scholarly journals Weed community structure and soybean yields in a long-term organic cropping systems experiment

Weed Science ◽  
2019 ◽  
Vol 67 (6) ◽  
pp. 673-681 ◽  
Author(s):  
Margaret G. Ball ◽  
Brian A. Caldwell ◽  
Antonio DiTommaso ◽  
Laurie E. Drinkwater ◽  
Charles L. Mohler ◽  
...  
Keyword(s):  
Community Structure ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Nutrient Inputs ◽  
Weed Species ◽  
Soybean Yield ◽  
Weed Density ◽  
Weed Species Richness

AbstractWeed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (1) high fertility (HF), (2) low fertility (LF), (3) enhanced weed management (EWM), and (4) reduced tillage (RT). In addition, we created weed-free subplots within each system to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in weed-free subplots was 10% greater than soybean yield in the ambient weed subplots that received standard management practices for the systems in which they were located. Although weed competition limited soybean yield across all systems, the EWM system, which had the lowest weed density, also had the lowest soybean yield. Future research should aim to overcome such trade-offs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.

scholarly journals Studies on weed cover and diversity in coriander (Coriandrum sativum L.) as influenced by weed management and balanced fertilization techniques

2017 ◽  
Vol 5 (3) ◽  
pp. 387-395
Author(s):  
Raj Kumar Nagar ◽  
Dinesh Kumar Jain
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Cyperus Rotundus ◽  
Weed Species ◽  
Significant Interaction Effect ◽  
Weed Density ◽  
Chenopodium Murale ◽  
Balanced Fertilization ◽  
Biological Yield ◽  
Hand Weeding

A field experiment was conducted to analyze the types of flora, intensity, cover and effects on yields of coriander. Pooled analysis of data indicated that Goose foot (Chenopodium murale L.), Corn spurry (Spergula arvensis L.) among dicots and Purple nutsedge (Cyperus rotundus L.) among monocots were found most dominant weeds at all stages of crop growth. Of the total eight weed species reported dicot weeds were found most dominating weed species and comprises 78-80 percent of total weed density throughout crop cycle. All weed management practices significantly reduced the density of monocot and dicot weeds and improved the yield (seed and biological yield) of crop as compared to control. Two hand weeding at 30 and 45 DAS resulted in maximum reduction in total weed density and gave the highest seed (15.84 q/ha) and biological yield (41.11 q/ha) of coriander. However, seed and biological yields was obtained at par by pendimethalin 1.0 kg/ha + one hand weeding at 45 DAS. This treatment also resulted in favorably lowest weed competition index as compared to rest of other practices. Balanced fertilization with N+P+K+S also improved monocot and dicot weed density but the effect was not significant over N+P and N+P+K fertilization. N+P+K+S fertilization significantly enhanced crop seed and biological yields over N+P (1.86 q/ha and 4.36 q/ha, respectively) and N+P+K application (0.94 q/ha and 2.20 q/ha, respectively). Weed management and balanced fertilization practices also found to have significant interaction effect on seed and biological yield of coriander.

scholarly journals Assessing weeds at risk of evolving glyphosate resistance in Australian sub-tropical glyphosate-resistant cotton systems

2011 ◽  
Vol 62 (11) ◽  
pp. 1002 ◽  
Author(s):  
Jeff Werth ◽  
David Thornby ◽  
Steve Walker
Keyword(s):  
High Risk ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Cropping System ◽  
Glyphosate Resistance ◽  
Management Approach ◽  
Weed Species ◽  
Summer Fallow ◽  
Very High

Glyphosate resistance will have a major impact on current cropping practices in glyphosate-resistant cotton systems. A framework for a risk assessment for weed species and management practices used in cropping systems with glyphosate-resistant cotton will aid decision making for resistance management. We developed this framework and then assessed the biological characteristics of 65 species and management practices from 50 cotton growers. This enabled us to predict the species most likely to evolve resistance, and the situations in which resistance is most likely to occur. Species with the highest resistance risk were Brachiaria eruciformis, Conyza bonariensis, Urochloa panicoides, Chloris virgata, Sonchus oleraceus and Echinochloa colona. The summer fallow and non-irrigated glyphosate-resistant cotton were the highest risk phases in the cropping system. When weed species and management practices were combined, C. bonariensis in summer fallow and other winter crops were at very high risk. S. oleraceus had very high risk in summer and winter fallow, as did C. virgata and E. colona in summer fallow. This study enables growers to identify potential resistance risks in the species present and management practices used on their farm, which will to facilitate a more targeted weed management approach to prevent development of glyphosate resistance.

Effect of weed management practices and organic sources of nitrogen supplementation on weed density and yield of wheat

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Bhupesh Kumar Mishra ◽  
Santosh Pandey
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Management Practices ◽  
Maximum Yield ◽  
Poultry Manure ◽  
Dry Weight ◽  
Control Methods ◽  
Weed Species ◽  
Weed Density ◽  
Hand Weeding

The different weed control methods (two hand weeding at 25 and 45 days after sowing (DAS) and one hand weeding at 25 DAS along with unweeded control ), organic sources of nitrogen (vermicompost, poultry manure, city manure and FYM) and their interaction were compared for their efficiency on various weed species and yield of wheat. Two hand weeding (W2) gave significantly maximum weed control. This was followed by one hand weeding at 25 DAS and control. These weed control methods significantly enhanced the yield and yield components of wheat. Among organic sources of nitrogen vermicompost (M1) recorded minimum weed density, weed dry weight and maximum yield, followed by poultry manure, city manure and FYM.

scholarly journals Weed species richness, density and relative abundance on farms in the subtropical grain region of Australia

2005 ◽  
Vol 45 (6) ◽  
pp. 711 ◽  
Author(s):  
L. J. Rew ◽  
R. W. Medd ◽  
R. Van de Ven ◽  
J. J. Gavin ◽  
G. R. Robinson ◽  
...  
Keyword(s):  
Species Richness ◽  
Relative Abundance ◽  
Weed Management ◽  
Management Practices ◽  
Raphanus Raphanistrum ◽  
Weed Species ◽  
Separate Species ◽  
Obvious Effect ◽  
Lactuca Serriola ◽  
Weed Species Richness

Weed management is one of the most important economic and agronomic issues facing farmers in Australia’s grain regions. Weed species occurrence and abundance was monitored between 1997 and 2000 on 46 paddocks (sites) across 18 commercial farms located in the Northern Grain Region. The sites generally fell within 4 disjunct regions, from south to north: Liverpool Plains, Moree, Goondiwindi and Kingaroy. While high species richness was found (139 species or species groups), only 8 species occurred in all 4 regions and many (56 species) only occurred at 1 site or region. No species were observed at every site but 7 species (Sonchus spp., Avena spp., Conyza spp., Echinochloa spp., Convolvulus erubescens, Phalaris spp. and Lactuca serriola) were recorded on more than 70% of sites. The average number of species observed within crops after treatment and before harvest was less than 13. Species richness tended to be higher in winter pulse crops, cotton and in fallows, but overall was similar at the different sampling seasons (summer v. winter). Separate species assemblages associated with the Goondiwindi and Kingaroy regions were identified by correspondence analysis but these appeared to form no logical functional group. The species richness and density was generally low, demonstrating that farmers are managing weed populations effectively in both summer and winter cropping phases. Despite the apparent adoption of conservation tillage, an increase in opportunity cropping and the diversity of crops grown (13) there was no obvious effect of management practices on weed species richness or relative abundance. Avena spp. and Sonchus spp. were 2 of the most dominant weeds, particularly in central and southern latitudes of the region; Amaranthus spp. and Raphanus raphanistrum were the most abundant species in the northern part of the region. The ubiquity of these and other species shows that continued vigilance is required to suppress weeds as a management issue.

Effects of crop rotation and field management methods on weed density and species composition in the southeastern part of Latvia

2015 ◽  
Vol 2 ◽  
pp. 235
Author(s):  
Jevgenija Ņečajeva ◽  
Zane Mintāle ◽  
Ieva Dudele ◽  
Anda Isoda-Krasovska ◽  
Jolanta Čūrišķe ◽  
...  
Keyword(s):  
Species Composition ◽  
Weed Control ◽  
Crop Rotation ◽  
Weed Management ◽  
Management Practices ◽  
Integrated Weed Management ◽  
Weed Species ◽  
Southeastern Part ◽  
Weed Density ◽  
Field Management

<p class="R-AbstractKeywords"><span lang="EN-GB">Integrated weed management (IWM) is a complex approach to weed control that is based on use of several different methods complementing each other, instead of relying on one single method, like chemical weed control. Weed control methods that can be used as parts of IWM strategy include mechanical weed control, application of herbicides, low tillage, changes in the rate and application time of fertilizers, use of undersown crops and crop rotation. Weed surveys were carried out in 2013 and 2014 in the southeastern part of Latvia. The aim of this study was to assess the effect of crop rotation and other field management practices on weed density and weed species composition using the data collected in the surveys. Survey was carried out in the arable fields of conventional farms within four different size categories. One of the significant factors that explained the variation of weed composition within a field was a proportion of cereals in crop rotation within a four year period. Further surveys are required to estimate the effects of climatic variables. Density-dependence can also be important for practical management decisions for particular weed species and should be investigated.</span></p>

Assessment of crop and weed management strategies prior to introduction of auxin-resistant crops in Brazil

2020 ◽  
pp. 1-11
Author(s):  
Maxwel C. Oliveira ◽  
Anelise Lencina ◽  
André R. Ulguim ◽  
Rodrigo Werle
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Control Strategies ◽  
Management Strategies ◽  
Acetolactate Synthase ◽  
Weed Species ◽  
Research Education ◽  
No Till

Abstract A stakeholder survey was conducted from April through June of 2018 to understand stakeholders’ perceptions and challenges about cropping systems and weed management in Brazil. The dominant crops managed by survey respondents were soybean (73%) and corn (66%). Approximately 75% of survey respondents have grown or managed annual cropping systems with two to three crops per year cultivated in succession. Eighteen percent of respondents manage only irrigated cropping systems, and over 60% of respondents adopt no-till as a standard practice. According to respondents, the top five troublesome weed species in Brazilian cropping systems are horseweed (asthmaweed, Canadian horseweed, and tall fleabane), sourgrass, morningglory, goosegrass, and dayflower (Asiatic dayflower and Benghal dayflower). Among the nine species documented to have evolved resistance to glyphosate in Brazil, horseweed and sourgrass were reported as the most concerning weeds. Other than glyphosate, 31% and 78% of respondents, respectively, manage weeds resistant to acetyl-CoA carboxylase (ACCase) inhibitors and/or acetolactate synthase (ALS) inhibitors. Besides herbicides, 45% of respondents use mechanical, and 75% use cultural (e.g., no-till, crop rotation/succession) weed control strategies. Sixty-one percent of survey respondents adopt cover crops to some extent to suppress weeds and improve soil chemical and physical properties. Nearly 60% of survey respondents intend to adopt the crops that are resistant to dicamba or 2,4-D when available. Results may help practitioners, academics, industry, and policy makers to better understand the bad and the good of current cropping systems and weed management practices adopted in Brazil, and to adjust research, education, technologies priorities, and needs moving forward.

Relative influence of crop rotation, tillage, and weed management on weed associations in spring barley cropping systems

Weed Science ◽  
1999 ◽  
Vol 47 (1) ◽  
pp. 112-122 ◽  
Author(s):  
Anne Légère ◽  
Nathalie Samson
Keyword(s):  
Crop Rotation ◽  
Analysis Of Variance ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Spring Barley ◽  
Life Cycles ◽  
Relative Importance ◽  
Weed Species ◽  
Management Factors

Generalizations concerning the effects of management practices on weed community dynamics often lack robustness, most likely because of the concomitant effects of agronomic and environmental factors. However, such generalizations, when valid, provide useful grounds for predictions and are thus desirable. This study attempted to evaluate the relative importance of crop rotation, tillage, and weed management as factors affecting weed communities and tested the hypothesis of an association between management practices and weeds from certain life cycle groups. Principal component analysis (PCA) of weed density data from a 4-yr field study conducted on a Kamouraska clay and a Saint-André gravelly sandy loam at La Pocatière QC, Canada, identified groups of weed species, while an analysis of variance (ANOVA) of PCA scores associated these groups with management factors. A multivariate analysis of variance (MANOVA) of regression coefficients describing time courses of density for each species confirmed treatment effects. Species segregated roughly according to life cycles. Interactions among weed management intensity, tillage, and crop rotation mostly explained species dominance in the various cropping systems. A first group of species, mostly annual dicots, largely dominated in minimum weed management treatments; their relative importance in each rotation varied with their level of susceptibility to postemergence herbicides. A second group included annuals and perennials, whose commonality seemed to be their tolerance to herbicides; these species also had a particular affinity for chisel and no-till treatments. A third group was formed by perennial species, each with a different response to tillage. The tenuous correspondence between commonly used classification schemes and management factors suggests that other aspects of weed biology (e.g., seed size, dispersal, production, germination requirements, and seedbank longevity) should be considered when trying to explain and predict the presence and dominance of certain weed species with regard to management practices.

Herbicide-Resistant Weeds: Management Tactics and Practices

2006 ◽  
Vol 20 (3) ◽  
pp. 793-814 ◽  
Author(s):  
Hugh J. Beckie
Keyword(s):  
Herbicide Resistance ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Integrated Weed Management ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Application Rates ◽  
Selection For ◽  
Reactive Management

In input-intensive cropping systems around the world, farmers rarely proactively manage weeds to prevent or delay the selection for herbicide resistance. Farmers usually increase the adoption of integrated weed management practices only after herbicide resistance has evolved, although herbicides continue to be the dominant method of weed control. Intergroup herbicide resistance in various weed species has been the main impetus for changes in management practices and adoption of cropping systems that reduce selection for resistance. The effectiveness and adoption of herbicide and nonherbicide tactics and practices for the proactive and reactive management of herbicide-resistant (HR) weeds are reviewed. Herbicide tactics include sequences and rotations, mixtures, application rates, site-specific application, and use of HR crops. Nonherbicide weed-management practices or nonselective herbicides applied preplant or in crop, integrated with less-frequent selective herbicide use in diversified cropping systems, have mitigated the evolution, spread, and economic impact of HR weeds.

scholarly journals Herbicide based weed management in aromatic rice of Bangladesh

2018 ◽  
Vol 16 (1) ◽  
pp. 31-40
Author(s):  
AKM Mominul Islam ◽  
Md Azhiat-Ul Huq Hia ◽  
Shubroto Kumar Sarkar ◽  
Md Parvez Anwar
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Aromatic Rice ◽  
Herbicide Application ◽  
Weed Species ◽  
Rice Varieties ◽  
Weed Density ◽  
Free Treatment ◽  
Manual Weeding ◽  
Density And Biomass

Selection of appropriate weed management strategy helps reduce rice yield loss due to weeds. Despite some undesirable side-effects, no viable alternative is currently available to shift the chemical weed management in rice. However, time of herbicide application is very important with respect to its efficacy. Keeping in mind the inevitability of herbicidal weed control, the current study was designed to evaluate the response of selected aromatic fine rice varieties of Bangladesh to different herbicides based weed management practices compare to farmers’ practices. The experiment was conducted in a randomized complete block design with three replications. The experiment consisted of five aromatic rice varieties; Kalijira, BRRI dhan34, BRRI dhan37, BRRI dhan38 and Binadhan-13, and six different weed management practices comprising no weeding, weed free, mechanical + manual weeding, pre–emergence herbicide + manual weeding, post–emergence herbicide + manual weeding and pre– + post–emergence herbicide. Eleven weed species belonging to five families were observed in the experimental plots. Based on the summed dominance ratio (SDR), grassy weed species Echinochloa crusgalli (SDR of 30.7) was the most dominant species, whereas broadleaf weed Nymphaea nouchali (SDR of 0.83) was the least one. Among the weed control treatments, application of pre–+ post emergence herbicides offered the highest reduction in weed density and biomass at all sampling dates which resulted in minimum crop-weed competition facilitating improvement in the yield contributing characters and finally resulted in the highest grain yield (2.5 t ha−1) and harvest index (30.7%) next to the weed free treatment. The variety BRRI dhan38 gave the highest grain yield (3.4 t ha−1) due to the highest performance of the yield contributing characters among the varieties. In interaction, BRRI dhan38 with pre–+ post–emergence herbicide application gave the highest yield (3.4 t ha−1) apart from the weed free treatment. Being efficient in weed density and biomass reduction as well as the highest yield producer, sequential application of pre–and post–emergence herbicides may be recommended for effective weed management practices in BRRI dhan38J. Bangladesh Agril. Univ. 16(1): 31-40, April 2018

Separating the effects of crop rotation from weed management on weed density and diversity

Weed Science ◽  
1999 ◽  
Vol 47 (6) ◽  
pp. 729-735 ◽  
Author(s):  
Colleen Doucet ◽  
Susan E. Weaver ◽  
Allan S. Hamill ◽  
Jianhua Zhang
Keyword(s):  
Crop Rotation ◽  
Weed Management ◽  
Management Practices ◽  
Cropping Systems ◽  
Management Strategies ◽  
Integrated Weed Management ◽  
Direct Result ◽  
Weed Density ◽  
Richness Index ◽  
Rotation Study

Crop rotation is thought to reduce weed density and maintain species diversity, thus preventing the domination of a few problem weeds. Because cropping sequence dictates other agricultural management practices, variations in weed populations between cropping systems may be the direct result of crop rotation, the result of different weed management practices associated with crop rotation, or both. Studies that fail to separate the effects of crop rotation from weed management may generate misleading results. A 10-yr crop rotation study was undertaken to study the dynamics of the standing weed vegetation inZea maysL.,Glycine maxL., andTriticum aestivumL. The present paper compared total weed density and diversity between monocultures and rotations under three levels of weed management. Weed management accounted for 37.9% of the variation in total weed density, whereas crop rotation accounted for only 5.5%. Weed density varied between monocultures and rotations in plots where herbicides were applied. The effectiveness of rotations in reducing weed density was dependent upon the crop. Margalef's species richness index (DMG), a measure of diversity, varied among weed management strategies, with 38.4% of the variance attributed to this factor. In the 10th year, when all plots were sown withZ. mays, few cumulative effects of crop rotation were apparent, with two exceptions. In weedy and herbicide-treated plots, weed density was higher on plots cropped withZ. maysthe previous year. Also, under these weed management treatments, including a cereal in the crop rotation reduced weed density. Crop rotation, when used in combination with herbicides, provides additional weed control and is therefore an effective tool in integrated weed management.

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