EFFECTS OF TIME OF EMERGENCE, POPULATION DENSITY AND INTERSPECIFIC COMPETITION ON HEMP-NETTLE (Galeopsis tetrahit) SEED PRODUCTION

1989 ◽  
Vol 69 (1) ◽  
pp. 185-194 ◽  
Author(s):  
ANNE LÉGÈRE ◽  
JEAN-MARC DESCHÊNES
Keyword(s):  
Population Density ◽  
Interspecific Competition ◽  
Seed Production ◽  
Unit Area ◽  
Initial Growth ◽  
Weed Seed ◽  
Weed Species ◽  
Crop Species ◽  
Thlaspi Arvense ◽  
Delayed Emergence

Various conditions of intra- and interspecific competition may influence weed seed production thus affecting the extent of seed return to the soil. The objective of this study was to measure the effects of time of emergence, population density, and weed crop interaction on seed production of hemp-nettle (Galeopsis tetrahit) in natural field populations. Hemp-nettle seed production was studied in pure hemp-nettle stands, mixed hemp-nettle-stinkweed (Thlaspi arvense) stands, hemp-nettle-crop stands, and hemp-nettle-stinkweed-crop stands. Crop species used were alfalfa (Medicago sativa) and oats (Avena sativa). In pure hemp-nettle stands, delayed emergence and high population density reduced seed production of individual hemp-nettle plants. Hemp-nettle seed production per unit area was comparable for all but the lowest population density. Stink-weed population densities up to 200 plants m−2 had no consistent effect on average seed production of individual hemp-nettle plants. Seed production of individual plants was scarcely affected by the presence of alfalfa whereas it was largely reduced in the presence of the oat crop. Oats were usually more competitive than alfalfa, the latter crop being disadvantaged by slow initial growth. Hemp-nettle was not as prolific as other weed species but still produced enough seeds to reinfest the soil, even under highly competitive conditions.Key words: Hemp-nettle, Galeopsis tetrahit, seed production, weed reproduction

scholarly journals Influence of crop rotation, tillage, and management inputs on weed seed production

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 175-183 ◽  
Author(s):  
George O. Kegode ◽  
Frank Forcella ◽  
Sharon Clay
Keyword(s):  
Seed Production ◽  
Crop Rotation ◽  
Crop Production ◽  
Conservation Tillage ◽  
Farming Systems ◽  
Crop Rotations ◽  
Weed Seed ◽  
Weed Species ◽  
Weed Seeds ◽  
Ridge Tillage

Approaches to crop production that successfully reduce weed seed production can benefit farming systems by reducing management inputs and costs. A 5-yr rotation study was conducted in order to determine the effects that interactions between crop rotation, tillage, and amount of herbicide and fertilizer (management inputs) have on annual grass and broad-leaved weed seed production and fecundity. There were 10 crop rotation and tillage system combinations and three levels of management inputs (high, medium, and low). Green and yellow foxtail were the major weed species, and together they yielded between 76 and 93% of collected weed seeds. From 1990 to 1994, average grass weed seed productions were 7.3 by 103, 3.7 by 1036.1 by 103and 5.7 by 103seeds m−-2, whereas average broad-leaved weed seed productions were 0.4 by 103, 0.4 by 103, 1.4 by 103, and 0.4 by 103seeds m−-2in crop rotations using conventional tillage (moldboard plow), conservation tillage, no tillage, and ridge tillage, respectively. Crop rotations using conventional or ridge tillage consistently produced more grass and broad-leaved weed seeds, especially in low-input plots. There was little difference in weed seed production among input levels for crop rotations using conservation tillage. Comparing rotations that began and ended with a corn crop revealed that by increasing crop diversity within a rotation while simultaneously reducing the amount of tillage, significantly fewer grass and broad-leaved weed seeds were produced. Among the rotations, grass and broad-leaved weed fecundity were highly variable, but fecundity declined from 1990 to 1994 within each rotation, with a concomitant increase in grass and broad-leaved weed density over the same period. Crop rotation in combination with reduced tillage is an effective way of limiting grass and broad-leaved weed seed production, regardless of the level of management input applied.

scholarly journals Influence of Postemergence Dicamba/Glyphosate Timing and Inclusion of Acetochlor as a Layered Residual on Weed Control and Soybean Yield

2021 ◽  
Vol 3 ◽  
Author(s):  
Sarah Striegel ◽  
Maxwel C. Oliveira ◽  
Ryan P. DeWerff ◽  
David E. Stoltenberg ◽  
Shawn P. Conley ◽  
...  
Keyword(s):  
Grain Yield ◽  
Weed Control ◽  
Seed Production ◽  
Developmental Stages ◽  
Weed Seed ◽  
Weed Species ◽  
Soybean Yield ◽  
Density Reduction ◽  
Giant Ragweed ◽  
Residual Herbicide

Roundup Ready 2 Xtend® [glyphosate- and dicamba-resistant (DR)] soybean is a novel trait option for postemergence (POST) control of herbicide-resistant broadleaf weeds in soybean. With increased use of labeled dicamba products POST in DR soybean and recommendations to include a soil-residual herbicide POST (e.g., layered residual approach), research on how combinations of these approaches influence weed control, weed seed production, and soybean grain yield is warranted. The objective of this research was to evaluate the effects of (1) flumioxazin applied preemergence (PRE) followed by (fb) dicamba plus glyphosate applied POST at different crop developmental stages and (2) acetochlor POST as a layered residual approach on weed control, weed seed production, and soybean yield to determine the optimal POST timing in DR soybean. A field study was conducted in Wisconsin at three sites in 2018 and four sites in 2019 to evaluate flumioxazin (43.4 g ai ha−1, WDG 51%) PRE fb dicamba (560 g ae ha−1, SL) plus glyphosate (1,101 g ae ha−1, SL) POST in DR soybean at three stages: early-POST (EPOST, V1-V2), mid-POST (MPOST, V3-V4), and late-POST (LPOST, V5-V6/R1) with or without a soil-residual herbicide POST (acetochlor, 1,262 g ai ha−1, ME). Weed community composition was site-specific; difficult-to-control broadleaf species included giant ragweed (Ambrosia trifida L.) and waterhemp [Amaranthus tuberculatus (Moq.) J.D. Sauer]. Dicamba plus glyphosate applied MPOST and LPOST provided greater control, weed biomass reduction, and density reduction of giant ragweed and waterhemp when compared with EPOST treatments. Giant ragweed and waterhemp had not reached 100% cumulative emergence at EPOST, and plants that emerged after EPOST produced seed. There was some benefit to including acetochlor as a layered residual at EPOST as indicated by a residual by POST timing interaction for waterhemp density reduction. Complete waterhemp control was not attained at one site-year. For remaining site-years, dicamba plus glyphosate applied MPOST (V3-V4) provided season-long weed control, reduced weed seed production, and optimized soybean grain yield compared with other POST treatments. Results highlight the importance of timely POST applications and suggest utilization of a POST layered residual needs to be timed appropriately for the window of active weed species emergence.

scholarly journals REVIEW OF THE INFLUENCE OF CROP ROTATION AND PRIMARY TILLAGE OPERATIONS ON WEED SEED BANK

2021 ◽  
Vol 9 (7) ◽  
pp. 407-421
Author(s):  
Nawal Al-Hajaj
Keyword(s):  
Seed Production ◽  
Crop Rotation ◽  
Seed Bank ◽  
Seedling Recruitment ◽  
Crop Productivity ◽  
Crop Rotations ◽  
Weed Seed ◽  
Weed Species ◽  
Primary Tillage ◽  
Weed Emergence

In this study, we reviewed weed seed bank dynamic and main agriculture operations to come up with the weed seed management modeling designed to increase crop productivity by removing weed competition. Weed contributing with 10% loss of total global grain production. Weed seed bank regulate by five demographic processes seedling recruitment and survival, seed production, dispersal and seed survival in soil. The main agriculture operations that interference with weed seed bank are crop rotation and primary tillage. Tillage systems affect weed emergence, management, and seed production; therefore, changing tillage practices changes the composition, vertical distribution, and density of weed seed bank in agricultural soils. Weed species vary in their response to various crop rotations, due to the variability of weed-crop competition in their relative capacity to capture growth–limiting resources. Crop rotations affect weed emergence, management, composition, and density of weed seed bank. Finally, the study suggests elevating crop competitiveness against weeds, through a combination of crop rotation and reduce_ zero tillage, has strong potential to reduce weed-induced yield losses in crop.

Tillage Effects on Weed Seed Return and Seedbank Composition

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 314-322 ◽  
Author(s):  
David R. Clements ◽  
Diane L. Benoit ◽  
Stephen D. Murphy ◽  
Clarence J. Swanton
Keyword(s):  
Seed Production ◽  
Unit Area ◽  
The Other ◽  
Similar Species ◽  
Weed Seed ◽  
Common Lambsquarters ◽  
Weed Population ◽  
No Till ◽  
Chisel Plow ◽  
Moldboard Plow

Weed seed return and seedbank composition, with particular reference to common lambsquarters, were studied in four tillage systems established on a site near Fingal, Ontario. The tillage treatments were moldboard plow, chisel plow, ridge-till, and no-till. The cropping system was a cornsoybean rotation. Tillage effects on weed population composition were assessed after all weed control measures had been implemented. More than 60% of the weed seedbank was concentrated in the upper 5 cm of soil in chisel plow and no-till. The seedbank of the moldboard plow system was more uniformly distributed over depth and larger than the other systems. Common lambsquarters comprised more than 50% of the seedbank in all systems except ridge-till, but only dominated the aboveground weed population in chisel plow. Seedbank populations of common lambsquarters with moldboard plowing were greater than those with ridge-till and no-till, and chisel plow seedbank populations were greater than those in ridge-till. Chisel and moldboard plow systems generally had higher aboveground plant populations of common lambsquarters than the other two systems. Seed production per plant by common lambsquarters was equivalent among the four systems, but estimated seed production per unit area was higher in moldboard plow and chisel plow systems than in the other systems. Populations of common lambsquarters and similar species may produce more seeds and persist in moldboard plow and chisel plow systems; these weeds may produce fewer seeds per unit area and be easier to manage in no-till and ridge-till systems.

Seed Retention of Grass Weeds at Wheat Harvest in the Pacific Northwest

Weed Science ◽  
2020 ◽  
pp. 1-32
Author(s):  
Carolina San Martín ◽  
Mark E Thorne ◽  
Jennifer A Gourlie ◽  
Drew J Lyon ◽  
Judit Barroso
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Secale Cereale ◽  
Bromus Tectorum ◽  
Wheat Crop ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Seed Retention ◽  
The Pacific

Abstract Harvest weed seed control (HWSC) may control problematic weeds by decreasing contributions to the weed seed bank. However, HWSC practices will not be effective if plants have shed a great part of their seeds before harvest, or if a low proportion of seed production is retained at a height that enables collection during harvest. The seed shattering pattern of several weed species was evaluated over three growing seasons to determine their potential to be controlled with HWSC in the Pacific Northwest (PNW). The studied weed species were downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), Italian ryegrass [Lolium perenne ssp. multiflorum (Lam.) Husnot,], and rattail fescue [Vulpia myuros (L.) C.C. Gmel.]. Seed retention at harvest, seed production, and plant height differed among species, locations, and years. Environmental conditions influenced seed shattering patterns, particularly the time plants started to shatter seeds and the rate of the shattering. Agronomic factors such as herbicide use, inter-row space, or crop height/vigor also seemed to affect shattering patterns and seed production, but more specific studies must be conducted to determine their individual effects. Bromus tectorum, L. perenne ssp. multiflorum, and V. myuros had an average seed retention at harvest of less than 50%. In addition, the low seed retention height of V. myuros makes this species a poor candidate for HWSC. Secale cereale had average seed retention at harvest greater than 50% and seed retention height was greater than 30 cm. The variability of seed retention in different species will make the efficacy of HWSC practices species and environment dependent in PNW winter wheat cropping systems. Harvesting the wheat crop as early as possible will be crucial to the success of HWSC.

Weed seed destruction by arthropods and rodents in low-input soybean agroecosystems

1988 ◽  
Vol 3 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Gerald E. Brust ◽  
Garfield J. House
Keyword(s):  
Conventional Tillage ◽  
Ground Beetles ◽  
Amaranthus Retroflexus ◽  
Ambrosia Artemisiifolia ◽  
Carabid Beetles ◽  
No Tillage ◽  
Weed Seed ◽  
Weed Species ◽  
Crop Species ◽  
Low Input

AbstractWeed seed consumption experiments involving comparison of rates of seed loss by seed feeders were conducted over a five-week period in low-input (no insecticide, low herbicide usage) conventional- and no-tillage soybean agroecosystems. Seeds of four broadleaf weed species (ragweed[Ambrosia artemisiifoliaL.], pigweed[Amaranthus retroflexusL.], sicklepod[Cassia obtusifoliaL.], and jimsonweed[Datura stramoniumL.]) and one grain crop species (wheat[Triticum aestivumL.]) were provided in a free choice design at densities of 10, 25, and 50 seeds/24 cm3. Approximately 2.3 times more seeds overall, and 1.4 times more large seeds as a group were consumed in notillage systems than in conventional-tillage systems. In our experimental low-input, notillage treatments, large ground beetles (Carabidae: Coleoptera) (15–25 mm) and mice preferentially fed on the larger seed species, while small carabids (< 15 mm), ants and crickets, fed almost exclusively on the smaller seed species. Carabid beetles were responsible for more than half of all seeds consumed. Laboratory and field studies indicated that ground beetles selectively consumed specific seed species. In conventional-tillage, ants were one of the dominant consumers of seeds, suggesting different patterns of resource partitioning in each tillage system. We suggest that selective feeding by arthropod seed feeders, in combination with their high number, could affect the species composition and possibly the abundance of weeds in low-input, no-tillage agroecosystems.

scholarly journals Archaeobotanical reconstructions of field habitats and crops: the grange in Pomorzany near Kutno, 18th/19th c.

2015 ◽  
Vol 37 (1) ◽  
pp. 75-81
Author(s):  
Joanna Koszałka ◽  
Joanna Ewa Strzelczyk
Keyword(s):  
Cannabis Sativa ◽  
Plant Macrofossils ◽  
Wild Plant ◽  
Plant Residues ◽  
Raphanus Raphanistrum ◽  
Weed Species ◽  
Crop Species ◽  
Thlaspi Arvense ◽  
Reconstruction Methods ◽  
Anthemis Arvensis

Abstract The paper presents the results of research of plant macrofossils from the grain deposit deriving from the 18th/19th centuries. The analysed material included 24760 diaspores representing 73 taxa. The majority were cultivated cereal crop species, and there was also abundance of accompanying segetal weed species. About 95% of the gathered crop material was Secale cereale. Another important crop was Hordeum vulgare and there were also some remains of Avena sativa, Triticum aestivum, Fagopyrum esculentum. Cannabis sativa and Linum usitatissimum were found as well. Weeds competing with these crops were, among others, the following species: Agrostemma githago, Raphanus raphanistrum, Apera spica-venti, Bromus secalinus, Centaurea cyanus, Spergula arvensis, Thlaspi arvense, Viola arvensis/tricolor, Fallopia convolvulus, Polygonum persicaria, Mentha arvensis, Anthemis arvensis, Papaver rhoeas, Rumex acetosella, Scleranthus annuus, Aphanes arvensis, Setaria pumila, Setaria viridis/verticilata. Extremely large presence of wild plant diaspores in the material allowed conducting economic and environmental interpretations. Reconstruction methods applied, used primarily in the case of macroremains from granaries, were fully applicable to the analysed plant residues. Weed species composition in the analysed material showed that they were mostly typical for the main winter crop. Some amount of species typical for other habitats were also found and they probably came from the near-by rye field. The presence of perennial diaspores indicated that the field was probably set aside

Influence of Early-Season Yield Loss Predictions from WeedSOFT®and Soybean Row Spacing on Weed Seed Production from a Mixed-Weed Community

2004 ◽  
Vol 18 (2) ◽  
pp. 412-418 ◽  
Author(s):  
Andrew A. Schmidt ◽  
William G. Johnson
Keyword(s):  
Seed Production ◽  
Crop Yield ◽  
Weed Management ◽  
Yield Potential ◽  
Management Decision ◽  
Yield Reduction ◽  
Weed Seed ◽  
Weed Species ◽  
Early Season ◽  
Giant Foxtail

Seed production from weeds that are missed by herbicide application can affect future weed populations and management decisions. It may be possible to expand the utility of computerized weed management decision aids to include an estimate of weed seed production resulting from selected treatments based on crop yield potential. Field studies were conducted in soybean near Columbia, MO, to determine whether weed control recommendations based on crop yield potential from a computerized weed management decision aid influence weed seed production in two soybean row spacings. At approximately 28 d after planting, weed densities and heights were entered into WeedSOFT®to generate a list of treatments ranked by predicted crop yields. Treatments included: (1) highest predicted crop yield in a glyphosate-resistant system, (2) highest predicted crop yield in a nonglyphosate-resistant system, (3) a 10% yield reduction, (4) a 20% yield reduction, and (5) an untreated control. These treatments were applied to soybean grown in 38- and 76-cm rows. Treatments that provided 90% or higher control of an individual species at 22 d after treatment usually produced less seed than untreated checks. Weed seed production based on early-season herbicide efficacy showed a linear relationship and was relatively predictable (r2≥ 0.52) for the predominant weed species. For less dominant weed species, weed seed production was not strongly correlated (r2≤ 0.27) to early-season herbicide efficacy but apparently influenced by control of other weed species. Narrow row spacing reduced giant foxtail biomass both years but did not reduce common ragweed and ivyleaf morningglory biomass. Narrow rows did not decrease giant foxtail, common ragweed, and ivyleaf morningglory seed production.

Dynamics of weed populations in a northern subarctic community

1991 ◽  
Vol 69 (4) ◽  
pp. 814-821 ◽  
Author(s):  
Richard J. Staniforth ◽  
Peter A. Scott
Keyword(s):  
Seed Production ◽  
Chenopodium Album ◽  
Weed Species ◽  
Growing Seasons ◽  
Thlaspi Arvense ◽  
Introduced Plants ◽  
Future Events ◽  
Species Dynamics ◽  
Weedy Species ◽  
Refuse Tips

The introduced flora of Churchill, northern Manitoba, was studied to draw some conclusions about the dynamics of weeds in northern subarctic communities in general. One hundred and six introduced species have been recorded at Churchill. Fifty-five percent of these were "temporary," dying out when original colonizers senesced (e.g., Avena spp., Setaria viridis). Seventeen percent were "established," i.e., able to set viable seed and maintain their populations (e.g., Thlaspi arvense, Crepis tectorum). Twenty-eight percent "persisted" locally by vegetative propagation or repeated seed input (e.g., Linaria vulgaris, Chenopodium album s.l.). The findings were compared with those of an earlier study. The number of species and their local distributions around Churchill have increased in the last 30 years. This may be due to an increase and diversification in the traffic with southern regions or to an amelioration in the climate. Although one in five species in the vicinity of Churchill are introduced, usually fewer than 12 weed species were established at any one site. Abandoned sites exhibited a rapid disappearance of weeds. Depauperate individuals of a few species were found away from inhabited areas, with none occurring in natural communities. Organic material in refuse tips provided a mild environment with a long growing season. Refuse tips may act as refuges for weeds and as potential sources of their seeds. Aliens that were successful at seed production were either perennials, winter annuals, or biennials. These plants flowered early and hence are able to ripen their seeds. Years with long growing seasons may allow seed production in otherwise temporary species. Dynamics of weedy species around Churchill will likely reflect current and (or) future events in other, more isolated northern communities. Key words: subarctic, weeds, introduced plants.

scholarly journals Soil management systems and their effect on the weed seed bank

2018 ◽  
Vol 53 (4) ◽  
pp. 435-442 ◽  
Author(s):  
Cesar Tiago Forte ◽  
Leandro Galon ◽  
Amauri Nelson Beutler ◽  
Felipe José Menin Basso ◽  
Felipe Nonemacher ◽  
...  
Keyword(s):  
Seed Bank ◽  
Cover Crops ◽  
Soil Seed Bank ◽  
Block Design ◽  
Experimental Unit ◽  
Weed Seed ◽  
Weed Species ◽  
Crop Species ◽  
Tillage System ◽  
Winter Cover

Abstract: The objective of this work was to evaluate the density and composition of the soil weed seed bank when bean, corn, and soybean are cultivated in the no-tillage system (NTS) in rotation with winter cover crop species and in the conventional tillage system (CTS). The experiment was installed in a complete randomized block design with three replicates. The evaluation of the seed bank was performed on soil samples (0-10 and 10-20 cm) in four points of each experimental unit, at 15, 30, 60, and 90 days of cultivation. Bean, corn, and soybean crops were sown in the NTS with different soil cover crops in rotation, as well as in the CTS. The NTS provided a more dense and abundant soil seed bank of the species Gnaphalium spicatum and Oxalis corniculata when corn, soybean, and bean were cultivated. The species Lolium multiflorum showed lower density and less seeds in the soil seed bank when the NTS was adopted. The use of the winter cover crops black oat and cow vetch, cultivated individually or in consortium, resulted in a lower density of weed species, especially of L. multiflorum. The NTS provides a lower density of weed species in the soil seed bank than the CTS.

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