Innovative Approaches to Seedbank Studies

Seedbank studies often suffer from major methodological inadequacies such as absence of appropriate statistical data analysis and low sampling intensity. Multivariate analysis and computer mapping are innovative ways to treat seedbank data. Computer contour mapping was used to visualize spatial patterns of a population of common lambsquarters at three intervals during a growing season. At one site, high spring seed density of 600 000 seed m-2 was decreased to 18.3% of its original size by July, while at another site, low spring seedbank of common lambsquarters of 25 000 seed m-2 increased to 40 000 seed m-2 by autumn. Seedbank studies usually report results on total seed density or on densities of the most abundant species because of difficulties in analyzing large species matrices using parametric statistics. Multivariate analysis and specifically canonical discriminant analysis (CDA) are well suited for seedbank populations. The seedbanks of six agricultural habitats were demonstrated to be floristically different based on the analysis of the relative abundance of weed species in each site using CDA. Organic soils either under grassland or cultivated had significantly larger total seedbanks than mineral soils. If seedbanks are to be used in predictive population models, quantitative data that are reliable, rapidly obtained with limited resources, and logistically feasible for large sampling protocols are needed. Image analysis may be a potential rapid technique for weed seed recognition of washed soil samples.

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Residual Weeds of Processing Sweet Corn in the North Central Region

Weed Technology ◽

10.1614/wt-08-012.1 ◽

2008 ◽

Vol 22 (4) ◽

pp. 646-653 ◽

Cited By ~ 21

Author(s):

Martin M. Williams ◽

Tom L. Rabaey ◽

Chris M. Boerboom

Keyword(s):

Central Region ◽

Sweet Corn ◽

Abundant Species ◽

North Central Region ◽

Weed Species ◽

North Central ◽

Common Lambsquarters ◽

Weed Density ◽

Proso Millet ◽

The North

Knowledge of weed community structure in vegetable crops of the north central region (NCR) is poor. To characterize weed species composition present at harvest (hereafter called residual weeds) in processing sweet corn, 175 fields were surveyed in Illinois, Minnesota, and Wisconsin from 2005 to 2007. Weed density was enumerated by species in thirty 1-m2quadrats placed randomly along a 300- to 500-m loop through the field, and additional species observed outside quadrats were also recorded. Based on weed community composition, population density, and mean plant size, overall weed interference level was rated. A total of 56 residual weed species were observed and no single species dominated the community of NCR processing sweet corn. Several of the most abundant species, such as common lambsquarters and velvetleaf, have been problems for many years, while other species, like wild-proso millet, have become problematic in only the last 20 yr. Compared to a survey of weeds in sweet corn more than 40 yr ago, greater use of herbicides is associated with reductions in weed density by approximately an order of magnitude; however, 57% of fields appeared to suffer yield loss due to weeds. Sweet corn harvest in the NCR ranges from July into early October. Earlier harvests were characterized by some of the highest weed densities, while late-emerging weeds such as eastern black nightshade occurred in fields harvested after August. Fall panicum, giant foxtail, wild-proso millet, common lambsquarters, and velvetleaf were the most abundant species across the NCR, yet each state had some unique dominant weeds.

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Weed Control in Corn (Zea mays) as Affected by Till-Plant Systems and Herbicides

Weed Technology ◽

10.1017/s0890037x00031535 ◽

1989 ◽

Vol 3 (1) ◽

pp. 162-165 ◽

Cited By ~ 1

Author(s):

Edward E. Schweizer ◽

Robert L. Zimdahl ◽

Rome H. Mickelson

Keyword(s):

Weed Management ◽

Management Systems ◽

Weed Seed ◽

Weed Species ◽

Corn Production ◽

Common Lambsquarters ◽

Seed Reserves ◽

Total Seed ◽

Annual Weeds ◽

The Impact

The impact of three till-plant and two weed management systems on weed seed reserves of soil, yearly weed problems, and corn production was assessed under center-pivot irrigation for 3 consecutive years. Annual weeds were controlled in disced, bedded, and strip rotary till-plant systems with a moderate or intensive level of herbicides. Weed seed of seven annual weed species were identified, with common lambsquarters and stinkgrass, comprising 45 and 41%, respectively, of the initial 305 million seed/ha in the upper 25 cm of the soil profile. After the third cropping year, overall decline in total seed number in soil was 45% when averaged over till-plant and weed management systems. Grain yields did not differ between weed management systems, but the disced till-plant system produced 16% less grain than the bedded and strip rotary till-plant systems over 2 yr.

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The Effect of Piperonyl Butoxide and Adjuvants on Sulfonylurea Herbicide Activity

Weed Technology ◽

10.1017/s0890037x00045826 ◽

1996 ◽

Vol 10 (1) ◽

pp. 127-133 ◽

Cited By ~ 1

Author(s):

Chae Soon Kwon ◽

Donald Penner

Keyword(s):

Seed Oil ◽

Oxidase Inhibitor ◽

Piperonyl Butoxide ◽

Mixed Function Oxidase ◽

Sulfonylurea Herbicide ◽

Weed Species ◽

Common Lambsquarters ◽

Giant Foxtail ◽

Herbicide Activity ◽

Grass Weed

Greenhouse studies showed that the mixed function oxidase inhibitor, piperonyl butoxide (PBO), tank-mixed with the sulfonylurea herbicides, nicosulfuron, primisulfuron, and thifensulfuron, in the absence of effective adjuvants enhanced herbicide activity on both broadleaf and grass weed species. Effective adjuvants for nicosulfuron were K-3000 for common lambsquarters, Sylgard® 309 Surfactant for velvetleaf, K-2000 for barnyardgrass, and K-2000, K-3000, and Scoil® methylated seed oil for giant foxtail control. K-3000 and Sylgard 309 enhanced velvetleaf control with primisulfuron and thifensulfuron. The 28% urea and ammonium nitrate (UAN) was more effective as an adjuvant with thifensulfuron for velvetleaf than for common lambsquarters control. The enhancement of sulfonylurea herbicide activity with PBO was most apparent when other adjuvants were least effective.

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Evaluation of Imazethapyr for Weed Control in Leafy Vegetable Crops

Weed Technology ◽

10.1017/s0890037x00039907 ◽

1996 ◽

Vol 10 (2) ◽

pp. 253-257 ◽

Cited By ~ 4

Author(s):

Joan A. Dusky ◽

William M. Stall

Keyword(s):

Regression Analysis ◽

Weed Control ◽

Crop Yield ◽

Relative Sensitivity ◽

Leafy Vegetable ◽

Field Conditions ◽

Vegetable Crops ◽

Weed Species ◽

Common Lambsquarters ◽

Common Purslane

Imazethapyr was evaluated PRE and POST in five lettuce types and chicory under Florida field conditions. The relative sensitivity of leafy crop vigor (most sensitive to most tolerant) to imazethapyr PRE, based on 20% inhibition determined using regression analysis, was as follows: Boston > bibb > crisphead > romaine > leaf > escarole > endive. Leafy crop injury increased as the rate of imazethapyr applied POST increased, with all leafy crops responding in a similar manner. Surfactant addition increased imazethapyr phytotoxicity. Imazethapyr PRE treatments at 0.067 kg ai/ha provided greater than 80% control of livid amaranth, common purslane, flatsedge, and common lambsquarters. Imazethapyr POST at 0.067 kg/ha, with surfactant provided control greater than 85% of all weed species. Greater than 85% spiny amaranth control was provided by imazethapyr POST at 0.017 kg/ha. Use of surfactant with imazethapyr did not improve spiny amaranth control over imazethapyr with no surfactant. POST treatments did not decrease leafy crop yield compared with the hand-weeded check. Imazethapyr applied PRE reduced crop yield compared to the POST treatments and the hand-weeded control.

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Root Growth of Neighboring Maize and Weeds Studied with Minirhizotrons

Weed Science ◽

10.1614/ws-d-12-00120.1 ◽

2013 ◽

Vol 61 (2) ◽

pp. 319-327 ◽

Cited By ~ 1

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.

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Evaluating the EPA's Comparative Product Performance Testing Guidelines for Herbicides in Snap Bean (Phaseolus vulgaris)

Weed Technology ◽

10.1017/s0890037x00043712 ◽

1998 ◽

Vol 12 (2) ◽

pp. 215-222

Author(s):

Robin R. Bellinder ◽

Marija Arsenovic ◽

Jonathan J. Kirkwyland ◽

Russell W. Wallace

Keyword(s):

Weed Control ◽

Environmental Protection Agency ◽

Performance Testing ◽

Good Control ◽

Field Trials ◽

Weed Species ◽

Snap Bean ◽

Common Lambsquarters ◽

Redroot Pigweed ◽

Product Comparison

Following suggested guidelines developed by the Environmental Protection Agency (EPA), comparative snap bean herbicide performance field trials were conducted from 1993 to 1995 in New York. Data were obtained on crop injury, weed control, and weed biomass, and crop yield, quality, and losses during harvest. Trifluralin, EPTC, and pendimethalin applied preplant incorporated (PPI) and applications of metolachlor applied preemergence (PRE) provided less than adequate control of redroot pigweed, common lambsquarters, and hairy galinsoga. Cultivation improved weed control with PPI and PRE applications. Metolachlor + fomesafen PRE provided good control of hairy galinsoga, adequate redroot pigweed control, and marginal control of common lambsquarters. Fomesafen applied postemergence (POST), combinations of metolachlor applied PRE with fomesafen or bentazon applied POST, and fomesafen + bentazon applied POST adequately controlled the three weed species without cultivation. Herbicide treatments had little measurable impact on snap bean quality or losses during harvest. Information from product comparison trials may be useful in developing recommendations for growers but may prove less than adequate in providing data necessary for a thorough evaluation of the relative benefits of individual herbicides as intended by EPA guidelines. Difficulties were encountered in following the guidelines, and costs of conducting the product comparison trials for a single crop in one growing region exceeded $90,000 over 3 yr.

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Phosphorus effects on competitive interactions of smooth pigweed (Amaranthus hybridus) and common purslane (Portulaca oleracea) with lettuce (Lactuca sativa)

Weed Science ◽

10.1017/s0043174500089463 ◽

1998 ◽

Vol 46 (3) ◽

pp. 307-312 ◽

Cited By ~ 17

Author(s):

Bielinski M. Santos ◽

Joan A. Dusky ◽

William M. Stall ◽

Donn G. Shilling ◽

Thomas A. Bewick

Keyword(s):

Competitive Ability ◽

Organic Soils ◽

Weed Species ◽

Population Densities ◽

Replacement Series ◽

Amaranthus Hybridus ◽

Extractable P ◽

Common Purslane ◽

Smooth Pigweed ◽

Water Extractable

Replacement series studies were conducted under controlled conditions to determine the effect of phosphorus (P) rates and population densities on the competitiveness of smooth pigweed and common purslane with lettuce. Densities were 2, 4, and 8 plants per 113 cm2, whereas P rates were 0, 0.4, and 0.8 g PL−1soil. A P-deficient Histosol (0.3 mg water-extractable P L−1soil) was used. High P fertility enhanced the competitive ability of lettuce in smooth pigweed-lettuce mixtures. Smooth pigweed was not responsive to P rates. However, luxurious P consumption by smooth pigweed occurred, reducing the amount of the nutrient available for lettuce absorption. In common purslane-lettuce mixtures, the weed was responsive to P rates, increasing its competitive ability, whereas no increase in lettuce competitive ability was observed. Both weed species were more competitive than lettuce. Competition for P appears to be the main mechanism of common purslane interference on lettuce grown in low-P organic soils. Alternative fertilization strategies (i.e., banded applications) may reduce the effect of smooth pigweed on lettuce.

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Tolpyralate Efficacy: Part 1. Biologically Effective Dose of Tolpyralate for Control of Annual Grass and Broadleaf Weeds in Corn

Weed Technology ◽

10.1017/wet.2018.82 ◽

2018 ◽

Vol 32 (6) ◽

pp. 698-706 ◽

Cited By ~ 4

Author(s):

Brendan A. Metzger ◽

Nader Soltani ◽

Alan J. Raeder ◽

David C. Hooker ◽

Darren E. Robinson ◽

...

Keyword(s):

Effective Dose ◽

Weed Management ◽

Field Studies ◽

Biologically Effective Dose ◽

Limited Information ◽

Weed Species ◽

Common Lambsquarters ◽

Wild Mustard ◽

Low Field ◽

Green Foxtail

AbstractTolpyralate is a new 4-hydroxyphenyl-pyruvate dioxygenase (HPPD)-inhibiting herbicide for POST weed management in corn; however, there is limited information regarding its efficacy. Six field studies were conducted in Ontario, Canada, over 3 yr (2015 to 2017) to determine the biologically effective dose of tolpyralate for the control of eight annual weed species. Tolpyralate was applied POST at six doses from 3.75 to 120 g ai ha−1and tank mixed at a 1:33.3 ratio with atrazine at six doses from 125 to 4,000 g ha−1. Regression analysis was performed to determine the effective dose (ED) of tolpyralate, and tolpyralate+atrazine, required to achieve 50%, 80%, or 90% control of eight weed species at 1, 2, 4, and 8 wk after application (WAA). The ED of tolpyralate for 90% control (ED90) of velvetleaf, common lambsquarters, common ragweed, redroot pigweed or Powell amaranth, and green foxtail at 8 WAA was ≤15.5 g ha−1; however, tolpyralate alone did not provide 90% control of wild mustard, barnyardgrass, or ladysthumb at 8 WAA at any dose evaluated in this study. In contrast, the ED90for all species in this study with tolpyralate+atrazine was ≤13.1+436 g ha−1, indicating that tolpyralate+atrazine can be highly efficacious at low field doses.

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Isoxaflutole and metribuzin interactions in isoxaflutole-resistant soybean

Weed Science ◽

10.1017/wsc.2019.25 ◽

2019 ◽

Vol 67 (05) ◽

pp. 485-496

Author(s):

Andrea Smith ◽

Nader Soltani ◽

Allan C. Kaastra ◽

David C. Hooker ◽

Darren E. Robinson ◽

...

Keyword(s):

Chenopodium Album ◽

Ambrosia Artemisiifolia ◽

Herbicide Application ◽

Weed Species ◽

Control Efficacy ◽

Rainfall Events ◽

Common Lambsquarters ◽

Herbicide Resistant ◽

Synergistic Interactions ◽

Soybean Leaf

AbstractHerbicide-resistant weeds are a growing concern globally; in response, new herbicide resistance traits are being inserted into crops. Isoxaflutole-resistant soybean [Glycine max (L.) Merr.] will provide a new mode of action for use in this crop. Ten experiments were conducted over a 2-yr period (2017, 2018) to determine herbicide interactions between isoxaflutole and metribuzin on soybean injury, weed control efficacy, and soybean yield on a range of soil types. Soybean leaf-bleaching injury caused by isoxaflutole was most severe at sites with higher levels of rainfall after application. Control of weed species with isoxaflutole (52.5, 79, and 105 g ai ha−1) and metribuzin (210, 315, and 420 g ai ha−1) differed by site based on amount of rainfall after application. At sites where there was sufficient rainfall for herbicide activation, isoxaflutole at all rates controlled common lambsquarters (Chenopodium album L.), Amaranthus spp., common ragweed (Ambrosia artemisiifolia L.), and velvetleaf (Abutilon theophrasti Medik.) >90%; metribuzin at all rates controlled Amaranthus spp. and witchgrass (Panicum capillare L.) >80%. Control of every weed species evaluated was reduced when there was limited rainfall after herbicide application. The co-application of isoxaflutole + metribuzin resulted in additive or synergistic interactions for the control of C. album, Amaranthus spp., A. artemisiifolia, A. theophrasti, Setaria spp., barnyardgrass [Echinochloa crus-galli (L.) P. Beauv], and P. capillare. Isoxaflutole and metribuzin can be an effective management strategy for common annual broadleaf and grass weeds in Ontario if timely rainfall events occur after herbicide application.

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Response of Weed Seeds to Ethylene and Related Hydrocarbons

Weed Science ◽

10.1017/s004317450004337x ◽

1979 ◽

Vol 27 (1) ◽

pp. 7-10 ◽

Cited By ~ 49

Author(s):

R. B. Taylorson

Keyword(s):

Chenopodium Album ◽

Active Form ◽

Amaranthus Retroflexus ◽

Weed Species ◽

Hydrocarbon Gases ◽

Common Lambsquarters ◽

Setaria Faberi ◽

Redroot Pigweed ◽

Giant Foxtail ◽

Common Purslane

AbstractGermination of seeds of 10 grass and 33 broadleaved weed species was examined for response to ethylene. Germination was promoted in nine species, inhibited in two, and not affected in the remainder. Of the species promoted, common purslane (Portulaca oleraceaL.), common lambsquarters (Chenopodium albumL.), and several Amaranths, including redroot pigweed (Amaranthus retroflexusL.), were affected most. Transformation of phytochrome to the active form (Pfr) gave interactions that ranged from none to syntergistic with the applied ethylene. In subsequent tests seeds of purslane, redroot pigweed, and giant foxtail (Setaria faberiHerrm.), a species not responsive to ethylene, were examined for germination response to 14 low molecular weight hydrocarbon gases other than ethylene. Some stimulation by the olefins propylene and propadiene was found for purslane and pigweed. Propionaldehyde and butyraldehyde were slightly stimulatory to purslane only.

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