Effects of Weed Control in Established Alfalfa (Medicago sativa) on Forage Yield and Quality

Weed Science ◽  
1987 ◽  
Vol 35 (4) ◽  
pp. 564-567 ◽  
Author(s):  
Dennis R. Cosgrove ◽  
Michael Barrett

The effects of weed control measures in established alfalfa (Medicago sativaL.) on forage yield and quality were investigated at three sites with varying alfalfa densities and weed populations. Herbicide treatments were 0.56 and 1.12 kg/ha metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] applied in fall or spring, respectively, 1.68 kg/ha pronamide [3,5-dichloro (N-1,1-dimethyl-2-propynyl)benzamide] applied in fall, and combinations of these treatments. First-harvest forage yields (weeds plus alfalfa) were either reduced or unchanged by herbicide treatments. Total forage yield was not altered by the herbicide treatments, but first-harvest and total alfalfa yield as well as first-harvest forage protein content were increased by several treatments, depending on stand density and weed pressure. Little effect was observed on in vitro digestible dry matter or acid detergent fiber content.

Weed Science ◽  
1978 ◽  
Vol 26 (2) ◽  
pp. 193-198 ◽  
Author(s):  
R. S. Fawcett ◽  
R. G. Harvey ◽  
D. A. Schlough ◽  
I. R. Block

The degree and longevity of quackgrass [Agropyron repens(L.) Beauv.] control provided by autumn applications of pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide] was influenced greatly by alfalfa(Medicago sativaL.) stand density, as well as by rate of application and soil type. When applications were made to a field with a sparse alfalfa stand (10 to 20 crowns/m2), quackgrass yields were reduced the year following pronamide application, but quackgrass reinfested the plots the second year after treatment. Quackgrass yields one and two seasons following autumn treatment with 2.2 kg/ha pronamide were 1480 and 3890 kg/ha compared to 4480 and 4870 kg/ha for control plots. Annual applications of pronamide were necessary to maintain quackgrass control in the sparse alfalfa stand. Pronamide application to a vigorous, dense alfalfa stand (40 to 50 crowns/m2) provided quackgrass control which persisted into the second year after treatment. Quackgrass control ratings one and two seasons after application of 1.1 kg/ha pronamide were 100 and 90%. Pronamide treatments reduced first cutting quackgrass yields, and increased first cutting alfalfa yields. Treatment of the sparse alfalfa stand with 2.2 kg/ha pronamide resulted in first cutting alfalfa and quackgrass yields of 2420 and 990 kg/ha compared to 1430 and 3940 kg/ha for controls. Treatment of a dense alfalfa stand with 1.1 kg/ha pronamide resulted in first cutting alfalfa and quackgrass yields of 3850 and 300 kg/ha compared to 1710 and 1660 kg/ha for controls. Total herbage yields from all cuttings were either slightly decreased when fields with sparse alfalfa stands were treated or remained constant or slightly increased when more dense alfalfa stands were treated. Pronamide applied with potash as the carrier was as effective as when applied in water. Pronamide treatment resulted in increased crude protein concentration in first cutting herbage at all locations in all years. Crude protein concentration in first cutting control herbage ranged from 13.3 to 16.1%. Crude protein concentration in first cutting herbage from plots treated with 1.1 kg/ha pronamide ranged from 17.7 to 20.6%, depending on year and location. In vitro digestible dry matter (IVDDM) concentrations were increased by most rates of pronamide in first, second, and third cutting herbage. IVDDM for first cutting control herbage was 51.4% compared to 61.3% for herbage treated with 2.2 kg/ha pronamide. Acid detergent fiber concentration in first cutting herbage was not affected by pronamide.


1999 ◽  
Vol 13 (2) ◽  
pp. 399-403 ◽  
Author(s):  
W. Thomas Lanini ◽  
Steve B. Orloff ◽  
Warren E. Bendixen ◽  
W. Michael Canevari ◽  
Jerry L. Schmierer ◽  
...  

Paraquat, cultivation, or cultivation plus oat interseeding (56 or 84 kg/ha) into established alfalfa were evaluated for their effect on weeds, forage yield, and forage composition at Santa Ynez, Lancaster, and Stockton, CA. Treatments were applied during the winter to dormant alfalfa and evaluated in the subsequent harvest season. Paraquat reduced first harvest total forage yields 20 to 33% compared to untreated alfalfa, whereas oat interseeding increased total forage yields 16 to 36%. Cultivation reduced total forage yield in the first cutting by 26% at Lancaster but did not affect forage yield at the other sites. Total or component forage yields were not affected by any treatment in the second and subsequent harvests, with the exception of weeds. Paraquat reduced weed biomass in the first harvest by 45 and 49% at Lancaster and Stockton. Oat interseeding reduced first harvest weed biomass by 80% at Lancaster but did not affect weed biomass at Stockton or Santa Ynez. Oat interseeding or paraquat treatment reduced weed biomass in the second harvest at Stockton, but did not affect weeds in any other harvest at any of the sites. Oat interseeding was comparable to paraquat treatment for weed control, with the advantage of also increasing first harvest forage yield.


1992 ◽  
Vol 72 (4) ◽  
pp. 1199-1206 ◽  
Author(s):  
D. J. Thompson ◽  
D. G. Stout

Annual ryegrass (Lolium multiflorum Lam. ’Maris Ledger’) was seeded at rates ranging from 5 to 30 kg ha−1 as either a monocrop or an intercrop with 50, 100 or 150 kg ha−1 of spring barley (Hordeum vulgare L. ’Diamond’). When ryegrass is intercropped with barley, cuts 1 and 2 are usually ensiled and the remainder of seasonal production is pastured (the equivalent of two forage cuts). Monocropped annual ryegrass produced 91% as much dry matter (DM) in the silage cuts as intercropped annual ryegrass and barley but produced 105% as much pasture. Over the season, monocropped ryegrass produced 11.1 t ha−1 of forage compared with 11.7 t ha−1 for intercropped annual ryegrass and barley. Among the intercropping treatments, increased barley seeding rate resulted in greater cut 1 yields, but this was offset by reduced cut 2 yields, so barley seeding rate did not affect the yield of DM for silage. Only 50 kg ha−1 of barley seed was required to obtain maximum yearly forage yields when intercropping with annual ryegrass. No more than 10 kg ha−1 of ryegrass seed was required for optimal yield when monocropping, and no more than 15 kg ha−1 when ryegrass was intercropped with barley. Monocropped ryegrass produced superior quality forage for silage. When quality was weighted for the relative yields of cuts 1 and 2, the monocrop averaged 16% protein and 72% in vitro disappearance of dry matter (IVDDM) compared with 12% protein and 58% IVDDM for the intercrops. Among the intercrops, increasing barley seeding rate from 50 kg ha−1 to 150 kg ha−1 did not affect the protein content of silage cuts, but it decreased IVDDM from 60% to 56%. Pasture forage quality was not affected by barley seeding rate.Key words: Intercropping, annual ryegrass, barley, seeding rate, yield


1995 ◽  
Vol 9 (2) ◽  
pp. 270-276 ◽  
Author(s):  
Joseph L. Moyer ◽  
Kenneth W. Kelley

Four broadleaf herbicides and combinations were compared for two years with mefluidide, a growth regulator, for effects on ‘Ky 31’ and ‘Fawn’ tall fescue. Seedhead densities averaged 33% of the check with 8.4 g ai/ha of metsulfuron, 17% with 70 g ai/ha of imazethapyr, and 9% with 280 g ai/ha of mefluidide, while forage yields were reduced to about 40% of the check. Forage crude protein (CP) concentrations were increased by mefluidide, imazethapyr, and 8.4 g/ha of metsulfuron. Neutral-detergent fiber (NDF) of Ky 31 but not Fawn forage was reduced by mefluidide, imazethapyr, and metsulfuron at 6.3 and 8.4 g/ha, but Fawn NDF was increased by dicamba plus 2,4-D. In vitro dry matter digestibility was increased by metsulfuron at 6.3 and 8.4 g/ha, mefluidide, and imazethapyr in one of two years. Adding 2,4-D to metsulfuron reduced some effects of metsulfuron. Total CP/ha was no more adversely affected by imazethapyr and metsulfuron than mefluidide. Imazethapyr and metsulfuron can thus be used to control weeds without reducing fescue forage value.


Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 550
Author(s):  
Panagiotis Kanatas ◽  
Ioannis Gazoulis ◽  
Ilias Travlos

Irrigation is an agronomic practice of major importance in alfalfa (Medicago sativa L), especially in the semiarid environments of Southern Europe. Field experimentation was conducted in Western Greece (2016–2018) to evaluate the effects of irrigation timing on weed presence, alfalfa yield performance, and forage quality. In a randomized complete block design (four replications), two cultivars (“Ypati 84” and “Hyliki”) were the main plots, while three irrigation timings were the subplots (split-plot). The irrigation timings were IT-1, IT-2, and IT-3, denoting irrigation 1 week before harvest, 1 week after harvest, and 2 weeks after harvest, respectively. IT-1 reduced Solanum nigrum L. density by 54% and 79% as compared to IT-3 and IT-2, respectively. Chenopodium album L. density was the highest under IT-2. IT-3 resulted in 41% lower Amaranthus retroflexus L. density in comparison to IT-2, while the lowest values were observed under IT-1. Stand density and stems·plant−1 varied between years (p ≤ 0.05). Mass·stem−1 and alfalfa forage yield were affected by the irrigation timings (p ≤ 0.001). Total weed density and forage yield were negatively correlated in both the second (R2 = 87.013%) and the fourth (R2 = 82.691%) harvests. IT-1 and IT-3 increased forage yield, leaf per stem ratio, and crude protein as compared to IT-2. Further research is required to utilize the use of cultural practices for weed management in perennial forages under different soil and climatic conditions.


2017 ◽  
Vol 9 (11) ◽  
pp. 234
Author(s):  
Alexandre M. Brighenti ◽  
Juarez C. Machado ◽  
Francisco J. S. Ledo ◽  
Leonardo H. F. Calsavara ◽  
Yago V. Guerra Varotto

The interference imposed by weeds is one of the most important factors limiting elephant grass forage yield. Two experiments were carried out in 2015/2016 and 2017 to evaluate the selectivity and weed control of 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides applied alone or in combination with atrazine in elephant grass. The treatments applied in the experiment conducted in Valença, Rio de Janeiro State, Brazil, were as follows: two rates of mesotrione (0.072 and 0.144 kg ha-1 + 0.5% v/v mineral oil - Assist®), two rates of tembotrione (0.075 and 0.100 kg ha-1 + 0.5% v/v mineral oil - Aureo®), atrazine + mesotrione (1.25 + 0.072 kg ha-1 + 0.5% v/v mineral oil - Assist®), atrazine + tembotrione (1.25 + 0.100 kg ha-1 + 0.5% v/v mineral oil - Aureo®), atrazine + mesotrione (1.25 + 0.072 kg ha-1), atrazine + tembotrione (1.25 + 0.100 kg ha-1) and two checks (weed-free check and weedy check). The same herbicide treatments and a check without application were applied in an experiment conducted in Coronel Pacheco, Minas Gerais State, Brazil. Two application rates of mesotrione with the addition of mineral oil or the tank mixture of atrazine plus mesotrione, with or without the addition of mineral oil, did not provide injuries capable to reduce elephant grass forage yield. Tembotrione was phytotoxic to elephant grass when applied with mineral oil. Atrazine plus tembotrione in a tank-mix, with or without mineral oil, were also phytotoxic to elephant grass. All treatments provided satisfactory weed control.


Weed Science ◽  
1986 ◽  
Vol 34 (3) ◽  
pp. 444-448 ◽  
Author(s):  
Gilles D. Leroux ◽  
Robert G. Harvey

Established stands of alfalfa (Medicago sativaL.) at two field locations were treated at one date in the fall with pronamide [3,5-dichloro (N-1,1-dimethyl-2-propynil) benzamide] at 0.8 and 1.6 kg ai/ha and at two dates in the spring with sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} at 0.3 and 0.6 kg ai/ha for the control of quackgrass [Agropyron repens(L.) Beauv. # AGRRE]. Herbicide efficacy was compared by measuring botanical and chemical composition and yield of forage. Both chemicals suppressed quackgrass in first-cutting herbage. While sethoxydim at the higher rate was equivalent to pronamide for increasing the proportion of alfalfa in forage, pronamide was superior for increasing seasonal total yield. Late postemergence applications of sethoxydim were more effective for quackgrass regrowth control than earlier spring applications. Controlling quackgrass in late spring resulted in lower crude protein (CP) content in first-cutting forage than did controlling it in fall. Alfalfa competing with untreated quackgrass had a lower CP content than where quackgrass was controlled with herbicides. All herbicide treatments reduced the neutral-detergent fiber (NDF) of the herbage. As measured by the acid-detergent fiber (ADF) concentration of alfalfa, sethoxydim slightly retarded spring growth of the legume.


Weed Science ◽  
1973 ◽  
Vol 21 (2) ◽  
pp. 119-122 ◽  
Author(s):  
George Kapusta

Herbicide treatments were applied to established alfalfa (Medicago sativaL.) in 1969 and 1970 to determine winter annual weed control efficacy, crop tolerance, and influence on alfalfa yield and protein. Common chickweed (Stellaria media(L.) Cyrillo) was the predominant species in both years. Excellent weed control was achieved in 1969 with 2-sec-butylamino-4-ethylamino-6-methoxy-s-triazine (GS 14254) at 1.7 kg/ha, 2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl]amino]-2-methyl-propionitrile (cyanazine) at 4.5 kg/ha, 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) at 1.7 kg/ha, and 3-tert-butyl-5-chloro-6-methyluracil (terbacil) at 1.1 kg/ha. Several other treatments also significantly reduced weed yields. All herbicides significantly reduced weed yields in 1970. First harvest alfalfa yields in 1969 were not increased significantly despite the excellent weed control afforded by several treatments. Second harvest alfalfa yields did not differ significantly, however, weeds were not a problem in the regrowth. In 1970 four of the 19 treatments did yield significantly more than control plots. Alfalfa protein was not altered by any of the treatments either year.


2019 ◽  
Vol 33 (03) ◽  
pp. 431-440
Author(s):  
Thomas J. Peters ◽  
Andrew B. Lueck ◽  
Aaron L. Carlson

AbstractSugarbeet growers only recently have combined ethofumesate, S-metolachlor, and dimethenamid-P in a weed control system for waterhemp control. Sugarbeet plant density, visible stature reduction, root yield, percent sucrose content, and recoverable sucrose were measured in field experiments at five environments between 2014 and 2016. Sugarbeet stand density and stature reduction occurred in some but not all environments. Stand density was reduced with PRE application of S-metolachlor at 1.60 kg ai ha–1 and S-metolachlor at 0.80 kg ha–1 + ethofumesate at 1.68 kg ai ha–1 alone or followed by POST applications of dimethenamid-P at 0.95 kg ai ha–1. Sugarbeet visible stature was reduced when dimethenamid-P followed PRE treatments. Stature reduction was greatest with ethofumesate at 1.68 or 4.37 kg ha–1 PRE and S-metolachlor at 0.80 kg ha–1 + ethofumesate at 1.68 kg ha–1 PRE followed by dimethenamid-P at 0.95 kg ha–1 POST. Stature reduction ranged from 0 to 32% 10 d after treatment (DAT), but sugarbeet recovered quickly and visible injury was negligible 23 DAT. Although root yield and recoverable sucrose were similar across herbicide treatments and environments, we caution against the use of S-metolachlor at 0.80 kg ha–1 + ethofumesate at 1.68 kg ai ha–1 PRE followed by dimethenamid-P at 0.95 kg ha–1 in sugarbeet.


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