Browsing by Author "Sykes, Virginia R."

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    Comparing Digital and Visual Evaluations for Accuracy and Precision in Estimating Tall Fescue Brown Patch Severity
    Sykes, Virginia R.; Horvath, Brandon J.; Warnke, Scott E.; Askew, Shawn D.; Baudoin, Antonius B.; Goatley, James M. (2017-11)
    Brown patch (Rhizoctonia solani Kuhn), a destructive disease of tall fescue (Festuca arundinacea Schreb.), is typically evaluated visually. The subjectivity of visual evaluations may be reduced using technology like digital image analysis (DIA). This study compared DIA and visual evaluations for accuracy and precision of brown patch ratings of glasshouse grown tall fescue plants. Across four experiments, 112 plants were inoculated with R. solani. Disease was rated visually and using DIA-WP (digital image analysis whole plant canopy). In two experiments, disease evaluations were replicated using three images and three visual evaluations per pot. Absolute error was calculated as the difference between actual disease severity [calculated using an individual leaf DIA method previously quantified as highly predictive of actual brown patch disease severity on tall fescue (r(2) = 0.99)] and DIA-WP and visual evaluations, respectively. Standard deviations within repeated measures were also calculated. A mixed-model ANOVA was used to determine differences (P < 0.05) in mean absolute error and mean standard deviation by method, disease range, and method by disease range. Disease ranged from 0 to 100%. Mean absolute error did not differ between methods but did by disease range, exhibiting a bell-shaped curve from 0% to 100% disease severity. Mean standard deviation exhibited significant method by disease range interaction. Mean standard deviation did not differ across the disease range within DIA-WP evaluations but did across the disease range within visual evaluations. The more consistent precision of DIA across the disease range could reduce variability in brown patch evaluations of tall fescue.
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    Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage
    Rieke, Elizabeth L.; Cappellazzi, Shannon B.; Cope, Michael; Liptzin, Daniel; Mac Bean, G.; Greub, Kelsey L. H.; Norris, Charlotte E.; Tracy, Paul W.; Aberle, Ezra; Ashworth, Amanda; Banuelos Tavarez, Oscar; Bary, Andy, I; Baumhardt, R. L.; Borbon Gracia, Alberto; Brainard, Daniel C.; Brennan, Jameson R.; Briones Reyes, Dolores; Bruhjell, Darren; Carlyle, Cameron N.; Crawford, James J. W.; Creech, Cody F.; Culman, Steve W.; Deen, Bill; Dell, Curtis J.; Derner, Justin D.; Ducey, Thomas F.; Duiker, Sjoerd W.; Dyck, Miles F.; Ellert, Benjamin H.; Espinosa Solorio, Avelino; Fonte, Steven J.; Fonteyne, Simon; Fortuna, Ann-Marie; Foster, Jamie L.; Fultz, Lisa M.; Gamble, Audrey, V; Geddes, Charles M.; Griffin-LaHue, Deirdre; Grove, John H.; Hamilton, Stephen K.; Hao, Xiying; Hayden, Zachary D.; Honsdorf, Nora; Howe, Julie A.; Ippolito, James A.; Johnson, Gregg A.; Kautz, Mark A.; Kitchen, Newell R.; Kumar, Sandeep; Kurtz, Kirsten S. M.; Larney, Francis J.; Lewis, Katie L.; Liebman, Matt; Lopez Ramirez, Antonio; Machado, Stephen; Maharjan, Bijesh; Martinez Gamino, Miguel Angel; May, William E.; McClaran, Mitchel P.; McDaniel, Marshall D.; Millar, Neville; Mitchell, Jeffrey P.; Moore, Amber D.; Moore, Philip A.; Mora Gutierrez, Manuel; Nelson, Kelly A.; Omondi, Emmanuel C.; Osborne, Shannon L.; Osorio Alcala, Leodegario; Owens, Philip; Pena-Yewtukhiw, Eugenia M.; Poffenbarger, Hanna J.; Ponce Lira, Brenda; Reeve, Jennifer R.; Reinbott, Timothy M.; Reiter, Mark S.; Ritchey, Edwin L.; Roozeboom, Kraig L.; Rui, Yichao; Sadeghpour, Amir; Sainju, Upendra M.; Sanford, Gregg R.; Schillinger, William F.; Schindelbeck, Robert R.; Schipanski, Meagan E.; Schlegel, Alan J.; Scow, Kate M.; Sherrod, Lucretia A.; Shober, Amy L.; Sidhu, Sudeep S.; Solis Moya, Ernesto; St Luce, Mervin; Strock, Jeffrey S.; Suyker, Andrew E.; Sykes, Virginia R.; Tao, Haiying; Trujillo Campos, Alberto; Van Eerd, Laura L.; Verhulst, Nele; Vyn, Tony J.; Wang, Yutao; Watts, Dexter B.; William, Bryan B.; Wright, David L.; Zhang, Tiequan; Morgan, Cristine L. S.; Honeycutt, C. Wayne (Pergamon-Elsevier, 2022-05)
    Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity.
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    Screening Tall Fescue for Resistance to Rhizoctonia solani and Rhizoctonia zeae Using Digital Image Analysis
    Sykes, Virginia R.; Horvath, Brandon J.; McCall, David S.; Baudoin, Antonius B.; Askew, Shawn D.; Goatley, James M.; Warnke, Scott E. (2020-02)
    Brown patch, caused by Rhizoctonia solani, is a destructive disease on tall fescue. Compared with R. solani, Rhizoctonia zeae causes indistinguishable symptoms in the field but varies in geographic distribution. This may contribute to geographic variability observed in the resistance response of improved brown patch resistant cultivars. This study examined R. solani and R. zeae susceptibility of four cultivars, selected based on brown patch performance in the National Turfgrass Evaluation Program (NTEP), and nine plant introductions (PIs). Twenty genotypes per Pl/cultivar were evaluated by using four clonal replicates in a randomized complete block design. Plants were inoculated under controlled conditions with two repetitions per pathogen. Disease severity was assessed digitally in APS Assess, and analysis of variance and correlations were performed in SAS 9.3. Mean disease severity was higher for R. solani (65%) than for R. zeae (49%) (P = 0.0137). Interaction effects with pathogen were not significant for PI (P = 0.0562) but were for genotype (P < 0.001). Moderately to highly resistant NTEP cultivars compared with remaining PIs exhibited lower susceptibility to R. zeae (P < 0.0001) but did not differ in susceptibility to R. solani (P = 0.7458). Correlations between R. solani and R. zeae disease severity were not significant for either PI (R = 0.06, P = 0.8436) or genotype (R = 0.11, P = 0.09). Breeding for resistance to both pathogens could contribute to a more geographically stable resistance response. Genotypes were identified with improved resistance to R. solani (40), R. zeae (122), and both pathogens (26).