School of Plant and Environmental Sciences
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SPES was formed in 2017 from three departments: Crop and Soil Environmental Sciences; Horticulture; and Plant Pathology, Physiology, and Weed Science.
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Browsing School of Plant and Environmental Sciences by Content Type "Article"
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- Blowin’ in the Wind: The use of UAVs to track airborne crop pathogens takes offKing, Carolyn (2016-04)
- Brief Overview: Field Measurements of Soil CracksStewart, Ryan D.; Abou Najm, Majdi R. (2018-05)
- Charles Edward Miller, 1925-1984Johnson, Terry W., Jr.; Dylewski, Daniel P. (Mycological Society of America, 1985)A professional lifetime is not fulfilled unless one is privileged to have had an associate from whom one learns the necessity of standards. The colleague who teaches by example, gentle cajoling, or outright insistence never to compromise accuracy and precision is indeed one of inestimable value. In his endlessly patient, tolerant, and flexible but exacting way, Charles Edward Miller was such a colleague. Whether one was an established investigator or a novice first testing the waters of mycology before plunging in, the treatment was the same: generous responsiveness and impartiality, a demand for responsible thought and evaluation, and an uncompromising principle that one could never lose face by being accurate.
- Comparison of benthic macroinvertebrate assessment methods along a salinity gradient in headwater streamsPence, Rachel A.; Cianciolo, Thomas R.; Drover, Damion R.; McLaughlin, Daniel L.; Soucek, David J.; Timpano, Anthony J.; Zipper, Carl E.; Schoenholtz, Stephen H. (Springer, 2021-12-01)Benthic macroinvertebrate community assessments are used commonly to characterize aquatic systems and increasingly for identifying their impairment caused by myriad stressors. Yet sampling and enumeration methods vary, and research is needed to compare their abilities to detect macroinvertebrate community responses to specific water quality variables. A common assessment method, rapid bioassessment, uses subsampling procedures to identify a fixed number of individual organisms regardless of total sample abundance. In contrast, full-enumeration assessments typically allow for expanded community characterization resulting from higher numbers of identified organisms within a collected sample. Here, we compared these two sampling and enumeration methods and their abilities to detect benthic macroinvertebrate response to freshwater salinization, a common stressor of streams worldwide. We applied both methods in headwater streams along a salinity gradient within the coal-mining region of central Appalachia USA. Metrics of taxonomic richness, community composition, and trophic function differed between the methods, yet most metrics exhibiting significant response to SC for full-enumeration samples also did for rapid bioassessment samples. However, full-enumeration yielded taxonomic-based metrics consistently more responsive to the salinization gradient. Full-enumeration assessments may potentially provide more complete characterization of macroinvertebrate communities and their response to increased salinization, whereas the more cost-effective and widely employed rapid bioassessment method can detect community alterations along the full salinity gradient. These findings can inform decisions regarding such tradeoffs for assessments of freshwater salinization in headwater streams and highlight the need for similar research of sampling and enumeration methodology in other aquatic systems and for other stressors.
- Current Insights into Nonuniform Flow across Scales, Processes, and ApplicationsAbou Najm, Majdi R.; Lassabatere, Laurent; Stewart, Ryan D. (2019-12-05)This introduction to the special section Nonuniform Flow across Vadose Zone Scales is a brief summary of this special section's diverse contributions covering nonuniform flow across a wide range of scales, processes, and applications. We summarize the 17 articles constituting this special section and hope that those contributions are positive steps toward a new, generalizable, and comprehensive paradigm to modeling flow and transport in porous media.
- Draft genome sequence of mortierella alpina strain LL118, isolated from an aspen (populus tremuloides) leaf litter sampleYang, Shu; Vinatzer, Boris A. (American Society for Microbiology, 2021-11-01)Mortierella alpina is a filamentous fungus commonly associated with soil and is one of very few fungal species known to include strains with ice nucleation activity. Here, we report the draft genome sequence of the ice nucleation-active M. alpina strain LL118, isolated from aspen leaf litter collected in Alberta, Canada.
- Effect of silvopasture system on fearfulness and leg health in fast-growing broiler chickensPaneru, Bidur; Pent, Gabriel J.; Nastasi, Shawna; Downing, Adam K.; Munsell, John F.; Fike, John H.; Jacobs, Leonie (2023-02)A silvopasture system intentionally integrates trees, forages, and livestock, allowing dual land use. These systems can provide high-quality habitat for broiler chickens; however, such systems have not been widely adopted by the broiler industry in the United States. The objective of this study was to examine the effect of silvopasture versus open pasture access on fearfulness and leg health in fast-growing broiler chickens. A total of 886 mixed-sex Ross 708 chicks in Experiment 1 (Exp 1) and 648 chicks in Experiment 2 (Exp 2) were housed in coops and had access to 16 (Exp 1) or 12 (Exp 2) 125m2 silvopasture plots (x̄ = 32% canopy cover) or open pasture plots (no canopy cover) from day 24 of age. Fearfulness was measured using a tonic immobility test (tonic immobility duration), and leg health was assessed by quantifying footpad dermatitis, hock burns, gait, and performing a latency-to-lie test on days 37-39 of age. Birds in the silvopasture treatment were less fearful than birds in the open pasture treatment. Overall, birds in both silvopasture and open pasture systems had excellent leg health. Silvopasture birds had lower footpad dermatitis scores than open pasture birds. Silvopasture birds tended to have worse gait than open pasture birds in Exp 1, but not in Exp 2. Hock burn scores and latency-to-lie did not differ between treatments in Exp 1 or Exp 2. Raising birds in silvopasture reduced fear and improved footpad health compared to birds raised in open pastures, which indicates that silvopasture systems provide some benefits for affective state and leg health in fast-growing broilers.
- Evaluation of Insecticides to Control Stink Bug in Edamame, 2019Sutton, Kemper L.; Kuhar, Thomas P.; Rideout, Steven L.; Zhang, Bo (Oxford University Press, 2020-01-01)
- First Report of Laurel Wilt Disease Caused by Raffaelea lauricola on Sassafras in VirginiaGazis, R.; DeWitt, K. M.; Johnson, L. K.; Chamberlin, L. A.; Kennedy, A. H.; Hansen, Mary Ann; Bush, Elizabeth Ann (American Phytopathological Society, 2022-06)
- Harmful algal blooms and toxic air: The economic value of improved forecastsMoeltner, Klaus; Fanara, Tracy; Foroutan, Hosein; Hanlon, Regina; Lovko, Vince; Ross, Shane D.; Schmale, David G. III (2021-02)The adverse economic impacts of harmful algal blooms can be mitigated via tailored forecasting methods. Adequate provision of these services requires knowledge of the losses avoided, or, in other words, the economic benefits they generate. The latter can be difficult to measure for broader population segments, especially if forecasting services or features do not yet exist. We illustrate how Stated Preference tools and Choice Experiments are well-suited for this case. Using as example forecasts of respiratory irritation levels associated with airborne toxins caused by Florida red tide, we show that 24-hour predictions of spatially and temporally refined air quality conditions are valued highly by the underlying population. This reflects the numerous channels and magnitude of red tide impacts on locals' life and activities, which are also highlighted by our study. Our approach is broadly applicable to any type of air quality impediment with risk of human exposure.
- Incidence of Per-And Polyfluoroalkyl Substances (PFAS) in Private Drinking Water Supplies in Southwest Virginia, USAHohweiler, Kathleen; Krometis, Leigh-Anne H.; Ling, Erin; Xia, Kang (2024)Per- and polyfluoroalkyl substances (PFAS) are a class of man-made contaminants of increasing human health concern due to their resistance to degradation, widespread environmental occurrence, bioaccumulation in organ tissue, and potential negative health impacts. Private drinking water supplies may be uniquely vulnerable to PFAS contamination, as these systems are not subject to federal regulations and often include limited treatment prior to use. The goal of this study was to determine the incidence of PFAS contamination in private drinking water supplies in two counties in Southwest Virginia, USA (Floyd and Roanoke), and to examine the potential for reliance on citizen-science based strategies for sample collection in subsequent broader efforts. Samples for inorganic ions, bacteria, and PFAS analysis were collected on separate occasions by participants and experts at the home drinking water point of use (POU) for comparison. Experts also collected outside tap samples for PFAS analysis. At least one PFAS was detectable in 88% of POU samples collected (n=60), with an average total PFAS concentration of 23.5±30.8 ppt. PFOA and PFOS, two PFAS compounds which presently have EPA health advisories, were detectable in 13% and 22% of POU samples, respectively. Of the 31 compounds targeted, 15 were detectable in at least one sample. On average, each POU sample contained approximately 3.3 PFAS compounds, and one sample contained as many as 8 compounds, indicating that exposure to a mixture of PFAS in drinking water may be occurring. Although there were significant differences in total PFAS concentrations between expert and participant collected samples (Wilcoxon, alpha = 0.05), collector bias was inconsistent, and may be due to the time of day of sampling (i.e. morning, afternoon) or specific attributes of a given home. Future studies reliant on participant collection of samples appear possible given proper training, coordination, and instruction.
- Production, composition, and ecological function of sweet basil seed mucilage during hydrationZhou, Dongfang; Barney, Jacob; Welbaum, Gregory E. (Cambridge University Press, 2019-11)Sweet basil (Ocimum basilicum L.) fruit/pericarp produces mucilage that engulfs fruit and seed within minutes of hydration. Seed mucilage is produced by plant species adapted to arid, sandy soils, though its significance in determining ecological fitness is unclear. Basil fruit/seeds were examined using light and environmental scanning electron microscopy. Basil mucilage forms columnar structures that unfold from the pericarp upon hydration. Dilute hydrochloric acid removed mucilage and decreased water content 4-fold but did not inhibit laboratory seed germination. Fourier transform mid-infrared (FTIR) spectroscopy analysis showed mucilage is composed of hemicellulose that enabled basil seeds to cling to a smooth incline board set to a 70° steeper slope than seeds without mucilage. The fully hydrated seeds approached zero water potential, so the mucilage did not prevent full hydration. Seeds with mucilage had from 12 to 28% higher germination than seeds without mucilage planted in growing media. Seeds with mucilage also had higher survival percentages after 10 days. Basil fruit/seed mucilage provides a reservoir of loosely bound water at high water potential for seed germination and early seedling development, thus improving survivability under adverse moisture conditions.
- Quantifying short-term responsiveness and consistency of soil health parameters in row crop systems. Part 1: Developing a multivariate approachGyawali, Ayush Joshi; Strickland, Michael S.; Thomason, Wade E.; Reiter, Mark S.; Stewart, Ryan D. (Elsevier, 2022-05-01)Quantifying soil health requires measuring different physical, chemical and biological soil properties, yet limits in time and resources often restrict the number of parameters that can be analyzed. The main objective of this research was to identify soil health parameters that showed measurable and consistent responses to reduced tillage and cover cropping over a short (2-year) study period. In September 2015, four treatments – reduced tillage with cover crops, reduced tillage without cover crops, conventional tillage with cover crops and conventional tillage without cover crops – were installed in five sites across Virginia. Sites were managed for corn or tobacco production. Soils were analyzed for 32 properties associated with soil health, and cash crop yields were also measured in September 2016 and September 2017. A multivariate approach was used to detect treatment differences and determine parameters driving those differences. We then developed two new indices to quantify the responsiveness and consistency of soil health parameters. The results showed that surface soil layers had more parameters with significant differences between treatments than subsurface layers. Tillage effects were observed within 0.5 years, which may be due to the lack of tillage history in 4 of the 5 sites. Cover crop effects appeared after 1.5 years, indicating that this practice can also induce changes in soil properties over relatively short periods. Soil aggregate stability, potassium, calcium, magnesium, boron and cash crop yield were the most responsive parameters to reduced tillage and cover crop practices, while aggregate stability also showed high consistency. These findings suggest that aggregate stability effectively indicated short-term changes in soil health within row cropping systems of Virginia.
- Roland Jay StipesRoane, Curtis W. (Virginia Tech, 2003)An overview of the career of Roland Stipes, Professor of Plant Pathology at Virginia Tech, including graduate student advisees and an extensive publications list.
- A selective sweep in the Spike gene has driven SARS-CoV-2 human adaptationKang, Lin; He, Guijuan; Sharp, Amanda K.; Wang, Xiaofeng; Brown, Anne M.; Michalak, Pawel; Weger-Lucarelli, James (Virginia Tech, 2021-03-05)While SARS-CoV-2 likely has animal origins, the viral genetic changes necessary to adapt this animal-derived ancestral virus to humans are largely unknown, mostly due to low levels of sequence polymorphism and the notorious difficulties in experimental manipulations of coronavirus genomes. We scanned more than 182,000 SARS-CoV-2 genomes for selective sweep signatures and found that a distinct footprint of positive selection is located around a non-synonymous change (A1114G; T372A) within the Receptor-Binding Domain of the Spike protein, which likely played a critical role in overcoming species barriers and accomplishing interspecies transmission from animals to humans. Structural analysis indicated that the substitution of threonine with an alanine in SARS-CoV-2 concomitantly removes a predicted glycosylation site at N370, resulting in more favorable binding predictions to human ACE2, the cellular receptor. Using a novel bacteria-free cloning system for manipulating RNA virus genomes, we experimentally validated that this SARS-CoV-2-unique substitution significantly increases replication in human cells relative to its putative ancestral variant. Notably, this mutation’s impact on virus replication in human cells was much greater than that of the Spike D614G mutant, which has been widely reported to have been selected for during human-to-human transmission.
- Soil Physics with HYDRUS: Modeling and Applications [Book review]Selker, John; Stewart, Ryan D. (Wiley, 2011)
- Soil water repellency after wildfires in the Blue Ridge Mountains, United StatesChen, Jingjing; Pangle, Luke A.; Gannon, John P.; Stewart, Ryan D. (CSIRO Publishing, 2020-08-12)It is not well understood if wildfires induce soil water repellency in broadleaf deciduous forests, such as those endemic to the Blue Ridge Mountains of the eastern United States. In 2016, widespread wildfires provided an opportunity to study soil water repellency in this region. We selected sites in four locations with low to moderate burn severities, along with unburned controls. We estimated soil water repellency using water drop penetration time measurements from the surface (i.e. ash or organic) layer to ∼5 cm within the underlying mineral layer. Two months after the fires, water repellency was detected in all locations and was greater in more severely burned sites. One location had the greatest water repellency in surface ash (frequency of occurrence: 68-74%), whereas the other locations showed greatest repellency at the ash-mineral interface (40-96%). Unburned soils rarely showed repellency (0-18%). Burned soils also exhibited water repellency 1 year post fire. The study results suggest that combustion of non-resinous foliage within litter layers can cause water repellency in deciduous forests, meaning that this condition is not exclusive to coniferous and dryland forests. The duration of impact depends on fire severity, and may enhance overland flow and sediment transport in affected landscapes.
- Welcome small patches; beware of the risks of changing conservation prioritiesChaves, Rafael B.; Reid, J. Leighton; Hohlenwerger, Camila; Calaboni, Adriane; Mendes, Mariana E.; Baptista, Mozart S. P.; Mori, Danilo P.; Tambosi, Leandro R. (Wiley, 2022-08)
- Write, write, write... Right?Stewart, Ryan D. (Soil Science Society of America Journal, 2022-05-01)