Effects of competition with weeds on growth, development and yield of groundnuts.

Competition between weeds and groundnuts was studied in two field experiments in the inland Zanderij area of Suriname. The crop was kept weed-free or without weed control for increasing periods of time after planting. Observations made at the end of each period with or without weed control provided an analysis of the growth of a crop with weed control and of a crop without weed control. Uncontrolled weed growth was concentrated between the rows. Competition with weeds reduced ground cover and LAI of the crop. DM accumulation was affected, resulting in lower yields. Plant density and number of branches per plant were not influenced. Weed competition increased stem length and reduced the number of leaves and pods per plant. Timing of flowering was not influenced. Competition for nutrients was absent, but there was competition for light and water. About 15 weed-free days after planting were sufficient to prevent yield losses. Yield losses were due to a reduction in number of pods per plant. Competition should especially be prevented in the period when the number of pods per plant is established, i.e. around 35-60 days after planting. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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Effects of competition with weeds on the growth, development and yield of sorghum

The Journal of Agricultural Science ◽

10.1017/s0021859600074220 ◽

1993 ◽

Vol 120 (2) ◽

pp. 187-196 ◽

Cited By ~ 7

Author(s):

A. P. Everaarts

Keyword(s):

Weed Control ◽

Field Experiments ◽

Canopy Structure ◽

Ground Cover ◽

Stem Length ◽

Yield Reduction ◽

Area Index ◽

Weed Growth ◽

Competition For Light ◽

Number Of Leaves

SUMMARYIn two field experiments in Suriname, competition between weeds and sorghum (Sorghum bicolor(L.) Moench) was studied in the rainy seasons of 1982 and 1983. The crop was kept either weed-free or without weed control for each of six different periods of time from planting. Observations made at the end of each period allowed an analysis to be made of the growth and development of a crop with and without weed control.Due to the crop canopy structure and fertilizer placement near the row, weed growth was concentrated in the rows. Starting atc.20–30 days after planting, competition with weeds reduced ground-cover and leaf area index of the crop. Competition reduced growth rates, leading to lower yields. Plant population density was not affected, but competition reduced the number of leaves present. Stem length initially increased with competition in one season, but was retarded in another. Competition for nutrients was strong and was found as early as 15 days after planting. Nitrogen was the element most competed for initially. Competition for water occurred, but competition for light seemed unlikely. About 20 weed-free days after planting were necessary to avoid yield losses and around 30 weed-free days to attain negligible weed growth at harvest. Yield reduction was mainly due to a decrease in number of grains per panicle. Competition during floret establishment (c.30–40 days after planting) should be avoided.

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Effects of competition with weeds on growth, development and yield of soyabeans.

Netherlands Journal of Agricultural Science ◽

10.18174/njas.v40i1.16531 ◽

1992 ◽

Vol 40 (1) ◽

pp. 91-107

Author(s):

A.P. Everaarts

Keyword(s):

Weed Control ◽

Field Experiments ◽

Plant Density ◽

Ground Cover ◽

Yield Reduction ◽

Weed Competition ◽

Lower Weight ◽

Weed Growth ◽

Competition For Light ◽

Number Of Branches

Two field experiments were carried out in the inland Zanderij area of Suriname to study competition between soyabeans and weeds. The crop was kept weed-free or without weed control for increasing periods of time after sowing. An analysis of the growth and development of a crop with weed control and of a crop without weed control was obtained by making observations at the end of each period of time with or without weed control. Uncontrolled weed growth concentrated mainly between the rows. Competition with weeds reduced ground cover and LAI of the crop, leading to a lower weight and yield. Plant density was not affected, but weed competition reduced the number of branches, inflorescences, and pods per plant. Timing of flowering was not influenced. Competition for water was inferred and competition for light seemed likely. Competition for nutrients was weak. Weeding in the period of pod initiation, i.e. around 45-70 days after sowing, appeared to be essential to avoid competition with weeds. A period of around 4 weed-free weeks after sowing was necessary to avoid yield reduction or too much weed growth at harvest. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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Cultural Practices Affecting Season-Long Weed Control in Irrigated Corn (Zea mays)

Weed Science ◽

10.1017/s0043174500059348 ◽

1984 ◽

Vol 32 (4) ◽

pp. 460-467 ◽

Cited By ~ 9

Author(s):

Russell S. Moomaw ◽

Alex R. Martin

Keyword(s):

Zea Mays ◽

Weed Control ◽

Seed Production ◽

Field Experiments ◽

Cultural Practices ◽

Fine Sand ◽

Corn Yield ◽

Weed Seed ◽

Weed Growth ◽

Herbicide Use

Season-long weed control has been a goal of some producers of irrigated corn (Zea maysL.) to reduce competition, lessen weed seed production, facilitate crop harvest, improve water efficiency (particularly with furrow irrigation), and improve aesthetic properties of fields. Field experiments were conducted for 3 yr on sprinkler-irrigated corn on a loamy fine sand. Five herbicides applied at layby generally provided season-long control of grass weeds and reduced weed seed production up to 100%. Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] was particularly effective. Yields of irrigated corn were not increased by layby herbicide application. Use of corn rows spaced 91 cm apart and use of a shorter, early-maturing, horizontal-leaf corn cultivar resulted in greater weed growth and weed seed production than did use of 76-cm rows and a taller, full-season, upright-leaf corn cultivar. After nearly complete weed control with herbicides for 2 yr, withholding herbicide use in the third year allowed weed growth which reduced corn yield. Indications were that weed control efforts need to be continuous in irrigated corn production.

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Sugarbeet tolerance when dimethenamid-P follows soil-applied ethofumesate and S-metolachlor

Weed Technology ◽

10.1017/wet.2019.23 ◽

2019 ◽

Vol 33 (03) ◽

pp. 431-440

Author(s):

Thomas J. Peters ◽

Andrew B. Lueck ◽

Aaron L. Carlson

Keyword(s):

Control System ◽

Weed Control ◽

Field Experiments ◽

Plant Density ◽

Stand Density ◽

Sucrose Content ◽

Root Yield ◽

Visible Injury ◽

Herbicide Treatments

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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Effect of Herbicides on Field Violet (Viola arvensis) in Direct-Seeded Spring Wheat

Weed Technology ◽

10.1614/wt-04-152r.1 ◽

2005 ◽

Vol 19 (2) ◽

pp. 359-371 ◽

Cited By ~ 4

Author(s):

Rory F. Degenhardt ◽

Dean Spaner ◽

K. Neil Harker ◽

William R. Mcgregor ◽

Linda M. Hall

Keyword(s):

Spring Wheat ◽

Crop Production ◽

Field Experiments ◽

Plant Density ◽

Dry Weight ◽

Effective Control ◽

Weed Species ◽

Weed Growth ◽

Direct Seeded ◽

Cereal Fields

The agrestal field violet, a pervasive weed in Europe, has been identified in reduced-tillage cereal fields in Alberta. The efficacy of herbicides in direct-seeded spring wheat was assessed on natural field violet infestations in Alberta in 2002 and 2003. Only fluroxypyr + 2,4-D, applied postemergence, provided control of field violet in 2002 when rainfall was limiting. Over both years, this herbicide combination reduced biomass by 59 to 69% and plant density by 83 to 91%, relative to nontreated plots. The herbicides metsulfuron, sulfosulfuron, and thifensulfuron + tribenuron only suppressed weed growth under drought conditions in 2002 but controlled the weed in 2003 when rainfall was greater, reducing plant density by 82 to 92% and rendering remaining plants sterile. Suppression was also observed with MCPA + mecoprop + dicamba in 2002 and 2003 and with metribuzin only in 2003. Effective control of field violet was conferred by a pre–crop emergence application of glyphosate at 445 g ae/ha in 2003, the only year that this treatment was evaluated. Activity of herbicides on three- to four-leaf seedlings was also evaluated in a greenhouse dose– response assay. All herbicides had greater efficacy in the greenhouse, and those that provided control in situ reduced field violet dry weight by 85% at less than the recommended rate used in field experiments. Management of field violet is possible with herbicides registered for use on spring wheat in Alberta. However, the weed does not appear to cause significant crop production losses; hence, herbicide selection should be based on knowledge of all weed species present within the field.

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Effect of neem fertilizer rates and weed control methods on the growth and yield of soybeans (Glycine max (L.) merrill) in north Central Nigeria

Journal of Agriculture and Food Sciences ◽

10.4314/jafs.v19i1.3 ◽

2021 ◽

Vol 19 (1) ◽

pp. 31-47

Author(s):

Y. Garba ◽

Z. Yakubu ◽

A.I. Yakubu ◽

J. Alhassan ◽

M. Gana ◽

...

Keyword(s):

Weed Control ◽

Field Experiments ◽

Block Design ◽

Growth And Yield ◽

Control Methods ◽

North Central ◽

Glycine Max L ◽

Number Of Leaves ◽

Experimental Treatments ◽

Fertilizer Rates

Two field experiments were conducted at the Research Farm of the Ibrahim Badamasi Babangida University, Lapai, Niger State during the 2018 and 2019 rainy seasons to determine the effect of neem fertilizer rates and weed control methods on the growth and yields of soybeans. The experimental treatments were made up of four neem fertilizer rates (0, 50, 100 and 150 kg ha-1) and six weed control methods (pendimethalin at 1.5 kg a.i ha-1 followed by one hoe weeding, pendimethalin at 2.0 kg a.i. ha-1 followed by diuron at 1.5 kg a.i ha-1, weeding once at 3 WAS, weeding twice at 3 and 6 WAS, weed free and weedy check. The experiment was a 3 × 3 factorial experiment laid out in a Randomize complete block design replicated three times. TGX 1448 – 2E variety of soybean was used for the study. Result showed that weed control efficiency was better with the use of 150 kg ha-1 of neem fertilizer, while decrease in weed dry matter was obtained at 50 kg ha-1. Increase in number of leaves and leaf area were encouraged with 150 kg ha-1 of neem fertilizer. Weed free treatments recorded the highest grain yield and 100 seed weight of soybean. Pendimethalin at 1.5 or 2.0 kg a.i ha-1 supplemented with one hoe weeding or diuron at 1.5 kg a.i ha-1 respectively can be an alternative for better control of weeds to obtain greater yield of soybean in the study area.

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Interference and Control of Large Crabgrass (Digitaria sanguinalis) and Southern Sandbur (Cenchrus echinatus) in Forage Bermudagrass (Cynodon dactylon)

Weed Technology ◽

10.1017/s0890037x00044584 ◽

1998 ◽

Vol 12 (4) ◽

pp. 707-711 ◽

Cited By ~ 5

Author(s):

Robert H. Walker ◽

Glenn Wehtje ◽

John S. Richburg

Keyword(s):

Weed Control ◽

Field Experiments ◽

Cynodon Dactylon ◽

Ground Cover ◽

Weed Competition ◽

Minor Importance ◽

Digitaria Sanguinalis ◽

Competitive Species ◽

And Control ◽

Large Crabgrass

Field experiments were conducted at two locations in central Alabama to evaluate competitiveness of large crabgrass and southern sandbur with ‘Tifton 78’ hybrid bermudagrass as influenced by diuron application and sprigging rate. Large crabgrass was the more competitive species. In late season, bermudagrass ground cover with no weed competition was 96% compared with 72 and 81% where large crabgrass and southern sandbur, respectively, were present. Similarly, large crabgrass and southern sandbur reduced the proportion of bermudagrass in the cumulative harvested forage by at least 59 and 38%, respectively. Application of diuron preemergence (PRE) at 1.1 kg ai/ha was more effective than postemergence (POST) application, both in terms of weed control and bermudagrass safety. With diuron applied PRE, large crabgrass and southern sandbur reduced the proportion of bermudagrass in the harvested forage only 32 and 25%, respectively. Increasing bermudagrass sprigging rate was beneficial for weed control but of relatively minor importance compared with diuron PRE.

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Effect of volunteer barley (Hordeum vulgareL.) interference on field pea (Pisum sativumL.) yield and profitability

Weed Science ◽

10.1017/s0043174500092791 ◽

1997 ◽

Vol 45 (2) ◽

pp. 249-255 ◽

Cited By ~ 10

Author(s):

John T. O'Donovan ◽

Robert E. Blackshaw

Keyword(s):

Regression Analysis ◽

Seed Yield ◽

Nonlinear Regression ◽

Field Experiments ◽

Plant Density ◽

Barley Plant ◽

Yield Losses ◽

Nonlinear Regression Analysis ◽

Economic Thresholds ◽

Pea Seed

Relationships between volunteer barley plant density and both pea and volunteer barley yield were determined in field experiments conducted over 2 yr at Vegreville and Lethbridge, Alberta. Nonlinear regression analysis indicated that severe pea yield losses due to volunteer barley occurred at both locations. Averaged over both years, pea seed yield losses per volunteer barley plant (initial slopes) varied from 1.7% at Vegreville to 5.4% at Lethbridge. Based on certain assumptions, economic thresholds calculated from the equations were approximately 2 and 6 volunteer barley plants m−2at Lethbridge and Vegreville, respectively. Revenue from the volunteer barley seed partially alleviated the monetary losses caused by the reduced pea seed yield. The effects of pea density on pea and volunteer barley yield were inconsistent and marginal. This suggested that there was little advantage, in terms of increasing pea yield or reducing volunteer barley interference, to seeding pea above the recommended rate of 100 plants m−2.

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Control and Competitiveness of Johnsongrass (Sorghum halepense) in Cotton (Gossypium hirsutum)

Weed Science ◽

10.1017/s0043174500062123 ◽

1981 ◽

Vol 29 (3) ◽

pp. 356-359 ◽

Cited By ~ 14

Author(s):

P. E. Keeley ◽

R. J. Thullen

Keyword(s):

Gossypium Hirsutum ◽

Weed Control ◽

Field Experiments ◽

Yield Loss ◽

Sorghum Halepense ◽

Cotton Yield ◽

Yield Losses ◽

Seed Cotton ◽

Average Yield ◽

Labor Costs

Four field experiments conducted over 3 yr indicated that cultivation alone failed to prevent johnsongrass [Sorghum halepense(L.) Pers.] from reaching densities that severely reduced yields of cotton (Gossypium hirsutumL. ‘Acala SJ-2’). Density of johnsongrass in plots cultivated four times and hoed weekly for 8 weeks after emergence was reduced to 1 shoot/m2at harvest compared to 74 shoots/m2for plots that were only cultivated. In addition to a 60% average yield loss of seed cotton, yield losses ranging from 40 to 76%, ginning losses were also greater from cultivated than from hand-weeded plots. Compared to cultivated plots, supplementing cultivation with two postemergence applications of 3.0 kg/ha of DSMA (disodium methanearsonate) increased the average yield of cotton by 20% and reduced perennial johnsongrass densities by 64% at harvest. Although yields were improved by applying DSMA, they averaged 40% less than those of hand-weeded plots. The temporary weed control obtained with DSMA was profitable in terms of the additional lint and seed obtained, but insufficient cotton was produced to pay expenses for producing the crop by any of the methods of weed control. High labor costs for hoeing prevented this treatment from being profitable.

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Influence of Application Variables on Efficacy of Glyphosate

Weed Technology ◽

10.1017/s0890037x00043062 ◽

1997 ◽

Vol 11 (2) ◽

pp. 354-362 ◽

Cited By ~ 96

Author(s):

David L. Jordan ◽

Alan C. York ◽

James L. Griffin ◽

Patrick A. Clay ◽

P. Roy Vidrine ◽

...

Keyword(s):

Ammonium Sulfate ◽

Weed Control ◽

Field Experiments ◽

Redroot Pigweed ◽

Weed Growth ◽

Pitted Morningglory ◽

Three Stages ◽

Hemp Sesbania ◽

Prickly Sida ◽

Potential Interactions

Field experiments were conducted from 1993 to 1995 to compare weed control by the isopropylamine salt of glyphosate at 0.21, 0.42, 0.63, and 0.84 kg ae/ha applied at three stages of weed growth. Weed control by glyphosate applied at these rates alone or with ammonium sulfate at 2.8 kg/ha was also evaluated. In other experiments, potential interactions between glyphosate and acifluorfen, chlorimuron, and 2,4-DB were evaluated. Velvetleaf, prickly sida, sicklepod, pitted morningglory, entireleaf morningglory, palmleaf morningglory, and hemp sesbania were controlled more easily when weeds had one to three leaves compared with control when weeds had four or more leaves. Glyphosate controlled redroot pigweed, velvetleaf, prickly sida, sicklepod, and barnyardgrass more effectively than pitted morningglory, entireleaf morningglory, palmleaf morningglory, or hemp sesbania. Increasing the rate of glyphosate increased control, especially when glyphosate was applied to larger weeds. Greater variation in control was noted for pitted morningglory, palmleaf morningglory, prickly sida, and velvetleaf than for redroot pigweed, sicklepod, entireleaf morningglory, or hemp sesbania. Ammonium sulfate increased prickly sida and entireleaf morningglory control but did not influence sicklepod, hemp sesbania, or barnyardgrass control. Acifluorfen applied 3 d before glyphosate or in a mixture with glyphosate reduced barnyardgrass control compared with glyphosate applied alone. Chlorimuron did not reduce efficacy. Mixtures of glyphosate and 2,4-DB controlled sicklepod, entireleaf morningglory, and barnyardgrass similar to glyphosate alone.

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