Plant Biology Commons^™

Leaf Traits Within Communities: Context May Affect The Mapping Of Traits To Function, Jennifer L. Funk, William K. Cornwell

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The leaf economics spectrum (LES) has revolutionized the way many ecologists think about quantifying plant ecological trade-offs. In particular, the LES has connected a clear functional trade-off (long-lived leaves with slow carbon capture vs. short-lived leaves with fast carbon capture) to a handful of easily measured leaf traits. Building on this work, community ecologists are now able to quickly assess species carbon-capture strategies, which may have implications for community-level patterns such as competition or succession. However, there are a number of steps in this logic that require careful examination, and a potential danger arises when interpreting leaf-trait variation among species …

Seed Burial Physical Environment Explains Departures From Regional Hydrothermal Model Of Giant Ragweed (Ambrosia Trifida) Seedling Emergence In U.S. Midwest, Adam S. Davis, Sharon Clay, John Cardina, Anita Dille, Frank Forcella, John Lindquist, Christy Sprague

Department of Agronomy and Horticulture: Faculty Publications

Robust predictions of weed seedling emergence from the soil seedbank are needed to aid weed management. A common seed accession (Illinois) of giant ragweed was buried in replicate experimental gardens over 18 site years in Illinois, Michigan, Kansas, Nebraska, Ohio, and South Dakota to examine the importance of site and climate variability by year on seedling emergence. In a nonlinear mixed-effects modeling approach, we used a flexible sigmoidal function (Weibull) to model giant ragweed cumulative seedling emergence in relation to hydrothermal time accumulated in each site-year. An iterative search method across a range of base temperature (T_b) …

Major Fusarium Diseases On Corn, Wheat, And Soybeans In Nebraska, Bo Liu, Loren J. Giesler, Tamra A. Jackson-Ziems, Stephen N. Wegulo, Robert M. Harveson, Kevin A. Korus, Robert N. Klein

Department of Plant Pathology: Faculty Publications

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.

Marketing Contracts, Overconfidence, And Timing In The Canadian Wheat Market, Fabio L. Mattos, Stefanie A. Fryza

Department of Agronomy and Horticulture: Faculty Publications

This paper investigates factors that impact marketing performance in the Canadian wheat market. Using data provided by the Canadian Wheat Board (CWB) for six crop years, results indicate that producers were not able to profitably use all marketing contracts offered by the CWB, earlier pricing tended to generate better performance, there was a negative relationship between activeness and performance (suggesting overconfidence in marketing skills), and performance was generally worse in volatile crop years. Further analysis reveals some of these findings differ when outperforming and underperforming producers are investigated separately, particularly with respect to activeness and volatility.

Streptomycin Resistance Of Erwinia Amylovora, Causal Agent Of Fire Blight, Claudia Nischwitz

All Current Publications

No abstract provided.

Functional Analysis Of Three Arabidopsis Argonautes Using Slicer-Defective Mutants, Alberto Carbonell, Noah Fahlgren, Hernan Garcia-Ruiz, Kerrigan B. Gilbert, Taiowa A. Montgomery, Tammy Nguyen, Josh T. Cuperus, James C. Carrington

Department of Plant Pathology: Faculty Publications

In RNA-directed silencing pathways, ternary complexes result from small RNA-guided ARGONAUTE (AGO) associating with target transcripts. Target transcripts are often silenced through direct cleavage (slicing), destabilization through slicerindependent turnover mechanisms, and translational repression. Here, wild-type and active-site defective forms of several Arabidopsis thaliana AGO proteins involved in posttranscriptional silencing were used to examine several AGO functions, including small RNA binding, interaction with target RNA, slicing or destabilization of target RNA, secondary small interfering RNA formation, and antiviral activity. Complementation analyses in ago mutant plants revealed that the catalytic residues of AGO1, AGO2, and AGO7 are required to restore the defects …

Enhancement Or Attenuation Of Disease By Deletion Of Genes From Citrus Tristeza Virus, Satyanarayana Tatineni, William O. Dawson

Department of Plant Pathology: Faculty Publications

Stem pitting is a common virus-induced disease of perennial woody plants induced by a range of different viruses. The phenotype results from sporadic areas of the stem in which normal xylem and phloem development is prevented during growth of stems. These alterations interfere with carbohydrate transport, resulting in reduced plant growth and yield. Citrus tristeza virus (CTV), a phloem-limited closterovirus, induces economically important stem-pitting diseases of citrus. CTV has three nonconserved genes (p33, p18, and p13) that are not related to genes of other viruses and that are not required for systemic infection of some species of citrus, which allowed …

Efficacy And Stability Of Integrating Fungicide And Cultivar Resistance To Manage Fusarium Head Blight And Deoxynivalenol In Wheat, K. T. Willyerd, C. Li, L. V. Madden, C. A. Bradley, G. C. Bergstrom, L. E. Sweets, M. Mcmullen, J. K. Ransom, A. Grybauskas, L. Osborne, S. N. Wegulo, D. E. Hershman, K. Wise, W. W. Bockus, D. Groth, R. Dill-Macky, E. Milus, P. D. Esker, K. D. Waxman, E. A. Adee, S. E. Ebelhar, B. G. Young, P. A. Paul

Department of Plant Pathology: Faculty Publications

Integration of host resistance and prothioconazole + tebuconazole fungicide application at anthesis to manage Fusarium head blight (FHB) and deoxynivalenol (DON) in wheat was evaluated using data from over 40 trials in 12 U.S. states. Means of FHB index (index) and DON from up to six resistance class–fungicide management combinations per trial (susceptible treated [S_TR] and untreated [S_UT]; moderately susceptible treated [MS_TR] and untreated [MS_UT]; moderately resistant treated [MR_TR] and untreated [MR_UT]) were used in multivariate meta-analyses, and mean log response ratios across trials were estimated and transformed to estimate mean percent control ( C ) due to the management …

Effects Of Single And Double Infections Of Winter Wheat By Triticum Mosaic Virus And Wheat Streak Mosaic Virus On Yield Determinants, E. Byamukama, S. Tatineni, G. L. Hein, R. A. Graybosch, P. Stephen Baenziger, R. French, S. N. Wegulo

Department of Plant Pathology: Faculty Publications

Triticum mosaic virus (TriMV) is a recently discovered virus infecting wheat (Triticum aestivum) in the Great Plains region of the United States. It is transmitted by wheat curl mites (Aceria tosichella) which also transmit Wheat streak mosaic virus (WSMV) and Wheat mosaic virus. In a greenhouse study, winter wheat ‘Millennium’ (WSMV susceptible) and ‘Mace’ (WSMV resistant) were mechanically inoculated with TriMV, WSMV, TriMV+WSMV, or sterile water at the two-leaf growth stage. At 28 days after inoculation, final chlorophyll meter (soil plant analysis development [SPAD]) readings, area under the SPAD progress curve (AUSPC), the number of …

Composting Manure And Other Organic Materials, Charles S. Wortmann, Charles A. Shapiro

Department of Agronomy and Horticulture: Faculty Publications

The Composting Process

Composting is the aerobic decomposition of manure or other organic materials in the thermophilic temperature range (104-149oF). Composted material is odorless, fine-textured, and low-moisture. It can be bagged and sold for use in gardens or nurseries, or used as fertilizer on cropland with little odor or fly breeding potential. Composting improves the handling characteristics of any organic residue by reducing its volume and weight. Composting can kill pathogens and weed seeds.

Disadvantages of composting organic residues include loss of nitrogen and other nutrients, time for processing, cost for handling equipment, available land for composting, odors, marketing, diversion …

Escape From Preferential Retention Following Repeated Whole Genome Duplications In Plants, James C. Schnable, Xiaowu Wang, J. Chris Pires, Michael Freeling

Department of Agronomy and Horticulture: Faculty Publications

The well supported gene dosage hypothesis predicts that genes encoding proteins engaged in dose–sensitive interactions cannot be reduced back to single copies once all interacting partners are simultaneously duplicated in a whole genome duplication. The genomes of extant flowering plants are the result of many sequential rounds of whole genome duplication, yet the fraction of genomes devoted to encoding complex molecular machines does not increase as fast as expected through multiple rounds of whole genome duplications. Using parallel interspecies genomic comparisons in the grasses and crucifers, we demonstrate that genes retained as duplicates following a whole genome duplication have only …

Root-Knot Nematodes In Golf Course Greens Of The Western United States, Claudia Nischwitz

All Current Publications

No abstract provided.

Plant Wounding And Ophiostoma Mitovirus 3a (Omv3a) Influence Infection Of Creeping Bentgrass By Sclerotinia Homoeocarpa, Angela M. Orshinsky, Michael J. Boehm, Greg J. Boland

Department of Plant Pathology: Faculty Publications

Colonization and lesion development by virulent, asymptomatic and hypovirulent isolates of Sclerotinia homoeocarpa on nonwounded (NW) and wounded (W) leaves of creeping bentgrass were characterized. Hypovirulent and asymptomatic isolates contain the fungal virus, Ophiostoma mitovirus 3a, and virulent isolates are virus-free. On NW leaves, all isolates infected leaves with appressoria along cell walls and through stomata by 48 hours post-inoculation (hpi). Inter- and intracellular hyphae formed on heavily colonized, NW leaves at 96 hpi. Wound-inoculated grass had a colonization front characterized by inter- and intracellular hyphal colonization within nonsymptomatic tissues at 8 hpi by direct infection of the wound …

2011 Vadose Zone Nitrate Study At Hastings, Ne (Revised), Roy F. Spalding, Martin Toavs

Department of Agronomy and Horticulture: Faculty Publications

In an effort to assist Hastings Utilities in the management of their well-head protection area (WHP A) and to protect the groundwater from the impact of nitrate loading from potential nonpoint and point sources, Hastings Utilities subcontracted with the Department of Agronomy and Horticulture at the University of Nebraska for deep vadose zone coring. Continuous 60-ft soil cores were obtained at 36 sites within the apparent WHP A (Figure 1). The sites were selected by Marty Stange on the basis of availability for sampling, management, landuse , cropping history, and location within the WHPA. Nitrogen analyses of these deep soil …

Genome-Wide Analysis Of Syntenic Gene Deletion In The Grasses, James C. Schnable, Michael Freeling, Eric Lyons

Department of Agronomy and Horticulture: Faculty Publications

The grasses, Poaceae, are one of the largest and most successful angiosperm families. Like many radiations of flowering plants, the divergence of the major grass lineages was preceded by a whole-genome duplication (WGD), although these events are not rare for flowering plants. By combining identification of syntenic gene blocks with measures of gene pair divergence and different frequencies of ancient gene loss, we have separated the two subgenomes present in modern grasses. Reciprocal loss of duplicated genes or genomic regions has been hypothesized to reproductively isolate populations and, thus, speciation. However, in contrast to previous studies in yeast and teleost …

Soybean Disease Profiles I: Foliar Diseases, Loren J. Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Kevin A. Korus, Bo Liu, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1093 (EC1903).

Disease photographs and descriptions of Bacterial Blight, Bacterial Pustule, Brown Spot, Cercospora Leaf Blight and Purple Seed Stain, Downy Mildew, Frogeye Leaf Spot, Soybean Rust, Powdery Mildew, and Bean Pod mottle and Soybean Mosaic.

Effects Of Foliar Fungicides And Application Timing On Field Corn In Nebraska, 2011, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 2 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked with soybean as the previous year’s crop. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) was applied to …

Evaluation Of Application Timing Of Foliar Fungicides On Efficacy Of Field Corn At Ardc In Eastern Nebraska, 2011, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln Agricultural Research and Development Center near Mead, NE. Pioneer corn hybrid P0832XR was planted on 10 May in 30 in. rows with a target population of 30,000 plants/A. The trial area was disked in the early spring with corn as the previous year’s crop. A herbicide program of Lexar (3 pts/A) + Roundup PowerMax (22 fl oz/A) +AMS was applied to the trial. Nine treatments and a non-treated control were replicated five times in a randomized complete block design. Each plot was four rows (10 ft) wide …

Evaluation Of Application Timing Of Foliar Fungicides On Efficacy Of Field Corn In Central Nebraska, 2011, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 3 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked with a crop history of seven years of continuous corn. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) …

Efficacy Evaluation Of Foliar Fungicides In Field Corn With Low Disease Pressure In Central Nebraska, 2011, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 3 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked with a crop history of seven years of continuous corn. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) was …

Morphogenetic And Developmental Functions Of The Aspergillus Nidulans Homologues Of The Yeast Bud Site Selection Proteins Bud4 And Axl2, Haoyu Si, William R. Rittenour, Kaimei Xu, Mark Nicksarlian, Ana M. Calvo, Steven D. Harris

Department of Plant Pathology: Faculty Publications

The yeast bud site selection system represents a paradigm for understanding how fungal cells regulate the formation of a polarity axis. In Saccharomyces cerevisiae, Bud4 and Axl2 are components of the axial bud site marker. To address the possibility that these proteins regulate cellular morphogenesis in filamentous fungi, we have characterized homologues of Bud4 and Axl2 in Aspergillus nidulans. Our results show that Bud4 is involved in septum formation in both hyphae and developing conidiophores. Whereas Axl2 appears to have no obvious role in hyphal growth, it is required for the regulation of phialide morphogenesis during conidiation. In …

Efficacy Evaluation Of Foliar Fungicide Application Timing In Field Corn In Central Nebraska, 2011, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 3 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked with a crop history of seven years of continuous corn. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) …

Sunflower Disease Profiles I: Foliar Diseases, Robert M. Harveson, Loren J. Giesler, Tamra A. Jackson, Bo Liu, Stephen N. Wegulo, Kevin A. Korus

Department of Plant Pathology: Faculty Publications

Extension Circular 1900 (EC1900).

Photographs and disease descriptions of Viruses, Apical Chlorosis, Downy Mildew, Rust, Alternia Leaf Spot, and Bacterial Leaf Spot.

Natural Variation In Iron Use Efficiency And Mineral Remobilization In Cucumber (Cucumis Sativus), Brian M. Waters, Grace Troupe

Department of Agronomy and Horticulture: Faculty Publications

Aims: Iron (Fe) is an essential micronutrient, and plant-available Fe is often limited in alkaline soils. Fe deficiency chlorosis decreases plant growth and yield. Identification of germplasm with high and low Fe use efficiency will allow studies to better understand the genetic components for breeding Fe efficient varieties.

Methods: A screen using cucumber (Cucumis sativus) seedlings identified varieties that maintained contrasting levels of chlorophyll under Fe deficiency or limitation. A time course of mineral dynamics in cotyledons was conducted.

Results: The variety Ashley had the highest chlorophyll under Fe deficiency and per unit Fe in the leaf, while …

Tritimovirus P1 Functions As A Suppressor Of Rna Silencing And An Enhancer Of Disease Symptoms, Brock A. Young, Drake C. Stenger, Feng Qu, T. Jack Morris, Satyanarayana Tatineni, Roy French

Department of Plant Pathology: Faculty Publications

Wheat streak mosaic virus (WSMV) is an eriophyid mite-transmitted virus of the genus Tritimovirus, family Potyviridae. Complete deletion of helper component-proteinase (HC-Pro) has no effect on WSMV virulence or disease synergism, suggesting that a different viral protein suppresses RNA silencing. RNA silencing suppression assays using Nicotiana benthamiana 16C plants expressing GFP were conducted with each WSMV protein; only P1 suppressed RNA silencing. Accumulation of GFP siRNAs was markedly reduced in leaves infiltrated with WSMV P1 at both 3 and 6 days post infiltration relative to WSMV HC-Pro and the empty vector control. On the other hand, helper component-proteinase …

Evaluation Of Application Timing Efficacy Of Evito Fungicide On Field Corn In Nebraska, 2010, C. M. Schleicher, T. A. Jackson

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 61-69, rating of “good” (5 out of 9) for gray leaf spot and “very good” (3 out of 9) for common rust, was planted on 29 Apr in 30-in. rows with a target population of 30,000 plants/A. The trial area was disked the previous fall with a crop history of six years of continuous corn. Three treatments and a non-treated control were replicated six times in a randomized complete block design. Each plot was four …

Evaluation Of Foliar Fungicide Application Timing On Efficacy Of Field Corn At Wcrec In Western Nebraska, 2011, C. M. Schleicher, C. Langemeier, G. Kruger, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln West Central Research and Extension Center at North Platte, NE. NuTech corn hybrid 3A513, rating of 5 out of 9 (1=best, 9=worst) for gray leaf spot was planted on 10 May in 30 in. rows with a target population of 32,000 plants/A. The trial area was disked prior to planting with corn as the previous year’s crop. Furrows were built in season for flood irrigation. A herbicide program of Lumax (2.5 qt/A) + Atrazine (1 lb/A) + Glystar (20 oz/A) was applied on 25 Apr. 200 lb …

Evaluation Of Foliar Fungicide Application Timing On Efficacy Of Field Corn At Scal In Central Nebraska, 2011, C. M. Schleicher, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

A foliar fungicide efficacy timing trial was conducted at the University of Nebraska-Lincoln South Central Agricultural Laboratory near Clay Center, NE. DeKalb corn hybrid DKC 62-54, rating of “good” (6 out of 9) for gray leaf spot (GLS) and “excellent” (2 out of 9) for common rust (CR), was planted on 5 May in 30 in. rows with a target population of 32,000 plants/A. The trial area had soybean as the previous year’s crop. On 9 May before plant emergence, a herbicide program of Roundup (1 pt/A), Verdict (16 fl oz/A) and Atrazine (1 lb/A) was applied to the trial …

Soybean Disease Profiles Ii: Stem And Root Rot Diseases, Loren J. Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Kevin A. Korus, Bo Liu, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1904 (EC1904).

Photographs and disease descriptions of Brown Stem Rot (BSR), Charcoal Rot, Fusarium Wilt and Root Rot, Phytophthora Root and Stem Rot, Pod and Stem Blight, Phomopsis Seed Decay, Rhizoctonia Root and Cortical Rot, Sclerotinia Stem Rot, Seedling Blights, Soybean Cyst Nematode (SCN), Stem Canker, and Sudden Death Syndrome (SDS).

Corn Disease Profile Iii: Ear Rot Diseases And Grain Molds, Tamra A. Jackson-Ziems, Loren J. Giesler, Robert M. Harveson, Kevin A. Korus, Bo Liu, Stephen N. Wegulo

Department of Plant Pathology: Faculty Publications

Extension Circular 1901 (EC1901).

Under certain conditions, corn ear rot and grain mold diseases are common and can lead to loss of grain quality. Moldy grain can be docked or rejected at the elevator. Additionally, some ear and grain pathogens may produce secondary metabolites called mycotoxins, which are toxic to animals and humans consuming the contaminated grain. Mycotoxin-contaminated grain can also be docked or rejected. Mycotoxin production may start in the field and continue after harvest, or it may start during storage if mold infection begins there. When grain storage is necessary, drying grain to less than 15 percent moisture …