Agronomy and Crop Sciences Commons^™

Population Dynamics Of Triticum Mosaic Virus In Various Host Species, Melissa S. Bartels

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

It has been established that RNA viruses should be genetically diverse, due to the high error rate of their RNA-dependent RNA polymerases and the lack of proof-reading capabilities. Plant RNA viruses are not as genetically diverse as expected. Evolutionary factors, such as purifying selection and bottlenecks that favor genetic stability, might be affecting plant viral populations. Otherwise RNA virus populations, with their potential for extreme diversity, might acquire a lethal number of mutations leading to the collapse of the population.

Triticum mosaic virus (TriMV) populations maintained in a controlled greenhouse environment displayed genetic stability. The mutation frequency per nucleotide of …

Fungicide Resistance In Botrytis Cinerea From Strawberry - Molecular Mechanisms And Management, Anja Grabke

All Theses

The United States is the largest producer of strawberries worldwide, generating approximately $2.4 billion worth of fruit each year. Strawberry production, however, is often threatened by pathogens. One of the most destructive fungal pathogens is Botrytis cinerea, the causal agent of gray mold disease. The control of gray mold in commercial fields is largely dependent on the application of fungicides, including the dicarboximide iprodione and the hydroxyanilide fenhexamid. Because both fungicides are prone to resistance development, a survey was conducted to determine the occurrence and prevalence of fungicide resistance. Single-spore isolates were collected from strawberry fields in Florida (for …

Efficacy Of Rice Insecticide Seed Treatments At Selected Nitrogen Rates For Control Of The Rice Water Weevil, Lissorhoptrus Oryzophilus Kuschel, Mallory Elise Everett

Graduate Theses and Dissertations

Seed-applied insecticides are the standard control method used to prevent rice water weevil (Lissorhoptrus oryzophilus Kuschel) injury to rice (Oryza sativa L.) roots, and often results in greater yields than rice that receives no seed-applied insecticide. Yield increases from seed-applied insecticides often occur even when insect pressure is low and should not cause yield loss. The research objective was to evaluate the effect of urea-nitrogen rate and seed-applied insecticide on number of rice water weevil larvae, nitrogen uptake and rice grain yield. Six trials were conducted at the Pine Tree Research Station (PTRS) and the Rice Research Extension Center (RREC) …

Application And Timing Effects Of Qoi And Dmi Fungicides And A Foliar Fertilizer On Overall Plant Health And Grain Yield In Corn, Jason Phillip Geis

Open Access Theses

The use of fungicides on corn has recently increased as a result of higher grain market prices, changes in cropping practices, higher disease incidence and severity, and the availability and marketing claims of new fungicides. Some of the marketed potential "plant health(TM)" benefits include improved tolerance to drought and heat, improved N utilization, and increased stalk strength. Previous studies have displayed delayed canopy senescence, changes in water use efficiency, and reduced ozone damage in controlled environments. Foliar fertilization has also increased in popularity in recent years due to an increase in grain prices, manufacturer claims, and product availability.

Large-scale field …

Effects Of Wheat Grain Moisture: Quality, Germination, And Relationship To Accumulated Growing Degree Days, Kirsten Thomas

Open Access Theses

Bread wheat (Triticum aestivum L.) is a cereal crop of global importance. As global demand increases, it is essential to increase the quality and efficiency of crop production. Harvesting wheat early provides an opportunity for increased grain quality, and it may also allow the grower to double-crop soybean ( Glycine max L.) after wheat more effectively. Our objectives were to determine if harvesting grain early, at high moisture would, 1) increase milling and baking quality and 2) improve germination potential. As a result of these objectives, we will develop a model to predict dry-down of wheat. Five soft red …

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

Development Of Fad7-1 Single Mutant Arabidopsis Thaliana Plants That Are Resistant To Aphids, Kaleb L. Vaughn, Carlos A. Avila, Carmen S. Padilla-Marcia, Fiona L. Goggin

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Aphids are a group of sap-feeding insects that attack most of the world’s crops. The loss of function of fatty acid desaturase7 (FAD7) in Solanum lycopersicum (tomato plant) induces aphid resistance that is dependent upon the accumulation of plant defense hormones such as salicylic acid (SA). Tomato lacks most of the genetic resources found in the model plant Arabidopsis (Arabidopsis thaliana). There is an analogous fad7-1 line of Arabidopsis; however, the line has a background mutation, the glabra-1 (gl1), that causes the absence of trichomes (small hairs), which are essential to plant defense. In order to study aphid resistance, a …

Pertumbuhan Bibit Batang Bawah Karet (Hevea Brasiliensis (Willd.) Mull.-Arg.) Klon Pr 261 Yang Diberi Fungi Mikoriza Arbuskula (Fma) Dan Pupuk Fosfat, Cucu Suherman, Ari Wahyudi

Jurnal Kultivasi

This Research aims to determine the effect of interaction between the dosage AMF and dosage of P fertilizer on growth of rootstock seedling of rubber Clone PR 261. The experiments started in April until August 2009 at Cikumpay Plantation, PT. Perkebunan Nusantara VIII, Purwakarta, West Java, with altitude ± 70 m above sea level. Randomize Block Design (RBD) with factorial pattern used in this experiment, consisted of two treatment factors and repeated three times. The first factor was the dosage of AMF, consisted of four dosages level, without AMF, 10 g/seedling, 15 g/seedling and 20 g/seedling. The second factor was …

Soybean (Glycine Max) Response To Imazosulfuron Drift And Carryover From Rice (Oryza Sativa), Sandeep Singh Rana

Graduate Theses and Dissertations

In the Midsouth, soybean is often grown in close proximity to rice or in rotation with rice. Herbicides used in rice can injure soybean via drift or carryover. Consequently, field trials were conducted to determine the response of soybean (cv. AG 4703) to imazosulfuron drift and carryover (at Fayetteville, Marianna, Keiser and Pine Tree, AR) from rice. To assess the potential for carryover, soybean was planted into rice fields treated the previous year with imazosulfuron (rotation study). To evaluate in-season sensitivity of soybean to imazosulfuron (tolerance study) relative to halosulfuron, a common sulfonylurea herbicide applied to rice, both imazosulfuron and …

Distribution And Control Of Glyphosate-Resistant Johnsongrass (Sorghum Halepense) In Arkansas Soybean, Dennis Brent Johnson

Graduate Theses and Dissertations

Johnsongrass, once the most persistent and troublesome grass weed of row crops throughout the southern U.S., has previously been confirmed resistant to the acetolactate synthase (ALS) and acetyl-coenzyme A carboxylase-inhibiting herbicides in the Midsouth and has recently evolved resistance to glyphosate in Arkansas. The goal of this research was to establish the geographical distribution of herbicide-resistant johnsongrass in Arkansas and to develop herbicide programs for controlling glyphosate-resistant johnsongrass in Arkansas soybean. Johnsongrass accessions were collected from 14 counties in the Mississippi River Delta region of Arkansas and screened for resistance to four of the most commonly used postemergence herbicides for …

Brassica Variety Trials 2012, Rebecca Brown

University of Rhode Island Vegetable Production Research Reports

Variety trials of broccoli, cauliflower and Brussels sprouts conducted in Kingston, RI, USA.

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 …

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 …

Resistance Screening And Control Options For Glyphosate-Resistant Palmer Amaranth (Amaranthus Palmeri) In Cotton (Gossypium Hirsutum), Ryan Christopher Doherty

Graduate Theses and Dissertations

In the mid-2000's, glyphosate-resistant Palmer amaranth biotypes began to emerge in many southern states. In 2006, glyphosate-resistant Palmer amaranth was identified in a field in Mississippi County, Arkansas. A greenhouse experiment was conducted in 2008 to screen Palmer amaranth accessions, collected in this survey, for glyphosate resistance. Inflorescence were collected from a total of 276 plants from fields were glyphosate failure occurred, representing 74 accessions in 14 counties, including Clay, Craighead, Crittenden, Greene, Jackson, Jefferson, Lawrence, Lee, Mississippi, Phillips, Poinsett, Randolph, St. Francis, and White Counties. Eight of the 74 accessions did not produce viable seed. In the greenhouse, 32 …

Environmental Triggers Of Winter Annual Weed Emergence And Management To Reduce Soybean Cyst Nematode Reproduction On Winter Annual Weed Hosts, Rodrigo Werle

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Winter annual weeds are becoming more common in many row crop fields in the midwestern USA. The impact of winter annual weeds in cropping systems is often overlooked because these weeds complete their lifecycle near the time of crop sowing. However, delayed soil warming, competition for nutrients during initial establishment of the main crop, difficult planting operations, and yield loss are some of the problems caused by dense mats of winter annual weeds. Moreover, some of these weeds have been reported as alternative hosts for pests such as the soybean cyst nematode (Heterodera glycines, SCN), considered the most …

False Smut Of Rice: Histological Analysis Of Infection, Liem Thi Thanh Nguyen

Graduate Theses and Dissertations

False smut of rice, caused by Ustilaginoidea virens (Cooke) Takahashi (Teleomorph: Villosiclava virens), has become a common disease in most major rice growing regions throughout the world. Considerable confusion exists regarding the infection process and the disease cycle. Therefore, a clearer understanding of pathogenesis caused by Ustilaginoidea virens is critical for future efforts to develop genetic and chemical tools to manage false smut in Arkansas and other regions of the world. The overall goal of this research was to clarify the infection process underlying false smut, with emphasis on comparing and contrasting the histological basis of root and foliar infections. …

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, …

Effects Of Meloidogyne Incognita, Soil Physical Parameters, And Thielaviopsis Basicola On Cotton Root Architecture And Plant Growth, Jianbing Ma

Graduate Theses and Dissertations

The root-knot nematode, Meloidogyne incognita, and the seedling pathogen, Thielaviopsis basicola, commonly co-exist in Arkansas cotton fields and may interact resulting in increased losses. The primary objective of this research was to evaluate the effects of soil physical parameters on these soilborne pathogens and cotton growth in controlled environmental, field, and microplot studies. Controlled environmental experiments used two soil bulk densities and four pathogen treatments: non-infested soil, soil infested with M. incognita or T. basicola and soil infested with both pathogens. The results indicated bulk density generally did not affect seedling growth or disease since soils had low penetration resistance …

Strawberry Growth, Yield, Fruit Nutrition, And Control Of Verticillium Wilt With Pre-Plant Soil Fumigants, Ozone, And Biological Control, Justin J. Scurich

Master's Theses

Verticillium wilt is a widespread soilborne disease of strawberry historically controlled by soil fumigation with methyl bromide (MB). MB was banned by the United Nations in 1995 and will be completely phased out by 2015. Research has concentrated on alternative methods of disease control without finding a single alternative able to replace MB in widespread disease control and yield increase. For the current study, strawberries were greenhouse grown in container pots filled with soil from both infested and non-infested areas of a commercial strawberry field in Watsonville, CA. Treatments included pre-plant soil fumigation with commercially available formulations of methyl bromide, …

Determining The Virulence Of Corn Pathogen Fusarium Verticillioides Utilizing Deletion Mutants Lacking Genes Fv_00027 Or Fv_Nps6, Abigail Zieman

Honors Program Theses

Fusarium verticillioides is an important fungal pathogen of com. Many pathogens have virulent genes which are genes that increase infectivity of the pathogen. After a bioinformatics study, it was determined that genes Fv _ 00027 and Fv _ NPS6 are potential virulent genes in F. verticillioides. To determine if either gene ·contributes to the virulence of the fungus, deletion mutants of F. verticillioides were created lacking either Fv _ 00027 or Fv _ NPS6 genes. These deletion mutants were utilized in an optimized com assay to determine the effect of infectivity on com. To test these deletion mutants, com seeds …

Gata-Family Transcription Factors In Magnaporthe Oryzae, Cristian F. Quispe

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The filamentous fungus, Magnaporthe oryzae, responsible for blast rice disease, destroys around 10-30% of the rice crop annually. Infection begins when the specialized infection structure, the appressorium, generates enormous internal turgor pressure through the accumulation of glycerol. This turgor acts on a penetration peg emerging at the base of the cell, causing it to breach the leaf surface allowing its infection.

The enzyme trehalose-6- phosphate synthase (Tps1) is a central regulator of the transition from appressorium development to infectious hyphal growth. In the first chapter we show that initiation of rice blast disease requires a regulatory mechanism involving an …

Biology, Systematics, Phylogenetic Analysis And Dna Character-Based Species Diagnosis Of The False Root-Knot Nematode Nacobbus Aberrans (Thorne, 1935) Thorne & Allen 1944 (Nemata: Pratylenchidae), Angel Ramirez-Suarez

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The False Root-Knot nematode Nacobbus aberrans is a plant parasitic nematode that causes yield losses in several crops and plant protection agencies have established regulations to prevent infestations from spreading to new agricultural areas. The taxonomic status of the nematode has been the subject of controversy due to wide degree of variation exhibited by the species. This variability has led to the suggestion that N. aberrans is actually a species complex rather than a single species. In order to test this hypothesis, we compared twelve N. aberrans populations, which include isolates from western Nebraska, two distinct regions of Mexico and …

Fusarium Head Blight: Winter Wheat Cultivar Responses And Characterization Of Pathogen Isolates, John Fredy Hernandez Nopsa

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Fusarium Head Blight (FHB) is a destructive disease of wheat (Triticum aestivum L). FHB reduces yield and grain quality and causes accumulation of the mycotoxin deoxynivalenol (DON) in grain. Cultivar resistance is one of the most effective management strategies for FHB. Experiments were conducted to 1) identify winter wheat cultivars with resistance to FHB and DON accumulation, 2) determine the effect of winter wheat cultivar on the relationship between FHB and DON concentration, and 3) identify the major species of Fusarium causing FHB in Nebraska and characterize its isolates. Differences (P ≤ 0.05) were detected among cultivars in …

Environmental Variables Influencing The Severity Of Pierce's Disease In California Grapevines, Christopher James Boisseranc

Master's Theses

This project was designed to correlate environmental variables with the development of Pierce’s Disease (PD), an infection caused by the gram negative bacterium Xylella fastidiosa (Xf), in grapes (Hopkins et al. 2002). PD is one of the most difficult crop pathogens to manage because it is vectored by insects and its continued presence in the vine is usually fatal. PD is influenced by the interaction of host, disease and vector, and probably many other environmental variables. The general objective was to study and identify the most important variables involved in the expression of Pierce’s Disease.

Over a two year period, …

Crop Updates 2010 - Crop Specific, Hugh J. Beckie, Wallace Cowling, T. N. Khan, K. Adhikari, K. Siddique, J. Garlinge, L. Smith, S. Morgan, C. Boyd, Ian Pritchard, Chris Veitch, Alan Harris, Tony Leonforts, Murray Blyth, Shari Dougal, Kristy Hobson, Ben Curtis, Doug Sawkins, D. Stephens, Ciara Beard, Kith Jayasena, Kazue Tanaka, Anne Smith, Brenda Coutts, Roger Jones, Jean Galloway, Pip Payne, Tess Humphreys, William Macleod, Ravjit Khangura, M. Aberra, H. Mian, Geoff Thomas, Dusty Severtson, Peter Mangano, Monica Kehoe, Madeline A. Tucker, Neil Barker, Robert Loughman, Larisa Cato, Ken Quail, Mohammad Amjad, Mark Seymour, Justin Kudnig, Mark Thompson, Anton Mannes, Michael Uttley, Chris Fletcher, Andrew Etherton, Nick Joyce, Kate Light, Peter Hamblin, Michael Lamond, Alan Meldrum, Wayne Parker, Steve Penny Jr, Sarah Ellis, Brenda Shackley, Christine Zaicou, Shajahan Miyan, Darshan Sharma, Ben Curtis, Greg Shea, Bevan Buirchell, David Harris, Bob French

Crop Updates

This session covers twenty four papers from different authors:

PLENARY

1. Challenges facing western Canadian cropping over the next 10 years, Hugh J Beckie, Research Centre, Agriculture and Agri-Food Canada, Saskatoon,

Saskatchewan

CROP SPECIFIC

Breeding

2. The challenge of breeding canola hybrids – new opportunities for WA growers, Wallace Cowling, Research Director, Canola Breeders Western Australia Pty Ltd

3. Chickpea 2009 crop variety testing of germplasm developed by DAFWA/CLIMA/ICRISAT/COGGO alliance. Khan, TN1,3, Adhikari, K1,3, Siddique, K2, Garlinge, J1, Smith, L1, Morgan, S1 and Boyd, C1 1Department …

Crop Updates 2010 - Weeds, Lorinda Hunt, Andrew Blake, Catherine Borger, Glen Riethmuller, Abul Hashem, Harmohinder Dhammu, David Nicholson, Vince Lambert, Russell Quartermaine, Roberto Busi, Todd Gaines, Sudheesg Manalil, Stephen Powles, Aik Cheam, Siew Lee, Peter Newman, Greg Doncon, Steve Davies, Michael Walsh, John Moore, Murray Gillespie, Sally Peltzer, Alex Douglas

Crop Updates

This session covers eighteen papers from different authors:

Herbicides

1. Herbicide control of slender iceplant, Lorinda Hunt, and Andrew Blake Department of Agriculture and Food

2. Herbicide tolerance of saltbush and bluebush, Lorinda Hunt, and Andrew Blake Department of Agriculture and Food

3. Chemical control of windmill grass, Catherine Borger, Glen Riethmuller and Abul Hashem, Department of Agriculture and Food

4. Use high water rates when applying pre-seeding herbicides to fields with high stubble density, Catherine Borger and Abul Hashem, Department of Agriculture and Food

5. Herbicide tolerance of lupins – influence of soil type and …

Crop Updates 2010 - Farming Systems, Christopher R. Newman, Jonathan England, Stephen Gherardi, Mohammad Amjad, David Ferris, Phil Ward, Roger Lawes, Tim Wiley, Perry Dolling, Philip Barrett-Lennard, John Kirkegaard, Susan Sprague, Hugh Dove, Walter Kelman, Peter Hamblin, Brad Nutt, Angelo Loi, Wayne Parker, Glen Riethmuller, Ken Flowers, Neil Cordingley, Shane Micin, Senthold Asseng, Peter Mcintosh, Mike Pook, James Risbey, Guomin Wang, Oscar Alves, Ian Foster, Imma Farre, Nirav Khimashia, W. Anderson, D. Beard, J. Blake, R. Grieve, M. Lang, J. Lemon, R. Mctaggart, D. Gray, M. Price, D. Stephens, P. Carmody, Doug Abrecht, Greg Kirk, Peter Rowe, Comeron Weeks, Peter Tozer, Derk Bakker, Frank D'Emden, Quenten Knight, Luke Marquis, Roger Mandel

Crop Updates

This session covers twenty papers from different authors:

Pests and Disease

1. Preserving phosphine for use in Grain Storage Industry, Christopher R Newman, Department of Agriculture and Food

Farming Systems Research

2. Demonstrating the benefits of grazing canola in Western Australia, Jonathan England, Stephen Gherardi and Mohammad Amjad, Department of Agriculture and Food

3. Buloke barley yield when pasture-cropped across subtropical perennial pastures, David Ferris, Department of Agriculture and Food, Phil Ward and Roger Lawes, CSIRO

4. Is pasture cropping viable in WA? Grower perceptions and EverCrop initiatives to evaluate, David Ferris, Tim Wiley, Perry Dolling …

Whole Genome Wide Expression Profiles Of Vitis Amurensis Grape Responding To Downy Mildew By Using Solexa Sequencing Technology, Jiao Wu, Yali Zhang, Huiqin Zhang, Hong Huang, Kevin M. Folta, Jiang Lu

School of Information Faculty Publications

Background: Downy mildew (DM), caused by pathogen Plasmopara viticola (PV) is the single most damaging disease of grapes (Vitis L.) worldwide. However, the mechanisms of the disease development in grapes are poorly understood. A method for estimating gene expression levels using Solexa sequencing of Type I restriction-endonuclease-generated cDNA fragments was used for deep sequencing the transcriptomes resulting from PV infected leaves of Vitis amurensis Rupr. cv. Zuoshan-1. Our goal is to identify genes that are involved in resistance to grape DM disease.

Results: Approximately 8.5 million (M) 21-nt cDNA tags were sequenced in the cDNA library derived from PV pathogen-infected …