Modeling the Impact of Harvest Weed Seed Control on Herbicide-Resistance Evolution

AbstractHarvest weed seed control (HWSC) techniques have been implemented in Australian cropping systems to target and reduce the number of weed seeds entering the seedbank and thereby reduce the number of problematic weeds emerging in subsequent years to infest subsequent crops. However, the influence of HWSC on ameliorating herbicide-resistance (HR) evolution has not been investigated. This research used integrated spatial modeling to examine how the frequency and efficacy of HWSC affected the evolution of resistance to initially effective herbicides. Herbicides were, in all cases, better protected from future resistance evolution when their use was combined with annual HWSC. Outbreaks of multiple HR were very unlikely to occur and were nearly always eliminated by adding annual, efficient HWSC. The efficacy of the HWSC was important, with greater reductions in the number of resistance genes achieved with higher-efficacy HWSC. Annual HWSC was necessary to protect sequences of lower-efficacy herbicides, but HWSC could still protect herbicides if it was used less often than once per year, when the HWSC and the herbicides were highly effective. Our results highlight the potential benefits of combining HWSC with effective herbicides for controlling weed populations and reducing the future evolution of HR.

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The nature and consequence of weed spread in cropping systems

Weed Science ◽

10.1017/s004317450009295x ◽

1997 ◽

Vol 45 (3) ◽

pp. 337-342 ◽

Cited By ~ 42

Author(s):

Donald C. Thill ◽

Carol A. Mallory-Smith

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Short Distance ◽

Crop Production ◽

Cropping Systems ◽

Weed Seed ◽

Management Options ◽

Crop Species ◽

Weed Seeds ◽

Pollen Movement

Weeds spread through movement of seeds and vegetative reproductive propagules. Pollen movement can spread weedy traits, such as herbicide resistance, between related weed and crop species. Weed seeds can spread short or long distances by natural plant dehiscence mechanisms, wind, water, animals, and man&s activities. This symposium paper is a practical review of short-distance spread of weed seeds in and between nearby arable fields and noncrop lands, examining some of the causes of spread and subsequent effects on crop production. Pollen movement, as it affects the spread of herbicide resistance, also is considered a component of short-distance weed spread. Specific weed management options can be used to reduce man-caused weed seed spread within and between nearby fields, thus reducing potential crop yield losses. Long-term management will be more difficult for weed seed spread by natural dispersal mechanisms.

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Factors Affecting Weed Seed Devitalization with the Harrington Seed Destructor

Weed Science ◽

10.1017/wsc.2017.23 ◽

2017 ◽

Vol 65 (5) ◽

pp. 650-658 ◽

Cited By ~ 8

Author(s):

Breanne D. Tidemann ◽

Linda M. Hall ◽

K. Neil Harker ◽

Hugh J. Beckie

Keyword(s):

Seed Size ◽

Cropping Systems ◽

Weed Seed ◽

Weed Species ◽

Factors Affecting ◽

Weed Seeds ◽

High Control ◽

Relationship Of ◽

The Impact ◽

Levels Of Control

The Harrington Seed Destructor (HSD), a novel weed control technology, has been highly effective in Australian cropping systems. To investigate its applicability to conditions in western Canada, stationary threshing was conducted to determine the impact of weed species, seed size, seed number, chaff load, and chaff type on efficacy of seed destruction. Control varied depending on species, with a range of 97.7% to 99.8%. Sieve-sized volunteer canola seed had a linear relationship of increasing control with increasing 1,000-seed weight. However, with greater than 98% control across all tested seed weights, it is unlikely that seed size alone will significantly influence control. Consistently high levels of control were observed at all tested seed densities (10 seeds to 1 million seeds). The response of weed seed control to chaff load was quadratic, but a narrow range of consistently high control (>97%) was again observed. Chaff type had a significant effect on weed seed control (98% to 98.6%); however, seed control values in canola chaff were likely confounded by a background presence of volunteer canola. Overall, the five parameters studied statistically influence control of weed seeds with the HSD. However, small differences between treatments are unlikely to affect the biological impact of the machine, which provides high levels of control for those weed seeds that can be introduced into the harvester.

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Fate of Weed Seeds after Impact Mill Processing in Midwestern and Mid-Atlantic United States

Weed Science ◽

10.1017/wsc.2019.66 ◽

2019 ◽

pp. 1-23 ◽

Cited By ~ 1

Author(s):

Lovreet S. Shergill ◽

Kreshnik Bejleri ◽

Adam Davis ◽

Steven B. Mirsky

Keyword(s):

Seed Size ◽

Weed Management ◽

Production Systems ◽

Cropping Systems ◽

Weed Seed ◽

Seed Mortality ◽

Weed Seeds ◽

Highly Effective ◽

Original Size ◽

The Impact

Abstract Harvest weed seed control (HWSC) technology such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans and weeds common to soybean production systems in the Midwest and Mid-Atlantic US. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015-2016 and 2017-2018 to determine (i) the efficacy of the impact mill to target weed seeds of seven common weeds in Midwestern and five in Mid-Atlantic US, and (ii) the fate of impact mill processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5-99.8% weed seed destruction in 2015 and 85.6-100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill, and high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d over winter to determine the fate of weed seeds after winter burial. At 90 d after burial (DAB), the impact mill processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality over winter. A very small fraction (< 0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as a HWSC tactic for weed management in this region.

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Dissemination of Weed Seeds by Surface Irrigation Water in Western Nebraska

Weed Science ◽

10.1017/s0043174500027831 ◽

1980 ◽

Vol 28 (1) ◽

pp. 87-92 ◽

Cited By ~ 14

Author(s):

R. G. Wilson

Keyword(s):

Irrigation Water ◽

Water Surface ◽

Growing Season ◽

Surface Irrigation ◽

Weed Seed ◽

Platte River ◽

The North ◽

Seed Content ◽

Weed Seeds ◽

The Impact

Studies were conducted in 1977 and 1978 to evaluate the impact of surface irrigation water on the dissemination of weed seed in the North Platte River Project from May through September each year. Seventy-seven different plant species were found in irrigation water, with germination averaging 26%. Two to five times more weed seed were found in two irrigation canals than in the North Platte River. As water moved through the canals, the weed seed content of the water increased dramatically. The majority of seed collected was found floating on the water surface. Amounts of seed collected varied with time with the largest amounts being collected in June and July and gradually declining in August and September. Samples also were taken to determine the amount of seed entering the field with irrigation water during the growing season. During the 1978 growing season irrigation water disseminated 48,400 seed per ha in the sampled fields.

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Weed Seed Decline in Irrigated Soil after Rotation of Crops and Herbicides

Weed Science ◽

10.1017/s0043174500058550 ◽

1984 ◽

Vol 32 (1) ◽

pp. 84-89 ◽

Cited By ~ 39

Author(s):

Edward E. Schweizer ◽

Robert L. Zimdahl

Keyword(s):

Weed Management ◽

Conventional Tillage ◽

Barley Grain ◽

Amaranthus Retroflexus ◽

Management Systems ◽

Weed Seed ◽

Weed Seeds ◽

Seed Reserves ◽

The Impact ◽

Intensive System

The impact of two weed management systems on the weed seed reserves of the soil, on the yearly weed problem, and on barley (Hordeum vulgareL. ‘Steptoe’), corn (Zea maysL. ‘Pioneer 3709′), and sugarbeet (Beta vulgarisL. ‘Mono Hy D2′) production was assessed where these crops were grown in rotation for 6 consecutive years. Weeds were controlled in each crop with a moderate (system I) or intensive (system II) level of herbicides, plus conventional tillage. Weed seeds from seven annual genera were identified, with redroot pigweed(Amaranthus retroflexusL. ♯3AMARE) andChenopodiumcomprising 56 and 30%, respectively, of the initial 1377 million weed seeds/ha that were present in the upper 25 cm of the soil profile. After the sixth cropping year, the overall decline in the total number of weed seeds in soil was 96% in system I and 97% in system II. Over the 6-yr period, about 1.3 times more weeds escaped control in system I than in system II; and within a crop, the fewest number of weeds escaped annually in sugarbeets, and the most in barley. Yields of barley grain, corn silage, and recoverable sucrose were similar each year in the two weed management systems.

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Selecting for Weed Resistance: Herbicide Rotation and Mixture

Weed Technology ◽

10.1614/wt-09-008.1 ◽

2009 ◽

Vol 23 (3) ◽

pp. 363-370 ◽

Cited By ~ 107

Author(s):

Hugh J. Beckie ◽

Xavier Reboud

Keyword(s):

Herbicide Resistance ◽

Seed Bank ◽

Rotation Frequency ◽

Acetolactate Synthase ◽

Resistance Evolution ◽

Mixture Treatment ◽

Field Pennycress ◽

Inhibitor Resistance ◽

Als Inhibitor ◽

The Impact

Herbicide rotations and mixtures are widely recommended to manage herbicide resistance. However, little research has quantified how these practices actually affect the selection of herbicide resistance in weeds. A 4-yr experiment was conducted in western Canada from 2004 to 2007 to examine the impact of herbicide rotation and mixture in selecting for acetolactate synthase (ALS) inhibitor resistance in the annual broadleaf weed, field pennycress, co-occurring in wheat. Treatments consisted of the ALS-inhibitor herbicide, ethametsulfuron, applied in a mixture with bromoxynil/MCPA formulated herbicide (photosystem-II inhibitor/synthetic auxin), or in rotation with the non-ALS inhibitor at an ALS-inhibitor application frequency of 0, 25, 50, 75, and 100% (i.e., zero to four applications, respectively) over the 4-yr period. The field pennycress seed bank at the start of the experiment contained 5% ethametsulfuron-resistant seed. Although weed control was only marginally reduced, resistance frequency of progeny of survivors increased markedly after one ALS-inhibitor application. At the end of the experiment, the level of resistance in the seed bank was buffered by susceptible seed, increasing from 29% of recruited seedlings after one application to 85% after four applications of the ALS inhibitor. The level of resistance in the seed bank for the mixture treatment after 4 yr remained similar to that of the nontreated (weedy) control or 0% ALS-inhibitor rotation frequency treatment. The results of this study demonstrate how rapidly ALS-inhibitor resistance can evolve as a consequence of repeated application of herbicides with this site of action, and supports epidemiological information from farmer questionnaire surveys and modeling simulations that mixtures are more effective than rotations in mitigating resistance evolution through herbicide selection.

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Rapid Evolution of Herbicide Resistance by Low Herbicide Dosages

Weed Science ◽

10.1614/ws-d-10-00111.1 ◽

2011 ◽

Vol 59 (2) ◽

pp. 210-217 ◽

Cited By ~ 99

Author(s):

Sudheesh Manalil ◽

Roberto Busi ◽

Michael Renton ◽

Stephen B. Powles

Keyword(s):

Herbicide Resistance ◽

Rapid Evolution ◽

Wheat Crop ◽

Potted Plants ◽

Resistance Evolution ◽

Crop Field ◽

Response Profiles ◽

Rigid Ryegrass ◽

The Impact ◽

Resistance Traits

Herbicide rate cutting is an example of poor use of agrochemicals that can have potential adverse implications due to rapid herbicide resistance evolution. Recent laboratory-level studies have revealed that herbicides at lower-than-recommended rates can result in rapid herbicide resistance evolution in rigid ryegrass populations. However, crop-field-level studies have until now been lacking. In this study, we examined the impact of low rates of diclofop on the evolution of herbicide resistance in a herbicide-susceptible rigid ryegrass population grown either in a field wheat crop or in potted plants maintained in the field. Subsequent dose–response profiles indicated rapid evolution of diclofop resistance in the selected rigid ryegrass lines from both the crop-field and field pot studies. In addition, there was moderate level of resistance in the selected lines against other tested herbicides to which the population has never been exposed. This resistance evolution was possible because low rates of diclofop allowed substantial rigid ryegrass survivors due to the potential in this cross-pollinated species to accumulate all minor herbicide resistance traits present in the population. The practical lesson from this research is that herbicides should be used at the recommended rates that ensure high weed mortality to minimize the likelihood of minor herbicide resistance traits leading to rapid herbicide resistance evolution.

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Weed Seed Decline in Irrigated Soil after Six Years of Continuous Corn(Zea mays)and Herbicides

Weed Science ◽

10.1017/s0043174500058549 ◽

1984 ◽

Vol 32 (1) ◽

pp. 76-83 ◽

Cited By ~ 89

Author(s):

Edward E. Schweizer ◽

Robert L. Zimdahl

Keyword(s):

Zea Mays ◽

Weed Management ◽

Chenopodium Album ◽

Amaranthus Retroflexus ◽

Management Systems ◽

Weed Seed ◽

Common Lambsquarters ◽

Redroot Pigweed ◽

Weed Seeds ◽

The Impact

The impact of two weed management systems on the weed seed reserves of the soil, on the yearly weed problem, and on corn (Zea maysL.) production was assessed where corn was grown under furrow irrigation for 6 consecutive years. In one system, 2.2 kg/ha of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] was applied annually to the same plots as a preemergence treatment. In the other system, a mixture of 1.7 kg/ha of atrazine plus 2.2 kg/ha of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] was applied preemergence, followed by a postemergence application of 0.6 kg/ha of the alkanolamine salts of 2,4-D [(2,4-dichlorophenoxy)acetic acid]. The response of weeds and corn is presented only where atrazine was applied annually because the results were similar between both weed management systems. Weed seeds from eight annual species were identified, with redroot pigweed (Amaranthus retroflexusL. ♯ AMARE) and common lambsquarters (Chenopodium album♯ CHEAL) comprising 82 and 12%, respectively, of the initial 1.3 billion weed seeds/ha that were present in the upper 25 cm of the soil profile. After the sixth cropping year, the overall decline in the total number of redroot pigweed and common lambsquarters seeds was 99 and 94%, respectively. Very few weeds produced seeds during the first 5 yr, and no weed seeds were produced during the sixth year where atrazine was applied annually. When the use of atrazine was discontinued on one-half of each plot at the beginning of the fourth year, the weed seed reserve in soil began to increase due to an increase in the weed population. After 3 yr of not using atrazine, the weed seed reserve in soil had built up to over 648 million seeds/ha, and was then within 50% of the initial weed seed population. In the fifth and sixth years, grain yields were reduced 39 and 14%, respectively, where atrazine had been discontinued after 3 yr.

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Seed destruction of weeds in southern US crops using heat and narrow-windrow burning

Weed Technology ◽

10.1017/wet.2020.36 ◽

2020 ◽

Vol 34 (4) ◽

pp. 589-596

Author(s):

Jason K. Norsworthy ◽

Jeremy K. Green ◽

Tom Barber ◽

Trent L. Roberts ◽

Michael J. Walsh

Keyword(s):

Wind Speed ◽

Field Experiments ◽

Cropping Systems ◽

Palmer Amaranth ◽

Italian Ryegrass ◽

Weed Seed ◽

Weed Species ◽

Harvest Residues ◽

Southern Us ◽

Weed Seeds

AbstractNarrow-windrow burning has been a successful form of harvest weed seed control in Australian cropping systems, but little is known about the efficacy of narrow-windrow burning on weed seeds infesting U.S. cropping systems. An experiment was conducted using a high-fire kiln that exposed various grass and broadleaf weed seeds to temperatures of 200, 300, 400, 500, and 600 C for 20, 40, 60, and 80 s to determine the temperature and time needed to kill weed seeds. Weeds evaluated included Italian ryegrass, barnyardgrass, johnsongrass, sicklepod, Palmer amaranth, prickly sida, velvetleaf, pitted morningglory, and hemp sesbania. Two field experiments were also conducted over consecutive growing seasons, with the first experiment aimed at determining the amount of heat produced during burning of narrow windrows of soybean harvest residues (chaff and straw) and the effect of this heat on weed seed mortality. The second field experiment aimed to determine the effect of wind speed on the duration and intensity of burning narrow windrows of soybean harvest residues. Following exposure to the highest temperature and longest duration in the kiln, only sicklepod showed any survival (<1% average); however, in most cases, the seeds were completely destroyed (ash). A heat index of only 22,600 was needed to kill all seeds of Palmer amaranth, barnyardgrass, and Italian ryegrass. In the field, all seeds of the evaluated weed species were completely destroyed by narrow-windrow burning of 1.08 to 1.95 kg m−2 of soybean residues. The burn duration of the soybean harvest residues declined as wind speed increased. Findings from the kiln and field experiments show that complete kill is likely for weed seeds concentrated into narrow windrows of burned soybean residues. Given the low cost of implementation of narrow-windrow burning and the seed kill efficacy on various weed species, this strategy may be an attractive option for destroying weed seed.

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Quantifying the impact of a periodic presence of antimicrobial on resistance evolution in a homogeneous microbial population of fixed size

10.1101/279091 ◽

2018 ◽

Author(s):

Loïc Marrec ◽

Anne-Florence Bitbol

Keyword(s):

Antimicrobial Resistance ◽

Microbial Population ◽

Fitness Landscape ◽

Resistant Bacteria ◽

Fixed Size ◽

Variable Environment ◽

Resistance Evolution ◽

Evolution Of Resistance ◽

The Impact ◽

Analytical Approaches

AbstractThe evolution of antimicrobial resistance often occurs in a variable environment, as antimicrobial is given periodically to a patient or added and removed from a medium. This environmental variability has a huge impact on the microorganisms’ fitness landscape, and thus on the evolution of resistance. Indeed, mutations conferring resistance often carry a fitness cost in the absence of antimicrobial, which may be compensated by subsequent mutations. As antimicrobial is added or removed, the relevant fitness landscape thus switches from a fitness valley to an ascending landscape or vice-versa.Here, we investigate the effect of these time-varying patterns of selection within a stochastic model. We focus on a homogeneous microbial population of fixed size subjected to a periodic alternation of phases of absence and presence of an antimicrobial that stops growth. Combining analytical approaches and stochastic simulations, we quantify how the time necessary for fit resistant bacteria to take over the microbial population depends on the period of the alternations. We demonstrate that fast alternations strongly accelerate the evolution of resistance, and that a plateau is reached once the period gets sufficiently small. Besides, the acceleration of resistance evolution is stronger for larger populations. For asymmetric alternations, featuring a different duration of the phases with and without antimicrobial, we shed light on the existence of a broad minimum of the time taken by the population to fully evolve resistance. At this minimum, if the alternations are sufficiently fast, the very first resistant mutant that appears ultimately leads to full resistance evolution within the population. This dramatic acceleration of the evolution of antimicrobial resistance likely occurs in realistic situations, and can have an important impact both in clinical and experimental situations.

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