Weed diversity and weed management

The story of agriculture is the story of weed interference. After millennia of weed control we still have weeds. This situation has led many growers to observe that “the weeds always win.” One of the most important reasons weeds are so successful is their biodiversity. Biodiversity is an inevitable consequence of the struggle an individual weed species undergoes in the presence of neighbors, and by occupying a physical space in an agroecosystem. Weeds have evolved in response to cropping system practices by adapting and occupying niches left available in agroecosystems. Forces created by our cropping practices over evolutionary time have led to the weed diversity we observe today. Diversity underlies weed management in several important ways. A plant experiences diversity among its neighbors in at least five different ways. Weeds have adapted to selection in agroecosystems in several ways: (1) genetic variants within a species; (2) somatic polymorphism of plant parts; (3) success in diverse habitat microsites; (4) temporal adaptations within the community; and (5) floristic diversity of a community at higher levels than the species. Herein, weed diversity is discussed in this broader context, in terms of population behaviors that emerge as a consequence of the activities of individual components at lower levels of organization. Diversity is also discussed in terms of its implications for weed management. The potential exists to develop management strategies based on differences in weed and crop diversity. These strategies might be developed by characterization of weedy genetic and phenotypic diversity; enhancement of crop, cropping system, and agroecosystem diversity; and characterization of the spatial distribution of weed populations.

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Weeds and Their Effect on the Performance of Maize and Finger Millet in Mid-Hills of Nepal

International Journal of Applied Sciences and Biotechnology ◽

10.3126/ijasbt.v2i3.10790 ◽

2014 ◽

Vol 2 (3) ◽

pp. 275-278 ◽

Cited By ~ 1

Author(s):

Tika Bahadur Karki ◽

Shrawan K. Sah ◽

Resam B. Thapa ◽

Andrew J. McDonald ◽

Adam S. Davis ◽

...

Keyword(s):

Weed Management ◽

Crop Production ◽

Finger Millet ◽

Crop Yields ◽

Management Strategies ◽

Cropping System ◽

Weed Species ◽

Ageratum Conyzoides ◽

Alternative Crop ◽

Weed Infestation

Relay cropping of maize with fingermillet (maize/fingermillet) is the predominant cropping system for sustaining food security situation in the hilly regions of Nepal. In this region weed pressure severely reduces crop yields. Basic information on weed species composition, biomass production and their effect on crop yields and economics are lacking for this region. This information will be necessary to develop effective weed management strategies for the future. In light of this an empirical study was carried out in two representatives mid hill districts of Parbat and Baglung during summer season of 2010/2011 in Nepal. A total of 10 major weed species with densities of 172 in Parbat and 311 per 0.25m2 area in Baglung were observed. The highest percentage of both relative and absolute densities were recorded for Ageratum conyzoides in Parbat and Polygonum chinensis in Baglung. Weed infestation under farmers practice of crop management reduced the grain yield of maize by 1.985 Mt ha-1 (117%) in Baglung and 1.760 Mt ha-1 (108%) in Parbat. Similarly, in finger millet it was 0.489 Mt ha-1 (63%) in Baglung and 0.403 Mt ha-1 in Parbat. Similarly, the combined yield of both the crops was also significantly reduced by 79.3% and 61.7% in Baglung and Parbat respectively. Hence, weeds are directly affecting the crop performance in the region. Therefore, there is an urgent need to develop an alternative crop production system in the hills. DOI: http://dx.doi.org/10.3126/ijasbt.v2i3.10790Int J Appl Sci Biotechnol, Vol. 2(3): 275-278

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Weeds Hosting the Soybean Cyst Nematode (Heterodera glycines Ichinohe): Management Implications in Agroecological Systems

Agronomy ◽

10.3390/agronomy11010146 ◽

2021 ◽

Vol 11 (1) ◽

pp. 146

Author(s):

Leonardo F. Rocha ◽

Karla L. Gage ◽

Mirian F. Pimentel ◽

Jason P. Bond ◽

Ahmad M. Fakhoury

Keyword(s):

Weed Management ◽

Soybean Cyst Nematode ◽

Heterodera Glycines ◽

Integrated Management ◽

Cropping System ◽

Cyst Nematode ◽

Weed Species ◽

Initial Inoculum ◽

Herbicide Resistant ◽

Sites Of Action

The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is a major soybean-yield-limiting soil-borne pathogen, especially in the Midwestern US. Weed management is recommended for SCN integrated management, since some weed species have been reported to be hosts for SCN. The increase in the occurrence of resistance to herbicides complicates weed management and may further direct ecological–evolutionary (eco–evo) feedbacks in plant–pathogen complexes, including interactions between host plants and SCN. In this review, we summarize weed species reported to be hosts of SCN in the US and outline potential weed–SCN management interactions. Plants from 23 families have been reported to host SCN, with Fabaceae including most host species. Out of 116 weeds hosts, 14 species have known herbicide-resistant biotypes to 8 herbicide sites of action. Factors influencing the ability of weeds to host SCN are environmental and edaphic conditions, SCN initial inoculum, weed population levels, and variations in susceptibility of weed biotypes to SCN within a population. The association of SCN on weeds with relatively little fitness cost incurred by the latter may decrease the competitive ability of the crop and increase weed reproduction when SCN is present, feeding back into the probability of selecting for herbicide-resistant weed biotypes. Therefore, proper management of weed hosts of SCN should be a focus of integrated pest management (IPM) strategies to prevent further eco–evo feedbacks in the cropping system.

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Interactions of Nitrogen Source and Rate and Weed Removal Timing Relative to Nitrogen Content in Corn and Weeds and Corn Grain Yield

International Scholarly Research Notices ◽

10.1155/2017/8961367 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Alexandra M. Knight ◽

Wesley J. Everman ◽

David L. Jordan ◽

Ronnie W. Heiniger ◽

T. Jot Smyth

Keyword(s):

Grain Yield ◽

Weed Management ◽

Management Strategies ◽

Field Studies ◽

Weed Species ◽

Weed Interference ◽

Coated Urea ◽

N Fertility ◽

Corn Grain ◽

Corn Grain Yield

Adequate fertility combined with effective weed management is important in maximizing corn (Zea mays L.) grain yield. Corn uptake of nitrogen (N) is dependent upon many factors including weed species and density and the rate and formulation of applied N fertilizer. Understanding interactions among corn, applied N, and weeds is important in developing management strategies. Field studies were conducted in North Carolina to compare corn and weed responses to urea ammonium nitrate (UAN), sulfur-coated urea (SCU), and composted poultry litter (CPL) when a mixture of Palmer amaranth (Amaranthus palmeri S. Wats.) and large crabgrass (Digitaria sanguinalis L.) was removed with herbicides at heights of 8 or 16 cm. These respective removal timings corresponded with 22 and 28 days after corn planting or V2 and V3 stages of growth, respectively. Differences in N content in above-ground biomass of corn were noted early in the season due to weed interference but did not translate into differences in corn grain yield. Interactions of N source and N rate were noted for corn grain yield but these factors did not interact with timing of weed control. These results underscore that timely implementation of control tactics regardless of N fertility management is important to protect corn grain yield.

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Relation between Soil Weed Seedbank and Weed Management Practises and Diversity in Farms in Kisii Central Sub County, Nyanza

Journal of Horticulture and Plant Research ◽

10.18052/www.scipress.com/jhpr.10.1 ◽

2020 ◽

Vol 10 ◽

pp. 1-14

Author(s):

Charles N. Nyamwamu ◽

Rebecca Karanja ◽

Peter Mwangi

Keyword(s):

Seed Bank ◽

Weed Management ◽

Management Practices ◽

Soil Seed Bank ◽

Shannon Index ◽

Weed Seed ◽

Weed Species ◽

Western Kenya ◽

Weed Diversity ◽

Hand Weeding

This study sought to determine the relation between soil weed seed bank and weed management practices and diversity in farms in Kisii Central Sub County, Western Kenya. Eight administrative sub-locations were randomly selected. Ten farms were selected at equal distance along transect laid across each sub-location. Weed soil seed bank was assessed from soil samples collected from each of the farms; a sub-sample was taken from a composite sample of ten soil cores of 5cm diameter and 15cm deep and placed in germination trays in a greenhouse. Weed diversity in soil weed seedbank was calculated using the Shannon index (H’). Twelve weed species from 12 genera of nine families were recorded. Diversity of the weed species in soil weed seed bank was (H'=1.48). Weed management practises significantly affected weed species soil weed seedbank reserves. Use of inefficient and ineffective hand-weeding techniques resulted in high weed species diversity and abundance.

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Model of rice (Oryza sativa) yield reduction as a function of weed interference

Weed Science ◽

10.1017/s0043174500092742 ◽

1997 ◽

Vol 45 (2) ◽

pp. 218-224 ◽

Cited By ~ 21

Author(s):

Karl W. VanDevender ◽

Thomas A. Costello ◽

Roy J. Smith

Keyword(s):

Weed Management ◽

Management Strategies ◽

Economic Assessment ◽

Richards Equation ◽

Yield Reduction ◽

Published Data ◽

Weed Species ◽

Individual Parameter ◽

Alternative Weed Control ◽

Parameter Values

Economic assessment of weed management strategies in rice is dependent upon a quantitative estimate of the yield impact of a given weed population. To assist rice producers in making such assessments, a mathematical model was developed to predict rice yield reduction as a function of weed density and duration of interference. The nonlinear empirical model was a unique 3-dimensional adaptation of the Richards equation with 4 parameters. Using published data, individual parameter values were fitted for each of 6 weed species interfering with either conventional or semi-dwarf statured rice cultivars. The functional form of the equation produced surfaces that were qualitatively consistent with available data and experience regarding rice-weed biology. Hence, predictions from the model should be useful and reliable in assessing the economic impact of weeds and in determining the feasibility of alternative weed control treatments for various field scenarios.

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Floristic and Phytosociology of Weeds in Upland Rice in the Humid Tropics

Planta Daninha ◽

10.1590/s0100-83582017350100083 ◽

2018 ◽

Vol 35 (0) ◽

Author(s):

M.R.M. SILVA ◽

E.A. COSTA ◽

M.J.P. CORRÊA ◽

A.A.C. RODRIGUES ◽

M.L.R. MESQUITA

Keyword(s):

Weed Management ◽

Upland Rice ◽

Management Strategies ◽

Floristic Composition ◽

Humid Tropics ◽

Reproductive Stage ◽

Rice Crop ◽

Weed Species ◽

Floristic Similarity ◽

Abstract Knowledge

ABSTRACT: Knowledge of the floristic composition and vegetation structure are essential conditions for development of more efficient and economic weed management strategies in crops in the humid tropics. The objective of the research was to carry on floristic and phytosociological surveys to know the main weeds in upland rice fields in the humid tropics of the Brazilian State of Maranhão. Weed samples were done by means of an open metal rectangle of 0.15 m2 thrown at random in the vegetative and reproductive stages of rice crop in 2009/10 and 2010/2011 harvest. A total of 65 species from 23 families was identified 35 (53.85%) from the eudicotyledons botanical group, 29 (44.06%) from the monocotyledonous and one (1.53%) belonged to the pteridophytes. The most representative families were from the monocotyledonous botanical group including Poaceae and Cyperaceae, followed by Amaranthaceae and Malvaceae, both from the eudicotyledons group. The weed species with higher importance values in the upland rice crop vegetative stage were Urochloasp., Panicumsp., C. flavus, C. benghalensis and C. argutus whereas in the reproductive stage the higher importance values were recorded for S. latifolia, C. argutus, L. octovalvis, A.tenella and P.maximum. The most important weeds in the crop vegetative phase were mainly from the monocotyledonous group, while in reproductive one they were the eudicotyledons. Weed diversity was high and the floristic similarity was lower in the vegetative one compared to the reproductive stage of upland rice cultivation in the humid tropics.

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Smoke-Isolated Trimethylbutenolide Inhibits Seed Germination of Different Weed Species by Reducing Amylase Activity

Weed Science ◽

10.1614/ws-d-14-00068.1 ◽

2015 ◽

Vol 63 (1) ◽

pp. 312-320 ◽

Cited By ~ 6

Author(s):

Heino B. Papenfus ◽

Manoj G. Kulkarni ◽

Martin Pošta ◽

Jeffrey F. Finnie ◽

Johannes Van Staden

Keyword(s):

Seed Germination ◽

Weed Management ◽

Amylase Activity ◽

Management Strategies ◽

Biologically Active ◽

Weed Species ◽

Water Control ◽

Weed Seeds ◽

Dark Conditions ◽

Smoke Water

Weeds pose a great problem to farmers worldwide, and controlling weeds demands a high input cost for herbicides and labor. Because of current environmental regulations, a limited number of herbicides are commercially available (with limited modes of action) to control weeds. Smoke water and the biologically active compounds isolated from smoke affect seed germination in a significant way. Smoke water (SW) and karrikinolide (KAR1, the germination stimulant isolated from smoke) have been tested extensively for their ability to promote seed germination in a vast array of plant species. In addition to KAR1, a germination inhibitor, trimethylbutenolide (TMB), was also isolated from plant-derived smoke. The effects of SW, KAR1, and TMB were tested on five major weed species of South Africa: fleabane, hairy wild lettuce, bugweed, spilanthes, and fameflower. Seeds of these weed species were subjected to 16/8 h light/dark conditions or to constant dark conditions at constant temperatures of 20, 25, 30 C and alternating 30/20 C. SW and KAR1significantly increased germination, whereas TMB significantly inhibited germination of these weed species. Furthermore, TMB treatment reduced the amylase activity of the tested weed seeds compared with the water control. These results indicate the possibility of manipulating germination of certain weed seeds by SW, KAR1, and TMB. Thus, smoke and smoke-isolated compounds could potentially be used in new weed management strategies.

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The impact of different weed management strategies on weed flora of wheat-based cropping systems

PLoS ONE ◽

10.1371/journal.pone.0247137 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0247137

Author(s):

Muhammad Shahzad ◽

Khawar Jabran ◽

Mubshar Hussain ◽

Muhammad Aown Sammar Raza ◽

Leonard Wijaya ◽

...

Keyword(s):

Weed Management ◽

Cropping Systems ◽

Management Strategies ◽

Cropping System ◽

Herbicide Application ◽

Water Extracts ◽

The World ◽

Weed Flora ◽

Weed Infestation ◽

The Impact

The world population will rise in future, which would demand more wheat production to fulfil dietary needs of wheat-dependent population of the world. Food security in wheat-dependent regions will greatly rely on wheat productivity. Weed infestation is a major constraint reducing wheat productivity globally. Nonetheless, cropping systems and weed management strategies strongly influence weed infestation in modern agriculture. Herbicides are the key weed management tool in conventional agriculture. However, frequent use of herbicides have resulted in the evolution of herbicide-resistance weeds, which made weed management a challenging task. Sustainable and eco-friendly weed management strategies shift weed-crop competition in the favour of crop plants. Limited studies have evaluated the interactive effect of cropping systems and weed management strategies on weed flora of wheat-based cropping systems (WBCSs). This two-year study evaluated the impact of different weed management strategies (WMSs) on weed flora of WBCSs, i.e., fallow-wheat (FW), rice-wheat (RW), cotton-wheat (CW), mungbean-wheat (MW) and sorghum-wheat (SW). The WMSs included in the study were, false seedbed, allelopathic water extracts and herbicide application, while weed-free and weedy-check were maintained as control treatments. Data relating to diversity and density of individual and total broadleaved and narrow-leaved weeds were recorded. The WBCSs, WMSs and their interaction significantly altered diversity and density of individual, total, broadleaved and narrow-leaved weeds. Weed-free and weedy-check treatments recorded the lowest and the highest values of diversity and density of individual, total, broadleaved and narrow-leaved weeds. Herbicide application effectively reduced density and diversity of weeds. Allelopathic water extracts and false seedbed proved less effective than herbicides. On the other hand, SW cropping system not only reduced weed density but also limited the weed flora. It is concluded that false seedbed and SW cropping system can be efficiently used to manage weeds in WBCSs. However, long-term studies are needed to infer the impact of SW cropping system and false seedbed on soil properties, soil microbes and productivity of wheat crop.

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Weed Management Strategies in Chickpea (Cicer arietinum): A Review

Agricultural Reviews ◽

10.18805/ag.r-1996 ◽

2020 ◽

Author(s):

Akashdeep Singh ◽

S. S. Rana ◽

Anju Bala

Keyword(s):

Weed Control ◽

Cicer Arietinum ◽

Weed Management ◽

Management Practices ◽

Management Strategies ◽

Detailed Knowledge ◽

Basic Requirement ◽

Weed Species ◽

The World ◽

Hand Weeding

Chickpea (Cicer arietinum) is one of the most important pulse crops but it’s productivity in India is quite low. There are various reasons for low productivity. Weed control is the basic requirement and the major component of crop management. Weeds on an average reduce the crop yield by 40-87 per cent. Deciding time to control weeds requires detailed knowledge of the weed populations in the field. Different management practices like altering spacing, competitive cultivars, etc. can help in enhancing the productivity. With the world entering the precision-farming era, more emphasis is being put on the use of post-emergence herbicides. Application of two or more herbicide at the same time or as a double knockdown and integrating with hand-weeding provides desirable control of different weed species besides reducing the hazard of chemical weed control.

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