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Evaluation Of Soybean [Glycine Max (L.) Merr.] Cultivar Response To Prophylactic Fungicide Application, Steven B. Stoker

Theses and Dissertations

Soybean growers in the southern United States commonly deal with disease issues that can limit yield potential. As a result, growers have adopted prophylactic fungicide application targeted at specific growth stages as a standard management practice. However, yield responses to prophylactic applications have become sporadic over time. One major change that has occurred is adoption of cultivars with improved disease tolerances. Therefore, the objective of this research was to evaluate yield response of cultivars representing multiple genetic backgrounds to fungicides applied prophylactically at the R4 soybean growth stage. Experiments were conducted in 2020 and 2021 to determine the yield impact …

Micronutrient Concentration Effects On Lettuce Growth And Susceptibility To Pythium, Kalyn M. Helms

Graduate Theses and Dissertations

In hydroponic production waterborne pathogens such as Pythium are ubiquitous and continually threaten a wide range of Controlled Environment Agriculture (CEA) crops in hydroponic production, including but not limited to: lettuce, spinach, basil, arugula, cucumber, tomato, sweet pepper, roses, chrysanthemums, and cannabis (Sutton et al., 2006; Gull, 2002; McGehee and Raudales, 2021; Gillespie, 2020). Despite extensive sanitation measures, disease control in hydroponics is fallible and requires constant surveillance and management to minimize outbreaks (Sutton et al., 2006). A potential disease suppression strategy is to increase micronutrient concentrations within hydroponic systems to naturally strengthen plant defenses against pathogens such as Pythium. …

Comparative Genomics And Virulence Studies Of Streptomyces Soil Rot And Scab Pathogen Species, Natasha Soares

LSU Doctoral Dissertations

Comparative genomic analyses were performed to gain insights into the organization and content of the genome of Streptomyces ipomoeae, the soil rot pathogen that infects sweetpotatoes. Unlike Streptomyces scab pathogens, the thaxtomin phytotoxin gene cluster (txt) in S. ipomoeae does not appear to reside within a genomic island and has diverged from its scab pathogen counterparts. Increased usage of the rare TTA codon, particularly for the txt cluster, suggests greater translational control by the bldA tRNA in S. ipomoeae. Orthologous gene searches and secondary metabolite profiling yielded ortholog groups and metabolite gene clusters that were exclusive …

Using Uav Technology Paired With Multispectral Cameras To Assess Crown Rust Epidemics In Oats, Turner A. Graham

LSU Master's Theses

Crown rust, caused by Puccinia cornonata f. sp. avenae, is a common disease of oats (Avena sativa) found virtually everywhere oats are cultivated. This disease has caused yield losses of 10 to 40% worldwide. Early detection is important for effective management. A more recently utilized technology in agriculture is unmanned aerial vehicles (UAVs). UAVs, or drones, equipped with cameras are now being used as a resource to take images of fields to identify pests and other issues that may be occurring. Normalized differentiated vegetative index (NDVI) is a numerical indicator used to determine the vegetative health of …

The Virome Of Peony And The Population Structure Of Its Most Prominent Viruses, Cullen Shaffer

Graduate Theses and Dissertations

Peony (Peonia lactiflora, Pall.) is a popular ornamental that has been cultivated for millennia. Due to its popularity, plant material is frequently moved across international borders allowing for the spread of viruses. The virome of several peony plants was investigated and four viruses; namely Amazon lily mild mottle virus (ALiMMV), Cycas necrotic stunt virus (CNSV), Gentian Kobu-sho associated virus (GKaV) and Lychnis mottle virus (LycMoV) were detected for the first time in the Western Hemisphere. Incidence ranged from a few plants for ALiMMV to near universal infection for CNSV. GKaV was found in individuals that were infected with Lemoine’s disease …

Population Structure And Reproductive Biology Of Monilinia Vaccinii-Corymbosi (Reade) Honey In Lowbush Blueberry In Maine, Katherine A. Ashley

Electronic Theses and Dissertations

Lowbush blueberry, Vaccinium angustifolium Aiton, is both an economically and culturally important crop in Maine, being one of the few endemic crops to North America. The fungus Monilinia vaccinii-corymbosi (Mvc) causes mummy berry disease and is a significant pathogen of both highbush (Vaccinium corymbosum) and lowbush blueberries. While impacts of this disease are not regularly documented, it is estimated that 30-50% of the yield in an unmanaged field can be lost because of Mvc. This disease is typically managed with fungicides or burning of the field during years when the field is pruned, however, the impacts to the …

Natural Selection For Disease Resistance In Hybrid Poplars Targets Stomatal Patterning Traits And Regulatory Genes., Karl Christian Fetter

Graduate College Dissertations and Theses

The evolution of disease resistance in plants occurs within a framework of interacting

phenotypes, balancing natural selection for life-history traits along a continuum of

fast-growing and poorly defended, or slow-growing and well-defended lifestyles. Plant

populations connected by gene flow are physiologically limited to evolving along a

single axis of the spectrum of the growth-defense trade-off, and strong local selection

can purge phenotypic variance from a population or species, making it difficult to

detect variation linked to the trade-off. Hybridization between two species that have

evolved different growth-defense trade-off optima can reveal trade-offs hidden in either

species by introducing phenotypic and …

The Role Of Calcium In Pathogen Defense Responses In The Moss Mnium Cuspidatum, Morgan Blake

Undergraduate Honors Thesis Collection

When exposed to stress, whether that be by pathogen, thermal or weather changes, or other components of the environment, plants employ a variety of defense mechanisms depending on the severity of the stress. When attacked by a pathogen, the moss Mnium cuspidatum utilizes an innate, basal response followed by hypersensitive response (HR) and systemic acquired resistance (SAR). Calcium is known to be involved in signaling cascades that mediate defense responses in other organisms. In the present study, lanthanum nitrate (LaNO3), methoxyerapamil (D600), and ethylene glycol tetraacetic acid (EGTA) were used to inhibit the presence of calcium in M. cuspidatum in …

Pythium: Characterization Of Resistance In Soybean And Population Diversity, Keiddy Esperanza Urrea Romero

Graduate Theses and Dissertations

Pythium spp. are an important group of pathogens causing stand losses in Arkansas soybean production. New inoculation methods and advances in molecular techniques allow a better understanding of cultivar resistance and responses of Pythium communities to cultural practices. The objectives of this research were to i) characterize the resistance of soybean to P. aphanidermatum with two phenotyping assays that evaluated the seed rot phase of the disease; and ii) understand the effect of long term crop rotation on species diversity and iii) to determine the effect of location, temperature and continuous soybean and soybean-rice rotation on Pythium spp. diversity in …

The Pythium Suppressive Ability Of Glomus Intraradices In Cherry Tomato Propagation, Stanley Graham

Biological Sciences

No abstract provided.

Effects Of Iron On Cercospora Leaf Blight Of Soybean, Eduardo Chagas Ferreira Da Silva

LSU Master's Theses

Cercospora leaf blight (CLB) of soybean caused by Cercospora kikuchii is an important disease in Lousiana. Preliminary screening of foliar applications of the micronutrients Fe, Mn, Cu, Zn, B, Mo and Al, showed that Fe decreased CLB severity consistently. The objective of this work was to test the effects of commercial formulations of Fe, Manny Plex Fe and Fe EDTA (Brandt Consolidated, Springfield, IL) on leaf colonization by C. kikuchii, symptom development (blight and purple leaves), and yield. Four rates of Manny Plex Fe and four rates of Fe EDTA were applied to field plots at R5 growth stage. Leaf …

Spatial Distributions Of Rhizoctonia Species In Soybean Fields Undergoing Annual Rotations With Rice, Terry Neil Spurlock

Graduate Theses and Dissertations

Aerial blight is caused by Rhizoctonia solani AG1-IA. This pathogen also causes sheath blight of rice. In Arkansas, many soybean and rice fields undergo an annual rotation of these two crops which facilitates a continuous source of inoculum from one year to the next. Aerial blight is a two stage disease in that R. solani AG1-IA colonizes the plant during the early vegetative growth stages and then aerial blight develops after the soybean canopy closes in the later reproductive stages of development. As a result of the upper portion of the canopy often being asymptomatic, significant yield loss can occur …

Pathogen Induced Hypersensitive Response And Systemic Acquired Resistance In The Moss Amblystegium Serpens, Collin Elliot Bowman

Undergraduate Honors Thesis Collection

The moss Amblystegium serpens and the pathogenic fungus Pythium irregulare were used to study plant-pathogen interactions in a non-vascular plant. The major findings in this report include that P. irregulare does infect A. serpens but entire moss death was not noted, 25°C is the optimum temperature for P. irregulare appressoria formation, most appressoria were found on A. serpens leaves, and the SAR response within A. serpens seems to be reducing the number of P. irregulare penetrated moss cells. Future research on the pathogen defense mechanisms of A. serpens is important and promising. When we elucidate these complex chemical processes in …

Simplicillium Lanosoniveum, A Mycoparasite Of Phakopsora Pachyrhizi And Its Use As A Biological Control Agent, Nicole A. Ward

LSU Doctoral Dissertations

In 2007, a filamentous fungus was recovered from sori of soybean rust (SBR), caused by Phakopsora pachyrhizi, collected from Louisiana and Florida. This fungus was identified as Simplicillium lanosoniveum on the basis of ITS sequence data and morphological traits. Simplicillium lanosoniveum was found coiling within sori and around urediniospores and showed a trophic attraction to rust sori, extending from sorus to sorus. In co-inoculated soybean leaves, the fungus did not grow or establish on leaf surfaces until sori erupted. Similarly, S. lanosoniveum colonized within 3 days and sporulated within 4 days on leaves showing disease symptoms. In field studies, when …

A Comparison Of Soil And Corn Kernel Aspergillus Flavus Populations: Evidence For Niche Specialization, Rebecca Ruth Sweany

LSU Master's Theses

Aspergillus flavus is an opportunistic fungal pathogen that infects peanuts, cotton, corn and tree nuts. Aspergillus flavus is a major problem globally due to the production of acutely toxic and carcinogenic aflatoxins. Louisiana climatic conditions lead to annual threats of corn aflatoxin contamination. The purpose of this study was to determine the specific ability of different strains of A. flavus to infect corn. Five soil samples and 10 corn ears were collected from each of seven corn fields throughout Louisiana. In addition, Francis Deville of Monsanto Company collected 7, 6, 2, and 4 soil samples and corn ears from four …

Studies On Control Of Root Rot And Dieback Of Camellias ., Luther Willis Baxter

LSU Historical Dissertations and Theses

No abstract provided.

Rhizoctonia Aerial Blight Of Lespedeza., William Hugh Stroube

LSU Historical Dissertations and Theses

No abstract provided.

Studies On The White Tip Disease Of Rice., Edwin Harkness Todd

LSU Historical Dissertations and Theses

No abstract provided.

Studies On The Cause And Transmission Of A Louisiana Citrus Disease Similar To Tristeza., Charles Adam Schexnayder

LSU Historical Dissertations and Theses

No abstract provided.

Studies Of Vetch Anthracnoses., Norman Louis Horn

LSU Historical Dissertations and Theses

No abstract provided.

An Etiological And Host Range Study Of Celery Mosaic In Utah, Dennis H. Hall

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Celery mosaic is a virus disease of major economic importance in Utah. In years of severe epiphytotics, it has been a limiting factor in celery production. In 1947 losses due to this disease were estimated to exceed 8 per cent of the total crop. This estimate does not include losses resulting from reduction in grade or from plants discarded in the packing sheds. The celery acreage in Utah dropped from a high of 950 acres in 1946 to 750 acres in 1947 and dropped again in 1948 to 420 acres. Leaders in the industry attributed this reduction in acreage, in …

Two Fungus Diseases Of Soybeans., Quintin Lee Holdeman

LSU Historical Dissertations and Theses

No abstract provided.

Studies On Method Of Infection And Control Of The Red Rot Fungus Of Sugarcane., Rene John Steib

LSU Historical Dissertations and Theses

No abstract provided.

Studies Of Black-Scale Disease Of Easter Lily., Frank J. Reynolds

LSU Historical Dissertations and Theses

No abstract provided.

Leaf Diseases Of Sorghum., Douglas C. Bain

LSU Historical Dissertations and Theses

No abstract provided.

Hot Water Treatment Of Sugarcane., Chuin Shuh Loh

LSU Historical Dissertations and Theses

No abstract provided.

Seed Treatment For The Control Of Bean Blight., Kermit William Kreitlow

LSU Historical Dissertations and Theses

No abstract provided.