Plant Pathology Commons^™

Ecological Risks Of The Conventional Insecticide/Fungicide Seed Treatment Mixture Of Thiamethoxam And Mefenoxam In Soybean On Beneficial Insects, Carolina Camargo

Department of Entomology: Dissertations, Theses, and Student Research

The impact of neonicotinoid seed treatments on beneficial insects has been a controversial topic during the last years. While neonicotinoids are usually used as mixtures with systemic fungicides, few studies have examined the impact of the mixtures on beneficial insects. Pesticide mixtures can have synergistic, additive, or antagonistic effects on the toxicity of neonicotinoids on non-target species.

Thiamethoxam with mefenoxam is the most used neonicotinoid insecticide/fungicide mixture applied to soybean. Based on the systemic nature of thiamethoxam and mefenoxam, residues of this insecticide/fungicide mixture can be present in soybean vegetative and floral tissue with potential impacts to beneficial insects. This …

Proceedings Of The 43rd Annual Meeting, Southern Soybean Disease Workers (March 9-10, 2016, Pensacola Beach, Florida), Trey Price, Tom Allen, Travis Faske, Eduardo Chagas Da Silva

Southern Soybean Disease Workers: Conference Proceedings

Contents

Schedule

Southern United States Soybean Disease Loss Estimates for 2015. TW Allen, CA Bradley, JP Damicone, NS Dufault, TR Faske, CA Hollier, T Isakeit, RC Kemerait, NM Kleczewski, SR Koenning, HL Mehl, JD Mueller, C Overstreet, PP Price, EJ Sikora, TN Spurlock, and H Young

Soilborne Disease Symposium (Tom Allen, moderator)

Integrated management of sudden death syndrome. D Mueller, L Leandro, Y Kandel, C Bradley, M Chilvers, A Tenuta, and K Wise

Field screening for stem canker: an outdated exercise or a necessary service for soybean growers? K Rowe and T Kirkpatrick

Nematode associated diseases in soybean. C Overstreet, …

Demography And Disease Of The Rare Shrub Buckleya Distichophylla (Santalaceae) In Northeastern Tennessee, William Seth Ratliff

Undergraduate Honors Theses

Piratebush (Buckleya distichophylla (Nutt.) Torr.) is a rare, hemiparasitic shrub with the only extant populations in western North Carolina, northeastern Tennessee, and southwestern Virginia. The preferred natural hosts of piratebush, Carolina and eastern hemlocks, have seen sharp declines over the last decade due to the invasive hemlock woolly adelgid. Virginia pine, another important host of piratebush, is also susceptible to disease, specifically Cronartium appalachianum, a rust fungus for which piratebush is the secondary host. This study described and analyzed current demographic parameters of three Tennessee piratebush populations. Additionally, spatial patterns of disease and demographic characters were analyzed. These …

Canola: A Modern Crop For A Modern Era, Kenneth J. Roché

Doctor of Plant Health Program: Dissertations and Student Research

The University of Nebraska-Lincoln Doctor of Plant Health program is a professional doctorate program with a comprehensive approach to plants and agriculture. The program emphasizes a broad interdisciplinary education across all plant-related disciplines, practical learning, research, and experience through internships. For my final required internship, I worked as a senior agricultural research intern with Research Designed for Agriculture (RD4AG) in Montana. RD4AG is a contract research organization based in Yuma, AZ with over thirty-years of experience. During my three month internship at RD4AG in Montana, a large portion of my responsibilities centered on managing regulated canola trials that were undertaken …

Detecting Genomic Regions Responsible For Resistance In Arabidopsis, Valeria Cancino, Anjali Iyer-Pascuzzi, Rucha Karve

The Summer Undergraduate Research Fellowship (SURF) Symposium

Ralstonia solanacearum is a soil-borne plant root colonizing pathogen and the casual agent of bacterial wilt (BW) disease. BW leads to severe yield loss in a wide variety of agricultural commodity crops, such as tomato, banana, and pepper. In this study, we look at the plant-pathogen interaction between Ralstonia solanacearum and various ecotypes of Arabidopsis thaliana with the goal of finding resistant ecotypes. To identify resistant ecotypes, seeds are first sterilized and left to soak in the dark. Then the seeds are plated on agar media, transferred to a growth chamber, and allowed to grow for 5 days. On day …

Evaluation Of Control Strategies For The Spread Of Citrus Greening, Vicente Valle Martinez

Theses and Dissertations - UTB/UTPA

Huanglongbing, also known as citrus greening, is a vector-based disease in citrus (with no cure known to date) that has drastically affected the citrus production in Florida in less than a decade and has been recently detected in Texas and California. In this paper, an epidemic model of the spatial spread of the disease is implemented among commercial and residential groves by taking into consideration the diffusion patterns of the psyllid vectors. A system of differential equations resembling one for malaria infection in humans is derived to evaluate different control methods such as quarantine, treatment, removal, foliar treatment, and pest …

Characterization Of A Novel Clade Of Transporters In Phytophthora, Stephanie Padula, Paul F. Morris Dr, Howard Casey Cromwell Dr., Menaka Ariyaratne, Andrew Wagner

Honors Projects

The oomycete Phytophthora parasitica has a worldwide distribution and is an economically important pathogen of more than 100 species⁴. RNA-seq analysis showed that one gene, PPTG_16698 has the 5^th highest level of expression of all transport proteins in the zoospore stage, and is highly conserved throughout Phytophthora species. This project attempts to characterize the important biological role that PPTG_16698 plays in P. parasitica and other oomycetes. Three strategies have been implemented to accomplish this goal: growth analysis by heterologous expression in yeast, metabolite analysis in yeast, and construction of a GFP fusion protein to enable localization of …

Producing Quality Barley For The Malting Industry, Haley H. Oser Dph

Doctor of Plant Health Program: Dissertations and Student Research

The University of Nebraska – Lincoln Doctor of Plant Health program requires each student to fulfill a professional internship over the last summer of the program. For my internship, I worked as a Barley Scientist Intern for MillerCoors and Golden Malting in Golden, Colorado. During this internship I gained a fundamental understanding of malting barley production with a significant emphasis on grain quality. Barley produced for malting must fulfill strict industry quality standards before it is accepted by the head maltsters. These quality standards include: a high germination rate, low moisture content, protein content within an acceptable range and the …

Proceedings Of The 42nd Annual Meeting, Southern Soybean Disease Workers (March 11-12, 2015, Pensacola Beach, Florida), Craig Rothrock, Ed Sikora, Trey Price, Danise Beadle, Myra Purvis, Tom Allen, Loren Giesler

Southern Soybean Disease Workers: Conference Proceedings

Contents

Schedule

Southern United States Soybean Disease Loss Estimates for 2014. TW Allen, JP Damicone, NS Dufault, TR Faske, DE Hershman, CA Hollier, T Isakeit, RC Kemerait, NM Kleczewski, SR Koenning, HL Mehl, JD Mueller, C Overstreet, P Price, EJ Sikora, and H Young

Graduate student competition (Trey Price, moderator)

Effect of Secondary Nutrient Applications on Suppression of Charcoal Rot in Soybean. T Wilkerson, M Tomasu-Peterson, BR Golden, S Lu, AB Johnson, and TW Allen

Molecular Characterization of the G143A Mutation Leading to QoI Fungicide Resistance among Fungal Pathogens Causing Cercospora Leaf Blight and Purple Seed Stain of Soybean. S …

Bacterial Wilt Of Dry-Edible Beans In The Central High Plains Of The U.S.: Past, Present, And Future, Robert M. Harveson, Howard F. Schwartz, Carlos A. Urrea, C. Dean Yonts

Panhandle Research and Extension Center

Bacterial wilt, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens, was first recognized and described as a new dry bean disease near Redfield, South Dakota, after the 1921 growing season on the farm of the Office of Forage Investigations. The grower on this farm informed the federal investigators that he believed the disease to be the same one that killed 90% of his crop in 1920. For the 1921 season, he saved and planted the seed harvested from the previous year, resulting in an estimated 25% loss.

. . .

It is likely that wilt has “reappeared” and become widely established throughout …

Generation Of An Attenuated, Cross-Protective Pepino Mosaic Virus Variant Through Alignment-Guided Mutagenesis Of The Viral Capsid Protein, Godwill M. Chewachong, Sally A. Miller, Joshua J. Blakeslee, David M. Francis, Thomas Jack Morris, Feng Qu

School of Biological Sciences: Faculty Publications

Mild variants of many viruses are able to protect infected plants from subsequent invasion by more severe variants of the same viruses through a process known as cross-protection. In the past, the cross-protective viral variants were commonly derived from mild field isolates that were sometimes genetically heterogeneous, providing variable levels of crossprotection. Here, we report a novel approach to rapidly generate crossprotective variants of the tomato-infecting Pepino mosaic virus (PepMV) independently of the availability of mild field isolates. Our approach sought to attenuate PepMV by mutating less conserved amino acid residues of the abundantly produced capsid protein (CP). These less-conserved …

Spatial Distribution And Genetic Variability Of Reniform And Lance Nematodes In Cotton Agroecosystems, Claudia Holguin

All Dissertations

Rotylenchulus reniformis (reniform nematode) and Hoplolaimus columbus (Columbia lance nematode) are two of the main plant-pathogenic nematode species affecting cotton production in the United States. For the selection and implementation of effective management practices it is important to understand distribution patterns and population genetic structure of these two nematodes in cotton agroecosystems. In a three-year field study, the spatial distribution of reniform nematode was characterized in two commercial fields in South Carolina to determine the effects of relations with soil texture and crop rotation on reniform nematode distribution (Chapter 1). Results of this project suggest that population densities of reniform …

Panicum Mosaic Virus Complex And Biofuels Switchgrass, Catherine Louise Stewart

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

New switchgrass (Panicum virgatum L.) cultivars are being developed for use as a biofuel pyrolysis feedstock. Viral pathogens have been reported in switchgrass, but their importance in biofuel cultivars is not well known. In 2012 surveys of five switchgrass breeding nurseries in Nebraska, plants with mottling and stunting— symptoms associated with virus infection—had an incidence of symptomatic plants within fields as high as 59%. Leaves from 120 symptomatic plants were analyzed by ELISA for Panicum mosaic virus (PMV) and four other viruses known to infect switchgrass. Most samples (87%) were positive for PMV, and fewer than 8% for the …

Management Of Root Knot Nematode (Meloidogyne Incognita ) In Indiana Soybeans, David Edgardo Perla Martinez

Open Access Theses

The aim of this project was to evaluate different strategies for management of Root Knot Nematode (RKN) on soybean and tomato in Indiana. Seed treatments were evaluated under field and greenhouse conditions, but no effect on RKN populations was observed. Soybean lines evaluated for resistance to RKN under greenhouse conditions showed that six lines may be resistant to RKN. Four different commercial mustard cover crops were evaluated for their bio-fumigant impact on RKN populations in the production of tomato. Euruca sativa, Cv. Nemat was a poor host of RKN. A positive impact on the vigor of the tomato plants followed …

Proceedings Of The 41st Annual Meeting, Southern Soybean Disease Workers (March 5-6, 2014, Pensacola Beach, Florida), Edward Sikora, Clayton A. Hollier, Craig Rothrock, Myra Purvis, Danise Beadle, Stephen R. Koenning

Southern Soybean Disease Workers: Conference Proceedings

Contents

Schedule

Southern United Station Soybean Disease Loss Estimates for 2013. Compiled by SR Koenning

Graduate student paper competition (Ed Sikora, moderator)

Association of Phomopsis longicolla and Macrophomina phaseolina with zone lines in soybean roots at maturity. ML Zaccaron, JC Rupe, and RT Holland

Molecular Phylogenetic Redefinition of Cercospora kikuchii. S Albu, P Price, V Doyle, and R Schneider

The effects of salinity on Pythium rot of soybean. TJ Stetina, CS Rothrock, and JC Rupe

Distribution of Cercospora sojina and sensitivity to Qol fungicides in Mississippi soybean fields. J Standish, M Tomaso-Peterson, TW Allen, S Sabanadzovic, N Aboughanem-Sabanadzovic

Effect …

No 1 2013 Eggplant Variety Trial, Rebecca Brown

University of Rhode Island Vegetable Production Research Reports

Descriptions of eggplant varieties trialed at the Gardiner Crop Research Farm of URI, Kingston, RI

No3 2013 Melon Variety Trial, Rebecca Brown

University of Rhode Island Vegetable Production Research Reports

Descriptions of melon varieties, including disease ratings, trialed at the Gardiner Crop Research Farm of URI, Kingston, RI

Soil Microbial Community Distributions And Disease Suppressiveness In The Coastal Plain Of Georgia, Michael J. Sabula

College of Graduate Studies: Theses & Dissertations

This study compared the soil microbial communities of three vegetation types in the coastal plain of Georgia: 1. crop land actively in use for agricultural production, 2. transitional grassland in early stages of secondary succession, and 3. pristine unmanaged forest land. Microbial species diversity and quantities of microbial DNA were determined from each of these vegetation types at three separate locations near Statesboro, Georgia. Length heterogeneity PCR(LH-PCR) methods and subsequent analysis of fungal, bacterial, and metazoan communities by analysis of similarity (ANOSIM) revealed high within-group similarity by vegetation type, indicating land management intensity and vegetation cover is a strong determining …

The Role Of Soil Microorganisms In The Resistance Of Giant Ragweed, Horseweed, And Common Lambsquarters To Glyphosate, Jessica Renee Schafer-Bugg

Open Access Dissertations

Continuous glyphosate use has contributed to an increasing number of problematic glyphosate-resistant (GR) weeds. The mechanism of resistance in many GR weeds is poorly understood, in part, due to a poor understanding of how exactly glyphosate kills a plant. In previous research, the efficacy of glyphosate was demonstrated to be strongly influenced by root invading soil-borne microorganisms. However, this interaction among plants, glyphosate, and soil microorganisms has only been studied in a number of crop plants, but not in weed species. This is surprising since the soil biotic environment has a strong impact on the activity of this important herbicide. …

The History Of Trial Gardens, Hallie Schmidt

Horticulture and Crop Science

Essay explores the history of home gardening and seed industry in America and the conditions that led to the development of the All-America Selections.

Proceedings Of The 40th Annual Meeting, Southern Soybean Disease Workers (March 13-14, 2013, Pensacola Beach, Florida), Clayton A. Hollier, Tom Allen, Edward J. Sikora, Myra Purvis, Danise Beadle, Stephen R. Koenning

Southern Soybean Disease Workers: Conference Proceedings

Contents

Southern United States Soybean Disease Loss Estimates for 2012. Compiled by SR Koenning

Update on Detection and Management of QoI Fungicide Resistant Cercospora sojina, the Causal Agent of Frogeye Leaf Spot in Soybean. C Bradley, G Zhang, V Chapara, R Ming, F Zeng, H Young Kelly, and M Newman

Identification of Soybean Genotypes to Cercopsora sojina by Field Screening and Molecular Markers. A Mengistu and R Mian

Soybean Vein Necrosis Virus. D Hershman

Single Applications of Triazole Fungicides at R1 for Management of Cercospora Leaf Blight and Rust in Soybean. RW Schneider, CL Robertson, BM Ward, and EC …

Identification Of Sources Of Resistance To Damping-Off And Early Root/Hypocotyl Damage From Rhizoctonia Solani In Common Bean (Phaseolus Vulgaris L.), P. A. Peña, James R, Steadman, Kent M. Eskridge, Carlos A. Urrea

Panhandle Research and Extension Center

Rhizoctonia solani causes economically important root and hypocotyl diseases in common bean throughout the world. Root health is a vital factor in plant development and root diseases would negatively influence water and nutrient uptake as well as cause direct stand reduction and root rot damage to the crop. An efficient common bean screening method to evaluate damping-off and early root/ hypocotyl damage from R. solani was developed and used to identify dry bean lines with levels of resistance to this disease. Two sets of 163 and 111 lines previously evaluated for drought tolerance in Nebraska and Puerto Rico were evaluated …

Alternative Methods Of Control For Phytophthora Nicotianae Of Tobacco, Anna M. Holdcroft

Theses and Dissertations--Plant Pathology

Kentucky is the nation’s leading producer of burley tobacco and the crop’s most economically important disease is black shank, caused by Phytophthora nicotianae (Pn). Current management is effective, however, problems with expense and pathogen persistence are issues. Two alternative methods for control of Pn were examined: biofumigation and soil application of an organic, yeast fermentation‐derived product (Soil‐Set). Field studies in 2009 and 2010 found no effect on populations of fungi, disease severity of Pn, and yield between mustard‐ and wheat‐amended plots. Experiments in the greenhouse suggested that survival of Pn was impacted by biomass rather than biofumigation. Biofumigation is not …

Sorghum Transformation: Overview And Utility, Tejinder Kumar, Arlene Howe, Shirley Sato, Ismail M. Dweikat, Tom E. Clemente

Department of Agronomy and Horticulture: Faculty Publications

Over the past decade genomics resources available for sorghum have rapidly expanded (Paterson Int J Plant Genomics 2008:6, 2008), these resources, coupled with the recent completion of the genome sequence which is relatively small in size (730 Mb) (Paterson et al. Nature 457:551–556, 2009) makes sorghum a rather attractive species to study. Moreover, the USDA germplasm system maintains 42,614 accessions, of which more than 800 exotic landraces have been converted to day length-insensitive lines to facilitate their use in breeding programs. In addition, a set of EMS mutation stocks developed by the USDA Plant Stress and Germplasm Development Unit in …

Control Of Erwinia Tracheiphila In Cucumis Melo, John R. Caudle

Theses and Dissertations--Plant and Soil Sciences

Currently there is no control of bacterial wilt disease, Erwinia tracheiphila, in susceptible cucurbit crops, once infection of the plant occurs. Conventional and organic production systems rely on insecticide applications to kill the vectors, striped and spotted cucumber beetles, Acalymma vittatum and Diabrotica undecimpunctata, respectively, prior to transmission of the pathogen which indirectly controls the disease to some extent. Physical barriers such as row covers are used to exclude the vectors from plants prior to flowering; however, pollination requirements expose plants to potential infection. Experimental field plots were developed to test various enhanced organic production systems in an …

Survey Of Endosymbionts In The Diaphorina Citri Metagenome And Assembly Of A Wolbachia Wdi Draft Genome, Surya Saha, Wayne B. Hunter, Justin Reese, J. Kent Morgan, Mizuri Marutani-Hert, Hong Huang, Magdalen Lindeberg

School of Information Faculty Publications

Diaphorina citri (Hemiptera: Psyllidae), the Asian citrus psyllid, is the insect vector of Ca. Liberibacter asiaticus, the causal agent of citrus greening disease. Sequencing of the D. citrimetagenome has been initiated to gain better understanding of the biology of this organism and the potential roles of its bacterial endosymbionts. To corroborate candidate endosymbionts previously identified by rDNA amplification, raw reads from the D. citri metagenome sequence were mapped to reference genome sequences. Results of the read mapping provided the most support for Wolbachia and an enteric bacterium most similar to Salmonella. Wolbachia-derived reads were extracted using …

Amelioration Of Root Disease Of Subterranean Clover (Trifolium Subterraneum) By Mineral Nutrients, Tim Scanlon, Tiernan A. O’Rourke, Megan H. Ryan, Martin J. Barbetti, Krishnapillai Sivasithamparam

Journal articles

Subterranean clover (Trifolium subterraneum) is a key pasture legume across southern Australia and elsewhere. Decline in subterranean clover pastures was first recognised in Australia during the 1960s and manifests as an increase in weeds and a decrease in desirable legume species. While both root disease and poor nutrition contribute to subterranean clover pasture decline, the relationships between root disease and nutrition have not been determined. The objective of this study was to define these relationships. Field experiments were undertaken to determine the nutritional and pathogen status of soils and subterranean clover from three Western Australian field sites. Subsequently, …

Genetic Characterization Of North American Populations Of The Wheat Curl Mite And Dry Bulb Mite, Gary L. Hein, Roy French, Benjawan Siriwetwiwat, James W. Amrine

Department of Entomology: Faculty Publications

The wheat curl mite, Aceria tosichella Keifer, transmits at least three harmful viruses, wheat streak mosaic virus (WSMV), high plains virus (HPV), and Triticum mosaic virus (TriMV) to wheat (Triticum aestivum L.) throughout the Great Plains. This virus complex is considered to be the most serious disease of winter wheat in the western Great Plains. One component of managing this disease has been developing mite resistance in wheat; however, identification of mite biotypes has complicated deployment and stability of resistance. This biotypic variability in mites and differential virus transmission by different mite populations underscores the need to better understand …

High School Horticulture Curriculum, Margaret Maratsos

Horticulture and Crop Science

Horticulture is just one of the many topics covered in a high school agriculture curriculum, and yet, there are very few lesson plans or resources available to teachers for these classes specifically. The objectives of this project were to compile a set of lesson plans, lab plans, and tests that would emphasize interactive and investigative learning. The lesson plans were written in such a way that they reflected a certain set of standards, set down by the state of California, and were meant to serve as a bare outline of topics that would be discussed within a week’s worth of …

Seasonal Population Dynamics Of The Potato Psyllid (Hemiptera: Triozidae) And Its Associated Pathogen “Candidatus Liberibacter Solanacearum” In Potatoes In The Southern Great Plains Of North America, John A. Goolsby, John J. Adamczyk Jr., J. M. Crosslin, Noel N. Troxclair, J. R. Ancisco, Gerhard G. Bester, J. D. Bradshaw, Edsel D. Bynum Jr., L. A. Carpio, Don C. Henne, Ankush Joshi, Joseph E. Munyaneza, Pat Porter, Phillip E. Sloderbeck, J. R. Supak, C. M. Rush, F. J. Willett, B. J. Zechmann, B. A. Zens

Department of Entomology: Faculty Publications

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), and its associated pathogen “Candidatus Liberibacter solanacearum” (Ca. L. solanacearum), the putative causal agent of zebra chip (ZC) disease in potatoes (Solanum tuberosum L.), were sampled in commercial potato fields and untreated control plots for 3 yr in multiple locations in Texas, Kansas, Nebraska, and Colorado. Populations of the potato psyllid varied across years and across potato growing regions. However, the percentage of potato psyllids infected with Ca. L. solanacearum although variable across years, was consistently highest in the Lower Rio Grande Valley of Texas (LRGV), the reported overwintering …