corn Belt based on collections from 40 populations. These estimates suggest that chromosome 8 Cry3Bb1 resistance allele frequency was generally low (<10%) for 65% of the landscape, though an estimated 13% of landscape has relatively high (>25%) resistance allele frequency.

scholarly journals The unemployment structure of the US states

2005 ◽  
Vol 45 (4-5) ◽  
pp. 848-868 ◽  
Author(s):  
Jesús Clemente ◽  
Luis Lanaspa ◽  
Antonio Montañés
Keyword(s):  
Us States ◽  
The Us
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