Virulence phenotypes of the wheat leaf rust pathogen, Puccinia triticina, in the United States 2018-2020

Collections of wheat leaves infected with the leaf rust fungus, Puccinia triticina, were obtained from the southeastern states, the Ohio Valley, the Great Plains, and Washington in 2018, 2019 and 2020 to determine the prevalent virulence phenotypes in the wheat growing regions of the United States. In the hard red winter wheat region of the southern and mid Great Plains, MNPSD, and MPPSD were the two most common phenotypes in 2018 and 2019. In 2020 BBBQD with high virulence to durum wheat was the most common phenotype in the southern Great Plains. In the hard red spring wheat region of the northern Great Plains, MNPSD, MPPSD, MBDSD, and TBBGS were the predominant phenotypes. In the soft red winter wheat region of the southeastern states and Ohio Valley region, MBTNB, MCTNB, and MNPSD were the three most common phenotypes. Collections in Washington had phenotypes LBDSG, LCDSG, LCDJG, and MBDSB that were not found in any other region. Isolates with virulence to Lr11 were most frequent in the southeastern states, and Ohio Valley regions. The frequency of isolates with virulence to Lr39 was highest in the Great Plains region and frequency of isolates with virulence to Lr21 was highest in the northern Great Plains region. Selection of virulence phenotypes by leaf rust resistance genes in the different market classes of wheat, combined with the effects of clonal reproduction, overwintering in southern regions, and low migration between the Great Plains region and eastern wheat producing regions, has maintained the different P. triticina populations in the United States.

Characteristics and Predictability of Midwestern United States Drought

Characteristics and predictability of drought in the Midwestern United States, spanning the Great Plains to the Ohio Valley, at local and regional scales are examined during 1916-2015. Given vast differences in hydroclimatic variability across the Midwest, drought is evaluated in four regions identified using a hierarchical clustering algorithm applied to an integrated drought index based on soil moisture, snow water equivalent, and three-month runoff from land surface models forced by observed analyses. Highlighting the regions containing the Ohio Valley (OV) and Northern Great Plains (NGP), the OV demonstrates a preference for sub-annual droughts, the timing of which can lead to prevalent dry epochs, while the NGP demonstrates a preference for annual-to-multi-annual droughts. Regional drought variations are closely related to precipitation, resulting in a higher likelihood of drought onset or demise during wet seasons: March-November in the NGP and all year in the OV, with a preference for March-May and September-November. Due to the distinct dry season in the NGP, there is a higher likelihood of longer drought persistence, as the NGP is four times more likely to experience drought lasting at least one year compared to the OV. While drought variability in all regions and seasons are related to atmospheric wave trains spanning the Pacific-North American sector, longer-lead predictability is limited to the OV in December-February because it is the only region/season related to slow-varying sea surface temperatures consistent with El Niño-Southern Oscillation. The wave trains in all other regions appear to be generated in the atmosphere, highlighting the importance of internal atmospheric variability in shaping Midwestern drought.

The Road Not Taken: How Early Landscape Learning and Adoption of a Risk-Averse Strategy Influenced Paleoindian Travel Route Decision Making in the Upper Ohio Valley

To evaluate a model of the travel-route selection process for upper Ohio Valley Paleoindian foragers (13,500–11,400 cal BP), this study investigates archaeological data through the theoretical framework of landscape learning and risk-sensitive analysis. Following initial trail placement adjacent to a highly visible escarpment landform, Paleoindians adopted a risk-averse strategy to minimize travel outcome variability when wayfaring between Sandy Springs, a significant Ohio River Paleoindian site, and Upper Mercer–Vanport chert quarries of east-central Ohio. Although a least-cost analysis indicates an optimal route through the lower Scioto Valley, archaeological evidence for this path is lacking. Geomorphic and archaeological data further suggest that site absence in the lower Scioto Valley is not entirely due to sampling bias. Instead, evidence indicates that Paleoindians preferred travel within the Ohio Brush Creek–Baker's Fork valley despite its longer path distance through more rugged, constricted terrain. Potential travel through the lower Scioto Valley hypothesizes high outcome variability due to the stochastic nature of the late Pleistocene hydroregime. In this case, perceived outcome variability appears more influential in determining travel-route decisions among Paleoindians than direct efforts to reduce energy and time allocation.

‘Giving Peace to Europe’

This chapter looks at colonial attitudes to British foreign policy during the War of the Austrian Succession (1740–8), the brief peace of 1748–57, and the Seven Years War (1757–63). It touches on themes including the balance of power, the Hanoverian connection, the Austrian, Prussian, and Dutch alliances, the Diplomatic Revolution of 1756, and the Treaties of Aix-la-Chapelle (1748) and Paris (1763). It follows how colonists understood struggles with France and Spain in the Americas within these larger conflicts, from the capture of Louisbourg by the Massachusetts militia in 1745 to events in the Ohio Valley in the mid-1750s, and came to view the colonies as part of the European geopolitics system. And it explores how colonial and metropolitan sentiments about European warfare began to diverge during these conflicts.

The Indigenous Roots of the American Revolution

Euro-Americans existed firmly on the periphery of an Indigenous North America in 1763, hubristic claims of continental sovereignty notwithstanding. Nowhere is this reality more clear than in the Ohio Valley and Illinois Country. Try as it might, the post-1763 British Empire could not assume jurisdictional control over this space. Even to begin to try was a task requiring significant investment—both in terms of more systematic Indigenous diplomacy and in terms of reforming colonial political structures unfit to accommodate imperial western policy. North American officials understood the problems quite well and were willing to spearhead reform. Between 1763 and 1775 they supported increased investment to defray North American expenses. They called for programs that would end colonial corruption, something they feared undermined Indigenous diplomacy and made a mockery of the rule of law. Ultimately, they concluded that centralizing Indian affairs offered the best means by which to stabilize North America. Colonials (generally) and speculators and their surveyor corps (specifically) powerfully disagreed, however, seeing Indian country as an untapped resource and imperial restraints as threats to local autonomy. They rejected the idea of centralizing power over Indigenous affairs and used the rhetoric of British constitutional liberty to reframe corrupt behavior into something it emphatically was not.

Impacts of Storm Track Variations on Wintertime Extreme Precipitation and Moisture Budgets over the Ohio Valley and Northwestern United States

Previous studies have shown that variations in extratropical cyclone activity significantly affect the frequency of extreme precipitation events over the Ohio Valley and northwestern United States. In this study, we examine the similarities and differences between the dynamics governing these events in these two regions. In the Ohio Valley, extreme precipitation events are associated with midlatitude synoptic-scale convergence northeast of cyclones and a southwestward oriented ridge near the Atlantic coast that drives strong water vapor transport from the Gulf of Mexico into the Ohio Valley. In the northwestern United States, extreme precipitation events are associated with a cyclonic and anticyclonic circulation pair aligned northwest to southeast, which together drive a long and strong moisture transport corridor from the lower latitude of the central Pacific Ocean toward the northwestern United States. Moisture budget analysis shows that moisture convergence due to dynamical convergence dominates in the Ohio Valley, whereas moisture advection dominates over the Pacific Northwest. Differences between the cases in the same region are examined by an empirical orthogonal function (EOF) analysis conducted on the vertically integrated moisture flux. Different EOFs highlight shifts in spatial location, orientation, and intensity of the moisture flux but demonstrate consistent roles of dynamics in the two regions. Composites based on these EOFs highlight the range of likely synoptic scenarios that can give rise to precipitation extremes over these two regions.