The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms, ostracodes, macroinvertebrates, plant macrofossils, insects, testate amoebae, geochronological data, and the recently added organic biomarkers, stable isotopes, and specimen-level data. Multiple avenues exist to obtain Neotoma data, including the Explorer map-based interface, an application programming interface, the neotoma R package, and digital object identifiers. As the volume and variety of scientific data grow, community-curated data resources such as Neotoma have become foundational infrastructure for big data science.

The objective of this field research was to compare relative effectiveness and profitability of alternative herbicides applied to the same plots for four consecutive years for controlling and reducing dense Canada thistle infestations in no-till spring wheat. Chlorsulfuron at 30 g ai ha−1 plus nonionic surfactant or clopyralid plus 2,4-D at 70 plus 280 g ae ha−1, respectively, applied annually for 4 yr controlled Canada thistle and was more effective for gradually reducing Canada thistle stands than 2,4-D at 560 g ae ha−1, MCPA plus bromoxynil at 280 plus 280 g ae ha−1, or tribenuron at 20 g ai ha−1. Chlorsulfuron and clopyralid plus 2,4-D also controlled Canada thistle ≥ 90% earlier (by 2 yr) than other treatments. Stochastic dominance analysis, a form of economic analysis, predicted that either chlorsulfuron or clopyralid plus 2,4-D would be preferred by farmers to the untreated check, MCPA plus bromoxynil, or 2,4-D treatments. Chlorsulfuron also would be preferred to clopyralid plus 2,4-D by risk-neutral farmers, whereas clopyralid plus 2,4-D would be preferred to chlorsulfuron by highly risk-averse farmers, those who are most likely to pick only consistently effective herbicides.

The goal of this research was to determine whether crop management practices could substitute for a herbicide for managing mixed populations of green and yellow foxtail in hard red spring wheat. Crop yield and foxtail growth were measured in two years of field research in North Dakota. Spring wheat yields were as great or greater when early seeding date or 2× seeding rate were substituted for POST diclofop3 at 0.75 kg ai ha−1 for managing foxtail in spring wheat. Yield of spring wheat competing with foxtails was greater for the high seeding rate (2× = 270 kg ha−1) than both the normal (1× = 130 kg ha−1) and low (0.5× = 70 kg ha−1) seeding rates for early or middle seeding dates, but not for the late seeding date. For both early and middle seeding dates, wheat yield at the 2×seeding rate without diclofop was equal to or greater than that of the 1× seeding rate with diclofop. Late-seeded wheat did not yield well in competition with dense foxtail stands for any treatment combination. Early and middle seeding dates favored the relative increase of green foxtail over yellow foxtail in wheat, whereas late seeding favored yellow foxtail over green foxtail. Economic analysis demonstrated that early seeding date was the most critical factor in determining the stochastic dominance of treatments without diclofop over treatments with diclofop. Seeding rate was much less important than seeding date in determining the ranking of treatments in stochastic dominance analysis.

Geostatistical methods were used to describe and map nonrandom distribution and variation (standard deviation) of shoot density and root growth across a well-established patch of Canada thistle, a perennial weed. Semivariogram functions and kriging, an interpolation method, were used to prepare isoarithmic contour maps and associated error maps. Maps consisted of interpolated contours of uniform weed density and other measured or calculated regionalized variables between measured X-Y control points, as well as maps of error (standard deviation) associated with contour estimation. Mapped regions of greatest shoot density across a patch not only had the greatest underlying root biomass and, often, greatest density of adventitious root buds, but also had more deeply growing root biomass.

Several sequences of POST herbicides applied each year in fall alone, in spring alone, or both in fall and again in spring controlled Canada thistle stands in spring wheat by severely decreasing root biomass and the numbers of adventitious root buds to a depth of 50 cm over four years. These treatments included dicamba applied at 1.7 or 2.2 kg ae ha–1 for the first two successive falls followed in wheat by either chlorsulfuron at 30 g ai ha–1 plus nonionic surfactant, MCPA plus bromoxynil at 280 plus 280 g ha–1, or 2,4-D amine at 560 g ha–1 applied annually for each of four consecutive years from the start. Chlorsulfuron at 30 g ha–1 applied alone in spring for each of four years also reduced and prevented Canada thistle root growth as effectively as a sequence of fall-applied dicamba followed by spring-applied chlorsulfuron in spring wheat.

Seed survival of jointed goatgrass over 2 yr was related to cyclical seasonal changes in ability to germinate, field emergence, and seasonal precipitation and air temperature. The ability of seed to germinate was studied by incubating spikelets under constant, defined incubation conditions after retrieving samples from the field every 2 weeks over 2 yr. Less than 8% of jointed goatgrass seed that were initially set outdoors survived beyond 2 yr when left undisturbed on the soil surface or buried 5 cm deep. Periods of greatest seed loss coincided with periods of peak emergence in fall (late September and October). The ability of seed to germinate also peaked in fall and preceded the period of greatest field emergence and greatest decreases in seed survival.

High herbicide costs and uncertainty about annual weed control at planting have limited adoption of no-till spring wheat production systems in the northern Great Plains. Chlorsulfuron, metsulfuron, and CGA-131036 at 10 to 20 g ai ha–1 plus nonionic surfactant generally controlled both emerged kochia and wild mustard equally well (>80%) whether or not combined with glyphosate at 250 g ha–1 plus nonionic surfactant. In two of three trials persistent phytotoxic residues of these sulfonylurea herbicides in soil controlled both weeds better in midseason and early summer 1 yr after treatment than did glyphosate, which has only foliar activity. While the absolute net returns of different treatments varied among herbicides, relative net returns were insensitive to changes in either herbicide or wheat price. Herbicide use tended to boost net returns for no-till spring wheat in years with good weather but depressed net returns in a drought year. Chlorsulfuron at 10 and 20 g ha–1 increased net returns in all three trials. Metsulfuron and combinations of either metsulfuron or chlorsulfuron with glyphosate had variable effects on net returns.

Jointed goatgrass (Aegilops cylindrica Host. ♯3 AEGCY) has a quantitative requirement for vernalization in order to flower. In greenhouse and field studies, increasing periods of vernalization progressively reduced the number of days needed for plants to mature following transfer from the cold treatment to favorable growing conditions. Plants that had been vernalized at 3 ± 2 C for 8 weeks as imbibed seed took 120 days to flower following transfer to the greenhouse. Unvernalized controls flowered 197 to 222 days after planting in the greenhouse. Lengthening periods of vernalization from 2 to 8 weeks increased the number of seedheads per plant and dry weight per seedhead. Vernalized plants partitioned more dry matter into seedheads than unvernalized controls. The ratio of seedhead dry weight to vegetative shoot dry weight increased with duration of vernalization, even though vernalization did not alter total shoot dry-matter production. In field studies, plants that were established in the fall flowered sooner and more synchronously after resumption of growth in the spring than those that were planted in the spring and flowered in the summer. Plants seeded after May failed to flower in the same summer.

Jointed goatgrass is a winter annual grass weed which is believed to have been introduced into North America as a contaminant in winter wheat seed. Although jointed goatgrass was first discovered in some states early in the 20th century, changing wheat production practices during the past 25 yr have encouraged its spread and increase. Winter wheat producers in the western United States are concerned about the lack of adequate selective control measures for this weed. Jointed goatgrass and wheat share the D chromosome in common and have similar growth habits. Jointed goatgrass lowers winter wheat yield by competing for growth requirements, reducing harvesting efficiency, and lowering crop quality by contaminating harvested grain. Jointed goatgrass is well adapted to stubble-mulch or reduced tillage crop production, particularly in regions where climate limits cropping options to the winter wheat-fallow rotation or continuous wheat. This review summarizes jointed goatgrass seed germination, dormancy, physiology, yield loss estimates in winter wheat, and both herbicidal and non-chemical methods of managing jointed goatgrass.

In eight of nine trials spanning 5 yr, relative yield of semidwarf hard red spring wheat (yield expressed as a percent of estimated weed-free yield) decreased linearly as Canada thistle shoot density increased when measured in late July to early August in the northern Great Plains. Differences between yield loss assessment (YLA) equations could not be distinguished statistically between no-tillage and chisel-plowed production systems. Multiple linear regression equations of relative wheat yield versus wheat density plus Canada thistle shoot density accounted for more variability in YLA equations than simple linear regression equations of wheat yield versus Canada thistle shoot density alone. Estimated weed-free wheat yield and negative slope (b) for yield loss assessment equations increased as cumulative growing-season (April to August) rainfall increased. Thus, relative wheat yield was decreased more by increasing Canada thistle density (slope b became more negative) in years of greater growing-season rainfall.

Greenhouse, growth chamber, and field studies were conducted to determine effects of temperature on the potential of cogongrass (Imperata cylindrica L. Beauv. # IMPCY) and torpedograss (Panicum repens L. # PANRE) to spread beyond present distribution in the Lower Coastal Plains of Southeastern United States. Johnsongrass [Sorghum halepense (L.) Pers. # SORHA] was included in the study for comparative purposes. Growth of each species was greater with day/night temperature regimes of 30/25 C than with 27/22 or 24/18 C. Apical six-node-long rhizome fragments of all three species were killed by a 24-h exposure to −4.5 C. Johnsongrass produced at least three to five times more dry matter than either cogongrass or torpedograss. Order of interspecific competitiveness under 30/25, 27/22, and 24/18 C day/night temperature regimes was johnsongrass > torpedograss > cogongrass. After 2 yr, johnsongrass and torpedograss competition reduced common bermudagrass [Cyndon dactylon (L.) Pers. # CYNDA] yield by 99 and 37%, respectively, while cogongrass competition did not affect common bermudagrass yield. It is concluded that cogongrass and torpedograss are unlikely to spread into more temperate regions of the United States. However, both species are apt to become even more widespread and troublesome in the Lower Coastal Plains of Southeastern United States.

Primary tillage is an inexpensive method to control foxtail barley, a perennial bunchgrass which is an increasing concern to no-till cereal farmers in the Northern Great Plains. Moldboard plowing or chisel plowing in fall followed by field cultivation-harrowing in spring effectively controlled established foxtail barley on previously untilled sites before planting spring wheat. In contrast, chisel plowing in spring followed by field cultivation-harrowing did not control this weed completely.

Applications of the substituted phthalimide growth regulators AC-94377 [1-(3-chlorophthalimido)cyclohexanecarboximide] and AC-99524 [1-tetrahydrophthalimido-cyclohexanecarboximide] to the soil surface stimulated germination and emergence of dormant wild mustard seed (Sinapsis arvensis L. ♯4 SINAR) shallowly planted in soil in greenhouse experiments. Surface applications of AC-94377 enhanced the germination and emergence of dormant wild mustard seed planted 0.6 cm deep in soil from nine locations as the rates were raised from 0.4 to 3.7 kg ai/ha. Surface application of AC-94377 increased emergence rates and also extended the period of wild mustard emergence. Increasing quantities of wheat (Triticum aestivum L.) straw on the soil surface reduced the effect of surface-applied AC-94377 on shallowly buried dormant wild mustard seed. When dormant wild mustard seed were buried 1.3, 2.5, or 3.8 cm deep, surface applications of AC-94377 also stimulated greater emergence than the dormant controls from these depths, strongly suggesting that the compound moved from the surface to the depth of planting.

The effect of Canada thistle on major yield components of spring wheat was characterized using path coefficient analysis, which provides insight concerning which yield components are most sensitive to Canada thistle competition. Increasing Canada thistle density decreased wheat stand in each of three years. Canada thistle also reduced spikes per plant and seed per spike to varying extents depending on year, but Canada thistle had comparatively little effect on wheat seed weight per 1000 seed. In the path coefficient model proposed, Canada thistle was assumed to reduce yield by directly reducing wheat yield components and through them, indirectly reducing yield. Path coefficient correlation analysis showed that Canada thistle reduced spring wheat yield chiefly by indirect effects of decreasing wheat density, the earliest formed yield component. Canada thistle reduced wheat density which, in turn, reduced wheat yield. These data suggest that Canada thistle must be controlled either before or shortly after wheat emergence if detrimental effects on wheat yield are to be minimized.

The basis for selectivity of phenmedipham (methyl-m-hydroxycarbanilate m-methylcarbanilate) and desmedipham (ethyl m-hydroxycarbanilate carbanilate) on wild mustard [Brassica kaber (DC.) L.C. Wheeler ‘pinnatifida’ (Stokes) L.C. Wheeler], redroot pigweed (Amaranthus retroflexus L.), and sugar beet (Beta vulgaris L.) was studied by evaluating spray retention, absorption, translocation, and metabolism. Total photosynthesis in wild mustard was severely inhibited in less than 5 hr after foliar application of either herbicide and did not recover. Total photosynthesis in sugar beet was slightly inhibited but recovered after 24 hr. Photosynthesis in redroot pigweed recovered from a treatment of phenmedipham but did not recover when treated with desmedipham. Differences in spray retention or foliar absorption did not explain selectivity. Within 5 hr after herbicide application, redroot pigweed had translocated more desmedipham than phenmedipham from the site of absorption and had metabolized a large amount of the phenmedipham but little desmedipham. The key factor explaining selectivity appeared to be at the initial detoxication reaction of the parent compound.

Standard operating procedures (SOPs) were developed for repetitive field research tasks to help ensure that instructions were complete and to provide consistency and continuity in the senior author's field research program. SOPs are explicit step-by-step instructions for carrying out experimental tasks that are components of experimental plans. SOPs are not the same as protocols for unique, new experimental plans. However, protocols may incorporate sequences of SOPs, if desired. SOPs are most useful for new workers and when research tasks need to be repeated infrequently in time (e.g., once every 6 mo or less per year). SOPs may help researchers enhance data accuracy, precision, and reproducibility as part of their own statistical quality control procedures. The authors' field-tested SOPs are available on diskette for critical review, modification, and use by interested weed scientists.

The persistence and germinability of jointed goatgrass (Aegilops cylindrica Host. # AEGCY) seed (caryopses) were studied over a five-year period between 1979 and 1984 at five locations in Colorado, Kansas, and Nebraska. Seed were buried in open-mesh packets and the sites were not disturbed for the duration of the study. Seed survival at burial depths of 5, 15, or 30 cm decreased rapidly over the first three years at all locations. By the third year, less than 7.4 ± 6.5% (mean ± SD) of the seed remained at 5 cm in the soil at all locations. By the third, fourth, and fifth year there was total loss of seed at one, two, and four sites at the 5-cm burial depth. Only three of five sites had total loss of seed at 30 cm after five years. The proportion of surviving seed that were germinable increased with time and was almost 100% after three years of burial. Because jointed goatgrass seed were relatively transient in the soil profile, fallowing of infested areas for a three-year period may significantly reduce populations of this weed or eradicate it, depending upon location.

Rapid biochemical tests developed for measuring viability of nondormant crop seed have been used for measuring dormant weed seed viability. The objective of this experiment was to propose and test a new method for validating one of these assays, the tetrazolium assay, for determining dormant weed seed viability. Subsamples of partially dormant jointed goatgrass seed from the same seed source were periodically subjected to sequential germination and tetrazolium assays as they afterripened until seed were completely nondormant. Changes in percent germinated, percent tetrazolium positive (presumably dormant), and percent tetrazolium negative (presumably dead) seed were graphed versus time, and compared with models of valid and invalid cases. The validation method showed that the tetrazolium assay accurately determined the viability of seed remaining after a 3-wk germination period for jointed goatgrass seed removed from joints at the start, but underestimated the viability for seed afterripened and germinated in joints. The validation method showed that additional research is needed to refine the tetrazolium assay for this latter purpose.

The spread of perennial weeds, such as foxtail barley, is a prime deterrent to adoption of no-till cereal production in the Northern Great Plains. In a 3-yr study, the isopropylamine salt of glyphosate at 0.56 kg ai/ha plus nonionic surfactant at 0.25% (v/v) did not control established perennial foxtail barley in early spring. However, adding ammonium sulfate at 2.8 kg/ha to glyphosate plus surfactant improved the effectiveness and year-to-year consistency of glyphosate for killing this weed. This spring treatment fits into no-till farm practice in the Northern Great Plains, providing no-till farmers with a defined strategy to manage this perennial bunch-grass weed.

This field research was designed to compare the long-term effectiveness of late-September applications of several herbicides for reducing Canada thistle shoot density on noncropped, untilled abandoned farmland when reapplied annually for 3 yr. Clopyralid at 560 and 840 g ae ha−1 or picloram at 280 and 560 g ae ha−1 reduced Canada thistle shoot density as well as either glyphosate3 at 0.8 to 2.8 kg ae ha−1 or dicamba at 1.1 and 2.2 kg ae ha−1. These treatments were much more effective than 2,4-D at 1.1 and 2.2 kg ae ha−1, chlorsulfuron at 34 and 67 g ai ha−1, and metsulfuron at 34 and 67 g ha−1 for progressively reducing Canada thistle shoot density over three annual fall applications. Picloram and clopyralid greatly reduced and delayed shoot emergence from adventitious root buds in spring after two fall-applied treatments compared with nontreated checks.