Download or read book Integration of Cereal Cover Crops and Synthetic Auxin Herbicides Into Rowcrop Production and Weed Management written by Ryan James Edwards and published by . This book was released on 2015 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: The occurrence of herbicide resistance weeds across the southern United States has been increasing. Research is needed to develop alternative control measures, while supporting sound agronomic practices. Greenhouse and field studies were conducted to evaluate cereal cover cropping techniques along with novel herbicides to determine their value for Mississippi growers. Field studies were performed to determine which combination of cereal cover crops (cereal rye, wheat and oats) and residual herbicides (S-metolachlor + metribuzin, S-metolachlor + fomesafen, pendimethalin, flumioxazin, sulfentrazone + metribuzin and pyroxasulfone + flumioxazin) would maximize soybean yield in the presence of weeds. Cereal cover crop termination methods were evaluated and a partial budget was generated to examine the total costs of growing soybeans utilizing cereal cover crops and residual herbicides. Residual herbicide applications averaged across all cereal cover crops controlled Amaranthus spp. greater than 89% by 28 DAT. Control by the cover crops alone was 67% for of Amaranthus spp. In all cereal species tested, cutting the cover crops 10 cm above the soil and leaving the residue reduced weed numbers compared to other termination methods. However, high production and implementation costs may prevent widespread adoption of cereal cover crops and residual herbicides in Mississippi. Aminocyclopyrachlor (AMCP) is a synthetic auxin herbicide currently labeled for non-crop use, but has characteristics which may make it useful as a preplant burndown (PPB) herbicide. The application of AMCP prior to planting of corn and cotton were evaluated and carryover effects to soybean were also evaluated. Tank mix combinations of AMCP with residual herbicides (rimsulfuron, flumioxazin, pyroxasulfone, pyroxasulfone+ flumioxazin and atrazine) were also evaluated. A rate titration of AMCP and its impacts on crop species were evaluated in the greenhouse. Corn showed tolerance to AMCP except at 0.28 kg ai ha-1 applied prior to planting. Cotton was sensitive to AMCP as rate increased closer to the planting date, but response depended upon soil texture. AMCP impacts on soybean showed greater sensitivity (90% injury) then all other species evaluated. Due to potential impacts on soybean and cotton, AMCP is not a potential PPB for use in Mississippi.

Download or read book Integrating Cover Crops in No till Corn and Soybean to Diversify Herbicide Resistant Weed Management in the Mid Atlantic written by Jess Marie Bunchek and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Widespread adoption of genetically-engineered, herbicide-resistant (HR) crops have simplified crop rotation diversity and the use of single-tactic, herbicide-based weed management programs. These practices have resulted in an HR weed epidemic, where glyphosate-resistant weeds are especially problematic. Glyphosate-resistant weeds like horseweed [Conyza canadensis (L.)] and pigweeds (Amaranthus spp.) threaten grower productivity and long-term efficacy of common agronomic herbicides. Thus, integrated weed management (IWM) programs that implement both ecological- and herbicide-based tactics are needed in no-till annual grain systems to (1) manage current HR weeds, (2) reduce HR selection pressure for evolution of resistance to other herbicides, (3) preserve effective herbicide technology, (4) enhance environmental stewardship, (5) safeguard soil conservation gains, and (6) maintain farm profits and productivity. To address these goals, we established three field studies at two sites in the Mid-Atlantic and identified combinations of cover crop and herbicide tactics that achieve effective season-long annual weed management, minimize HR selection pressure, and increase sustainability by reducing herbicide inputs. The first two studies assessed the complementarity of cover crops treatments and herbicide programs in corn and soybean, where integrating a cover crop treatment combined with applying a spring, pre-plant burndown herbicide application as well as a POST-emergent application provided the most effective season-long annual weed control. The third study assessed cover crop treatments and varied management practices, such as planting and termination dates, on HR selection pressure reduction at the time of herbicide applications. While cover crops intercepted a portion of the burndown herbicide application from reaching the soil surface, weeds were effectively controlled by the cover crops before the application, thus reducing the HR selection pressure.

Download or read book Utilizing Cover Crops to Improve Sustainability of Conventional Weed Management Programs written by Garret Brown Montgomery and published by . This book was released on 2016 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research was conducted from the fall of 2014 to the fall of 2016 to evaluate the optimal utilization of cover crops for weed control in no-till environments. Studies included a corn (Zea mays L.) termination timing study to evaluation different termination intervals of cereal rye (Cereal rye L.), hairy vetch (Vicia villosa Roth.), and a combination of cereal rye and hairy vetch cover crops on corn growth and development, an evaluation of a roller crimper for cover crop termination prior to corn study, an evaluation of a roller crimper for cover crop termination prior to soybeans [Glycine max (L.) Merr.], an evaluation of glyphosate + dicamba tolerant (GDT) soybean utilization in a cover cropping system, and a study to evaluate the effects of fall applied herbicides on four cover crop species from controlling Italian ryegrass (Lolium perenne ssp. multiflorum). Results from this research indicate that a cover crop termination interval prior to corn planting can influence corn growth, development, and yield, a roller crimper is not currently a viable tool for cover crop termination prior to planting corn, a roller crimper can be effectively used for cover crop termination prior to soybeans, GDT soybeans can be readily utilized into a cover cropping system, and that fall applied herbicides can be used with cover crops and aid in controlling Italian ryegrass.

Download or read book Cover Crops written by Taïga B. Cholette and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cover crops have many desirable attributes including reduced soil erosion, increased soil organic matter and reduced weed density. However, cover crops can be injured by residues from herbicides used for weed control in the previous crop and cover crops can negatively impact the main cash-generating crop through resource competition. Three field studies were conducted to determine the impact of winter wheat and soybean herbicides on the establishment and growth of oilseed radish, the suppression of glyphosate-resistant Canada fleabane in corn with cover crops seeded the previous summer/fall after winter wheat harvest and the suppression of annual ryegrass in corn with nicosulfuron to prevent grain corn yield losses due to cover crop interference. Winter wheat herbicides applied in the spring caused

Download or read book Organic Weed Control and Cover Crop Residue Integration Impacts on Weed Control Quality Yield and Economics in Conservation Tillage Tomato A Case Study written by Andrew J. Price and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The increased adoption of conservation tillage and organic weed control practices in vegetable production requires more information on the role of various cover crops in integrated weed control, tomato quality, and yield. Two conservation-tillage systems utilizing crimson clover and cereal rye as winter cover crops were compared to a conventional black polythene mulch system, with or without organic weed management options, for weed control, tomato yield, and profitability. All cover crops were terminated with a mechanical roller/crimper prior to planting. Organic weed control treatments included: 1) flaming utilizing a one burner hand torch, 2) PRE application of corn gluten, 3) PRE application of corn gluten followed by flaming, or 4) intermittent hand weeding as needed. A non-treated control and a standard herbicide program were included for comparison. The herbicide program consisting of a PRE application of S-metolachlor (1.87 kg a.i./ha) followed by an early POST metribuzin (0.56 kg a.i. /ha) application followed by a late POST application of clethodim (0.28 kg a.i./ha). In general, high-residue clover and cereal rye cover crops provided substantial suppression of Palmer amaranth, large crabgrass, and yellow nutsedge. Across systems, minimum input in high-residue systems provided the highest net returns above variable costs compared to organic herbicide treatments that are costly and provide marginal benefit.

Download or read book Value of Cover Crops in Suppressing Weeds and Protecting Cotton Yields and Likelihood of Residual Herbicide Carryover to Cover Crops written by Matheus Gabriel Palhano and published by . This book was released on 2017 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Weed-resistance management has become a topic of concern for modern agriculture. Cost related to herbicide usage has increased greatly due to evolution and proliferation of resistant weeds. Therefore, experiments were conducted to investigate the potential for using cover crops to suppress problematic weeds in cotton as well as chemical options for cover crop dessication, and sensitivity of cover crops to residual herbicides were evaluated. No differences were observed for cereal rye biomass production and consequently weed suppression between broadcast and drilled planting methods. Total amount of cover crop biomass was vital to effectively suppress weeds. Hence, of the cover crops evaluated, cereal rye proved to be superior to others for weed suppression due to its ability to produce large amounts of biomass. Cereal rye biomass production increased as the seeding rate increased, which led to greater weed suppression at a seeding rate of 112 kg ha-1 and 168 kg ha-1 compared to 56 kg ha-1. Control of cover crops prior to row crop planting can be difficult depending upon the cover crop species. Paraquat plus metribuzin and glufosinate adequately controlled the legume cover crops hairy vetch (Vicia villosa Roth) and Austrian winterpea (Lathryrus hirsutus L). Cereal cover crops were completely controlled by glyphosate alone. Rapeseed was not effectively controlled by any of the termination options evaluated. Based on a herbicide carryover trial from corn, residual herbicides commonly applied in corn that will be rotated to a cover crop and eventually cotton have low risk to interfere with the cover crop establishment and development after corn harvest.

Download or read book Integration of Cover Crop Residues Conservation Tillage and Herbicides for Weed Management in Corn Cotton Peanut and Tomato written by and published by . This book was released on 2009 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cover Crop and Herbicide Combinations for Session long Weed Control in Dry Beans written by Ryan T. Johnson and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Herbicides remain an important weed management tool in dry edible beans but reducing reliance on herbicides through integrated weed management practices is important. The objective of this study was to evaluate the effect of cover crops in combination with herbicides for weed suppression in dry bean (Phaseolus vulgaris). Field studies were conducted in 2021 and 2022 near Lingle and Powell, WY. Three small grain cover crop (winter wheat) treatments were planted in March (early), or in April (late), with a control treatment of no cover crop. Pinto beans were planted in early June and the cover crop was terminated with glyphosate on the day of bean planting. Each cover crop whole-plot was divided into four split-plots consisting of the following herbicide treatments: no herbicide, preemergence (PRE) herbicide application only (pendimethalin + dimethenamid-P), postemergence (POST) herbicide application only (bentazon + imazamox), and sequential PRE and POST herbicide application. Spring-planted winter wheat cover crop combined with herbicides had a beneficial effect on dry bean yield in 3 out of the 4 studies. Weed control failure in all treatments occurred at Lingle, 2022 due to presence of herbicide-resistant kochia. For the other three sites, POST herbicide had a greater impact on protecting dry bean yield than PRE herbicides or cover crops. Cover crop helped to reduce kochia and lambsquarters density but was even more consistent at reducing the aboveground biomass of these two weed species. The wheat cover crop failed to reduce hairy nightshade density, but this weed species was controlled by either PRE or POST herbicide application. POST herbicide application contributed the most to protecting dry bean grain yield, followed closely by PRE herbicide, and lastly by the cover crop.

Download or read book Response of Weeds to the Intensification of Kansas No Till Crop Rotations with Cover Cropping written by Justin Scott Petrosino and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: No-till producers can manage weeds by including cover crops during the fallow phase as part of an integrated weed management plan. Field experiments were conducted between 2007 and 2009 to quantify the influence of cover crops on weed emergence, biomass accumulation, and seed production. Field experiments were established near Garden City, KS with winter wheat or fallow as main plots and cover crop treatments as subplots including five spring- and five fall-sown individual or mixtures of crop species and a no-cover chemical fallow. Separate1-m2 quadrats were seeded with kochia or downy brome at 500 seed/m2. Kochia density was reduced by 75% and biomass reduced by 88% in fall-sown cover crops compared to chemical fallow across growing seasons. Spring-sown cover crop mixtures reduced kochia biomass in 2009 when kochia emergence was delayed. Downy brome biomass decreased exponentially as cover crop biomass increased. A second field experiment was established near Manhattan, KS with soybean, winter wheat, or grain sorghum phases of the rotation as main plots and six cover crop treatments as subplots sown after winter wheat harvest. Paired Palmer amaranth 1-m2 quadrats were seeded with 500 seed/m2 in each cover crop subplot. One quadrat was protected from any herbicide application made to the cover crop or to the grain sorghum. Combining burndown application with high biomass-producing cover crops reduced Palmer amaranth emergence and biomass. Influence of cover crop presence reduced early season Palmer amaranth emergence in the subsequent grain sorghum phase. Optimal seeding rate of forage soybean sown in winter wheat stubble and its impact on Palmer amaranth and downy brome emergence and growth were evaluated in field studies established near Manhattan and Hesston, KS in 2008 and 2009. Soybean was no-till drilled after wheat harvest at five rates ranging from 100,000 to 600,000 seeds/ha. A no-cover chemical fallow treatment was included. Separate 0.5-m2 quadrats were seeded with Palmer amaranth at 100 seed/0.5 m2 or with downy brome at 250 seed/0.5 m2. Three termination methods evaluated were killing frost, glyphosate application, or crop rolling. Palmer amaranth density was not affected by treatments but biomass decreased as soybean seeding rate and crop biomass increased. Downy brome emergence was less with rolled or sprayed termination methods in one site year as timing of termination was optimal. High biomass producing cover crops sown during the fallow phase of a crop rotation reduced weed emergence, density, and biomass accumulation. Cover crops can be part of an integrated weed management plan in Kansas.

Download or read book Herbicide Resistance and World Grains written by Stephen B. Powles and published by CRC Press. This book was released on 2001-03-13 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by experts from across the globe, Herbicide Resistance and World Grains evaluates the weed and herbicide management systems in major world grain crops such as soybean, maize, rice, and canola. The book examines the impact of transgenic crops and new technology on resistance management. It provides background information and offers practical

Download or read book Potential for Interseeded Cereal and Legume Cover Crops to Control Weeds in Potato Salanum Tuberosum L written by Riikka Marjukka Rajalahti and published by . This book was released on 1997 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Winter Cover Crop Impacts on Weed Dynamics in Eastern and Central Nebraska written by Elizabeth Ann Oys and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing tillage in cropping systems causes weed management to be dependent on chemical and cultural methods for weed control. Over time, herbicide-resistant weeds have developed due to the continuous selection pressures from herbicides, particularly in the Midwest Corn Belt. Integrated weed management strategies, such as cover crops, can be used to mitigate some of these issues. Cover crops are primarily known for their soil health benefits, but there is evidence that cover crops can suppress weeds. However, less research has been done at the field-scale level to address cover crop impacts on the weed seedbank and aboveground weeds during the growing season. In response, two experiments were designed to investigate above and belowground weeds in eastern and central Nebraska. The soil seedbank was germinated from soil samples and weed density and biomass were measured at two points during the growing season. Our results show that cover crops did not influence the total seedbank density, but increased the density of Amaranthus spp. seeds in the seedbank. Aboveground, reductions in weed density and biomass reductions occurred at two sites. More importantly, larger pigweed seedbank densities in the cover crop treatments were not expressed aboveground, signifying cover crop suppression of the weed seedbank through reduced germination withdrawals. This research provides insight on above and belowground weed dynamics under cover crops and shows that cover crops may be a viable integrated weed management tool for Amaranthus spp. management and mitigating risks of herbicide resistance over time by preventing seedbank withdrawals through germination.

Download or read book Herbicide Resistant Crops written by Stephen O. Duke and published by CRC Press. This book was released on 2018-01-18 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by a recognized leader in the field, Herbicide-Resistant Crops is the first book to cover all of the issues related to the controversial topic of herbicide-resistant crops. It provides extensive discussions of the modern biotechnological methods that have been used to develop such crops, and reviews the implications - both positive and negative - of developing crops that are resistant to herbicides. The creation and anticipated applications of specific herbicide-resistant crops are also discussed. In addition, the book covers the potential impact of herbicide-resistant crops on weed management practices and the environment, and presents issues related to the regulation and economics of these crops. The editor has brought together a diverse group of professionals, representing the several distinct areas impacted by the new technology of herbicide-resistant crops. The wide range of viewpoints presented in this book creates a balanced and complete survey, providing a notable contribution to the literature.

Download or read book QUANTIFYING RELATIVE SENSITIVITIES OF COVER CROPS TO CORN HERBICIDES TO REFINE COVER CROP INTERSEEDING PRACTICES written by Tosh Mazzone and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Few studies have quantified differences in the sensitivity of cover crop species to corn herbicide programs. Differences in corn herbicide efficacy on weed species can be categorized broadly by activity on taxonomic groups or species traits within taxonomic groups, such as seed mass, which are also likely sources of variation in cover crop sensitivity to herbicides. To improve cover crop species selection for interseeding, including the design of mixtures, dose-response assays were conducted from 2020-2022 at University Park, Pennsylvania. Relative sensitivity was quantified for twelve cover crop species within four taxonomic groups that ranged in seed mass within taxonomic group, in response to triazine (atrazine; Group 5 herbicide) and triazine/HPPD inhibiting herbicide programs (mesotrione, isoxaflutole, tembotrione, topramezone, tolpyralate; Group 27 herbicides). Nonlinear dose-response curves were fit to standardized biomass data and absolute ED50 coefficients were extracted for each cover crop by herbicide model. Results showed that cover crops exhibited low sensitivity to atrazine across taxonomic groups and seed sizes, and except for small-seeded legumes (medium red clover, crimson clover). In comparison, most cover crop species were sensitive to mesotrione/atrazine and isoxaflutole/atrazine, with absolute ED50 estimates at low soil concentrations. Intermediate sensitivity to tembotrione/atrazine was observed across all cover crop species, with annual ryegrass being the least sensitive species. Relative sensitivity of cover crop species to topramezone/atrazine and tolpyralate/atrazine were lower than other atrazine/HPPD programs, with brassica and large-seeded legume species ranking the least sensitive. These results demonstrate meaningful variation in cover crop species sensitivity to corn herbicides among taxonomic groups and seed mass within taxonomic groups. Relative rankings of sensitivity to atrazine or atrazine/HPPD herbicides generated from dose response models can be used to design cover crop mixtures with similar levels of tolerance, or identify species with greater risk of injury, to commonly used corn herbicides. Two complementary field experiments were conducted from 2021-2022 at three locations (Rock Springs, PA; Landisville, PA; Aurora, NY) to study the effect of PRE and POST herbicides that ranged in expected soil residual activity on interseeded cover crop mixtures that ranged in taxonomic group and seed mass. Herbicide treatment effects on cover crop and weed abundance were evaluated during the cover crop establishment phase and prior to corn harvest to measure persistence and composition of cover crop mixtures. In the PRE experiment, biomass of the small-seeded mixture composed of annual ryegrass, medium red clover and rapeseed during the establishment phase was lower and composition was more variable in the long-lived residual herbicide treatment compared to the large-seeded mixture. In comparison, herbicide treatments did not affect the large-seeded cover crop mixture composed of cereal rye, cowpea and daikon radish in the establishment phase. By corn dry down, the small-seeded mixture biomass production was negatively impacted where short-lived PRE herbicides failed to control weeds, while the large-seeded mixture produced greater biomass, but cereal rye failed to persist at five out of six site-years. Greenhouse bioassays and complementary field-based studies demonstrate that cover crop sensitivity to frequently used soil-applied herbicides (atrazine/HPPD) in corn systems differ among taxonomic group and, in some cases, seed mass within taxonomic groups. In general, small-seeded legumes are at greater risk for injury than large-seeded legumes to these herbicides. Field experiments also demonstrate that species selection for interseeding systems requires consideration of both herbicide tolerance and environmental stress tolerance to optimize conservation benefits.

Download or read book Manipulation of Allelopathic Crops for Weed Control written by Khawar Jabran and published by Springer. This book was released on 2017-02-22 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book clearly defines ways to maximize the allelopathic potential of important field crops for controlling weeds, either in the same crop or others. Compared to the use of herbicides, allelopathy is an attractive option to control weeds naturally under field conditions. The book highlights the allelopathic potential of several important cereals (wheat, maize, rice, barley, sorghum, rye) and two oilseed crops [sunflower and canola (as well as some other member of Brassicaceae family)]. Further, the book explains how the allelopathic potential of these crops can be manipulated under field conditions to suppress weeds. This is possible by growing allelopathic crop cultivars, using mulches from allelopathic crops, intercropping an allelopathic crop with a non-allelopathic crop, including allelopathic crops in crop rotation, or using allelopathic crops as cover crops. Equipped with several basic concepts of allelopathy, this book will be highly useful for the farming community as well as students and researchers.

Download or read book Integrating Cover Crops and Herbicides for Horseweed and Palmer Amaranth Management in No till Soybean written by Chelsea Marie McCall and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Palmer amaranth and horseweed are problematic weeds in no-till soybeans in Kansas. Integrating cover crops and herbicide programs could suppress weed populations. To determine the emergence pattern and survival of horseweed, a study was conducted across six locations in eastern KS in 2014-2015 and 2015-2016. Horseweed seedlings and leaf number per seedling were recorded at two-week intervals. Cumulative GDDs required to reach 50% horseweed emergence increased from north to south. Horseweed survival ranged from 4 to 90%, and majority of horseweed emerged in the fall. Field studies were conducted to determine effects of cover crops and herbicide programs on Palmer amaranth near Manhattan, KS in 2014-2015 and 2015-2016. Five cover crop treatments included no cover, fall-sown winter wheat, spring-sown oat, pea, and mixture of oat and pea. Cover crops were terminated in May with glyphosate and 2,4-D alone or with residual herbicides of flumioxazin and pyroxasulfone. By 10 weeks after termination in 2014-2015, Palmer amaranth biomass and density, averaged across cover crops. was 95 and 69% less with residual herbicides than without, respectively, and Palmer amaranth biomass was 98% less in winter wheat and 91% less in spring oat, averaged across termination methods, compared to no cover. Time to 50% Palmer amaranth emergence was delayed with winter wheat, spring oat, and spring oat/pea mix without residual herbicide. Soybean yields were greater with residual herbicide and greater with winter wheat or spring oat cover crop in 2014-2015. A field study was conducted to determine suppression effects of cover crop and herbicide programs on horseweed and Palmer amaranth near Manhattan, KS in 2015-2016. Three fall treatments included fall-sown rye, a residual herbicide tank mix of glyphosate, dicamba, chlorimuron-ethyl, tribenuron-methyl, and AMS, and no fall application. Four spring treatments included no spring application or three herbicide tank mixes: glyphosate, dicamba, and AMS alone or with flumioxazin and pyroxasulfone as early preplant, or as split applied with 2/3 preplant and 1/3 at soybean planting. Similar levels of horseweed suppression were observed when some control measure was used in fall or spring. Fall rye completely suppressed horseweed while the fall herbicide suppressed biomass by 93% and density by 86% compared to no fall application. Palmer amaranth suppression was observed when a spring herbicide application was used. In rye, total weed biomass was reduced by 97% or more across all spring treatments. Total weed biomass was reduced with a spring herbicide was used. Soybean yields were least when no herbicide treatment was used in the spring. An integrated program of fall cover crops or herbicide applications together with spring herbicide applications maintained soybean yields.

Download or read book Evaluating Cover Crops and Herbicides for Horseweed and Palmer Amaranth Management written by Larry Joe Rains (III) and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Horseweed and Palmer amaranth are common weeds in Kansas that compete against many row crops. Horseweed can emerge in different seasons depending on the year. Palmer amaranth emerges from spring throughout the summer months and has a rapid growth rate with higher temperatures. Three separate studies were conducted near Manhattan, KS from 2016 to 2018 to determine (1) horseweed control in no-till soybean with cover crops and herbicide programs with and without residual activity (2) emergence timing in KS of eight horseweed populations collected from MO, IL, KS, and KY, and (3) Palmer amaranth control in response to three Protoporphyrinogen Oxidase (PPO) inhibitors applied every three days once Palmer amaranth plants reached 2.5 cm tall. Cereal rye reduced weeds biomass by 78% and weed density by 75% by 8 weeks after cover crop seeding in the fall. At cover crop termination two weeks prior to soybean drilling. Cereal rye reduced horseweed biomass more than herbicide treatments, but after termination weed control was similar across treatments. Soybean yields were greater with herbicide treatments in year one, but there were no differences in soybean yields among cover crop and herbicide treatments in the second year. Emergence of all eight horseweed populations occurred at the same time. Most horseweed emergence occurred in the spring in the first year, while all horseweed populations emerged in the fall in the second year. Environmental conditions were driving factors for horseweed emergence, but horseweed seed source did not influence emergence timing. All PPO-inhibitor herbicides controlled Palmer amaranth at similar levels within an application timing. PPO-inhibitor herbicides need to be applied within three days after Palmer amaranth plants reach 2.5 cm tall to achieve greater than 90% control.