Influence of Imazapyr on the Control of Pitted Morningglory (Ipomoea lacunosa) and Johnsongrass (Sorghum halepense) with Chlorimuron, Imazaquin, and Imazethapyr

Weed Science ◽  
1988 ◽  
Vol 36 (5) ◽  
pp. 663-666 ◽  
Author(s):  
Dennis G. Riley ◽  
David R. Shaw

Field experiments were conducted to evaluate postemergence combinations of imazethapyr, imazquin, or chlorimuron with low rates of imazapyr for Johnsongrass and pitted morningglory control. Imazapyr applied alone at rates up to 4 g ai/ha gave little or no control of either weed species. However, the addition of imazapyr to various rates of imazethapyr or imazaquin synergistically increased both johnsongrass and pitted morningglory control 8 weeks after treatment. The rates of imazethapyr or imazaquin required for significant enhancement of johnsongrass control were higher than those required for pitted morningglory control. No synergistic increases in control of either weed species were noted with mixtures of imazapyr and chlorimuron. Although not synergistic in every case, the mixtures of imazapyr at 4 g/ha with imazethapyr, imazaquin, or chlorimuron gave johnsongrass and pitted morningglory control equal to or better than the next higher rate of these herbicides applied alone. Imazapyr did not increase soybean injury or decrease yield provided by chlorimuron, imazaquin, or imazethapyr.

1989 ◽  
Vol 3 (1) ◽  
pp. 95-98 ◽  
Author(s):  
Dennis G. Riley ◽  
David R. Shaw

Imazaquin and imazethapyr were applied postemergence to soybeans for control of 8- to 12-leaf rhizome johnsongrass and pitted morningglory in the field. At 8 weeks, johnsongrass control was 70% with 70 g ai/ha imazaquin plus 105 g ai/ha imazethapyr but was no more than 50% with a single application of either herbicide. Imazaquin at 70 g/ha plus imazethapyr at 35 g/ha interacted synergistically to provide 90% pitted morningglory control, while 140 g/ha imazaquin controlled 77%. Imazaquin at 70 g/ha with imazethapyr from 18 to 105 g/ha controlled both weed species equal to or better than that obtained with 140 g/ha imazaquin.


1990 ◽  
Vol 4 (4) ◽  
pp. 900-903 ◽  
Author(s):  
David R. Shaw ◽  
Sunil Ratnayake ◽  
Clyde A. Smith

Field experiments were conducted to evaluate the influence of application timing of imazethapyr and fluazifop-P on rhizome johnsongrass and pitted morningglory control in soybean. Herbicides were applied at three timings keyed to johnsongrass heights of 15, 30, and 60 cm and 3-, 6-, and 9-leaf pitted morningglory. Evaluations 6 wk after the final treatment indicated imazethapyr controlled both species best when applied at the 15-cm johnsongrass growth stage. Increasing imazethapyr rate did not increase control of pitted morningglory, but did increase johnsongrass control at the 15-cm application timing. However, at the 30-cm johnsongrass application timing, increasing the rate from 0.07 to 0.10 kg ha-1improved control of both species. Johnsongrass control with imazethapyr was no more than 64% when applications were delayed to 30-cm or larger johnsongrass. Fluazifop-P controlled johnsongrass well at all timings.


1997 ◽  
Vol 11 (4) ◽  
pp. 725-730 ◽  
Author(s):  
Joyce A. Tredaway ◽  
Michael G. Patterson ◽  
Glen R. Wehtje

Field experiments were conducted in 1994 and 1995 to determine if the sodium salt of pyrithiobac or bromoxynil applied in a low-volume, air-assist spray system controlled entireleaf morningglory, pitted morningglory, and smallflower morningglory as well as treatments applied with a conventional hydraulic fan spraying system, and to determine if herbicide rates could be reduced when using the low-volume spraying system. Pyrithiobac at 0.035 and 0.071 kg ai/ha and bromoxynil at 0.56 and 1.12 kg ai/ha were applied alone and in combination with DSMA at 1.7 kg ai/ha or MSMA at 1.7 kg ai/ha. Spraying systems were calibrated to deliver 26 L/ha and 140 L/ha for the low-volume and conventional systems, respectively. No significant differences in control were noted between low-volume and conventional spray systems when herbicides were applied at the suggested use rates of 0.071 and 1.12 kg ai/ha for pyrithiobac and bromoxynil, respectively. Morningglory control was reduced when pyrithiobac and bromoxynil were applied at one-half the suggested use rate regardless of the spraying systems. Bromoxynil alone generally controlled pitted and entireleaf morningglory better than pyrithiobac alone regardless of rate and application method. However, pyrithiobac generally provided better control of smallflower morningglory than bromoxynil. Adding MSMA or DSMA to bromoxynil and pyrithiobac increased control of both weed species.


Weed Science ◽  
1983 ◽  
Vol 31 (2) ◽  
pp. 264-270 ◽  
Author(s):  
G. H. Egley ◽  
J. M. Chandler

Seeds of 20 weed species buried at depths of 8, 23, and 38 cm in 1972 and 1973 were exhumed at regular intervals and tested for viability and germination. Burial depth had little to no significant influence on longevity. After 5.5 yr 48% of johnsongrass [Sorghum halepense(L.) Pers.], 36% of velvetleaf (Abutilon theophrastiMedic.), 33% of purple moonflower (Ipomoea turbinataLag.), 30% of spurred anoda [Anoda cristata(L.) Schlecht], 18% of hemp sesbania [Sesbania exaltata(Raf.) Cory], and 13% of pitted morningglory (Ipomoea lacunosaL.) seeds were still viable. No more than 6% of the original population for any other species was viable at 5.5 yr. Hard seeds comprised a high percentage of the longer-lived seeds. Seeds of longest-lived species were losing viability at an average of 26% of the existing population each year from 3.5 to 5.5 yr.


2018 ◽  
Vol 32 (3) ◽  
pp. 319-325 ◽  
Author(s):  
M. Ryan Miller ◽  
Jason K. Norsworthy

AbstractFlorpyrauxifen-benzyl is a new herbicide being developed for rice. Research is needed to understand its spectrum of control and optimal tank-mix partners. Multiple greenhouse and field experiments were conducted to evaluate florpyrauxifen-benzyl efficacy and tank-mix compatibility. In greenhouse experiments, florpyrauxifen-benzyl at 30 g ai ha–1provided ≥75% control of all weed species evaluated (broadleaf signalgrass, barnyardgrass, Amazon sprangletop, large crabgrass, northern jointvetch, hemp sesbania, pitted morningglory, Palmer amaranth, yellow nutsedge, rice flatsedge, smallflower umbrellasedge), and control was similar to or better than other herbicide options currently available in rice. Barnyardgrass was controlled 97% with florpyrauxifen-benzyl at 30 g ha–1, ultimately reducing height (86%) and aboveground biomass (84%). In these field studies at 30 g ha–1, no antagonism was observed when florpyrauxifen-benzyl was tank-mixed with contact (acifluorfen, bentazon, carfentrazone, propanil, and saflufenacil) or systemic (2,4-D, bispyribac, cyhalofop, fenoxaprop, halosulfuron, imazethapyr, penoxsulam, quinclorac, and triclopyr) rice herbicides. Although not every tank-mix or weed species was evaluated, the lack of antagonistic interactions herein highlights the flexibility and versatility of this new herbicide. Once florpyrauxifen-benzyl becomes commercially available, it will be beneficial to tank-mix this new herbicide with others without sacrificing efficacy, so as to apply multiple sites of action together and thus lessen the risk for evolution of herbicide resistance.


Weed Science ◽  
1980 ◽  
Vol 28 (1) ◽  
pp. 59-63 ◽  
Author(s):  
C. G. McWhorter ◽  
J. R. Williford

Field experiments were conducted to determine optimum nozzle settings for applying glyphosate [N-(phosphonomethyl)glycine] in the recirculating sprayer for postemergence control of johnsongrass [Sorghum halepense(L.) Pers.] in soybeans [Glycine max(L.) Merr.]. Herbicide sprays were directed across the row to johnsongrass growing taller than soybeans in July and August. Herbicide not sprayed on johnsongrass was trapped and reused. Glyphosate at 0.56, 1.12, and 2.24 kg/ha applied with commercially available 25° spray nozzles provided johnsongrass control and soybean yields equal to those following applications with specialized uniform droplet nozzles. Glyphosate at 1.7 kg/ha applied in the recirculating sprayer using only one nozzle per row provided control of johnsongrass equal to or better than that from applications made with two, three, or four nozzles per row. Soybean yield following application of glyphosate at 1.7 kg/ha with one nozzle per row was equal to yields obtained following its application with two, three, or four nozzles per row, with or without surfactant at 0.1% in spray solutions. Soybean yield was higher with four nozzles per row than with one nozzle per row when 0.5% surfactant was included in spray solutions. Soybean injury was lower and yield was higher when glyphosate was applied in the recirculating sprayer rather than over-the-top with a conventional sprayer. Glyphosate at 1.12 kg/ha applied in the recirculating sprayer caused more injury to ‘Hill’ and ‘Bragg’ than to ‘Forrest’ or ‘Tracy’ soybeans.


1994 ◽  
Vol 8 (1) ◽  
pp. 23-27 ◽  
Author(s):  
David L. Jordan ◽  
John W. Wilcut ◽  
Leslie D. Fortner

Field experiments conducted in 1988 and 1989 evaluated clomazone alone and in a systems approach for weed control in peanut. Clomazone PPI at 0.8 kg ai/ha controlled common ragweed, prickly sida, spurred anoda, and tropic croton better than ethalfluralin and/or metolachlor applied PPI. POST application of acifluorfen plus bentazon was not needed to control these weeds when clomazone was used. Acifluorfen plus bentazon improved control of these weeds when clomazone was not used and generally were necessary to obtain peanut yields regardless of the soil-applied herbicides. Alachlor PRE did not improve clomazone control of any weed species evaluated. Fall panicum and large crabgrass control was similar with clomazone or clomazone plus ethalfluralin.


Weed Science ◽  
2009 ◽  
Vol 57 (4) ◽  
pp. 357-361 ◽  
Author(s):  
Wesley J. Everman ◽  
Walter E. Thomas ◽  
James D. Burton ◽  
Alan C. York ◽  
John W. Wilcut

Greenhouse studies were conducted to evaluate absorption, translocation, and metabolism of14C-glufosinate in glufosinate-resistant cotton, nontransgenic cotton, Palmer amaranth, and pitted morningglory. Cotton plants were treated at the four-leaf stage, whereas Palmer amaranth and pitted morningglory were treated at 7.5 and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption of14C-glufosinate was greater than 85% 24 h after treatment in Palmer amaranth. Absorption was less than 30% at all harvest intervals for glufosinate-resistant cotton, nontransgenic cotton, and pitted morningglory. At 24 HAT, 49 and 12% of radioactivity was translocated to regions above and below the treated leaf, respectively, in Palmer amaranth. Metabolites of14C-glufosinate were detected in all crop and weed species. Metabolism of14C-glufosinate was 16% or lower in nontransgenic cotton and pitted morningglory; however, metabolism rates were greater than 70% in glufosinate-resistant cotton 72 HAT. Intermediate metabolism was observed for Palmer amaranth, with metabolites comprising 20 to 30% of detectable radioactivity between 6 and 72 HAT.


Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 568-572 ◽  
Author(s):  
G. A. Buchanan ◽  
J. E. Street ◽  
R. H. Crowley

Influence of time of planting and distance from the cotton row of pitted morningglory (Ipomoea lacunosaL.), prickly sida (Sida spinosaL.), and redroot pigweed (Amaranthus retroflexusL.) on yield of seed cotton (Gossypium hirsutumL. ‘Stoneville 213’) was determined on Decatur clay loam during 1975 through 1978. Weed growth was measured in 1977 and 1978. Seeds of the three weed species were planted 15, 30, or 45 cm from the cotton row at time of planting cotton or 4 weeks later. Weeds planted 4 weeks after planting cotton grew significantly less than did weeds planted at the same time as cotton. When planted with cotton, redroot pigweed produced over twice as much fresh weight as did prickly sida or pitted morningglory. The distance that weeds were planted from the cotton row did not affect weed growth in 1978, but did in 1977. The distance that weeds were planted from the cotton row did not affect their competitiveness in any year as measured by yield of cotton. However, in each year, yields of cotton were reduced to a greater extent by weeds planted with cotton than when planted 4 weeks later. In 3 of 4 yr, there were significant differences in competitiveness of each of the three weed species with cotton.


Weed Science ◽  
1971 ◽  
Vol 19 (3) ◽  
pp. 229-233 ◽  
Author(s):  
C. G. McWhorter

Field experiments were conducted to study the effectiveness of 2,2-dichloropropionic acid (dalapon) for the control of 55 morphologically distinct ecotypes of johnsongrass (Sorghum halepense(L.) Pers.) collected throughout the United States and from several foreign countries. Ecotypes varied widely in their response to dalapon whether collected from Mississippi, from 10 other states, or from eight foreign countries. Initial control of seven ecotypes with dalapon increased 8 to 35% when nitrogen fertilization was increased from 0 to 300 lb/A. Regrowth of surviving plants was more vigorous with increased nitrogen levels so increased fertility reduced final control. Comparative differences in the susceptibility of the seven selected ecotypes to monosodium methanearsonate (MSMA) were not as great as those obtained with dalapon. Varying the rate of nitrogen fertilization had less effect on johnsongrass susceptibility to MSMA than to dalapon. Dalapon controlled sorghum almum (Sorghum almumParodi) better than johnsongrass.


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