scholarly journals Biologically effective rates of a new premix (atrazine, bicyclopyrone, mesotrione, and S-metolachlor) for pre-emergence or post-emergence control of common waterhemp (Amaranthus rudis Sauer) in corn

2017 ◽  
Author(s):  
Debalin Sarangi ◽  
Amit J. Jhala
Keyword(s):  
Common Waterhemp ◽  
Amaranthus Rudis

Imidazolinone and Sulfonylurea Resistance in a Biotype of Common Waterhemp (Amaranthus rudis)

Weed Science ◽  
1996 ◽  
Vol 44 (4) ◽  
pp. 789-794 ◽  
Author(s):  
Sarah Taylor Lovell ◽  
Loyd M. Wax ◽  
Michael J. Horak ◽  
Dallas E. Peterson
Keyword(s):  
Acetolactate Synthase ◽  
The United States ◽  
Cross Resistance ◽  
Common Waterhemp ◽  
Whole Plant ◽  
Amaranthus Rudis ◽  
Plant Level ◽  
High Degree ◽  
Selection Agent ◽  
Weed Resistance

The incidence of weed resistance to acetolactate synthase (ALS) inhibiting herbicides has increased in the United States. In 1993, a population of ALS-resistant common waterhemp was discovered after two confirmed applications of an imidazolinone herbicide. Following another imazethapyr application in the glasshouse, the resistant biotype demonstrated 130-fold resistance to imazethapyr at the whole plant level. The concentration of imazethapyr required to inhibit the ALS activity by 50% was 520 times greater for the resistant biotype than the susceptible. Plants also demonstrated cross-resistance to the sulfonylureas, chlorimuron and thifensulfuron, at the whole plant and enzyme levels. This particular discovery is of concern due to the low number of applications of the selection agent (imazaquin 1989, imazethapyr 1992, and imazethapyr in the greenhouse) and the high degree of cross-resistance eliminating several options for weed control.

scholarly journals Performance of Two Bioherbicide Fungi for Waterhemp and Pigweed Control in Pumpkin and Soybean

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 469-477 ◽  
Author(s):  
Loretta M. Ortiz-Ribbing ◽  
Kenny R. Glassman ◽  
Gordon K. Roskamp ◽  
Steven G. Hallett
Keyword(s):  
Cropping Systems ◽  
Disease Incidence ◽  
Field Trials ◽  
Weed Biomass ◽  
Common Waterhemp ◽  
Air Temperatures ◽  
Amaranthus Rudis ◽  
Fungal Organisms ◽  
Sequential Treatments ◽  
Amaranthus Spp

Common waterhemp (Amaranthus rudis) and pigweeds (Amaranthus spp.) are troublesome weeds in many cropping systems and have evolved resistance to several herbicides. Field trials to further develop Microsphaeropsis amaranthi and Phomopsis amaranthicola as bioherbicides for control of waterhemp and pigweeds were conducted to test the effectiveness of these organisms in irrigated and nonirrigated pumpkin and soybean plots over 2 years at three locations in western Illinois. The bioherbicide was applied with lecithin and vegetable oil at 187 liters ha–1 in 2008 and 374 liters ha–1 in 2009. Treatments included spore suspensions of M. amaranthi and P. amaranthicola alone, a mixture of both organisms, and sequential treatments of the organisms with halosulfuron-methyl (Sandea Herbicide) in pumpkin or glyphosate (Roundup Original Max Herbicide) in soybean. Bioherbicide effectiveness was estimated at approximately 7 and 14 days after treatment, as disease incidence, disease severity, percent weed control, and weed biomass reduction. Significant reductions in weed biomass occurred in treatments with one or both of the fungal organisms, and potential exists to tank mix M. amaranthi with halosulfuron-methyl. Leaf surface moisture and air temperatures following application may account for inconsistencies in field results between year and locations. These fungal organisms show potential as bioherbicides for weeds in the genus Amaranthus.

Acetolactate Synthase Resistance in a Common Waterhemp (Amaranthus rudis) Population

1997 ◽  
Vol 11 (1) ◽  
pp. 13-18 ◽  
Author(s):  
John R. R. Hinz ◽  
Micheal D. K. Owen
Keyword(s):  
Plant Material ◽  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Grain Amaranth ◽  
Common Waterhemp ◽  
Resistant Species ◽  
Whole Plant ◽  
Amaranthus Rudis ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Research was initiated to determine (a) whether a common waterhemp population was resistant to acetolactate synthase (ALS) inhibiting herbicides, (b) the percentage of the population that was ALS-inhibitor resistant, (c) the resistance mechanism, and (d) the effectiveness of a whole plant assay to detect ALS-inhibitor resistance. ALS-inhibitor resistance was confirmed in a common waterhemp population near Davis City, IA. The Davis City common waterhemp population was cross resistant to both imidazolinone and sulfonylurea herbicides, but not to lactofen. Approximately 10% of the Davis City common waterhemp population was sensitive to a rate of imazaquin 4 times the normal field rate. Davis City common waterhemp isolated ALS was much less sensitive to imazaquin and primisulfuron inhibition than was grain amaranth or an ALS-sensitive common waterhemp isolated ALS. Imazaquin I50values were 366.4 and 3.4 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. Primisulfuron I50values were 3.6 and 0.007 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. A whole plant ALS assay was developed that allowed for much more rapid detection of an ALS-resistant species and used less plant material than a conventional ALS assay.

scholarly journals Management Options and Factors Affecting Control of a Common Waterhemp (Amaranthus rudis) Biotype Resistant to Protoporphyrinogen Oxidase-Inhibiting Herbicides

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Dana B. Harder ◽  
Kelly A. Nelson ◽  
Reid J. Smeda
Keyword(s):  
Herbicide Resistance ◽  
Herbicide Application ◽  
Management Options ◽  
Protoporphyrinogen Oxidase ◽  
Factors Affecting ◽  
Common Waterhemp ◽  
Control Options ◽  
Amaranthus Rudis ◽  
Repeated Use ◽  
Herbicide Activity

Repeated use of protox-inhibiting herbicides has resulted in a common waterhemp (Amaranthus rudisSauer) biotype that survived lactofen applied up to 10 times the labeled rate. Field and greenhouse research evaluated control options for this biotype of common waterhemp. In the field, PRE applications of flumioxazin at 72 g ai ha−1, sulfentrazone at 240 g ai ha−1, and isoxaflutole at 70 g ai ha−1controlled common waterhemp >90% up to 6 weeks after treatment. POST applications of fomesafen at 330 g ai ha−1, lactofen at 220 g ai ha−1, and acifluorfen at 420 g ai ha−1resulted in <60% visual control of common waterhemp, but differences were detected among herbicides. In the greenhouse, glyphosate was the only herbicide that controlled protox resistant waterhemp. The majority of herbicide activity from POST flumioxazin, fomesafen, acifluorfen, and lactofen was from foliar placement, but control was less than 40% regardless of placement. Control of common waterhemp seeded at weekly intervals after herbicide treatment with flumioxazin, fomesafen, sulfentrazone, atrazine, and isoxaflutole exceeded 85% at 0 weeks after herbicide application (WAHA), while control with isoxaflutole was greater than 60% 6 WAHA. PRE and POST options for protox-resistant common waterhemp are available to manage herbicide resistance.

Variable Response of Common Waterhemp (Amaranthus rudis) Populations and Individuals to Glyphosate

2006 ◽  
Vol 20 (2) ◽  
pp. 466-471 ◽  
Author(s):  
David A. Smith ◽  
Steven G. Hallett
Keyword(s):  
United States ◽  
Variable Response ◽  
Midwestern United States ◽  
Common Waterhemp ◽  
Leaf Stage ◽  
Amaranthus Rudis ◽  
Evolution Of Resistance ◽  
Different Parts

Putatively resistant (PR) and putatively susceptible (PS) common waterhemp populations were grown in the greenhouse and sprayed at the three- to four-leaf stage with glyphosate (0.63 kg ae/ha). Surviving plants from PR populations and randomly selected plants from PS populations were clonally propagated and the clones were sprayed with 0.1 to 10.0 kg/ha glyphosate. The glyphosate rates required to reduce growth by 50% (GR50) among the clones were relatively similar, but the concentration required to reduce growth by 90% (GR90) ranged from 1.5 to 16.3 kg/ha. The concentration of glyphosate required to kill 90% of plants (LD90) ranged from 2.3 kg/ha to over 10.0 kg/ ha. This range of responses to glyphosate in common waterhemp clones from different parts of the Midwestern United States indicates a risk of evolution of resistance in common waterhemp populations that are repeatedly selected by applications of glyphosate in the field.

Relative Competitiveness of Protoporphyrinogen Oxidase-Resistant Common Waterhemp (Amaranthus Rudis)

Weed Science ◽  
2009 ◽  
Vol 57 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Michael G. Duff ◽  
Kassim Al-Khatib ◽  
Dallas E. Peterson
Keyword(s):  
Leaf Area ◽  
Plant Height ◽  
Selection Pressure ◽  
Plant Biomass ◽  
Single Plant ◽  
Replacement Series ◽  
Protoporphyrinogen Oxidase ◽  
Common Waterhemp ◽  
Amaranthus Rudis ◽  
Series Study

Research was conducted to determine the competitiveness and fitness of a protoporphyrinogen oxidase (protox)-resistant common waterhemp biotype. Protox-resistant and protox-susceptible biotypes were grown under noncompetitive and competitive arrangements in the greenhouse. In the noncompetitive study, a single plant of each biotype was planted separately in 15-cm-diam pots. Photosynthesis, leaf area, and plant biomass were measured 10, 20, 30, and 40 d after transplanting (DATP). In general, photosynthesis rate and plant biomass were similar between biotypes. However, the protox-resistant biotype had higher leaf area than the susceptible biotype at 20, 30, and 40 DATP. A replacement series study was conducted in the greenhouse to evaluate the relative competitiveness of protox-resistant and protox-susceptible common waterhemp. Photosynthesis, leaf area, plant height, and plant biomass were measured 7, 14, 21, and 28 DATP. Protox-resistant and -susceptible common waterhemp were equally competitive 28 DATP. Relative crowding coefficient values 28 DATP were 0.86, 0.89, 1.09, and 1.13 for photosynthesis, leaf area, plant height, and plant biomass, respectively. This suggests protox-resistant and -susceptible common waterhemp were equally competitive and the frequency of protox-resistant biotype is unlikely to decrease in the absence of protox–herbicide selection pressure.

Control of Protoporphyrinogen Oxidase Inhibitor–Resistant Common Waterhemp (Amaranthus rudis) in Corn and Soybean

2004 ◽  
Vol 18 (2) ◽  
pp. 332-340 ◽  
Author(s):  
Douglas E. Shoup ◽  
Kassim Al-Khatib
Keyword(s):  
Field Experiments ◽  
Oxidase Inhibitor ◽  
Protoporphyrinogen Oxidase ◽  
Common Waterhemp ◽  
Herbicide Treatment ◽  
Amaranthus Rudis

Field experiments were conducted in 2001 and 2002 to evaluate the efficacy of herbicides on protoporphyrinogen oxidase (protox, EC 1.3.3.4) inhibitor–resistant common waterhemp in corn and soybean. All corn herbicides tested gave greater than 90% common waterhemp control by 8 wk after postemergence herbicide treatment (WAPT). In soybean, common waterhemp control was less than 40% by 8 WAPT with postemergence protox-inhibiting herbicides lactofen and acifluorfen. However, preemergence protox-inhibiting herbicides sulfentrazone and flumioxazin gave greater than 85% common waterhemp control in both years. The greatest common waterhemp control in soybean was with glyphosate alone, alachlor + metribuzin, alachlor followed by (fb) glyphosate, and S-metolachlor + metribuzin fb glyphosate.

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