Effect of Corn-Induced Shading and Temperature on Rate of Leaf Appearance in Redroot Pigweed (Amaranthus retroflexus L.)

Weed Science ◽  
1993 ◽  
Vol 41 (4) ◽  
pp. 590-593 ◽  
Author(s):  
Stephane M. Mclachlan ◽  
Clarence J. Swanton ◽  
Stephan F. Weise ◽  
Matthijs Tollenaar
Keyword(s):  
Field Experiments ◽  
Linear Increase ◽  
Amaranthus Retroflexus ◽  
Planting Date ◽  
Weed Interference ◽  
Redroot Pigweed ◽  
Field Temperature ◽  
Effects Of Temperature ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

Leaf development and expansion are important factors in determining the outcome of crop-weed interference. The comparative effects of temperature and corn canopy-induced shading on the rate of leaf appearance (RLA) of redroot pigweed were quantified in this study. Growth cabinet results indicated a linear increase in RLA with increased temperature. Weed RLA was predicted utilizing both this function and field temperature data. The ratio of observed to predicted RLA of redroot pigweed grown in field experiments decreased in 1990 and 1991 as shading increased with increased corn density and delayed weed planting date. Results indicated that RLA is substantially affected by canopy-induced shading in addition to temperature.

Interference of Redroot Pigweed (Amaranthus retroflexus) in Corn (Zea mays)

Weed Science ◽  
1994 ◽  
Vol 42 (4) ◽  
pp. 568-573 ◽  
Author(s):  
Stevan Z. Knezevic ◽  
Stephan F. Weise ◽  
Clarence J. Swanton
Keyword(s):  
Zea Mays ◽  
Grain Yield ◽  
Seed Production ◽  
Field Experiments ◽  
Amaranthus Retroflexus ◽  
Corn Yield ◽  
Leaf Stage ◽  
Redroot Pigweed ◽  
Emergence Date

Redroot pigweed is a major weed in corn throughout Ontario. Field experiments were conducted at two locations in 1991 and 1992 to determine the influence of selected densities and emergence times of redroot pigweed on corn growth and grain yield. Redroot pigweed densities of 0.5, 1, 2, 4 and 8 plants per m of row were established within 12.5 cm on either side of the corn row. In both years, redroot pigweed seeds were planted concurrently and with corn at the 3- to 5-leaf stage of corn growth. A density of 0.5 redroot pigweed per m of row from the first (earlier) emergence date of pigweed (in most cases, up to the 4-leaf stage of corn) or four redroot pigweed per m of row from the second (later) emergence date of pigweed (in most cases, between the 4- and 7-leaf stage of corn) reduced corn yield by 5%. Redroot pigweed emerging after the 7-leaf stage of corn growth did not reduce yield. Redroot pigweed seed production was dependent upon its density and time of emergence. The time of redroot pigweed emergence, relative to corn, may be more important than its density in assessing the need for postemergence control.

Temperature effects on germination and growth of redroot pigweed (Amaranthus retroflexus), Palmer amaranth (A. palmeri), and common waterhemp (A. rudis)

Weed Science ◽  
2003 ◽  
Vol 51 (6) ◽  
pp. 869-875 ◽  
Author(s):  
Peiguo Guo ◽  
Kassim Al-Khatib
Keyword(s):  
Seed Germination ◽  
Photosynthetic Apparatus ◽  
Amaranthus Retroflexus ◽  
Palmer Amaranth ◽  
Root Volume ◽  
Common Waterhemp ◽  
Redroot Pigweed ◽  
Higher Temperature ◽  
Effects Of Temperature ◽  
Germination And Growth

Experiments were conducted to determine the effects of temperature on seed germination and growth of redroot pigweed, Palmer amaranth, and common waterhemp. At 15/10 C day and night temperature, respectively, no seed germination was observed in any species. Seed germination increased gradually as temperature increased. Germination peaked at 25/20 C in common waterhemp and at 35/30 C in redroot pigweed and Palmer amaranth. Seed germination of all three species declined when temperatures increased above 35/30 C. All three species produced less biomass at 15/10 C than at 25/20 C and 35/25 C. Redroot pigweed and common waterhemp biomass were similar at 15/10 C and higher than that of Palmer amaranth. However, Palmer amaranth produced more biomass than redroot pigweed and common waterhemp at 25/20 and 35/30 C. At 45/40 C, redroot pigweed, common waterhemp, and Palmer amaranth plants died 8, 9, and 25 d after initiation of heat treatment, respectively. The largest root volume among the three species was in Palmer amaranth grown at 35/30 C, whereas the smallest root volume was produced by Palmer amaranth grown at 15/10 C. Potential quantum efficiency (Fv/Fmax) of Palmer amaranth was higher than that of redroot pigweed and common waterhemp at higher temperature. The greater growth of Palmer amaranth at higher temperatures may be attributed in part to its extensive root growth and greater thermostability of its photosynthetic apparatus.

Appearance and growth of individual leaves in the canopies of several potato cultivars

1995 ◽  
Vol 125 (3) ◽  
pp. 379-394 ◽  
Author(s):  
D. M. Firman ◽  
P. J. O'Brien ◽  
E. J. Allen
Keyword(s):  
Air Temperature ◽  
Field Experiments ◽  
Strong Dependence ◽  
N Fertilizer ◽  
Potato Cultivars ◽  
Main Stem ◽  
Planting Dates ◽  
Wide Range ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

SUMMARYLeaf appearance of contrasting potato cultivars was examined in field experiments at Cambridge, UK, between 1985 and 1990. Three experiments examined the effects of N fertilizer on the appearance and growth of leaves. Four experiments examined leaf appearance over a wide range of planting dates and in two of these experiments different physiological ages of seed were compared.Linear regression of rate of appearance of main-stem leaves on air temperature indicated a strong dependence of rate of leaf appearance on temperature in the cultivar Maris Piper with a phyllochron of c. 31 K d/leaf but in Estima variation in rate of leaf appearance was only partly explained by differences in air temperature. The phyllochron of main-stem leaves in Estima and Home Guard was shorter for old seed than young seed but there was little effect of seed age in four other cultivars. The phyllochron of main-stem leaves was longer without N fertilizer than with N but the difference in the phyllochron between rates of applied N was small. Leaf appearance on sympodial branches was slower and more variable than on the main-stem. Growth of branches differed between cultivars, particularly with no N fertilizer. In the determinate cultivars Estima and Diana there was restricted growth of branches but in the indeterminate cultivar Cara, significant leaf area was contributed by branches. The duration of leaf appearance and longevity of individual leaves is discussed in relation to N, temperature and cultivar.

scholarly journals Influence of Adjuvants on Efficacy of Imazapic and 2,4-DB

1999 ◽  
Vol 26 (1) ◽  
pp. 1-4 ◽  
Author(s):  
D. L. Jordan
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Amaranthus Retroflexus ◽  
Major Influence ◽  
Xanthium Strumarium ◽  
Redroot Pigweed ◽  
Eclipta Prostrata ◽  
Pitted Morningglory ◽  
Postemergence Herbicides ◽  
Organosilicone Surfactant

Abstract Adjuvants can have a major influence on efficacy of postemergence herbicides. Imazapic and 2,4-DB are applied postemergence in peanut (Arachis hypogaea L.) to control a variety of weeds. Determining how adjuvants influence efficacy of these herbicides could lead to more efficient weed management. Field experiments were conducted during 1997 and 1998 to determine the influence of nonionic surfactant, crop oil concentrate, organosilicone surfactant, and a blend of organosilicone surfactant and methylated seed oil on efficacy of imazapic and 2,4-DB. No-adjuvant and nontreated controls were also included. Adjuvants did not increase redroot pigweed (Amaranthus retroflexus L.) or common cocklebur (Xanthium strumarium L.) control by imazapic. Only minor differences in control of eclipta (Eclipta prostrata L.), entireleaf morningglory (Ipomoea hederacea var. integriuscula Gray), and pitted morningglory (Ipomoea lacunosa L.) by imazapic were noted among adjuvants. Sicklepod [Senna obtusifolia (L.) Erwin and Barneby] and pitted morningglory control increased when 2,4-DB was applied with adjuvants. Common cocklebur control was improved in one of three experiments when adjuvants were applied with 2,4-DB. Redroot pigweed and entireleaf morningglory control by 2,4-DB was not affected by adjuvants.

Mechanisms of Yield Loss in Maize Caused by Weed Competition

Weed Science ◽  
2012 ◽  
Vol 60 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Diego Cerrudo ◽  
Eric R. Page ◽  
Matthijs Tollenaar ◽  
Greg Stewart ◽  
Clarence J. Swanton
Keyword(s):  
Dry Matter ◽  
Field Experiments ◽  
Yield Loss ◽  
Kernel Weight ◽  
Rapid Decline ◽  
Weed Competition ◽  
Individual Plant ◽  
Rapid Loss ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

The physiological process underlying grain yield (GY) loss in maize as a result of weed competition is not understood clearly. We designed an experiment to test the hypotheses that early season stress caused by the presence of neighboring weeds will increase plant-to-plant variability (PPV) of individual plant dry matter (PDM) within the population. This increase in PPV will reduce GY through a reduction in harvest index (HI). Field experiments were conducted in 2008, 2009, and 2010. A glyphosate-resistant maize hybrid was cropped at a density of 7 plants m−2. As a model weed, winter wheat was seeded at the same time as maize and controlled with glyphosate at the 3rd or 10th to 12th leaf-tip stage of maize. Weed competition early in the development of maize decreased PDM and GY. This reduction in PDM, which occurred early in the development of maize, was attributed initially to a delay in rate of leaf appearance. Reductions in PDM were accompanied by an increase in PPV of PDM. This increase in PPV, however, did not reduce HI and did not contribute to the GY reductions created by weed competition, as hypothesized. As weed control was delayed, a reduction in fraction of photosynthetically active radiation (fIPAR) accounted for a further reduction in PDM and notably, a reduction in DMA from 17th leaf-tip stage through to maturity. The rapid loss of PDM and the subsequent inability to accumulate dry matter during maturation accounted for a rapid decline in kernel number (KN) and kernel weight (KW).

Weed Control in Soybeans by Glyphosate Applied in the Recirculating Sprayer

Weed Science ◽  
1977 ◽  
Vol 25 (2) ◽  
pp. 135-141 ◽  
Author(s):  
C.G. McWhorter
Keyword(s):  
Adverse Effect ◽  
Glycine Max ◽  
Field Experiments ◽  
Amaranthus Retroflexus ◽  
Sorghum Halepense ◽  
Redroot Pigweed ◽  
Sesbania Exaltata ◽  
Hemp Sesbania ◽  
June July ◽  
Over The Top

Field experiments were conducted to study the feasibility of applying glyphosate [N-(phosphonomethyl)glycine] postemergence for the control of johnsongrass [Sorghum halepense(L.) Pers.], redroot pigweed (Amaranthus retroflexusL.), and hemp sesbania [Sesbania exaltata(Raf.) Cory] in soybeans [Glycine max(L.) Merr.]. Herbicide sprays were directed across the row to weeds growing taller than soybeans in June, July, and August. Herbicide not sprayed on weeds was trapped and reused. Glyphosate at 1.12 and 1.68 kg/ha effectively controlled johnsongrass with little soybean injury and with greatly increased soybean yields. The use of 0.1% surfactant frequently increased the toxicity of glyphosate at 1.12 and 1.68 kg/ha to soybeans, but this adverse effect was overcome by the use of 0.1% anti-drift polymer in sprays. Control of redroot pigweed with glyphosate at 1.12 kg/ha was improved by the use of 0.1% surfactant, but surfactant did not increase control with glyphosate at 1.68 kg/ha. Glyphosate at 1.68 kg/ha, with 0.1% surfactant, was required to provide more than 80% control of hemp sesbania. Glyphosate applied at 1.12 kg/ha in the recirculating sprayer provided equal johnsongrass control, increased soybean yields and caused less soybean injury than when glyphosate at 0.56 kg/ha was applied over-the-top in water or in foam.

Influence of Cotton (Gossypium hirsutum) and Soybean (Glycine max) Planting Date on Weed Interference

Weed Science ◽  
1994 ◽  
Vol 42 (1) ◽  
pp. 61-65 ◽  
Author(s):  
Tracy E. Klingaman ◽  
Lawrence R. Oliver
Keyword(s):  
Field Experiments ◽  
Yield Loss ◽  
Planting Date ◽  
Cotton Yield ◽  
Yield Losses ◽  
Seed Cotton ◽  
Weed Species ◽  
Planting Dates ◽  
Seed Cotton Yield ◽  
Weed Interference

Separate field experiments were conducted for cotton and soybean in 1990 and 1991 to determine the influence of planting date on yield loss due to interspecific interference from entireleaf morningglory and sicklepod and to determine the relative competitiveness of each weed species. Percent soybean yield loss due to weed interference increased as planting date was delayed from early May to early June. Averaged over weed species, yield losses from 1.7 weeds m−1row were 10, 18, and 20% for soybeans planted in early May, mid-May, and early June, respectively. Yield loss from 6.7 weeds m−1row were 17, 31, and 35% at the early May, mid-May, and early June planting dates, respectively. Percent seed cotton yield losses averaged over weed species in 1990 were 33 and 28% for the early May and early June planting dates, respectively, at 1.7 weeds m−1and 50% for both planting dates at weed densities of 6.7 plants m−1. The only experimental factor that significantly affected seed cotton yield in 1991 was weed density. Unlike soybeans, planting date had little effect on weed interference in cotton. Entireleaf morningglory was more competitive than sicklepod in both crops. Results suggest that selection of optimum soy bean planting dates may be a viable means of reducing losses due to weed interference.

Control of Five Broadleaf Weeds in Sugarbeets (Beta vulgaris) with Glyphosate

Weed Science ◽  
1982 ◽  
Vol 30 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Edward E. Schweizer ◽  
Larry D. Bridge
Keyword(s):  
Beta Vulgaris ◽  
Field Experiments ◽  
Total Population ◽  
Chenopodium Album ◽  
Amaranthus Retroflexus ◽  
Kochia Scoparia ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
The Common ◽  
Vertical Roller

Field experiments were conducted to study the feasibility of applying glyphosate [N-(phosphonomethyl) glycine] postemergence with a recirculating sprayer and a vertical roller for the control of common lambsquarters (Chenopodium albumL.), common sunflower (Helianthus annuusL.), kochia [Kochia scoparia(L.) Schrad.], redroot pigweed (Amaranthus retroflexusL.), and velvetleaf (Abutilon theophrastiMedic.) in sugarbeets (Beta vulgarisL.). Glyphosate was applied twice each year at 1.7 kg/ha with a recirculating sprayer in 1977 and 1978, or twice as a 20% (v/v) solution with a vertical-roller applicator in 1979. By harvest, 70 to 74% of the total population of treated common sunflower, kochia, and redroot pigweed, 61% of the common lambsquarters, and 30% of the velvetleaf was dead. Root yields in glyphosate-treated plots, when averaged over 3 yr, were increased 5800, 8500, 12 500, and 13400 kg/ha at densities of 6, 12, 18, and 24 broadleaf weeds (equal densities of common lambsquarters, kochia, and redroot pigweed)/30m of row, respectively. Where equal densities of common sunflower and velvetleaf competed with sugarbeets, root yields in glyphosate-treated plots, when averaged over 2 yr, were increased 4400, 11900, 11700, and 10700 kg/ha, respectively, at these same densities.

Effect of Emergence Time on Growth and Fecundity of Redroot Pigweed (Amaranthus retroflexus) and Slender Amaranth (Amaranthus viridis): Emerging Problem Weeds in Australian Summer Crops

Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Asad M. Khan ◽  
Ahmadreza Mobli ◽  
Jeff A Werth ◽  
Bhagirath S. Chauhan
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Management Practice ◽  
Growth Period ◽  
Amaranthus Retroflexus ◽  
Planting Date ◽  
Late Spring ◽  
Planting Dates ◽  
Planting Time ◽  
Redroot Pigweed

Abstract Redroot pigweed (Amaranthus retroflexus L.) and Slender amaranth (Amaranthus viridis L.) are considered emerging problematic weeds in summer crops in Australia. An outdoor pot experiment was conducted to examine the effects of planting time of two populations of A. retroflexus and A. viridis at the research farm of the University of Queensland, Australia. Both species were planted every month from October to January (2017-18 and 2018-19), and their growth and seed production was recorded. Although both weeds matured at a similar number of growing degree days (GDDs), these weeds required a different number of days to complete their life cycle within each planting date. The growth period was reduced, and flowering occurred sooner as both species experienced cooler temperatures and shorter daylight hours. Compared to other planting times, both species exhibited increased height, biomass, and seed production for the October-sown plants, and these parameters were reduced by delaying the planting time. The shoot and root biomass of A. retroflexus and A. viridis (averaged over both populations) was reduced by more than 70% and 65%, respectively, when planted in January, in comparison to planting in October. When planted in October, A. retroflexus and A. viridis produced 11,350 and 5,780 seeds per plant, but these were reduced to 770 and 365 seeds per plant in planting date January, respectively. Although the growth and fecundity of these species were dependent on planting time, these weeds could emerge throughout the late spring to summer growing season (October to March) in southeast Australia and produce a significant number of seeds. The results showed that when these species emerged in the late spring (October), they grew vigorously and produced more biomass, in comparison with the other planting dates. Therefore, any early weed management practice for these species could be beneficial for minimizing the subsequent cost and inputs towards their control.

scholarly journals Collard—Cowpea Intercrop Response to Nitrogen Fertilization, Redroot Pigweed Density, and Collard Harvest Frequency

HortScience ◽  
1997 ◽  
Vol 32 (5) ◽  
pp. 850-853 ◽  
Author(s):  
Francis M. Itulya ◽  
Vasey N. Mwaja ◽  
John B. Masiunas
Keyword(s):  
Nitrogen Fertilization ◽  
Field Experiments ◽  
Cropping System ◽  
Dry Mass ◽  
N Fertilization ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Harvest Frequency ◽  
N Fertility ◽  
Crop Planting

Field experiments were conducted in 1992 and 1993 to determine the effect of N fertility, cropping system, redroot pigweed (Amaranthus retroflexus L.) density, and harvesting frequency on collard (Brassica oleracea var. acephala D.C) and cowpea [Vigna unguiculata (L.) Walp.] growth. The N fertilization regimes were 0, 80, 160, and 240 kg·ha-1, applied as urea in a split application. Four weeks after crop planting, redroot pigweed was seeded at 0, 300, and 1200 seeds/m2. Between weeks 6 and 12, collard leaves were harvested at 1- to 3-week intervals. Year, N fertility, and cropping system interacted to determine collard leaf number and mass. For example, in 1992, with N at 160 kg·ha-1, collards intercropped had more total leaf mass than those monocropped. Pigweed density had no effect on collard yields, which were greatest from the 3-week harvest frequency. Cropping system and pigweed density interacted to determine cowpea vine length, shoot dry mass, and branching. The high density of pigweed caused a 56% reduction of cowpea dry mass in 1992.

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