Exhumed fluvial landforms reveal evolution of late Eocene– Pliocene rivers on the Central and Northern Great Plains, USA

Cenozoic strata on the Great Plains are the products of a long- lived, continental sediment routing system, and yet strikingly little is known about these ancient rivers. This article details the discovery of ~3100 fluvial ridges—erosionally inverted alluvial- fan, channel- fill, channel- belt, and valley- fill deposits—extending from the Rocky Mountain front to the eastern margin of the Great Plains. The direct detection of these channel bodies reveals new insights into late Eocene– Pliocene drainage evolution. Late Eocene– Oligocene streams were morphologically diverse. Alluvial fans adjacent to the Rocky Mountain front changed eastward to parallel or downstream- divergent, fixed, single- thread, straight to slightly sinuous (S = 1.0– 1.5) streams \u3c50 m in width. At ~100 km from the Rocky Mountain front, streams became sinuous and laterally mobile, forming amalgamated channel bodies as much as 3 km in width. Streamflow in all these systems was highly dispersed (southeast to northeast) and temporally variable. These characteristics reveal a nascent Great Plains alluvial apron hosting small, poorly integrated drainages undergoing abrupt changes. By the Miocene, more uniform streamflow generally trended east- northeast. Channel deposits are identifiable 500 km from the Rocky Mountain front. Middle Miocene valley fills gave way to fixed, multithread channels a few kilometers in width by the late Miocene. These patterns evince a mature alluvial apron hosting bigger rivers in well- integrated drainages. We interpret the systematic changes between fixed and mobile channel styles to record spatially and temporally variable aggradation rates. The widening of channels in the late Miocene likely reflects increased discharge relating to wetter climates upstream or the integration of once- isolated Rocky Mountain drainage basins into a continental- scale drainage system

p_T-fluctuations in high-energy p-p and A-A collisions

The event-by-event p_T-fluctuations in proton-proton and central Pb-Pb collisions, which have been experimentally studied by means of the so-called Phi-measure, are analyzed. The contribution due to the correlation which couples the average p_T to the event multiplicity is computed. The correlation appears to be far too weak to explain the preliminary experimental value of Phi (p_T) in p-p interactions. The significance of the result is discussed.Comment: 5 pages, 2 figures, minor improvement

Geologic Mapping of Nebraska: Old Rocks, New Maps, Fresh Insights

Geologic mapping in Nebraska and environs is an ongoing endeavor that has spanned more than 170 years, involved dozens of scientists, and evolved through many changes. Digital mapping has risen to dominance in the state only since 1996. Geologic mapping in Nebraska today concentrates on surficial mapping, which emphasizes materials exposed at the land surface and their relationships with landforms, and which is particularly relevant because non- bedrock geologic materials (regolith) lie at the surface across at least 87% of the state. Moreover, surfi cial geologic maps assist the understanding of groundwater and sand and gravel resources, to name a few applications. The statewide bedrock map of Nebraska, which dates to 1986, remains an important and widely used geologic map, but it needs to be revised. Notwithstanding, when contemplated deeply, Nebraska’s statewide bedrock map reveals that (1) effects of gentle geologic structure, mainly those that came to be in the past 80 million years, can be discerned, and (2) some aspects of the map patterns (not the mapped sedimentary rocks per se) probably predate the beginning of the Pleistocene Epoch, about 2.6 million years ago. The geologic mapping of Nebraska, however, is far from completed

Three-dimensional architecture and hydrostratigraphy of cross-cutting buried valleys using airborne electromagnetics, glaciated Central Lowlands, Nebraska, USA

Buried valleys are characteristic features of glaciated landscapes, and their deposits host important aquifers worldwide. Understanding the stratigraphic architecture of these deposits is essential for protecting groundwater and interpreting sedimentary processes in subglacial and ice-marginal environments. The relationships between depositional architecture, topography and hydrostratigraphy in dissected, pre-Illinoian till sheets is poorly understood. Boreholes alone are inadequate to characterize the complex geology of buried valleys, but airborne electromagnetic surveys have proven useful for this purpose. A key question is whether the sedimentary architecture of buried valleys can be interpreted from airborne electromagnetic profiles. This study employs airborne electromagnetic resistivity profiles to interpret the threedimensional sedimentary architecture of cross-cutting buried valleys in a ca 400 km2 area along the western margin of Laurentide glaciation in North America. A progenitor bedrock valley is succeeded by at least five generations of tunnel valleys that become progressively younger northward. Tunnel-valley infills are highly variable, reflecting under-filled and over-filled conditions. Under-filled tunnel valleys are expressed on the modern landscape and contain fine sediments that act as hydraulic barriers. Over-filled tunnel valleys are not recognized in the modern landscape, but where they are present they form hydraulic windows between deep aquifer units and the land surface. The interpretation of tunnel-valley genesis herein provides evidence of the relationships between depositional processes and glacial landforms in a dissected, pre-Illinoian till sheet, and contributes to the understanding of the complex physical hydrology of glacial aquifers in general

Impacts of Drought on Disease Development and Management

Drought conditions such as those that occurred in Nebraska in 2012 can impact the development of plant diseases. In general drought slows down or prevents the development of plant diseases caused by pathogens that thrive under moist conditions. However, some diseases are favored by drought. This is because when plants are stressed due to lack of moisture or excessive heat, they become more susceptible to these diseases. This article presents examples of diseases of agronomic crops favored by drought and how to manage them. Data are provided on the effect of dry or wet conditions on the profitability of applying fungicides to control foliar fungal diseases of wheat. Charcoal Rot Diseases of Field Crops Aspergillus Ear Rot and Aflatoxin Contamination Fusarium Diseases Phoma Black Stem of Sunflower Root and Crown Diseases of Wheat Management of Foliar Diseases of Wheat with Fungicides in a Dry versus a Wet Growing Seaso

What’s New in Plant Pathology

Disease Management Products During the past year several new products have become available for disease management. The new products are summarized in Tables 1 and 2, as well as included in the 2014 Guide for Weed Management in Nebraska with Insecticide and Fungicide Information. In addition, fungicides labeled for use on sorghum and sunflower have also been added to the publication. Table 1. New Foliar Fungicides Table 2. New Seed Nematicide Disease Identification and Management Resource

Reconstruction of pre-Illinoian ice margins and glaciotectonic structures from airborne electromagnetic (AEM) surveys at the western limit of Laurentide glaciation, Midcontinent U.S.A.

Early and early Middle Pleistocene glaciations in midcontinental USA are poorly understood relative to more recent Illinoian and Wisconsinan glaciations, largely because pre-Illinoian glacial landforms and deposits are eroded and buried. In this paper, we present a new interpretation of buried, pre-Illinoian glacial features along the Laurentide glacial margin in northeastern Nebraska using Airborne ElectroMagnetics (AEM) supplemented with borehole logs and 2m LiDAR elevation data. We detect and map large-scale (101–102 km) geological features using contrasts in electrical resistivity. The Laurentide glacial limit is marked by a continuous (\u3e120 km) contrast between conductive (\u3c15 Ω-m), clayey tills and resistive (\u3e40 Ω-m) sandy sediments. Several smaller (102 km2) till salients extend 10s of km westward of this margin. We recognize a lithologically heterogeneous zone characterized by variable resistivity and complex geophysical structures extending as much as 17 km west of the glacial limit. This zone is interpreted as a glaciotectonic thrust complex, and it is analogous to a similar thrust complex in Denmark where structural analysis of co-located seismic and AEM surveys provides a standard for comparison. Our study suggests that the maximum advancement of pre-Illinoian glacial ice into Nebraska involved extensive deformation of sedimentary strata, local overriding of these deformed strata by smaller ice tongues, and emplacement of tills as much as 30 km west of the principal Laurentide ice margin. These insights provide the first glimpse of the large-scale stratigraphic architecture of glacial sediments in Nebraska and point to future clarifications of the geology and geomorphology of the Laurentide glacial limit

What\u27s New in Plant Pathology

Changes to the Disease Management Section of the 2016 Guide for Weed, Disease, and Insect Management in Nebraska Biological control Products Trivapro Fungicide Priaxor D. Fungicide Table 1. Foliar products for disease control that were updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska. Table 2. Seed treatment products for disease control that were updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska. Table 3. Seed treatment nematicide product that was updated in the 2016 Guide for Weed, Disease and Insect Management in Nebraska

Major Fusarium Diseases on Corn, Wheat, and Soybeans in Nebraska

Fusarium species are associated with diseases of corn, wheat, and soybean, causing significant yield loss in Nebraska. Some produce mycotoxins that are harmful to humans and animals

Weather Variability and Disease Management Strategies

This year’s title of “weather variability and disease management strategies” was chosen because we need to remember how weather conditions this year have impacted crop productivity and disease development. This will enable us to look forward and develop better management decisions for future growing seasons. Agricultural production is dependent on many climatic factors such as rain, humidity, temperature, and sunlight. These climate conditions have direct effects on yield as well as other indirect effects. One specific indirect effect of extreme weather events is increased pressure from pathogens and pests. Plant pathogens are commonly favored by very specific, and sometimes extreme, weather conditions. Pathogens take advantage of these conditions to infect, reproduce, and cause disease in crops that can lead to economic losses, ultimately in the loss of yield quality or quantity. Scientific projections indicate that climate change will continue to have major impacts on crops across the country and the world. It is therefore not surprising that this year the United Nations Summit in New York on September 23 focused on climate change in agriculture with discussions on Global Alliance for Climate-Smart Agriculture. Nebraska is known for its leadership in agricultural production and one germane concern is how we will be able to utilize the available climate data in a timely fashion to our advantage in protecting our crops from the negative impacts of climate change and pathogens. We need to act in a way that can leverage climate change to our advantage, where possible. It is important to monitor soil moisture and irrigation. Late planting and dryer than normal conditions in 2014 resulted in irrigation late into the season in some locations, which will unfortunately result in reduced profits for such farms. Temperature is also an important factor. When conditions are warmer, crops tend to grow faster and the time for seed maturity reduces. However, warmer conditions have the potential to reduce yield and, in addition, can promote certain diseases. The dry and hot weather conditions of 2014, for example, supported charcoal rot infections that were seen in both corn and soybean in many locations this year. Weed control and timely applications of herbicide will be crucial preparation steps in mitigating the impacts of climate change in 2015. Weeds not only act as alternate hosts for many pathogens but also deplete soil moisture. Below we present information on the influence of weather variability on development of diseases in Nebraska field crops. In 2015, crop production practices should be well planned to be climate-ready and climate-compliant