Application of synthetic auxin herbicides to suppress seed viability of Italian ryegrass (Lolium perenne ssp. multiflorum) in tall fescue seed production

2020 ◽  
Vol 34 (4) ◽  
pp. 489-497
Author(s):  
Lucas K. Bobadilla ◽  
Andrew G. Hulting ◽  
Daniel W. Curtis ◽  
Carol Mallory-Smith

AbstractItalian ryegrass is one of the most troublesome weeds worldwide because of the rapid evolution of herbicide resistance in this species. Oregon tall fescue seed production requires high seed purity, demanding good control of Italian ryegrass. The necessity to control herbicide-resistant Italian ryegrass and maintain tall fescue seed purity created interest in new chemical management options. The objectives of this study were to assess the effects of synthetic auxin herbicides on seed viability of Italian ryegrass biotypes and the feasibility of this management strategy for use in tall fescue seed production. Eight treatments of synthetic auxin herbicides were applied to Italian ryegrass and tall fescue at two growth stages (boot and anthesis): dicamba (1.0 and 2.2 kg ae ha−1), 2,4-D (1.1 and 2.2 kg ae ha−1), aminopyralid (0.5 kg ae ha−1), dicamba + 2.4-D (0.8 + 1.1 kg ae ha−1), 2.4-D + clopyralid (1.1 + 0.3 kg ae ha−1), and halauxifen-methyl + florasulam (0.4 kg ae ha−1 + 0.4 kg ai ha−1). Aminopyralid applied at boot and anthesis stages of Italian ryegrass reduced seed viability. Aminopyralid treatments reduced seed viability and weight of Italian ryegrass more than 50% compared to the control. Four biotypes from different locations in western Oregon with different types of herbicide resistance were sprayed, and differences in aminopyralid effect among Italian ryegrass biotypes were documented. Aminopyralid reduced the speed of germination by 1 to 2 d. Aminopyralid treatments had a greater effect when applied at the anthesis stage and had a greater negative impact on tall fescue. Tall fescue plants were more susceptible to aminopyralid, so this management practice is not feasible for tall fescue seed production. Future studies are needed to understand the physiological mechanisms involved in the reduced seed viability and to define an optimum aminopyralid rate for different Italian ryegrass biotypes.

2008 ◽  
Vol 36 (3) ◽  
pp. 710-720 ◽  
Author(s):  
S.L. Clement ◽  
R.C. Martin ◽  
J.E. Dombrowski ◽  
L.R. Elberson ◽  
M. Kynaston ◽  
...  

2020 ◽  
pp. 1-7
Author(s):  
Eric B. Scruggs ◽  
Mark J. VanGessel ◽  
David L. Holshouser ◽  
Michael L. Flessner

Abstract Palmer amaranth is an extremely troublesome weed for soybean growers because of its aggressive growth, adaptability, prolific seed production, and widespread resistance to many herbicides. Studies were initiated to determine the effects of herbicide application at first female inflorescence on Palmer amaranth control, biomass, seed production, cumulative germination, and seed viability. Enlist (2,4-D–resistant) soybean and Xtend (dicamba-resistant) soybean were planted and various combinations of either 2,4-D or dicamba with and without glufosinate and/or glyphosate were applied at first visible female Palmer amaranth inflorescence. Mixtures of 2,4-D + glufosinate and 2,4-D + glufosinate + glyphosate provided the greatest control at 4 wk after treatment in Enlist soybean. Similarly, in Xtend soybean, combinations of dicamba + glufosinate and dicamba + glufosinate + glyphosate provided the greatest control. The greatest reductions in biomass were from combinations of auxin herbicides (2,4-D or dicamba) plus glufosinate with and without glyphosate. Seed production was reduced most by treatments containing at least one effective site of action: an auxin herbicide (2,4-D or dicamba) or glufosinate. In contrast to previous research, cumulative germination and seed viability were not affected by herbicide treatments. This research indicates the efficacy of auxin herbicides or glufosinate alone and in combination to reduce the seed production of Palmer amaranth when applied at first female inflorescence. More research is needed to evaluate the full potential for applications of these herbicides at flower initiation to mitigate the evolution of herbicide resistance.


2003 ◽  
Vol 48 (1) ◽  
pp. 125-134 ◽  
Author(s):  
Savo Vuckovic ◽  
Aleksandar Simic ◽  
Branko Cupina ◽  
Ivana Stojanovic ◽  
R. Stanisavljevic

This paper surveys sowing norms (row spacing and seed rate) in both our country and the world, as well as the optimal seed rates in grass seed production. It gives a short overview of row spacings and seed rates applied in our and some other countries. Earlier, grass cultivated for the purpose of seed production was grown on small vegetation area. According to some researches, high seed yields can be achieved by cultivating grass on large vegetation area. Based on the results obtained, it can be concluded that the highest cocksfoot, timothy, meadow fescue, tall fescue seed yield was achieved with plants grown in 50 cm spaced rows employing lower seed rates (8 and 4 kg/ha of seeds). The highest Italian ryegrass and perennial ryegrass seed yield was achieved with plants grown in 20 cm spaced rows employing 20 kg/ha of seeds.


Weed Science ◽  
2014 ◽  
Vol 62 (3) ◽  
pp. 493-500 ◽  
Author(s):  
Dustin F. Lewis ◽  
Matthew D. Jeffries ◽  
Travis W. Gannon ◽  
Robert J. Richardson ◽  
Fred H. Yelverton

The synthetic auxin herbicides, aminocyclopyrachlor and clopyralid, control dicotyledonous weeds in turf. Clippings of turfgrass treated with synthetic auxin herbicides have injured off-target plants exposed to herbicide-laden clippings. Labels of aminocyclopyrachlor and clopyralid recommend that clippings of treated turfgrass remain on the turf following a mowing event. Alternative uses for synthetic auxin-treated turfgrass clippings are needed because large quantities of clippings on the turf surface interfere with the functionality and aesthetics of golf courses, athletic fields, and residential turf. A white clover bioassay was conducted to determine the persistence and bioavailability of aminocyclopyrachlor and clopyralid in turfgrass clippings. Aminocyclopyrachlor and clopyralid were each applied at 79 g ae ha−1 to mature tall fescue at 56, 28, 14, 7, 3.5, and 1.75 d before clipping collection (DBCC). Clippings were collected, and the treated clippings were recycled onto adjacent white clover plots to determine herbicidal persistence and potential for additional weed control. Clippings of tall fescue treated with aminocyclopyrachlor produced a nonlinear regression pattern of response on white clover. Calculated values for 50% response (GR50) for visual control, for normalized difference vegetative index (NDVI), and for reduction in harvested biomass were 20.5, 17.3, and 18.7 DBCC, respectively, 8 wk after clippings were applied. Clippings of tall fescue treated with clopyralid did not demonstrate a significant pattern for white clover control, presumably because clopyralid was applied at a less-than-label rate. The persistence and bioavailability of synthetic auxin herbicides in clippings harvested from previously treated turfgrass creates the opportunity to recycle clippings for additional weed control.


2021 ◽  
pp. 1-8
Author(s):  
Jose H. S. de Sanctis ◽  
Stevan Z. Knezevic ◽  
Vipan Kumar ◽  
Amit J. Jhala

Abstract Glyphosate-resistant (GR) Palmer amaranth is a troublesome weed that can emerge throughout the soybean growing season in Nebraska and several other regions of the United States. Late-emerging Palmer amaranth plants can produce seeds, thus replenishing the soil seedbank. The objectives of this study were to evaluate single or sequential applications of labeled POST herbicides such as acifluorfen, dicamba, a fomesafen and fluthiacet-methyl premix, glyphosate, and lactofen on GR Palmer amaranth control, density, biomass, seed production, and seed viability, as well as grain yield of dicamba- and glyphosate-resistant (DGR) soybean. Field experiments were conducted in a grower’s field infested with GR Palmer amaranth near Carleton, NE, in 2018 and 2019, with no PRE herbicide applied. Acifluorfen, dicamba, a premix of fomesafen and fluthiacet-methyl, glyphosate, or lactofen were applied POST in single or sequential applications between the V4 and R6 soybean growth stages, with timings based on product labels. Dicamba applied at V4 or in sequential applications at V4 followed by R1 or R3 controlled GR Palmer amaranth 91% to 100% at soybean harvest, reduced Palmer amaranth density to as low as 2 or fewer plants m−2, reduced seed production to 557 to 2,911 seeds per female plant, and resulted in the highest soybean yield during both years of the study. Sequential applications of acifluorfen, fomesafen and fluthiacet premix, or lactofen were not as effective as dicamba for GR Palmer amaranth control; however, they reduced seed production similar to dicamba. On the basis of the results of this study, we conclude that dicamba was effective for controlling GR Palmer amaranth and reduced density, biomass, and seed production without DGR soybean injury. Herbicides evaluated in this study had no effect on Palmer amaranth seed viability.


2020 ◽  
pp. 1-31
Author(s):  
Geoffrey P. Schortgen ◽  
Aaron J. Patton

The herbicide 2,4-D is used in a variety of cropping systems, especially in grasses since it is a selective postemergence broadleaf herbicide. However, the most common formulation (2,4-D dimethylamine) is antagonized when mixed in hard water. The objective of this research was to determine which formulations of 2,4-D or premixes of various formulations of synthetic auxin herbicides are subject to hard water antagonism. Formulations surveyed for hard water antagonism in the first experiment included 2,4-D dimethylamine, 2,4-D diethanolamine, 2,4-D monomethylamine, 2,4-D isopropylamine salt, 2,4-D choline salt, 2,4-D isooctyl ester, and 2,4-D ethylhexyl ester. Synthetic auxin formulation types in the second experiment included water-soluble, emulsifiable concentrates and emulsion-in-water. All formulations were mixed with both soft and hard water (600 mg CaCO3 L-1) and applied to dandelions to determine if antagonism occurred in hard water. Water-soluble (amine and choline) 2,4-D formulations were antagonized by hard water, but water-insoluble (ester) 2,4-D formulations were not antagonized. Similar results were found by formulation type with water-soluble synthetic auxin premixes antagonized but emulsifiable concentrates not antagonized. Further, water-soluble salt formulations were not antagonized when formulated in premixes with other synthetic auxin herbicides as an emulsion-in-water. This research demonstrates that all 2,4-D water-soluble formulations and water-soluble premixes with phenoxycarboxylic acid herbicides are subject to hard water antagonism. Formulations of 2,4-D containing emulsifying agents protect against antagonism by the water-insoluble nature of ingredients in their formulation.


2021 ◽  
pp. 1-17
Author(s):  
Leo Roth ◽  
José Luiz C. S. Dias ◽  
Christopher Evans ◽  
Kevin Rohling ◽  
Mark Renz

Garlic mustard [Alliaria petiolata (M. Bieb.) Cavara & Grande] is a biennial invasive plant commonly found in the northeastern and midwestern United States. Although it is not recommended to apply herbicides after flowering, land managers frequently desire to conduct management during this timing. We applied glyphosate and triclopyr (3% v/v and 1% v/v using 31.8% and 39.8% acid equivalent formulations, respectively) postemergence to established, second-year A. petiolata populations at three locations when petals were dehiscing, and evaluated control, seed production and seed viability. Postemergence glyphosate applications at this timing provided 100% control of A. petiolata by 4 weeks after treatment at all locations whereas triclopyr efficacy was variable, providing 38-62% control. Seed production was only reduced at one location, with similar results regardless of treatment. Percent seed viability was also reduced, and when combined with reductions in seed production, we found a 71-99% reduction in number of viable seed produced plant-1 regardless of treatment. While applications did not eliminate viable seed production, our findings indicate that glyphosate and triclopyr applied while petals were dehiscing is a viable alternative to cutting or hand-pulling at this timing as it substantially decreased viable A. petiolata seed production. Management Implications Postemergence glyphosate and triclopyr applications in the early spring to rosettes are standard treatments used to manage A. petiolata. However, weather and other priorities limit the window for management, forcing field practitioners to utilize more labor-intensive methods such as hand-pulling. It is not known how late in the development of A. petiolata these herbicides can be applied to prevent viable seed production. Since prevention of soil seedbank replenishment is a key management factor for effective long-term control of biennial invasive species, we hypothesized late spring foliar herbicide applications to second year A. petiolata plants when flower petals were dehiscing could be an effective management tool if seed production or viability is eliminated. Our study indicated that glyphosate applications at this timing provided 100% control of A. petiolata plants by 4 weeks after treatment at all locations, whereas triclopyr efficacy was inconsistent. Although both glyphosate and triclopyr decreased viable seed production to nearly zero at one of our three study locations, the same treatments produced significant amounts of viable seed at the other two locations. Our findings suggest late spring glyphosate and triclopyr applications should not be recommended over early spring applications to rosettes for A. petiolata management, as our late spring application timing did not prevent viable seed production, and may require multiple years of implementation to eradicate populations. Nonetheless, this application timing holds value in areas devoid of desirable understory vegetation compared to no management practices or mechanical management options including hand-pulling when fruit are present, as overall viable seed production was reduced to similar levels as these treatments.


2011 ◽  
Vol 150 (6) ◽  
pp. 717-724 ◽  
Author(s):  
M. V. BAGAVATHIANNAN ◽  
J. K. NORSWORTHY ◽  
K. L. SMITH ◽  
P. NEVE

SUMMARYThe spread of herbicide resistance in barnyardgrass (Echinochloa crus-galli(L.) Beauv.) poses a serious threat to crop production in the southern United States. A thorough knowledge of the biology of barnyardgrass is fundamental for designing effective resistance-management programmes. In the present study, seed production of barnyardgrass in response to time of emergence was investigated in cotton and rice, respectively, in Fayetteville and Rohwer, Arkansas, over a 2-year period (2008–09). Barnyardgrass seed production was greater when seedlings emerged with the crop, but some seed production was observed even if seedlings emerged several weeks after crop emergence. Moreover, barnyardgrass seed production was highly variable across environments. When emerging with the crop (0 weeks after crop emergence (WAE)), barnyardgrass producedc. 35 500 and 16 500 seeds/plant in cotton, andc. 39 000 and 2900 seeds/plant in rice, in 2008 and 2009, respectively. Seed production was observed when seedlings emerged up to 5 WAE (2008) or 7 WAE (2009) in cotton and up to 5 WAE (2008, 2009) in rice; corresponding seed production wasc. 2500 and 1500 seeds/plant in cotton, andc. 14 700 and 110 seeds/plant in rice, in 2008 and 2009, respectively. The results suggest that cultural approaches that delay the emergence of barnyardgrass or approaches that make the associated crop more competitive will be useful in integrated management programmes. In the context of herbicide resistance management, it may be valuable to prevent seed return to the seedbank, irrespective of cohorts. The findings are vital for parameterizing herbicide resistance simulation models for barnyardgrass.


2018 ◽  
Vol 32 (5) ◽  
pp. 597-602 ◽  
Author(s):  
Marcelo Zimmer ◽  
Bryan G. Young ◽  
William G. Johnson

AbstractSynthetic auxin herbicides such as 2,4-D and dicamba are often utilized to control broadleaf weeds in preplant burndown applications to soybean. Halauxifen-methyl is a new synthetic auxin herbicide for broadleaf weed control in preplant burndown applications to corn, cotton, and soybean at low use rates (5 g ae ha–1). Field experiments were conducted to evaluate efficacy and weed control spectrum of halauxifen-methyl applied alone and in mixtures with 2,4-D (560 g ae ha–1), dicamba (280 g ae ha–1), and glyphosate (560 g ae ha–1). Glyphosate-resistant (GR) horseweed was controlled with halauxifen-methyl applied alone (90% control) and in mixtures (87% to 97% control) 35 d after treatment (DAT). Common ragweed was controlled 93% with halauxifen-methyl applied alone and 91% to 97% in mixtures 35 DAT. Halauxifen-methyl applied alone resulted in poor giant ragweed control 21 DAT (73% control); however, mixtures of halauxifen-methyl with 2,4-D, dicamba, or glyphosate controlled giant ragweed (86% to 98% control). Halauxifen-methyl alone resulted in poor redroot pigweed control (62% control) 21 DAT; however, mixtures of halauxifen-methyl with dicamba, 2,4-D, or glyphosate controlled redroot pigweed (89% to 98% control). Halauxifen-methyl controls GR horseweed and common ragweed applied alone and in mixtures with other synthetic auxin herbicides and glyphosate. Furthermore, mixing 2,4-D or dicamba with halauxifen-methyl can increase the weed control spectrum in preplant burndown applications.


2007 ◽  
Vol 21 (1) ◽  
pp. 151-158 ◽  
Author(s):  
Chad S. Trusler ◽  
Thomas F. Peeper ◽  
Amanda E. Stone

An experiment was conducted at three sites in central Oklahoma to compare the efficacy of Italian ryegrass management options in no-till (NT) and conventional tillage (CT) winter wheat. The Italian ryegrass management options included selected herbicide treatments, wheat-for-hay, and a rotation consisting of double-crop soybean seeded immediately after wheat harvest, followed by early season soybean, and then by wheat. In continuous wheat, before application of glyphosate or tillage, Italian ryegrass plant densities in mid-September were 12,300 to 15,000 plants/m2in NT plots vs. 0 to 500 plants/m2in CT plots. When applied POST, diclofop controlled more Italian ryegrass than tralkoxydim or sulfosulfuron. In continuous wheat, yields were greater in CT plots than in NT plots at two of three sites. None of the Italian ryegrass management options consistently reduced Italian ryegrass density in the following wheat crop. Of the Italian ryegrass control strategies applied to continuous wheat, three herbicide treatments in NT at Chickasha and all treatments in NT at Perry reduced Italian ryegrass density in the following wheat crop. Italian ryegrass plant density in November and spike density were highly related to wheat yield at two and three sites, respectively. No management options were more profitable than rotation to soybean.


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