Differential Susceptibility of two Pigweed (Amaranthusspp.) Species to Napropamide

Weed Science ◽  
1979 ◽  
Vol 27 (2) ◽  
pp. 189-191 ◽  
Author(s):  
J. J. Jachetta ◽  
S. R. Radosevich ◽  
C. L. Elmore
Keyword(s):  
Root Growth ◽  
Field Study ◽  
Growth Rates ◽  
Differential Susceptibility ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Greenhouse Study ◽  
Cotyledon Stage ◽  
Differential Control

Differential napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] tolerance by redroot pigweed (Amaranthus retroflexusL.) and prostrate pigweed (Amaranthus blitoidesS. Wats.) was noted in field study. Redroot pigweed was readily controlled whereas prostrate pigweed was not. Germination studies in which both pigweed species were directly exposed to napropamide (0 to 25 ppm) indicated that prostrate pigweed was the most susceptible of the two species. Root growth rates of untreated prostrate pigweed were 30% greater than redroot pigweed. When seeds of both species were germinated in a 4-cm layer of napropamide in greenhouse study each species was controlled equally well. Exposure of germinating seedlings of the two pigweed species to napropamide 1 day before emergence resulted in differential control. Seedlings of redroot pigweed never developed beyond the cotyledon stage; whereas, prostrate pigweed seedlings were initially suppressed by the herbicide, but surviving plants continued to grow. An early preemergence application or mechanical incorporation of napropamide should enhance control of prostrate pigweed.

Vegetable crop emergence and weed control following amendment with different Brassicaceae seed meals

2007 ◽  
Vol 22 (3) ◽  
pp. 204-212 ◽  
Author(s):  
A.R. Rice ◽  
J.L. Johnson-Maynard ◽  
D.C. Thill ◽  
M.J. Morra
Keyword(s):  
Field Study ◽  
Weed Control ◽  
Amaranthus Retroflexus ◽  
Biologically Active ◽  
Growth Chamber ◽  
Biological Weed Control ◽  
Secondary Products ◽  
Redroot Pigweed ◽  
Study Results ◽  
The Impact

AbstractBrassicaceae seed meals produced through the oil extraction process release biologically active glucosinolate secondary products and may be useful as a part of biological weed control systems. Before meal can be used most efficiently, recommendations for suitable planting dates that maximize weed control but reduce crop injury must be determined. Our objectives were to determine the impact of 1 and 3% (w/w) meal applications of Brassica napus L. (canola), Brassica juncea L. (oriental mustard) and Sinapis alba L. (yellow mustard) on crop emergence and weed biomass in a growth chamber and field study. Results from the growth chamber experiment indicated that lettuce emergence was reduced by at least 75% when planted into 3% S. alba-amended soil earlier than 5 weeks after meal application. After 5 weeks, emergence was not different among treatments. Crop emergence was not reduced by any meal treatment as compared to the no-meal treatment in year 1 of the field study. In year 2, crop emergence in each 1.2-m row was inhibited by all meal treatments and ranged from 16 plants in the 3% B. juncea treatment to 81 plants in the no-meal treatment. The difference between emergence results in year 1 and year 2 is likely due to differing climatic conditions early in the season prior to irrigation, and the method of irrigation used. Redroot pigweed (Amaranthus retroflexus L.) biomass was 72–93% lower in 1% B. juncea and 3% treatments relative to the no-meal control in the first weed harvest of year 1. These same treatments had 87–99% less common lambsquarters (Chenopodium album L.) biomass. By the second weed harvest, redroot pigweed biomass in meal treatments (0.02–1.6 g m−2) was not different from that in the no-meal treatment (0.97 g m−2). Redroot pigweed biomass in 3% B. juncea plots was reduced by 74% relative to the no-meal treatment in the first harvest of year 2. This treatment also reduced common chickweed [Stellaria media (L.) Vill.] biomass by 99% relative to the 1% meal treatments. While pigweed biomass was reduced by 3% B. juncea in the early part of the season, by the second harvest this same treatment had the greatest pigweed biomass. Despite significant variability between years, 3% B. juncea did provide early season weed control in both years. Repeated meal applications, however, may be necessary to control late season weeds. Inhibition of crop emergence appears to be highly dependent on the amount and distribution of water and needs to be further studied in field settings.

scholarly journals Kenaf (Hibiscus cannabinus L.) Impact on Post-Germination Seedling Growth

2015 ◽  
Vol 7 (12) ◽  
pp. 91
Author(s):  
Charles L. Webber III ◽  
Paul M. White Jr ◽  
Dwight L. Myers ◽  
James W. Shrefler ◽  
Merritt J. Taylor
Keyword(s):  
Root Growth ◽  
Italian Ryegrass ◽  
Hibiscus Cannabinus ◽  
Green Bean ◽  
Hypocotyl Growth ◽  
Leaf Extracts ◽  
Radicle Growth ◽  
Redroot Pigweed ◽  
Mixed Response ◽  
The Impact

<p>The chemical interaction between plants, which is referred to as allelopathy, may result in the inhibition of plant growth and development. The objective of this research was to determine the impact of kenaf (<em>Hibiscus cannabinus</em> L.) plant extracts on the post-germination growth of five plant species. Four concentrations (0, 16.7, 33.3 and 66.7 g/L) of kenaf bark, core, and leaf extracts were applied to the germinated seeds of redroot pigweed (<em>Amaranthus retroflexus</em> L.), green bean (<em>Phaseolus vulgaris</em> L.), tomato (<em>Solanum lycopersicum </em>Mill.), cucumber (<em>Cucumis sativus</em> L.), and Italian ryegrass (<em>Lolium multiflorum</em> Lam.). After 7 days, the developing seedlings were measured to determine the length of their hypocotyls (mm) and radicles (mm), and the number of hair roots. Tomato, Italian ryegrass, and redroot pigweed followed similar negative trends in their responses to the extract source (kenaf bark, core, and leaves) and the impact of extract concentration, whereas, cucumber had a mixed response and green bean reacted positively to the kenaf extracts. Tomato was the most sensitive species tested across all kenaf extracts and concentrations, resulting in decreased hypocotyl, radicle, and root growth. Green bean exhibited no negative effects due to the kenaf extracts, but actually produced increased hypocotyl growth as a result of the kenaf bark, core, and leaf extracts. The kenaf extracts resulted in a mixed response for cucumber. The kenaf leaf and bark extract decreased cucumber radicle growth, whereas, the bark and core extracts increased hypocotyl growth. Italian ryegrass hypocotyl growth decreased across all extract sources (bark, core, and leaf), while the leaf extract also reduced root growth. All kenaf extracts reduced redroot pigweed radicle growth, while the core and leaf extracts reduced hypocotyl growth. The research demonstrated that kenaf leaf extracts were the most allelopathic and the hypocotyls were the most sensitive. Future research should isolate the chemicals responsible for both the negative and positive allelopathic impact on the various plant species, determine if the extracts will influence more mature plants, and pursue cultural practices to utilize these natural allelopathic materials to benefit crop production and limit weed competition.</p>

ATRAZINE RESISTANCE IN AMARANTHUS RETROFLEXUS (REDROOT PIGWEED) AND A. POWELLII (GREEN PIGWEED) FROM SOUTHERN ONTARIO

1980 ◽  
Vol 60 (4) ◽  
pp. 1485-1488 ◽  
Author(s):  
S. I. WARWICK ◽  
S. E. WEAVER
Keyword(s):  
Amaranthus Retroflexus ◽  
Washington State ◽  
Morphological Examination ◽  
The West ◽  
Southern Ontario ◽  
Redroot Pigweed ◽  
Atrazine Resistance ◽  
Resistant Population ◽  
Herbicide Atrazine ◽  
The One

Screening trials with the herbicide atrazine and a morphological examination of atrazine-resistant pigweed populations from southern Ontario and Washington state have established: (1) that the several resistant populations from the West Montrose area, Waterloo Co., Ontario and one from Washington state, previously reported as Amaranthus retroflexus, are, in fact, referable to A. powellii and (2) that the one resistant population near Ayr, Waterloo Co., Ontario, which had not been previously reported, is correctly identified as A. retroflexus. Features distinguishing the three pigweed taxa that are common in southern Ontario (A. powellii, A. retroflexus and A. hybridus) are reviewed.

scholarly journals Effects of Matric and Osmotic Priming Treatments on Broccoli Seed Germination

1996 ◽  
Vol 121 (3) ◽  
pp. 423-429 ◽  
Author(s):  
Lewis W. Jett ◽  
Gregory E. Welbaum ◽  
Ronald D. Morse
Keyword(s):  
Polyethylene Glycol ◽  
Seed Germination ◽  
Root Growth ◽  
Growth Rates ◽  
Germination Rate ◽  
Membrane Integrity ◽  
Seed Vigor ◽  
Radicle Emergence ◽  
The Mean ◽  
Peg 8000

Priming, a controlled-hydration treatment followed by redrying, improves the germination and emergence of seeds from many species. We compared osmotic and matric priming to determine which was the most effective treatment for improving broccoli seed germination and to gain a greater understanding of how seed vigor is enhanced by priming. Broccoli (Brassica oleracea L. var. italica) seeds were osmotically primed in polyethylene glycol (PEG 8000) at -1.1 MPa or matrically primed in a ratio of 1.0 g seed:0.8 g synthetic calcium silicate (Micro-Cel E):1.8 ml water at -1.2 MPa. In the laboratory, germination rates and root lengths were recorded from 5 to 42C and 10 to 35C, respectively. Broccoli seeds germinated poorly at >35C. Root growth after germination was more sensitive to temperatures >30C and <15C than radicle emergence. Matric and osmotic priming increased germination rate in the laboratory, greenhouse, and field. However, matric priming had a greater effect on germination and root growth rates from 15 to 30C. Neither priming treatment affected minimum or maximum germination or root growth temperatures. Both priming treatments decreased the mean thermal time for germination by >35%. The greater germination performance of matrically primed seeds was most likely the result of increased oxygen availability during priming, increased seed Ca content, or improved membrane integrity.

Root Growth of Neighboring Maize and Weeds Studied with Minirhizotrons

Weed Science ◽  
2013 ◽  
Vol 61 (2) ◽  
pp. 319-327 ◽  
Author(s):  
Deborah Britschgi ◽  
Peter Stamp ◽  
Juan M. Herrera
Keyword(s):  
Root Growth ◽  
Surface Area ◽  
Plant Density ◽  
Fluorescent Protein ◽  
Root Density ◽  
Weed Species ◽  
Belowground Competition ◽  
Higher Plant ◽  
Common Lambsquarters ◽  
Redroot Pigweed

Competition between crops and weeds may be stronger at the root than at the shoot level, but belowground competition remains poorly understood, due to the lack of suitable methods for root discrimination. Using a transgenic maize line expressing green fluorescent protein (GFP), we nondestructively discriminated maize roots from weed roots. Interactions between GFP-expressing maize, common lambsquarters, and redroot pigweed were studied in two different experiments with plants arranged in rows at a higher plant density (using boxes with a surface area of 0.09 m2) and in single-plant arrangements (using boxes with a surface area of 0.48 m2). Root density was screened using minirhizotrons. Relative to maize that was grown alone, maize root density was reduced from 41 to 87% when it was grown with redroot pigweed and from 27 to 73% when it was grown with common lambsquarters compared to maize grown alone. The calculated root : shoot ratios as well as the results of shoot dry weight and root density showed that both weed species restricted root growth more than they restricted shoot growth of maize. The effect of maize on the root density of the weeds ranged from a reduction of 25% to an increase of 23% for common lambsquarters and a reduction of 42 to 6% for redroot pigweed. This study constitutes the first direct quantification of root growth and distribution of maize growing together with weeds. Here we demonstrate that the innovative use of transgenic GFP-expressing maize combined with the minirhizotron technique offers new insights on the nature of the response of major crops to belowground competition with weeds.

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.

Stimulation of Common Cocklebur (Xanthium pensylvanicum) and Redroot Pigweed (Amaranthus retroflexus) Seed Germination by Injections of Ethylene into Soil

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 510-514 ◽  
Author(s):  
G. H. Egley
Keyword(s):  
Seed Germination ◽  
Laboratory Tests ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Plastic Bags ◽  
Viable Seeds ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Stimulation Of

The effects of ethylene upon germination of common cocklebur (Xanthium pensylvanicumWallr.) and redroot pigweed (Amaranthus retroflexusL.) seeds were studied. In laboratory tests with seeds in sealed flasks in the dark, 10 μl/L ethylene increased germination of redroot pigweed seeds from 7% to 52% at 30 C, and increased germination of large and small common cocklebur seeds from 30% and 0% to 100% and 90% respectively, at 25 C. At least 12 h of exposure to ethylene was necessary for appreciable stimulation of germination. In growth chamber studies with known numbers of seeds in pots of soil, ethylene at 11 kg/ha was injected into the soil, and the pots were enclosed in plastic bags for 24 h. One such injection at 2 weeks after planting, and successive injections at 2, 3, and 4 weeks, significantly increased redroot pigweed seedling emergence, and significantly decreased the numbers of dormant, viable seeds remaining in the soil. When pots were not enclosed, injections did not significantly effect redroot pigweed seeds, but significantly increased common cocklebur seedling emergence and decreased the number of viable common cocklebur seeds remaining in the soil.

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