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

2014 ◽  
Vol 2 (3) ◽  
pp. 275-278 ◽  
Author(s):  
Tika Bahadur Karki ◽  
Shrawan K. Sah ◽  
Resam B. Thapa ◽  
Andrew J. McDonald ◽  
Adam S. Davis ◽  
...  

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  

Author(s):  
Abhinandan Singh ◽  
S. Pazhanisamy ◽  
Rodda Chandana Devi ◽  
Amit Kumar Singh ◽  
Chandra Mohan Mehta

Farmers view weeds as the number one barrier to organic rice production. Also, organic rice-growing farmers feel weed management is their number one priority, so they need more research about weed management under organic conditions from the researchers. Weeds can be considered a significant problem because they have a tendency to decrease crop yields by increasing competition for moisture, sunlight and nutrients also serving as host plants for pests and diseases. Since the development of herbicides, farmers have been used these chemicals to eradicate weeds from their fields. Using herbicides not only increased crop yields as well as reduced the labour required to remove weeds. Today, some farmers have a renewed interest in organic methods of managing weeds since the widespread use of agrochemicals has affected the environment and health. It has also been found that in some cases herbicides use can cause some weed species to dominate fields because the weeds develop resistance to herbicides. Moreover, some herbicides are destroying weeds that are harmless to crops, resulting in a potential decrease biodiversity. It is important to understand that under an organic system of seed control, weeds will never be eliminated but only managed. Consistent methods of weed management can reduce the costs and contribute to economical crop production without endangers the environment.


PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247137
Author(s):  
Muhammad Shahzad ◽  
Khawar Jabran ◽  
Mubshar Hussain ◽  
Muhammad Aown Sammar Raza ◽  
Leonard Wijaya ◽  
...  

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.


Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 357-363 ◽  
Author(s):  
Jack Dekker

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.


CORD ◽  
2019 ◽  
Vol 35 (01) ◽  
pp. 8
Author(s):  
S.H.S. Senarathne

Pennisetum polystachion is a major problematic monocotyledonous weed species and a perennial problem in intermediate zone of coconut plantations in Sri Lanka. This study was carried out to evaluate the impacts of different management systems on P. polystachion seedling emergence patterns.The tested treatments were application of glyphosate (T1), cover cropping with Pueraria phaseoloides (T2), tractor harrowing (T3), tractor slashing (T4) and tractor ploughing (T5). All the treatments were applied twice a year except T2. As T2 cover crop at the initiation of the experiment and over grown conditions were managed by harrowing once a year. Based on the reduction in weed biomass, cover cropping (T2) was the best to reduce the P. polystachion population and to reduce P. polystachion seedling emergence density in the field. Chemical weeding was the second-best method to control the P. polystachion population in the field. The effectiveness of slashing in reducing weed seedling emergence density was lower than cover cropping and chemical weeding methods. The weed seedling emergence densities were almost similar in ploughed and harrowed plots. The seed depth of emerged seedling was very high in harrowed and ploughed treatments when compared to other treatments. Results given by T3 and T5 indicates that loosening the soil creates more favorable environment for the germination of weed seeds buried in soil. Therefore, it can be argued that the elimination of weed seeds in the top 2cm or 4cm in the soil seed bank by any means is likely to reduce the level of weed infestation by about 60% to 95%. Results also indicated that burying rhizomes in ploughing and harrowing treatment plots at the depths below 30 - 40 cm is effective in controlling germination of this weed species. This experiment also suggested that keeping rhizomes on the soil surface without burying for durations of 5 – 15 days would produce weak plants with poor development.


2019 ◽  
pp. 1819-1825
Author(s):  
Wesley E Santiago ◽  
Neucimar J Leite ◽  
Bárbara J Teruel ◽  
Manoj Karkee ◽  
Carlos AM Azania

Weeds interfere in agricultural production, causing a reduction in crop yields and quality. The identification of weed species and the level of infestation is very important for the definition of appropriate management strategies. This is especially true for sugarcane, which is widely produced around the world. The present study has sought to develop and evaluate the performance of the Bag-of-Features (BoF) approach for use as a tool to aid decision-making in weed management in sugarcane production. The support vector machine to build a mathematical model of rank consisted of 30553 25x25-pixel images. Statistical analysis demonstrated the efficacy of the proposed method in the identification and classification of crops and weeds, with an accuracy of 71.6% and a Kappa index of 0.43. Moreover, even under conditions of high weed density and large numbers of overlapping and/or occluded leaves, weeds could be distinguished from crops This study clearly shows that the system can provide important subsidies for the formulation of strategies for weed management, especially in sugarcane, for which the timing of weed control is crucial.


2013 ◽  
Vol 11 (1) ◽  
pp. 112-121 ◽  
Author(s):  
AB Siddique ◽  
BS Ismail

Allelopathy is an important factor which contributes in determining distribution of species and their abundance within communities. Plant-plant interference is the combined effect of allelopathy, resource competition, and many other factors. Weed infestation is a major problem limiting the growth and yield of rice. Synthetic herbicide has been used for over 50 years as the prime source of weed control. The repeated use of herbicides in rice has already led to the evolution of resistance in some weed species. The conventional synthetic herbicides are becoming less effective against the resistant weed biotypes. Due to increase in the number of herbicide-resistant weeds and environmental concerns in the use of synthetic herbicides, allelopathy has been gaining preference as one of the considerable efforts in designing alternative weed management strategies. Modern ecotoxicologists and allelopathy researchers have been trying to identify allelochemicals to use as biodegradable pesticide. Two allelochemicals have been discovered, namely hexanedioic acid dioctyl ester and di-n-octyl phthalate which can be used as biopesticide. However, still there is enough scope to conduct such research that will contribute to protect our environment as well as increase food safety. DOI: http://dx.doi.org/10.3329/agric.v11i1.15251 The Agriculturists 2013; 11(1) 112-121


2021 ◽  
Author(s):  
Kartik Sharma ◽  
Sachin Dhanda ◽  
Munish Leharwan ◽  
Kuldeep Singh

Agriculture is an important part of the India’s economy. India ranks first in net cropland area in the world with 179.8 mha which is 9.6% of global net cropland area and India’s agriculture sector makes up 16% of the country’s economy, while accounting for 49% of employment (FAOSTAT, 2020). The rice-wheat cropping system (RWCS) is extensive in the subtropical areas of the Indo-Gangetic Plains of India while maize-wheat is widespread in tropical, sub-tropical and warm temperate regions. In north India, rice is grown in the summer season (June/July to September/October) whereas wheat is grown in the winter season (October/November to February/March). The area under wheat in India was 30.59 mha with an annual production of 99.78 mt and average productivity of 3.22 t ha-1 (Anonymous, 2019). The weeds are accounting as a major factor in yield reduction of wheat. The mechanical weed control is not so much effective in controlling weeds in wheat because of narrow inter row spacing. Further, the manual weeding is not much feasible because of mimicry weeds like Phalaris minor which are very much similar to wheat during initial stages. Therefore, the role of herbicides cannot be neglected. But the continuous application of herbicides with same mode of action year by year has resulted in evolution of herbicide resistance in weed species. The management of herbicide resistant weeds in crop production is a major challenge. This review mainly focuses on the current status of herbicide resistant weeds in India associated with wheat along with their management strategies.


Weed Science ◽  
1980 ◽  
Vol 28 (4) ◽  
pp. 445-451 ◽  
Author(s):  
R. D. William ◽  
M. Y. Chiang

In tropical and subtemperate regions of the world, farmers plant vegetables and other crops in a vast array of cropping systems that often involve more than one crop being grown on the same parcel of land in a year. Weed communities within each cropping system shift depending on physical and climatic factors and the specific crop and weed management practices employed. Modern weed management strategies involve combinations of crop production practices and specific weed control technologies intended to reduce weed competition, thereby shifting the competitive balance in favor of the crop. Weed research and, training efforts, therefore, must focus on the entire cropping system with emphasis on year-round and multi-year management of weed communities.


2013 ◽  
Vol 93 (5) ◽  
pp. 759-764 ◽  
Author(s):  
K. N. Harker

Harker, K. N. 2013. Slowing weed evolution with integrated weed management. Can. J. Plant Sci. 93: 759–764. For millennia, weeds have slowly evolved in response to ever-changing environments and crop production practices. Weeds are now evolving much more quickly due to consistently repeated cropping systems and intense herbicide selection pressures. Weed resistance to herbicides now threatens cropping system sustainability in several industrialized nations. Integrated weed management (IWM) provides opportunities to reduce selection pressure for weed resistance while maintaining current crop yields. Combining optimal IWM tactics that discourage weeds by minimizing disturbance (no till, direct-seeding), adopting diverse crop rotations, and attempting to preclude resource acquisition by weeds are encouraged. New research knowledge on practical IWM systems is available, but despite current and looming threats of major weed resistance, most crop producers will require greater incentives than those currently available to more-fully adopt IWM systems in the near future.


Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 146
Author(s):  
Leonardo F. Rocha ◽  
Karla L. Gage ◽  
Mirian F. Pimentel ◽  
Jason P. Bond ◽  
Ahmad M. Fakhoury

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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