Effects of Tank Contamination and Impact of Drift-reducing Agents on Weed Control in Response to Dicamba Applications PDF Download

Author: Milos Zaric
Publisher:
ISBN:
Category :
Languages : en
Pages : 110

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Book Description
Availability of dicamba-tolerant (DT) crops from 2017 provided farmers with additional herbicides for weed control management in row crops. However, the technology alike this one has concerns regarding dicamba off-target movement (OTM) causing undesirable effects on sensitive vegetation. Even though dicamba has high water solubility OTM that has often been overlooked when it comes to unintended crop exposure is dicamba tank contamination. Considering the complexity of spraying equipment soybean response may be expected even when small amounts of residues are left in the spray equipment. Typically, the same field spray equipment is used to perform herbicide application through growing season there is a limited knowledge how various postemergence (POST) programs impacts soybean response when found in scenario with dicamba tank contamination and requires additional research. Furthermore, as one way to mitigate OTM potential release of DT crops was followed with registration of various agents also known as drift-reducing agents (DRAs). Increased awareness of both growers and commercial applicators to reduce unintended adjacent crops injury use of labeled DRAs in combination with drift-reduction nozzles represent common practice. Exposure of sensitive crops to sublethal doses of dicamba has been well documented over several years; however, there is limited information available how combination with commonly used DRA's may impact application process and weed control. Considering limitations on available literature the main objective of this research were: 1) evaluate response of non-DT soybean variety when exposed to commonly applied POST herbicide program in combination without or with dicamba as tank-contaminant and 2) evaluate impact of DRAs on weed control in response to dicamba applications. The results of this research expanded knowledge and will help in education in the future management decisions about potential implications associated with common mitigation techniques used with dicamba application as well as helped with understanding how various POST herbicide program affect soybean response.

Author: Vinicius Velho
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
The introduction of dicamba-tolerant (DT) soybeans (Glycine max L. Merr) and cotton (Gossypium hirsutum L) in 2017 provided an additional tool for herbicide resistant weeds management. In the subsequent years, off-target movement of dicamba allegedly caused damage to sensitive crops and vegetation. Possible causes of off-target movement include tank contamination, physical drift, and volatility. Additional products, such as herbicides to control grass, are often added to tank with dicamba, which is used to control broadleaf weeds, to increase the spectrum of control and application efficiency. Dicamba products registered for DT crops require the use of drift reducing agents to mitigate unintended effects to adjacent crops. Sprayers are complex machines with valves, hoses, tanks, and nozzles that can retain herbicide residues and cause symptomology and/or injury to crops if proper cleanout procedures are not performed. Recommended cleanout procedures can be found in dicamba product labels, but there is no information available reporting the effect of tank mixtures or different dicamba formulations on retention of residues. The objective of this research was to: 1) evaluate the dicamba retention of potential tank mixtures with dicamba and drift reducing adjuvants, clethodim as well as tank-cleaning agents on non-DT soybeans, 2) evaluate the cleanout procedures of commonly used dicamba products, on non-DT soybean, and 3) investigate how the rinsate following cleanout procedures of dicamba mixtures affect such as soybean, cotton, tomatoes (Lycopersicon esculentum) and peanuts (Arachis hypogaea L.).

Author: Mason Castner
Publisher:
ISBN:
Category :
Languages : en
Pages : 212

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Book Description
The introduction of dicamba-resistant (DR) soybean [Glycine max (L.) Merr.] and cotton (Gossypium hirsutum L.) followed by a label allowing over-the-top applications of dicamba in the 2017 provided growers an additional option for broadleaf weed control. Because non-DR soybean is sensitive to low concentrations of dicamba, postemergence dicamba applications present growers choosing to plant non-DR soybean with concerns of damage from off-target movement through physical drift and volatilization of the herbicide as well as tank-contamination from prior dicamba application. Consequences of low-dose dicamba exposure on sensitive vegetative and reproductive soybean have been well researched, but little is known regarding the interaction between low-dose dicamba exposure and commonly applied contact herbicides. There is also limited research assessing repercussions caused by dicamba exposure during reproductive development in corn (Zea mays L.) and rice (Oryza sativa L.), two common cereal crops in Arkansas in proximity to soybean and cotton. Experiments included evaluating the potential for dicamba to elicit a hormetic response to sensitive soybean, determining if contact herbicides exacerbated off-target dicamba symptomology, and evaluating potential for low-dose dicamba exposure on reproductive corn and rice to reduce grain yield. Low doses of dicamba did not improve soybean grain yield, which indicates a hormetic response is unlikely. Contact herbicides such as glufosinate and acifluorfen applied in close proximity to a low dose of dicamba increased visible auxin symptomology to soybean at 21 and 28 days after treatment (DAT) compared to dicamba alone, but no effect on grain yield occurred. Soybean was injured more when dicamba exposure followed a glufosinate application than when dicamba preceded glufosinate or was applied in a mixture with glufosinate, with yield reductions resulting when the contact herbicide was applied 7 to 10 days after a V3 dicamba exposure. Visible injury to corn from dicamba was negligible (0%), but rice treated with dicamba at 56 and 560 g ae ha-1 demonstrated auxin symptomology which led to reductions in grain yield. Corn grain yield could only be reduced from dicamba at 560 g ae ha-1. In conclusion, dicamba tank-contamination and possibly off-target movement pose a greater threat to sensitive soybean regarding visible symptomology and yield as opposed to corn and rice, and it is unlikely that soybean exposure to low-dose dicamba will improve grain yields.

Author: Andy J. Luke
Publisher:
ISBN:
Category :
Languages : en
Pages : 71

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Book Description
Introduction of dicamba-tolerant soybeans (Glycine max L. Merr.) will improve management of increasing populations of herbicide-resistant weeds. However, increased use will lead to risks for damage to susceptible crops such as adjacent soybeans. Research on cleaning commercial spray equipment used to apply dicamba on tolerant soybeans followed by application of other herbicides on sensitive soybeans is needed. Soybean injury and yield following application of spray tank rinsates containing dicamba was studied in 2015 and 2016. Dicamba was applied through two commercial sprayers and spray equipment was subsequently treated with water or one of four cleaning agents (water alone, ammonia, Cleanse® or Erase®). This initial treatment was considered a first rinsate, and was followed by two rinses of water (second and third rinsate). Rinsate solutions were applied on V3 or R1 soybeans. Visible damage was observed at 7 days after treatment (DAT), especially for first rinsates (6 to 16[percent] for V3 treated plants and up to 22[percent] for R1 plants). At 14 DAT, plant height was reduced up to 48 and 33[percent] on V3 and R1 treated soybeans, respectively. Stunting on R1 treated soybeans persisted until the end of the season. First risnates reduced yields up to 11 and 46[percent] for V3 and R1 soybeans respectively, compared to the untreated control. For third rinsates, yields for R1 plants were reduced up to 6[percent], with no effect on V3 plants. Cleaning agents can reduce residues of dicamba in contaminated equipment, but dilution of residues by a triple rinse procedure is most important.

Author: John Tyler Buol
Publisher:
ISBN:
Category :
Languages : en
Pages : 239

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Book Description
Distinguishing 2,4-D and dicamba herbicide formulations in cotton and soybean tissue is challenging in regulation of crop injury from these herbicides. Additionally, stewardship of 2,4- D and dicamba technologies is important to maximize their longevity and efficacy. Research was conducted to (1) characterize cotton and soybean response to various formulations of 2,4-D or dicamba with or without glyphosate, (2) develop a method for classifying these formulations in crop tissue, and (3) optimize use of chloroacetamide herbicides in dicamba systems for mitigation of selection pressure on dicamba. Formulations evaluated include dicamba diglycolamine (DGA), dimethylamine (DMA), N,N-Bis-(3-aminopropyl) methylamine (BAPMA), and DGA plus potassium acetate (KAc); and 2,4-D DMA, acid, isooctyl ester (ESTER), and choline. Weed management by the chloroacetamides s-metolachlor and acetochlor was evaluated with applications preemergence (PRE), early postemergence (EP), late postemergence (LP), PRE followed by (fb) EP, PRE fb LP, and EP fb LP. Cotton and soybean response differed by 2,4-D and dicamba formulation, and glyphosate presence. Cotton yield was reduced by 200 to 500 kg ha−1 following exposure to 2,4-D choline or DMA relative to acid or ESTER. Glyphosate presence led to a reduction in cotton and soybean yield of 377 and 572 kg ha−1, respectively. Exposure to dicamba DMA resulted in a 263 kg ha−1 reduction in soybean yield relative to dicamba DGA, and glyphosate presence reduced yield by 439 and 246 kg ha−1 in cotton and soybeans, respectively. Chemometric analyses generated models capable of up to 85% accuracy in identifying dicamba formulation in cotton and soybean tissue, and up to 80% accuracy in identifying 2,4-D formulation. Split chloroacetamide applications improved cotton yield up to 60%, reduced weed densities up to 90%, and improved control up to 56% relative to single applications. Cotton height was reduced up to 23% if a single chloroacetamide application was made. Soybean yield was maximized following any chloroacetamide application timing except PRE alone, and weed control was reduced up to 31% following single chloroacetamide application relative to split applications. These results will aid regulatory bodies in managing use of new weed control technologies and will assist producers in stewarding these new technologies.

Author: A. G. Dexter
Publisher:
ISBN:
Category : Crops
Languages : en
Pages : 12

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Author: Alana Maree Wylie
Publisher:
ISBN:
Category : Dichlorophenoxyacetic acid
Languages : en
Pages : 206

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Book Description
Herbicides destroy, subdue or inhibit the spread of weeds and are widely used across the world. Their use for agricultural or golf course maintenance is a major source of pollutants to fresh waters; however, studies which assess the ecological effects of herbicide mixtures are uncommon. Therefore, there is an urgent need for research to better understand the ecological relationships (e.g. synergistic) caused by multiple stressors. The aim of my study was to assess the response of aquatic communities when exposed to combinations of two of the most commonly used herbicides, 2, 4-Dichlorophenoxyacetic acid (2, 4-D) and Dicamba and to compare their response against the isolated response of each herbicide. Three experiments based on stream microcosms were conducted. The first was representative of the detritus food chain (including biofilms and amphipods), the second was representative of the algal food chain (including algae and Potamopyrgus antipodarum snails) and the third was a combination of both food chains in a single test system. Within each experiment the isolated and mixture effects of Dicamba and 2,4-D were determined over a range of concentrations through the measurement of the respiration rate, chlorophyll a concentration, pheophytin concentration and organism mortality. Within the detritus food chain, no synergistic relationships were found between the herbicides. However, exposure to a high Dicamba concentration resulted in a decline in biofilm respiration rates. Increasing concentrations of Dicamba and 2, 4-D increased the mortality of amphipods. Similarly, there were no synergistic relationships within the algal food chain; however, as Dicamba concentrations increased, chlorophyll a concentrations also increased. Furthermore, as the concentrations of Dicamba and 2, 4-D increased, the mortality of the snails increased. Results from the detritus food chain suggest that declines in biofilm respiration rates are related to high Dicamba concentrations triggering an oxidative stress response leading to DNA, RNA and protein damage which subsequently inhibited bacterial respiration. However, results from the algal food chain suggest that additions of Dicamba, which is a synthetic auxin, resulted in an increase in cellular expansion and subsequent algal biomass. The mortality of amphipods and snails observed in all three experiments may have been caused by oxidative stress, whereby DNA damage, RNA damage, protein damage, lipid peroxidation, endocrine disruption or reduced energy levels lead to organism mortality at the higher concentrations of the herbicides. Future studies should focus on combining Dicamba and 2, 4-D with other commonly used pesticides with different modes of action to gain a more comprehensive understanding of ecosystem responses. Studies could also add the toxicity data from this study to current data to advance the development of mixture predication models. The significant impacts of Dicamba and 2, 4-D on detrital and algal food chains suggest that regular monitoring of herbicides as pollutants should be carried out in New Zealand freshwaters.

Author: Andre de Oliveira Rodrigues
Publisher:
ISBN:
Category :
Languages : en
Pages : 93

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Book Description
One of the largest challenges in agriculture is weed management. Improper or sub-optimal application techniques can cause decreased weed control and increased environmental contamination. Effective weed management is highly correlated with the product and the application method. Herbicide performance are affected by environmental conditions; they influence the physiology and growth of a plant and as well the herbicide performance. Among all environmental factors, rain shortly after herbicide application is one of the most harmful issues to the performance of the herbicide. Droplet size is a key factor in pesticide applications in regards to both drift and efficacy. Droplet size can be altered by several application parameters, such as the nozzle type, pressure, orifice size and spray solution. Droplet size is a key component in pesticide application with respect to overall application efficacy and off-target movement. As tank mix ingredients can significantly influence the resulting droplet size, agitation systems are critical to ensuring proper mixing of all components and overall performance. Sitting time, a period where the tank is held in a non-agitated state, potentially affects droplet size as well. The objectives of this research were: 1) understand the influence of nozzle spacing, boom height, nozzle type, on weed control, also expand the scientific knowledge on aforementioned parameters. 2) Evaluate the effect of rainfall after herbicide application on weed control, following certain intervals in order to understand the wash off effect. 3) Analyze the impact of nozzle type, application speed and pressure on weed control, in order to contribute to a more reliable recommendation of such parameters. This research highlights the impact of parameters regulated by the sprayer on weed control and allow a better understanding of how non-chemical parameters affect the efficacy on weed management, as well as a greater understanding on absorption and evaporation of herbicide plus losses of application efficacy. The results will clarify some of the most concerning question on one of the most complex process in agriculture.

Author: Joel Steven Roehl
Publisher:
ISBN:
Category : Herbicides
Languages : en
Pages : 108

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Book Description

Author: D. Bruce Turner
Publisher: CRC Press
ISBN: 9781566700238
Category : Nature
Languages : en
Pages : 186

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Book Description
This completely updated and revised Second Edition of the popular Workbook of Atmospheric Dispersion Estimates provides an important foundation for understanding dispersion modeling as it is being practiced today. The book and accompanying diskette will help you determine the impacts of various sources of air pollution, including the effects of wind and turbulence, plume rise, and Gaussian dispersion and its limitations. Information is shown in summary graphs as well as in equations. The programs included on the diskette allow you to "get the feel" for the results you'll obtain through the input of various combinations of parameter values. The sensitivity of data to various parameters can be easily explored by changing one value and seeing the effect on the results. The book presents 37 example problems with solutions to show the estimation of atmospheric pollutant concentrations for many situations.