Weeds In Crop Production Research Articles

ИСПОЛЬЗОВАНИЕ ТОРФОПРОДУКЦИИ В СЕЛЬСКОМ ХОЗЯЙСТВЕ

Peat products play an important role in agriculture. An analysis of the use of peat products in agriculture was carried out. It was noted that in livestock farming, peat is used as bedding for livestock to produce peat manure, peatponics, the production of protein and feed additives, silos, and the production of drugs from peat in veterinary medicine. Peat is used to improve soil fertility, create substrates, for growing seedlings, for mulching the soil and protecting plants from frost and weeds in crop production. The use of peat briquettes as fuel for heating greenhouses and livestock buildings is possible. After burning them, peat ash remains - a good fertilizer. The organic and chemical composition of peat is shown. For the effective processing of peat and the use of peat products, it is proposed to create an agricultural consumer cooperative (ACC). A model of the interaction of structure-forming elements of ACC for peat processing is presented. The creation of an industrial complex for the processing and integrated use of peat products is promising, since it realizes the simplicity of technical solutions, the possibility of scaling processes, short lead times and the environmental friendliness of the resulting products. The integrated use of peat products in agriculture allows not only to improve soil fertility and increase crop yields, but also to ensure the effective use of peat as fuel, feed additives, animal bedding, oil product sorbent, etc.

​Challenges of Herbicide Resistant Weeds in Wheat in India and its Management: A Review

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.

Complementarity of grasslands and cereal fields ensures carabid regional diversity in French farmlands

Carabids (ground beetles) are important beneficial insects that contribute to biological control of pests and weeds in crop production. They can be found in different agricultural landscape habitats. However, little has been studied about the composition and similarity of carabid assemblages between two major land covers types: cropland and grassland. In a context of declining grassland areas in farmlands, highlighting complementarities of these two land covers is crucial to encourage land use planning that favors biodiversity. The objective of this study was to evaluate the relative and shared contribution of cereal crops and grasslands to carabid diversity in farmlands. Carabids were sampled in 104 pairs of cereal fields and grasslands in 3 agricultural regions of southeastern France. Carabid diversity was further analyzed with multiple regression models, including different local parameters. The correlations between assemblage similarities and geographical distance of sampled cereal fields and grasslands were also studied. Overall, 115 different species were found, 82 in cereal fields and 95 in grasslands. Per site species number and activity-density were higher in the two study regions with higher grassland cover. Evenness of carabid assemblages were higher in grasslands. Cropland and grassland remained strongly distinct, but assemblages showed higher similarity up to 4 km distance from each other. The study illustrates the major interest in preserving grassland within farmland for land use planners and/or policy makers. We found that grasslands and croplands complement each other. Though they host distinct communities, they provide continuous and different resources to the species throughout the year.

TILLAGE MANAGEMENT AS A METHOD OF WEED CONTROL IN MANGWENI, NKOMAZI LOCAL MUNICIPALITY, SOUTH AFRICA

The objective of the study was to determine the influence of tillage management strategies on weed\r\ncontrol, assess the impact of weed in crop production; and examine farmers’ adoption behaviour\r\nin the use of modern weed control methods. The study employed a survey of a randomized sample\r\nof 160 farmers in Mangweni in Mpumalanga Province. Logistic regression model was adopted to\r\nanalyse data collected from farmers. The results show that farmers are aware of the menace of\r\nweeds in terms of cost. Results also reveal that farmers who had lesser weed count in their crop\r\nfield were involved in practicing zero tillage. Furthermore, some socio-economic predictor\r\nvariables were found to have influence on the adoption of modern weed control methods.\r\nSignificant variables were age (P-value =.008), education (P-value = .056), household size (Pvalue = .005), income (P-value = 047) and number of children (P-value = .016). The paper\r\nrecommend that, for farmers with low resources, zero tillage remains a viable option and needs to\r\nbe evaluated further for weed control purposes. A good understanding of decision making process\r\nwill assist to intensify adoption of new methods of weed control. Farmers’ capacity building\r\nshould be enhanced through training as this will allow for well-informed decision making.

Smart weed management: A small step towards doubling farmers’ income

Increasing incomes by reducing crop losses due to various pests and improving productivity and input-use efficiency, are some of the major recommendations of the report on Doubling Farmers’ Income by 2022. Weeds are unwanted intruders into agro-ecosystems that compete for limited resources and reduce crop yields and farmers’ income. It was estimated that on an average the weed control costs around INR 6000/ha (USD 92.42/ha) in rainy season crops and around INR 4000/ha (USD 61.61/ha) for winter crops, which accounts for around 33% and 22% of total cost of cultivation, respectively. Thus, efficient weed management can help in increasing the farmers’ income by reducing the losses caused by weeds, decreasing the cost of production, and increasing the productivity through efficient utilization of resources. The present paper deals with the importance of weeds in crop production and farmers’ income, and role of smart weed management practices in reducing cost of production, and improving input-use efficiency and crop productivity.

Atmospheric pollen dispersion from herbicide-resistant horseweed (Conyza canadensis L.)

Horseweed (Conyza canadensis (L.) Cronq.) with evolved herbicide resistance has become an especially problematic weed in crop production across the USA and on four continents (North America, South America, Asia, and Europe). Spread of herbicide resistance can occur through pollen-mediated gene flow between resistant and susceptible horseweed populations. However, there are little knowledge, preventive guidelines, and mechanism modeling for pollen transport in this system. We need to better understand pollen dispersion and deposition in the context of atmospheric conditions, herbicide-resistant horseweed patch size, and buffer crop type, height, and field size. A mechanistic model is needed to account for these. A pollen dispersion and deposition model was calibrated and validated using 2013 experimental field data. The validated model was run for various combinations of atmospheric conditions, horseweed characteristics (source strength), and buffer species and size (pollen can be intercepted by crop plants). Large fields with crops with a high leaf area density and tall plants can effectively prevent pollen dispersion. The information will help provide guidelines for preventing herbicide resistance spread from herbicide-resistant weeds and genetically modified plants in general.

Weed Allelochemicals and Possibility for Pest Management

Purpose: Weed interference is a constraint in agricultural practice. The crop-weed interaction has been extensively described in literature, but the weed-weed interaction and their potential usage in crop production have not much been understood. In this paper, the interactions of allelochemicals of the weeds which cause troublesome in crop production and ecosystem against weeds, crops, and pathogens are described. Principal results: Weed allelochemicals are classified into many chemical classes, and the majority is consisting of phenolics acids, alkaloids, terpenes, flavonoids, long chain fatty acids, lactones, and other volatile compounds. Type of weed allelochemicals and their doses are varied among weed species. Some allelochemicals such as catechin (+/-) have been reported to be responsible for weed invasiveness. Some crops exude germination stimulants to parasitic weeds such as Striga spp. and Orobanche spp. In contrast to their negative impacts on crop production, many weeds can be exploited as promising sources to control harmful insects, fungi, bacteria, and weeds. For instance, Ageratum conyzoides is a destructive weed in crop production, but it exerted excellent insecticidal, antifungal, and herbicidal capacity and promoted citrus productivity in A. conyzoides intercropped citrus orchards. Major conclusions: In general, weeds compete with crops by chemical pathway by releasing plant growth inhibitors to reduce crop growth. Weed allelochemicals may be successfully exploited for pest and weed controls in an integrated sustainable crop productoiin. Some weed allelochemicals are potent for development of natural pesticides.

Weed Allelochemicals and Possibility for Pest Management

Purpose: Weed interference is a constraint in agricultural practice. The crop-weed interaction has been extensively described in literature, but the weed-weed interaction and their potential usage in crop production have not much been understood. In this paper, the interactions of allelochemicals of the weeds which cause troublesome in crop production and ecosystem against weeds, crops, and pathogens are described.Principal results: Weed allelochemicals are classified into many chemical classes, and the majority is consisting of phenolics acids, alkaloids, terpenes, flavonoids, long chain fatty acids, lactones, and other volatile compounds. Type of weed allelochemicals and their doses are varied among weed species. Some allelochemicals such as catechin (+/-) have been reported to be responsible for weed invasiveness. Some crops exude germination stimulants to parasitic weeds such asStrigaspp. andOrobanchespp. In contrast to their negative impacts on crop production, many weeds can be exploited as promising sources to control harmful insects, fungi, bacteria, and weeds. For instance,Ageratum conyzoidesis a destructive weed in crop production, but it exerted excellent insecticidal, antifungal, and herbicidal capacity and promoted citrus productivity inA. conyzoidesintercropped citrus orchards.Major conclusions: In general, weeds compete with crops by chemical pathway by releasing plant growth inhibitors to reduce crop growth. Weed allelochemicals may be successfully exploited for pest and weed controls in an integrated sustainable crop productoiin. Some weed allelochemicals are potent for development of natural pesticides.

Wind‐mediated horseweed (Conyza canadensis) gene flow: pollen emission, dispersion, and deposition

Horseweed (Conyza canadensis) is a problem weed in crop production because of its evolved resistance to glyphosate and other herbicides. Although horseweed is mainly self-pollinating, glyphosate-resistant (GR) horseweed can pollinate glyphosate-susceptible (GS) horseweed. To the best of our knowledge, however, there are no available data on horseweed pollen production, dispersion, and deposition relative to gene flow and the evolution of resistance. To help fill this knowledge gap, a 43-day field study was performed in Champaign, Illinois, USA in 2013 to characterize horseweed atmospheric pollen emission, dispersion, and deposition. Pollen concentration and deposition, coupled with atmospheric data, were measured in a source field (180 m by 46 m) and its surrounding areas up to 1 km downwind horizontally and up to 100 m vertically. The source strength (emission rate) ranged from 0 to 140 pollen grains per plant per second (1170 to 2.1×106 per plant per day). For the life of the study, the estimated number of pollen grains generated from this source field was 10.5×1010 (2.3×106 per plant). The release of horseweed pollen was not strongly correlated to meteorological data and may be mainly determined by horseweed physiology. Horseweed pollen reached heights of 80 to100 m, making long-distance transport possible. Normalized (by source data) pollen deposition with distance followed a negative-power exponential curve. Normalized pollen deposition was 2.5% even at 480 m downwind from the source edge. Correlation analysis showed that close to or inside the source field at lower heights (≤3 m) vertical transport was related to vertical wind speed, while horizontal pollen transport was related to horizontal wind speed. High relative humidity prevented pollen transport at greater heights (3–100 m) and longer distances (0–1000 m) from the source. This study can contribute to the understanding of how herbicide-resistance weeds or invasive plants affect ecology through wind-mediated pollination and invasion.

Influence of nitrogen and plant density on the growth and seed production of common ragweed (Ambrosia artemisiifolia L.)

Common ragweed is an important annual weed in crop production, and is also considered to be a serious public health problem. Determination of common ragweed growth under various nitrogen (N) rate and plant density could aid the development of an integrated control program. Greenhouse and field experiments were conducted to determine the effects of N fertilizer and density on common ragweed growth and seed production. In the greenhouse study, the greatest shoot dry matter (SDM) plant−1 was obtained with the 50 and 100 kg N ha−1. In the field experiment, SDM plant−1 in the low density plots responded favorably to the addition of medium and high levels of N compared to the field level of N. With increasing density, ragweed in higher density plots responded only with the highest N rate. The intensity of intraspecific competition increased with increasing density, thus total SDM plant−1 was significantly reduced, regardless of N rate. Intraspecific competition also reduced the reproductive production of common ragweed where seed production decreased as plant density increased. Plants grown at higher density produced less seeds per plant basis; however, they produced a considerable number of seed on a per area land basis, which is important for the survival of the species and further expansion in agricultural land and non-crop areas. Common ragweed is a fast-growing species, capable of producing considerable biomass and seed at various pure stand densities and N rates. It also justifies the need for early season control to prevent seed production.

Cucurbit yellow stunting disorder virus Detected in Pigweed in Florida.

Pigweeds (genus Amaranthus) are problematic weeds in crop production throughout the world and are responsible for significant yield losses in many crops (2). Members of this genus can produce hundreds of thousands of seeds per plant and are also capable of supporting populations of important crop pathogens including viruses, nematodes, fungi, and oomycetes. Thirty-one pigweed samples (tentatively identified as Amaranthus lividus L. based on leaf notch and growth habit) were collected in November and December of 2009 from a watermelon field near Immokalee, FL, previously found to contain watermelon plants infected with three whitefly-transmitted viruses: Cucurbit yellow stunting disorder virus (CYSDV), Cucurbit leaf crumple virus (CuLCrV), and Squash vein yellowing virus (SqVYV). Although no obvious virus symptoms were observed on any of the pigweed plants, whiteflies (Bemisia tabaci), a known vector of CYSDV, CuLCrV, and SqVYV, were observed on leaves. Consequently, replica tissue blots were made from all pigweed samples and tested independently by tissue blot nucleic acid hybridization assay for CYSDV, CuLCrV, or SqVYV (3). Tissue blots indicated CYSDV infection in six pigweed samples. Neither CuLCrV nor SqVYV was detected. Three of the tissue blot-positive pigweed samples were further tested by reverse transcription (RT)-PCR amplification from total RNA (extracted from leaf tissue with TRIzol Reagent [Invitrogen, Carlsbad, CA]) with HSP70 and coat protein (CP) gene primers (1). HSP70 and CP gene RT-PCR products of the expected sizes (175 and 707 nt, respectively) were amplified, sequenced, and found to be 100% identical for all three pigweed samples. The partial HSP70 gene sequence from pigweed shared 98.3 to 100% nucleotide identity with CYSDV isolates from Arizona, California, and Spain (GenBank Accession Nos. FJ492808, EU596530, and NC_004810, respectively). The partial CP gene sequence from pigweed shared 88.8 to 100% nucleotide identity with CYSDV isolates from Arizona, Saudi Arabia, Texas, and Spain (GenBank Accession Nos. EF210558, AF312811, AF312806, and AF312808, respectively). To our knowledge, this is the first report of CYSDV infection of pigweed in Florida. Infection of redroot pigweed (A. retroflexus) was recently reported in California (4). These results collectively indicate that control of noncucurbit weeds may be important for effective management of CYSDV in cucurbit crops.

Salicylic Acid Reduces Napropamide Toxicity by Preventing Its Accumulation in Rapeseed (Brassica napus L.)

Napropamide is a widely used herbicide for controlling weeds in crop production. However, extensive use of the herbicide has led to its accumulation in ecosystems, thus causing toxicity to crops and reducing crop production and quality. Salicylic acid (SA) plays multiple roles in regulating plant adaptive responses to biotic and environmental stresses. However, whether SA regulates plant response to herbicides (or pesticides) was unknown. In this study, we investigated the effect of SA on herbicide napropamide accumulation and biological processes in rapeseed (Brassica napus). Plants exposed to 8 mg kg(-1) napropamide showed growth stunt and oxidative damage. Treatment with 0.1 mM SA improved growth and reduced napropamide levels in plants. Treatment with SA also decreased the abundance of O (2) (-.) and H(2)O(2) as well as activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), and increased activities of guaiacol peroxidase (POD) and glutathione-S-transferase (GST) in napropamide-exposed plants. Analysis of SOD, CAT, and POD activities using nondenaturing polyacrylamide gel electrophoresis (PAGE) confirmed the results. These results may help to understand how SA regulates plant response to organic contaminants and provide a basis to control herbicide/pesticide contamination in crop production.

Sorption of clopyralid, dicamba and MCPA by two soils with conventional and no-till management

Sorption is one of the key processes controlling the fate of agrochemicals in soil systems. The sorption of agrochemicals on a soil matrix can be affected by changes in chemical and physical properties caused by different tillage practices. Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), dicamba (3,6-dichloro-2-methoxybenzoic acid), and MCPA ((4-chloro-2-methylphenoxy)acetic acid), weakly acidic herbicides, are commonly used to control broadleaf weeds in crop production. The sorption of the three herbicides by surface soils (0–5 cm) from different tillage systems was studied by batch equilibrium. Of the herbicides used, MCPA was sorbed on soil in the greatest quantity, dicamba was the least sorbed, and the sorption was dependent on the pKa values of herbicides. In a sandy loam soil, more herbicide was sorbed under no-tillage (NT) than conventional tillage (CT). However, in a clay soil the difference in herbicide sorption between the two tillage systems was not consistent. The results can be explained in terms of changes in soil pH and organic matter content. The presence of clopyralid and MCPA lowered the sorption of dicamba, and MCPA was more effective than clopyralid in competing for sorption sites with dicamba. Key words: Herbicide sorption, clopyralid, dicamba, MCPA, tillage