Influence of Carrier Water pH, Hardness, Foliar Fertilizer, and Ammonium Sulfate on Mesotrione Efficacy

2016 ◽  
Vol 30 (3) ◽  
pp. 617-628 ◽  
Author(s):  
Pratap Devkota ◽  
Douglas J. Spaunhorst ◽  
William G. Johnson
Keyword(s):  
Ammonium Sulfate ◽  
Plant Height ◽  
Water Hardness ◽  
Dry Weight ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Foliar Fertilizer ◽  
Greenhouse Study ◽  
Giant Ragweed ◽  
Water Ph

Carrier water pH, hardness, coapplied foliar fertilizer, water conditioning agents, and plant height are critical considerations for optimum herbicide performance. Field studies were conducted to evaluate the effect of carrier water pH (4, 6.5, and 9) and zinc (Zn) or manganese (Mn) foliar fertilizer on mesotrione for horseweed and Palmer amaranth control. Additionally, effect of carrier water pH and foliar fertilizer was evaluated on 7.5-, 12.5-, and 17.5-cm tall horseweed. Greenhouse treatments consisted of carrier water pH and foliar fertilizer (Zn, Mn, or without fertilizer); or water hardness (0 to 1,000 mg L−1) in the presence or absence of ammonium sulfate (AMS) for mesotrione control of giant ragweed, horseweed, and Palmer amaranth. Mesotrione activity was greater on horseweed with carrier water pH 6.5 compared to pH 4 or 9. Coapplied Zn fertilizer reduced mesotrione activity on Palmer amaranth in the field study in 2014 and horseweed in the greenhouse study. Mesotrione efficacy was greatly influenced by horseweed height. Percent control ranged from 96 to 99%, 75 to 89%, or 61 to 64% with mesotrione applied on 7.5-, 12.5-, or 17.5-cm tall horseweed, respectively, and results were similar for plant height and dry weight reduction. Increasing carrier water hardness from 0 to 1,000 mg L−1reduced mesotrione efficacy 28, 18, and 18% (or greater) on giant ragweed, horseweed, and Palmer amaranth, respectively. The addition of AMS enhanced mesotrione efficacy 9, 6, or 9% (or greater) for giant ragweed, horseweed, and Palmer amaranth control, respectively. Mesotrione should be applied at near neutral carrier water pH, hardness < 200 mg L−1, and with AMS for achieving optimum weed control.

Glufosinate Efficacy as Influenced by Carrier Water pH, Hardness, Foliar Fertilizer, and Ammonium Sulfate

2016 ◽  
Vol 30 (4) ◽  
pp. 848-859 ◽  
Author(s):  
Pratap Devkota ◽  
William G. Johnson
Keyword(s):  
Ammonium Sulfate ◽  
Plant Density ◽  
Control Plant ◽  
Water Hardness ◽  
Palmer Amaranth ◽  
Foliar Fertilizer ◽  
Density Reduction ◽  
Giant Ragweed ◽  
Water Ph ◽  
Biomass Reduction

Carrier water quality is an important consideration for herbicide efficacy. Effect of carrier water pH (4, 6.5, or 9) and coapplied Zn or Mn foliar fertilizer was evaluated on glufosinate efficacy for horseweed and Palmer amaranth control in the field. Greenhouse studies were conducted to evaluate the effect of: (1) carrier water pH, foliar fertilizer (Zn, Mn, or without fertilizer), and ammonium sulfate (AMS) (at 0 or 2.5% v/v); and (2) carrier water hardness (0 to 1,000 mg L−1) and AMS (at 0 or 2.5% v/v) on glufosinate efficacy for giant ragweed, horseweed, and Palmer amaranth control. In a 2014 field study, control, plant density reduction, and biomass reduction were at least 8% greater for horseweed and at least 14% greater for Palmer amaranth when glufosinate was applied at carrier water pH 4 compared with pH 9. Glufosinate efficacy was at least 10 and 17% greater for giant ragweed and Palmer amaranth control, respectively, with carrier water pH 4 compared with pH 9 in the greenhouse. In the greenhouse studies, coapplied Zn or Mn fertilizer had no effect on glufosinate efficacy. Increased carrier water hardness from 0 to 1,000 mg L−1negatively influenced glufosinate efficacy and resulted in 20 and 17% lesser control and biomass reduction, respectively, on giant ragweed or Palmer amaranth. Use of AMS enhanced glufosinate efficacy on giant ragweed control in both greenhouse studies, whereas only the Palmer amaranth control was enhanced in the water hardness study. Horseweed control with glufosinate as affected by carrier water pH, hardness, or AMS remained unaffected in both greenhouse studies. Carrier water at alkaline pH or hardness > 200 mg L−1has potential to reduce glufosinate efficacy. Therefore, carrier water free of hardness cations and at acidic condition (pH = 4 to 6.5) should be considered for optimum glufosinate efficacy.

Influence of carrier water pH, foliar fertilizer, and ammonium sulfate on 2,4-D and 2,4-D plus glyphosate efficacy

2019 ◽  
Vol 33 (04) ◽  
pp. 562-568 ◽  
Author(s):  
Pratap Devkota ◽  
William G. Johnson
Keyword(s):  
Field Study ◽  
Ammonium Sulfate ◽  
Weed Control ◽  
Palmer Amaranth ◽  
Weed Species ◽  
Foliar Fertilizer ◽  
Greenhouse Study ◽  
Giant Ragweed ◽  
Negative Effect ◽  
Water Ph

AbstractCarrier water pH is an important factor for enhancing herbicide efficacy. Coapplying agrochemical products with the herbicide might save time and resources; however, the negative effect of foliar fertilizers on herbicide efficacy should be thoroughly evaluated. In greenhouse studies, the effect of carrier water pH (4, 6.5, and 9), foliar fertilizer (zinc [Zn], manganese [Mn], or without fertilizer), and ammonium sulfate (AMS) at 0% or 2.5% vol/vol was evaluated on 2,4-D and premixed 2,4-D plus glyphosate efficacy for giant ragweed, horseweed, and Palmer amaranth control. In addition, a field study was conducted to evaluate the effect of carrier water pH (4, 6.5, and 9); and Zn or Mn foliar fertilizer on premixed 2,4-D plus glyphosate efficacy for horseweed and Palmer amaranth control. In the greenhouse study, 2,4-D and premixed 2,4-D plus glyphosate provided 5% greater weed control at acidic compared with alkaline carrier water pH. Coapplied Mn foliar fertilizer reduced 2,4-D and premixed 2,4-D plus glyphosate efficacy at least 5% for weed control. Addition of AMS enhanced 2,4-D and premixed 2,4-D plus glyphosate efficacy at least 6% for giant ragweed, horseweed, and Palmer amaranth control. In the field study, few significant differences occurred between coapplied Zn or Mn foliar fertilizer for any treatment variables. Therefore, carrier water pH, coapplied foliar fertilizer, and water-conditioning adjuvants have potential to influence herbicide performance. However, weed species could play a role in the differential response of these factors on herbicide efficacy.

Efficacy of dicamba and glyphosate as influenced by carrier water pH and hardness

2019 ◽  
Vol 34 (1) ◽  
pp. 101-106
Author(s):  
Pratap Devkota ◽  
William G. Johnson
Keyword(s):  
Field Study ◽  
Water Hardness ◽  
Palmer Amaranth ◽  
Common Ragweed ◽  
Common Lambsquarters ◽  
Greenhouse Study ◽  
Spray Solution ◽  
Giant Ragweed ◽  
Pitted Morningglory ◽  
Water Ph

AbstractHerbicide carrier water hardness and pH can be variable depending on the source and geographic location. Herbicide efficacy can be affected by the pH and hardness of water used for spray solution. Field and greenhouse studies were conducted to evaluate the effect of carrier water pH and hardness on premixed dicamba and glyphosate efficacy. Treatments were combinations of water pH at 4, 6.5, or 9; and water hardness at 0 (deionized water), 400, or 800 mg L−1 of CaCO3 equivalent. In the field study, dicamba and glyphosate were applied at 0.55 and 1.11 kg ae ha−1, respectively, and half of these rates were applied in the greenhouse study. There was no interaction between carrier water pH and hardness on dicamba and glyphosate efficacy; however, the main effects of carrier water pH and hardness were significant. Herbicide efficacy was reduced with carrier water at pH 9 compared with pH 4. In the field study, common lambsquarters, common ragweed, horseweed, or Palmer amaranth control was improved 6% or more at carrier water at pH 4 compared with pH 9. Similar results were observed with water pH for giant ragweed, Palmer amaranth, or pitted morningglory control in the greenhouse study. Carrier water hardness at 400 or 800 mg L−1 reduced common ragweed, giant ragweed, or horseweed control compared with 0 mg L−1. Similarly, common lambsquarters, Palmer amaranth, or pitted morningglory control was reduced at least 10% with carrier water hardness at 800 mg L−1 compared with 0 mg L−1. These results indicate carrier water at acidic pH and of no hardness is critical for dicamba and glyphosate application, and spray solution needs to be amended appropriately for an optimum efficacy.

Effect of Carrier Water Hardness and Ammonium Sulfate on Efficacy of 2,4-D Choline and Premixed 2,4-D Choline Plus Glyphosate

2016 ◽  
Vol 30 (4) ◽  
pp. 878-887 ◽  
Author(s):  
Pratap Devkota ◽  
William G. Johnson
Keyword(s):  
Water Quality ◽  
Ammonium Sulfate ◽  
Linear Trend ◽  
Water Hardness ◽  
Hard Water ◽  
Palmer Amaranth ◽  
Weed Species ◽  
Hardness Level ◽  
Spray Solution ◽  
Giant Ragweed

Spray water quality is an important consideration for optimizing herbicide efficacy. Hard water cations in the carrier water can reduce herbicide performance. Greenhouse studies were conducted to evaluate the influence of hard water cations and the use of ammonium sulfate (AMS) on the efficacy of 2,4-D choline and premixed 2,4-D choline plus glyphosate for giant ragweed, horseweed, and Palmer amaranth control. Carrier water hardness was established at 0, 200, 400, 600, 800, or 1,000 mg L−1using CaCl2and MgSO4, and each hardness level consisted of without or with AMS at 10.2 g L−1. One-third of the proposed use rates of 2,4-D choline at 280 g ae ha−1and 2,4-D choline plus glyphosate at 266 plus 283 g ae ha−1, respectively, were applied in the study. An increase in carrier water hardness showed a linear trend for reducing 2,4-D choline and 2,4-D choline plus glyphosate efficacy on all weed species evaluated in both studies. The increase in water hardness level reduced giant ragweed control with 2,4-D choline and the premix formulation of 2,4-D choline plus glyphosate to a greater extent without AMS than it did with AMS in the spray solution. Increases in water hardness from 0 to 1,000 mg L−1reduced weed control 20% or greater with 2,4-D choline. Likewise, the efficacy of the premixed 2,4-D choline plus glyphosate was reduced 21% or greater with increased water hardness from 0 to 1,000 mg L−1. The addition of AMS improved giant ragweed, horseweed, and Palmer amaranth control ≥ 17% and ≥ 10% for 2,4-D choline and 2,4-D choline plus glyphosate application, respectively. The biomass of all weed species was reduced by ≥ 8% and ≥ 5% with 2,4-D choline and 2,4-D choline plus glyphosate application, respectively, when AMS was added to hard water.

Evaluation of 2,4-D–based Herbicide Mixtures for Control of Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri)

2018 ◽  
Vol 33 (2) ◽  
pp. 263-271 ◽  
Author(s):  
Benjamin H. Lawrence ◽  
Jason A. Bond ◽  
Thomas W. Eubank ◽  
Bobby R. Golden ◽  
Donald R. Cook ◽  
...  
Keyword(s):  
Dry Weight ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Greenhouse Study ◽  
Synthetic Auxins ◽  
Control Options ◽  
Herbicide Mixture ◽  
Herbicide Mixtures ◽  
Sites Of Action

AbstractUnderstanding control of glyphosate-resistant (GR) Palmer amaranth with multiple herbicide sites of action, including synthetic auxins, is crucial for growers to minimize GR Palmer amaranth interference with crops. Field studies in 2013 and 2014 and a greenhouse study in 2014 were conducted in Stoneville, MS, to evaluate POST control of GR Palmer amaranth with 2,4-D alone and in mixtures with glyphosate and/or glufosinate. In the greenhouse study, control of 5- and 10-cm GR Palmer amaranth was 87% with 2,4-D at 0.84 kg ae ha−1. Dry weight reduction of GR Palmer amaranth was ≥81% with 2,4-D at 0.84 kg ha−1. In field studies, mixtures of glufosinate at 0.59 kg ai ha−1and 2,4-D at 0.56 or 1.12 kg ae ha−1controlled 5- to 10-cm GR Palmer amaranth 87% at 28 d after treatment (DAT). Averaged across glyphosate treatments, glufosinate applied alone applied to 5- to 10-cm GR Palmer amaranth reduced dry weight at 28 DAT to 20 g m−2from 82 g m−2and was comparable with that following 2,4-D applied alone at 1.12 kg ae ha−1and mixtures of glufosinate plus 2,4-D at 0.56 and 1.12 kg ae ha−1. Mixtures of 2,4-D plus glufosinate provided ≥92% control of 15- to 20-cm GR Palmer amaranth at 28 DAT. When applied to 15- to 20-cm plants, mixtures of 2,4-D plus glufosinate reduced GR Palmer amaranth density to ≤5 plants m−2compared with 65 plants m−2where no 2,4-D or glufosinate was applied. Glufosinate and 2,4-D are viable control options for 5- to 10-cm or 15- to 20-cm GR Palmer amaranth. However, 2,4-D did not improve GR Palmer amaranth control when added to any herbicide mixture except glyphosate and glufosinate applied to 15- to 20-cm plants at the 28 DAT evaluation.

The Influence of Adjusting Spray Solution pH on the Efficacy of Saflufenacil

2013 ◽  
Vol 27 (3) ◽  
pp. 445-447 ◽  
Author(s):  
Jared M. Roskamp ◽  
William G. Johnson
Keyword(s):  
Ammonium Sulfate ◽  
Weight Reduction ◽  
Seed Oil ◽  
Dry Weight ◽  
Final Solution ◽  
Solution Ph ◽  
Field Corn ◽  
Spray Solution ◽  
Initial Ph ◽  
Water Ph

Saflufenacil solubility and efficacy has been shown to be influenced by carrier water pH. This research was conducted to determine if altering the pH of a solution already containing saflufenacil would influence the efficacy of the herbicide. Saflufenacil at 25 g ai ha−1was applied to field corn in carrier water with one of five initial pH levels (4.0, 5.2, 6.5, 7.7, or 9.0) and then buffered to one of four final solution pH levels (4.0, 6.5, 9.0, or none) for a total of twenty treatments. All treatments included ammonium sulfate at 20.37 g L−1and methylated seed oil at 1% v/v. Generally, saflufenacil with a final solution pH of 6.5 or higher provided more dry weight reduction of corn than saflufenacil applied in a final pH of 5.2 or lower. When applying saflufenacil in water with an initial pH of 4.0 or 5.2, efficacy was increased by raising the final solution pH to either 6.5 or 9.0. Conversely, reduction in corn dry weight was less when solution pH of saflufenacil mixed in carrier water with an initial pH of 6.5 or 7.7 was lowered to a final pH of 4.0. When co-applying saflufenacil with herbicides that are very acidic, such as glyphosate, efficacy of saflufenacil may be reduced if solution pH is 5.2 or lower.

scholarly journals Sequential Applications of Synthetic Auxins and Glufosinate for Escaped Palmer Amaranth Control

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1425
Author(s):  
Frances B. Browne ◽  
Xiao Li ◽  
Katilyn J. Price ◽  
Ryan Langemeier ◽  
Alvaro Sanz-Saez de Jauregui ◽  
...  
Keyword(s):  
Field Studies ◽  
Co2 Assimilation ◽  
Palmer Amaranth ◽  
Leaf Biomass ◽  
Amaranthus Palmeri ◽  
Time Intervals ◽  
Greenhouse Study ◽  
Synthetic Auxins ◽  
Reverse Sequence ◽  
Henry County

Field and greenhouse studies were conducted to investigate the influence of sequence and timing of synthetic auxins and glufosinate on large Palmer amaranth (Amaranthus palmeri) control. Field studies were performed in Henry County, AL where treatments were applied to Palmer amaranth with average heights of 37 and 59 cm in 2018 and 2019, respectively. Sequential applications of 2,4-D/dicamba + glyphosate followed by (fb) glufosinate at labeled rates 3 or 7 days after initial treatment (DAIT) were used in addition to the reverse sequence with a 7-day interval. Time intervals of 3 or 7 days between applications did not influence Palmer amaranth control. Palmer amaranth was controlled 100% by dicamba + glyphosate fb glufosinate and 2,4-D + glufosinate fb glufosinate 7 DAIT in 2018. However, herbicide performance was reduced due to delayed application and taller plants in 2019 with up to 23% less visual injury. To further investigate Palmer amaranth response to dicamba and glufosinate applied sequentially, a greenhouse study was conducted in 2019 where physiological measurements were recorded over a 35-day period. Treatments were applied to Palmer amaranth averaging 38 cm tall and included dicamba + glyphosate fb glufosinate 7 DAIT, the reverse sequence, and a single application of dicamba + glufosinate + glyphosate. Glufosinate severely inhibited mid-day photosynthesis compared to dicamba with up to 90% reductions in CO2 assimilation 1 DAIT. In general, Palmer amaranth respiration and stomatal conductance were not affected by herbicides in this study. Applications of dicamba + glyphosate fb glufosinate 7 DAIT was the only treatment hindered Palmer amaranth regrowth with 52% reduction in leaf biomass compared to nontreated control. These data suggest Palmer amaranth infested fields are more likely to be rescued with sequential applications of synthetic auxins and glufosinate, but consistent control of large Palmer is not probable.

scholarly journals The effect of field dodder (Cuscuta campestris Yunck.) on morphological and fluorescence parameters of giant ragweed (Ambrosia trifida L.)

2013 ◽  
Vol 28 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Sava Vrbnicanin ◽  
Marija Saric-Krsmanovic ◽  
Dragana Bozic
Keyword(s):  
Chlorophyll Fluorescence ◽  
Plant Height ◽  
Dry Weight ◽  
Flowering Plant ◽  
Fresh Weight ◽  
Ambrosia Trifida ◽  
Fluorescence Parameters ◽  
Fluorescence Measurements ◽  
Giant Ragweed ◽  
Cuscuta Campestris

The effect of the parasitic flowering plant known as field dodder (Cuscuta campestris Yunck.) on morphological and fluorescence parameters of infested giant ragweed (Ambrosia trifida L.) plants was examined under controlled conditions. The parameters of chlorophyll fluorescence (Fo, Fv/Fm, ?PSII, Fv, Fm, ETR and IF) were measured on infested (I) and non-infested (N) A. trifida plants over a period of seven days, beginning with the day of infestation. Morphological parameters (plant height, dry and fresh weight) were measured on the last day of fluorescence measurements. C. campestris was found to affect the height, fresh and dry weight of the infested A. trifida plants, causing significant reduction in plant height and dry weight. Field dodder also affected several parameters of chlorophyll fluorescence (Fo, Fv/Fm, ?PSII and Fv) in infested A. trifida plants.

A Chlorophyll Assay to Assess Sethoxydim Activity in Two Grass Species

1991 ◽  
Vol 5 (2) ◽  
pp. 355-362 ◽  
Author(s):  
Anne M. Smith ◽  
William H. Vanden Born
Keyword(s):  
Ammonium Sulfate ◽  
Plant Height ◽  
Rapid Development ◽  
Chlorophyll Concentration ◽  
Dry Weight ◽  
Grass Species ◽  
Visual Rating ◽  
Wild Oats ◽  
Time Required ◽  
Better Than

The influence of ammonium sulfate on the activity of sethoxydim on wild oats and barley was examined under field conditions in 1989 and 1990. A chlorophyll assay, together with plant height and dry weight determinations, was used to quantify the visual ratings for sethoxydim activity. Ammonium sulfate enhanced the activity of 75 and 150 g ai ha-1sethoxydim in 1989. In 1990, ammonium sulfate increased the activity of the lower rate of sethoxydim only. Of the three quantitative assays, chlorophyll concentration alone differentiated the more rapid development of injury symptoms with added ammonium sulfate that was observed in the visual ratings. The chlorophyll assay was not better than the visual rating assessment, however, and appears to offer no advantages that would justify the time required.

Response of Palmer Amaranth (Amaranthus palmeri) Accessions to Glyphosate, Fomesafen, and Pyrithiobac

2006 ◽  
Vol 20 (4) ◽  
pp. 885-892 ◽  
Author(s):  
Jason A. Bond ◽  
Lawrence R. Oliver ◽  
Daniel O. Stephenson
Keyword(s):  
United States ◽  
Dry Weight ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Southern United States ◽  
Amaranthus Palmeri ◽  
Modes Of Action

Field studies were conducted at Fayetteville, Arkansas, to determine whether 47 Palmer amaranth accessions from different areas of the southern United States varied in response to postemergence applications of the registered rates of the isopropylamine salt of glyphosate (840 g ae/ha), fomesafen (420 g ai/ha), and pyrithiobac (70 g ai/ha). Glyphosate controlled all Palmer amaranth accessions at least 99% 21 d after treatment (DAT). Palmer amaranth control with fomesafen was equivalent for all accessions and at least 96% 21 DAT. Percent dry weight reductions were at least 92 and 94% for glyphosate and fomesafen, respectively. Palmer amaranth control with pyrithiobac was variable and ranged from 20 to 94% 21 DAT, but differences could not be attributed to accession origin. Herbicides with alternate modes of action from pyrithiobac should be utilized for Palmer amaranth control in regions where pyrithiobac has been used continuously.

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