The U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed–crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America’s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency’s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being.

This paper presents new benefit–cost estimates for the Tulsa universal pre-K program. These calculations are based on estimated effects, from two recent papers, of Tulsa pre-K on high-school graduation rates and college attendance rates of students who were in kindergarten in the fall of 2006. In the current paper, educational effects from these prior papers are used to infer lifetime earnings effects. Our conservative estimates suggest that per pre-K participant, the present value of earnings effects in 2021 dollars is $25,533, compared with program costs of $9,628, for a benefit–cost ratio of 2.65. Compared to prior benefit–cost studies of Tulsa pre-K, this benefit–cost ratio is below what was predicted from Tulsa pre-K’s effects on kindergarten test scores, but above what was predicted from Tulsa pre-K’s effects on grade retention by ninth grade. This fading and recovery of predicted pre-K effects as children go through K-12 and then enter adulthood is consistent with prior research. It suggests that pre-K may have important effects on “soft skills,” such as persisting in school, and reminds us that short-term studies of pre-K provide useful information for public policy.

We present the first Southern-Hemisphere all-sky imager and radio-transient monitoring system implemented on two prototype stations of the low-frequency component of the Square Kilometre Array (SKA-Low). Since its deployment, the system has been used for real-time monitoring of the recorded commissioning data. Additionally, a transient searching algorithm has been executed on the resulting all-sky images. It uses a difference imaging technique to enable identification of a wide variety of transient classes, ranging from human-made radio-frequency interference to genuine astrophysical events. Observations at the frequency 159.375 MHz and higher in a single coarse channel ( $\approx$ 0.926 MHz) were made with 2 s time resolution, and multiple nights were analysed generating thousands of images. Despite having modest sensitivity ( $\sim$ few Jy beam–1), using a single coarse channel and 2-s imaging, the system was able to detect multiple bright transients from PSR B0950+08, proving that it can be used to detect bright transients of an astrophysical origin. The unusual, extreme activity of the pulsar PSR B0950+08 (maximum flux density $\sim$ 155 Jy beam–1) was initially detected in a ‘blind’ search in the 2020 April 10/11 data and later assigned to this specific pulsar. The limitations of our data, however, prevent us from making firm conclusions of the effect being due to a combination of refractive and diffractive scintillation or intrinsic emission mechanisms. The system can routinely collect data over many days without interruptions; the large amount of recorded data at 159.375 and 229.6875 MHz allowed us to determine a preliminary transient surface density upper limit of $1.32 \times 10^{-9} \text{deg}^{-2}$ for a timescale and limiting flux density of 2 s and 42 Jy, respectively. In the future, we plan to extend the observing bandwidth to tens of MHz and improve time resolution to tens of milliseconds in order to increase the sensitivity and enable detections of fast radio bursts below 300 MHz.

Annual grass weeds reduce profits of wheat farmers in the Pacific Northwest. The very-long-chain fatty acid elongase (VLCFA)-inhibiting herbicides S-metolachlor and dimethenamid-P could expand options for control of annual grasses but are not registered in wheat, because of crop injury. We evaluated a safener, fluxofenim, applied to wheat seed for protection of 19 soft white winter wheat varieties from S-metolachlor, dimethenamid-P, and pyroxasulfone herbicides; investigated the response of six varieties (UI Sparrow, LWW 15-72223, UI Magic CL+, Brundage 96, UI Castle CL+, and UI Palouse CL+) to incremental doses of fluxofenim; established the fluxofenim dose required to optimally protect the varieties from VLCFA-inhibiting herbicides; and assessed the impact of fluxofenim dose on glutathione S-transferase (GST) activity in three wheat varieties (UI Sparrow, Brundage 96, and UI Castle CL+). Fluxofenim increased the biomass of four varieties treated with S-metolachlor or dimethenamid-P herbicides and one variety treated with pyroxasulfone. Three varieties showed tolerance to the herbicides regardless of the fluxofenim treatment. Estimated fluxofenim doses resulting in 10% biomass reduction of wheat ranged from 0.55 to 1.23 g ai kg−1 seed. Fluxofenim doses resulting in 90% increased biomass after treatment with S-metolachlor, dimethenamid-P, and pyroxasulfone ranged from 0.07 to 0.55, 0.09 to 0.73, and 0.30 to 1.03 g ai kg−1 seed, respectively. Fluxofenim at 0.36 g ai kg−1 seed increased GST activity in UI Castle CL+, UI Sparrow, and Brundage 96 by 58%, 30%, and 38%, respectively. These results suggest fluxofenim would not damage wheat seedlings up to three times the rate labeled for sorghum, and fluxofenim protects soft white winter wheat varieties from S-metolachlor, dimethenamid-P, or pyroxasulfone injury at the herbicide rates evaluated.

Antarctica's ice shelves modulate the grounded ice flow, and weakening of ice shelves due to climate forcing will decrease their ‘buttressing’ effect, causing a response in the grounded ice. While the processes governing ice-shelf weakening are complex, uncertainties in the response of the grounded ice sheet are also difficult to assess. The Antarctic BUttressing Model Intercomparison Project (ABUMIP) compares ice-sheet model responses to decrease in buttressing by investigating the ‘end-member’ scenario of total and sustained loss of ice shelves. Although unrealistic, this scenario enables gauging the sensitivity of an ensemble of 15 ice-sheet models to a total loss of buttressing, hence exhibiting the full potential of marine ice-sheet instability. All models predict that this scenario leads to multi-metre (1–12 m) sea-level rise over 500 years from present day. West Antarctic ice sheet collapse alone leads to a 1.91–5.08 m sea-level rise due to the marine ice-sheet instability. Mass loss rates are a strong function of the sliding/friction law, with plastic laws cause a further destabilization of the Aurora and Wilkes Subglacial Basins, East Antarctica. Improvements to marine ice-sheet models have greatly reduced variability between modelled ice-sheet responses to extreme ice-shelf loss, e.g. compared to the SeaRISE assessments.

A 3-yr watermelon experiment was established in fall 2013 to evaluate cover crop, polyethylene mulch, tillage, and herbicide application components for weed control, yield, and profitability. Conservation tillage, either with a cereal rye cover crop alone or integrated with polyethylene mulch, was compared to the standard industry practice of conventional tillage with bedded polyethylene mulch. The study also used a non-bedded conventional tillage system without polyethylene to determine polyethylene and cover crop residue effects. Within each of the four systems, herbicide treatments comprised halosulfuron applied (1) at 26.3 g ai ha–1 PRE, (2) at 26.3 g ai ha–1 POST, or (3) sequentially at 26.3 g ai ha–1 PRE and POST. Each system also had a nontreated control. In addition, clethodim was applied in all plots twice POST at 140 g ai ha–1, except for nontreated in each system. In 2014, polyethylene or cereal rye cover crop effectively controlled tall morningglory, coffee senna, and carpetweed early season in nontreated plots, whereas the integration of the two was effective at controlling common purslane. Tall morningglory and purslane control was insufficient late season regardless of production system and herbicide application. In 2015, polyethylene effectively controlled cutleaf eveningprimrose, sicklepod, and arrowleaf sida early season in nontreated plots. Yellow nutsedge control was insufficient late season regardless of production system and herbicide application. Utilizing sequential halosulfuron applications did not increase weed control over PRE or POST alone in all years. Polyethylene use resulted in yields higher than systems without in all years. Across all 3 yr, net returns were highest for polyethylene mulch systems. The results of this experiment underscore the need for more progress in developing integrated conservation systems for watermelon production. Effective herbicides, low-disturbance cultivation, and/or hand weeding are most likely the key to success in conservation specialty crop systems.

Isotopic investigations of human burials from excavations of the Autonomous University of Campeche (CIHS) at the prehispanic Maya capital of Calakmul in southeastern Mexico, near the border with Guatemala, include determination of radiocarbon dates; carbon and nitrogen isotope ratios in collagen; and strontium, carbon, and oxygen isotope ratios in tooth enamel. A total of 22 human and 5 faunal samples analyzed for strontium isotopes reveal a narrow range of variation in values, pointing to the likely local origin of over two-thirds of the central population of Calakmul, including two of its rulers. Carbon and nitrogen data confirm a typical Classic Maya diet at the site and identify a diet high in meat consumption for one dynastic individual. Interpreted jointly, the isotopic information offers new perspectives on the provenience and lifestyles of the residents of Calakmul, including a potential place of origin for the royal occupant of chamber tomb Burial VII-1.

Early life stress (ELS) is a significant risk factor for the emergence of internalizing problems in adolescence. Beginning in adolescence, females are twice as likely as males to experience internalizing disorders. The present study was designed to examine sex differences in the association between ELS and internalizing problems in early pubertal adolescents, and whether and how corticolimbic function and connectivity may underlie these associations. Fifty-nine early pubertal males and 78 early pubertal females, ages 9–13 years (all Tanner Stage 3 or below) underwent functional magnetic resonance imaging as they performed an emotion label task that robustly interrogates corticolimbic function. Participants were also interviewed about their experience of ELS. Females exhibited a positive association between ELS and internalizing problems, whereas males exhibited no such association. Whole-brain and amygdala region of interest analyses indicated that whereas females exhibited a positive association between ELS and the ventrolateral prefrontal cortex during implicit emotion regulation, males showed no such association. Activation in these regions was positively associated with internalizing problems in females but not males; however, activation in these regions did not mediate the association between ELS and internalizing problems. Finally, both boys and girls exhibited an association between ELS and increased negative connectivity between the right ventrolateral prefrontal cortex and bilateral amygdala. Using a carefully characterized sample of early pubertal adolescents, the current study highlights important sex differences in the development of corticolimbic circuitry during a critical period of brain development. These sex differences may play a significant role in subsequent risk for internalizing problems.

The efficacy of current wild oat herbicides and their high cost have resulted in use rates that are less than those recommended. While acceptable weed control may be attained at less cost, this practice does not consider the potential for increased wild oat seed production. The objective of this experiment was to determine the interaction of wild oat density and reduced imazamethabenz rates on wild oat seed production in spring barley. As wild oat densities increased from 8 to 1,100 plants m−2, wild oat seed production increased from 180 to 9,950 seed m−2 without herbicide, and from 0 to 2,810 seed m−2 using 0.53 kg ai ha−1 imazamethabenz. This general pattern was modeled using a cumulative logistic function. Estimates from this model indicated that < 1 wild oat seed m−2 was produced at population densities of ≤ 20 plants at any imazamethabenz rate. Imazamethabenz rates of 0.26 kg ha−1 or greater at wild oat densities of less than approximately 190 plants m−2 did not result in wild oat seed production above the initial population density. As wild oat density increased, however, imazamethabenz rates below 0.40 kg ha−1 resulted in substantially greater wild oat seed production compared to the recommended rate.

Spring barley often is grown in rotation with winter wheat, and sometimes barley can overwinter in the subsequent winter wheat crop reducing grain yield and quality. Studies were established during 1996 and 1997 in winter wheat fields in southeastern Washington and near Moscow, ID, respectively, to evaluate control of ‘Steptoe’ volunteer barley with MON 37500, diclofop, and fenoxaprop/2,4-D/MCPA. Herbicides were applied to volunteer barley at two growth stages: two leaves to four tillers and more than four tillers with stems beginning to elongate. MON 37500 at 0.018, 0.026, and 0.035 kg ai/ha visibly controlled volunteer barley 83% or more at both application times. Diclofop at 1.12 kg ai/ha did not control volunteer barley, whereas fenoxaprop/2,4-D/MCPA at 0.66 kg ai/ha controlled volunteer barley 64 to 97% in 1996, but only 0 to 23% in 1997. In 1996 and 1997, volunteer barley density was reduced 80 to 99% in MON 37500-treated plots compared to the untreated control plots. Wheat grain grade was #1 for all MON 37500 treatments compared to grade #4 in 1996 and #3 in 1997 in the untreated plots. Grain price was reduced by dockage (barley kernels) for MON 37500-treated wheat $0 to $3.12/metric ton (MT), whereas price was reduced $23 to $26/MT for grain from untreated plots. In greenhouse studies, visible injury and height and biomass reduction varied among the 36 barley varieties treated with MON 37500.

Field experiments were conducted to determine the effect of different rates and application times of MON 37500 on downy brome control in winter wheat and on rotational crop injury. In southeastern Washington, MON 37500 applied postemergence at 36 to 72 g ai/ha in the fall and spring controlled downy brome 90 to 97% and 45 to 71%, respectively. MON 37500 was applied postemergence to winter wheat at 18, 36, and 72 g/ha during fall 1995 and spring 1996 near Moscow, ID; Pendleton, OR; and Endicott, WA, to determine its effect on rotational crops planted during spring 1997. At Pendleton, OR, fall applications of MON 37500 at 18, 36, and 72 g/ha applied to actively growing wheat reduced seed yield of spring barley and pea 13 to 59% and 26 to 29%, respectively, when these crops followed winter wheat in the rotation. At this site, spring applications of 36 and 72 g/ha reduced seed yield of spring barley 17 to 34%; when applied in the fall or spring, MON 37500 reduced canola yield 31 to 73%. MON 37500 at 18 g/ha in the spring reduced pea biomass 32% at Endicott. Aboveground biomass and seed yield of barley, pea, lentil, and mustard at Moscow were not affected by MON 37500 carryover. However, using a grain sorghum bioassay, predicted final concentrations of MON 37500 in soil at all three locations 360 d after treatment (DAT) was similar, ranging from 0.5 to 2 ng ai/g. In growth chamber herbicide dose–response studies, grain sorghum shoot height was reduced more at lower doses (0.025 to 5 ng/g) of MON 37500 in Pendleton soil than in soils from the other field locations. Perhaps the greater rotational crop injury observed at the Pendleton location was partly related to greater soil activity of the herbicide.

Dose–response analysis is widely used in biological sciences and has application to a variety of risk assessment, bioassay, and calibration problems. In weed science, dose–response methodologies have typically relied on least squares estimation under the assumptions of normal, homoscedastic, and independent errors. Advances in computational abilities and available software, however, have given researchers more flexibility and choices for data analysis when these assumptions are not appropriate. This article will explore these techniques and demonstrate their use to provide researchers with an up-to-date set of tools necessary for analysis of dose–response problems. Demonstrations of the techniques are provided using a variety of data examples from weed science.

Information on jointed goatgrass caryopsis development is currently lacking in published literature. It is hoped that through a better understanding of jointed goatgrass caryopsis ontogeny more effective weed-management strategies will be developed. Greenhouse experiments were initiated in fall 2002 and 2003 and completed the following spring seasons. Jointed goatgrass plants were started from spikelets, vernalized for 8 wk at 4 C, and grown in a greenhouse. Treatments were the number of days after anthesis (DAA) that a spike was allowed to remain on the plant before harvesting and ranged from 2 to 34 DAA, in increments of 1 (2002) or 2 (2003) d. Individual spikes were divided at harvest into three sections: top, middle, and bottom, disarticulated from the rachis, placed into a germinator, and germination recorded each day. Goatgrass spikelets germinated as early as 2 DAA, although spikelets harvested <7 DAA had <3% germination for all spike sections and were extremely variable, especially for the middle and bottom sections. Time to germination was similar for all sections of the spike. Maximum average germination of the top section was 72% compared with 86% for the bottom and middle sections. Our data suggest that factors other than developmental rate (i.e., dormancy) may affect germination in sections of the spike. A second year of the experiment was conducted for validation. Model validation suggested that although trends were similar in both years, variation in germination response might be too great for accurate, predictive model construction. The early germination shown in this research demonstrates that control measures must be implemented earlier than previously prescribed to prevent jointed goatgrass reproduction.

Digital imagery from satellites and airborne remote sensing offer an opportunity to accurately detect weed infestations. Image resolution and plant growth stage are critical factors for maximum weed detection with low errors. Data analysis in traditional image assessment has relied on agreement measures, such as Cohen's kappa and asymptotic procedures, that compare what is on the image but not on the ground and what is on the ground but not on the image. Statistical comparisons of multispectral images, however, require some knowledge of the variability of the image classification results to determine significant differences among agreement measures. Bayesian methods were used to develop probability distributions for an agreement measure, conditional kappa, and were then subsequently applied to assess and compare image resolutions and plant growth stages. Results showed that images of a study site known to have yellow starthistle populations could identify the noninfested areas with greater accuracy than infested areas at spatial resolutions of 0.5, 1.0, 2.0, and 4.0 m. The detection accuracy of yellow starthistle in the images taken either prebloom or at flowering with 4.0-m spatial resolution usually was equal to or better than spatial resolutions of 0.5, 1.0, and 2.0 m for the cover classes that were not, moderately (31 to 70%), and highly (71 to 100%) infested. The 0.5-m resolution was better than 4.0-m spatial resolution when detecting the moderate cover class, but both resolutions had high omissional and commissional errors. Contrasting the best detection resolution for finding yellow starthistle colonies across flight times indicated that flying at flowering stage with the 4.0-m spatial resolution provided the best detection of the yellow starthistle cover classes considered. In the cases where different spatial resolutions resulted in equal detection accuracy, the larger spatial resolution was selected because of lower costs of acquiring and processing the data.

The Eurasian perennial mustard, hoary cress, Cardaria draba (Brassicaceae), is an invasive weed in western North America that can displace native plants and other desirable forage species in pastures and rangelands. This study investigated the competitive ability of 11 grasses representing nine species in the genera Festuca and Poa from either North America (NA) or Europe (EU) against hoary cress. Hoary cress was grown alone and with four different grass densities under controlled conditions with ample water and nutrient supply, typical for riparian and disturbed habitats, in which hoary cress infestations are commonly found. Of the five Festuca grasses tested, only Schedonorus phoenix (= F. arundinacea) decreased hoary cress biomass. Four of the six Poa grasses tested decreased hoary cress biomass and were ranked by decreasing competitive effects as follows: P. annua > P. compressa (EU) > P. pratensis (EU) > P. compressa (NA). The most competitive grass species also experienced higher intraspecific competition. Within both grass genera, Eurasian species were more competitive against hoary cress than their North American congeners, which suggests that hoary cress establishment may be facilitated by lower biotic resistance in the invaded range. Regardless of origin, sod-forming Poa species were competitive at low densities, while Festuca species only had significant effects at high densities if at all. Based on our results we recommend the use of Poa species for restoration of riparian and disturbed sites following the control of hoary cress infestations to restrict recolonization.