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Characterization Of Colletotrichum Nymphaeae Isolates From Apple With Reduced Sensitivity To Fluazinam And Tebuconazole, Rulyu Meng

All Theses

Apple bitter rot is caused by Colletotrichum nymphaeae and other Colletotrichum species and management relies primarily on synthetic pesticides. Very few fungicides are effective against the disease and resistance has further limited their usefulness. A recent study indicated relatively low EC₅₀ values (the concentration required to inhibit 50% of mycelial growth in vitro) of C. nymphaeae isolates from Brazilian apples to fluazinam and tebuconazole, two fungicides that are not routinely used for bitter rot control. Isolates on opposite sides of the sensitivity range were designated either sensitive (lowest EC₅₀ values) and reduced-sensitive (highest EC₅₀ values). The objective …

Unmanned Ground Vehicle Proximal Sensing For Forage Biomass Production Estimations, Curtis Erwin

All Theses

A large increase in productivity could be realized by small increases in efficiency and utilization on grasslands due to their large area. Pre-harvest biomass estimations can help forage producers make better informed management decisions. Producers of dry hay and hay silage can better identify plant growth stages and the optimal time to harvest. Grazers can better determine the most efficient number of animals and stocking density. The goal of this study was to create a novel pre-harvest biomass estimation method utilizing compressed height combined with an unmanned ground vehicle (UGV). A compression plate named a “compression ski” was constructed and …

In Vitro Rooting Techniques In Prunus Spp. For Propagation And Disease Screening For Armillaria Root Rot (Arr) Resistance, John Lawson

All Theses

Prunus is a genus widely cultivated to produce edible fruit including almond (P. amygdalus), peach (P. persica (L.) Batsch), cherries (P. avium and P. cerasus), among others. The cultivation of Prunus is economically important for several regions of the United States and relies on appropriate cultivars and rootstocks that are adapted to a growing region. Encroaching plant pathogens are forcing breeders to use sexually compatible germplasm from related species for introgression of novel alleles that confer tolerance or resistance. This is especially true in the rootstock breeding where interspecific hybridization is often used …

Addressing Meloidogyne Enterolobii Spread In The Sweetpotato Industry: Development Of A High Throughput Survey Detection Method For Root-Knot Nematodes And Quantification Of M. Enterolobii Damage On Storage Roots In Long-Term Assays, Julianna Culbreath

All Theses

Meloidogyne enterolobii is an aggressive root-knot nematode (RKN) species that has emerged as a significant pathogen of sweetpotato in the Southeastern US. Meloidogyne enterolobii is spread through the movement of infected ‘seed’ sweetpotatoes used for propagation, and the RKN resistance in commercial sweetpotato cultivars has proven ineffective against this nematode. This has prompted regulatory agencies to impose quarantines on regions infected with M. enterolobii. Sweetpotato storage roots can be rendered unmarketable due to M. enterolobii infection, resulting in potential overall yield loss. Visual detection of RKN in sweetpotato can be unreliable, and further distinguishing M. enterolobii from other RKN species …

Characterization Of Colletotrichum Nymphaeae Isolates, Causal Pathogen Of Apple Bitter Rot, With Reduced Sensitivity To Fluazinam And Tebuconazole, Rulyu Meng

All Theses

Apple bitter rot is caused by Colletotrichum nymphaeae and other Colletotrichum species and management relies primarily on synthetic pesticides. Very few fungicides are effective against the disease and resistance has further limited their usefulness. A recent study indicated a relatively low range of EC₅₀ values (the concentration required to inhibit 50% of mycelial growth in vitro) of C. nymphaeae isolates from Brazilian apples to fluazinam and tebuconazole, two fungicides that are not routinely used for bitter rot control. Isolates on opposite sides of the range were designated either sensitive (lowest EC₅₀ values) and reduced sensitive (highest EC_{50 …}

The Influence Of Water Stress And Rootstocks On Nutrient Uptake And Gas Exchange Of Young Peach Trees, Naif Alshammari

All Theses

Young peach trees are often rainfed in the southeastern U.S. and periods of dry weather can cause tree water deficit that can be detrimental to orchard productivity. There is a lack of understanding of the influence of water regimes and rootstocks on the nutritional status and gas exchange of the peach tree. Most peach growers in Southeastern United States do not irrigate their young peach trees because they do not produce fruit until the third leaf. In this region, peach growers use Guardian as a rootstock, although MP-29 is also interesting for growers with orchards that have Armillaria root rot …

Identifying Temporal Sensitivity Of Poinsettia Flowering To High Temperatures, Paul Millar

All Theses

High temperatures can cause delayed flowering in poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch), a phenomenon known in the industry as heat delay. The poinsettia wholesale market is concentrated to a relatively brief period from early-November through early-December putting growers at risk to heat delay. This problem is compounded by the unusual weather patterns created by climate change. The objective of this thesis was to identify periods in which poinsettia flowering is sensitive to high temperatures. First, the weeks within the growing season when the plants were sensitive to high temperatures were identified (Chpt. 2). Then within those sensitive weeks, …

Potassium Level Prediction Of Peach Tree Leaves Using A Hyperspectral Camera And Multivariate Analysis, Megan Io Ariadne Salimbangon Abenina

All Theses

The use of hyperspectral imaging is a valuable piece of technology used in precision agriculture. Hyperspectral imaging system could help farmers and researchers alike in analyzing tissue samples quicker compared to the current way of running a plant tissue analysis on the different nutrient levels that often takes time in generating results. The objective of this research was to measure the potassium level of peach trees using its leaves with a hyperspectral camera. The Senop HSC-2 was used to capture images of peach tree leaves during the fall of 2020 and 2021. The collected data were used to create a …

Pre-Breeding Of Kale (Brassica Oleracea Var. Acephala) – Organic Adaptation And Shelf Life, Craig Reda

All Theses

Kale (Brassica oleracea var. acephala) is a nutritionally rich leafy green that that contains vitamins, minerals, and prebiotic carbohydrates. As a popular organic crop, kale accounted for 1.3% of total US organic produce sales in 2020, a market valued at over 17 billion USD. However, organic production is limited by its inability to use synthetic pesticides and fertilizers and suffers from decreased yield when compared to conventional agriculture, partially due to the creation of a significantly different growing environment. Additionally, the absence of synthetic products can also negatively impact the shelf of leafy greens like kale. To determine …

Floating Treatment Wetlands For Brackish Waters: Plant Selection And Nutrient Uptake Potential., Andrea Landaverde

All Theses

Brackish water bodies in coastal regions provide critical ecosystem services that support human and environmental health. Anthropogenic activities such as agricultural and industrial activities, construction, urban settlements, and tourism contribute to increased inputs of nitrogen (N) and phosphorus (P) in brackish coastal ecosystems. Excess nutrients can lead to impaired water quality and affect marine organisms. Floating treatment wetlands (FTWs) are a vegetated-base technology used to remove contaminants from water column, that has been mainly studied and applied in freshwater systems. Application of FTWs in brackish systems requires further investigation, as high salinity in brackish waters could result in toxicity to …

Identification Of Cytospora Species Isolated From Canker In Peach Trees In South Carolina, Stephen T. Baker

All Theses

In 2016, a survey was conducted into the causes of twig blight on peach (Prunus persica) in five orchards across South Carolina. From this survey, isolates from the fungal genus of Cytospora (Sordariomycetes, Diaporthales) were reported on peach, for the first time, within the state. Cytospora species are known to cause oozing cankers on a wide range of woody hosts leading to dieback, loss of limbs, and reduction in yield, prompting concern for important economic crops. Past methods of identification of Cytospora species have been confounded by indistinguishable morphology, overlapping host preference among species, and genetic sequencing …

Distribution And Genomic Diversity Of Pollen-Borne Viruses And Viroids At The Interface Of Peach And Wild Prunus Spp. In The Southeastern United States, Fabian Omar Rodriguez Bonilla

All Theses

Prunus necrotic ringspot virus (PNRSV), prune dwarf virus (PDV), and peach latent mosaic viroid (PLMVd) are important pollen-borne pathogens that affect peach orchards in the southeastern United States. My aim with this research is to identify potential sources of virus/viroid inoculum sources in the wild and determine pathogen movement and interactions between wild Prunus spp. and cultivars of peach (P. persica). In Chapter I, I review the literature on pollen borne viruses and viroids in peach. In Chapter II, I surveyed for these pathogens near peach production areas in South Carolina and Georgia, sampling from three endemic wild …

Effects Of Thermal Processing On Peach Puree Of Different Cultivars: Analysis Of Biochemical Alteration, Non-Enzymatic Browning Reaction, And Color Changes, James Hayes

All Theses

The effects of pasteurization temperature and time on the change in seven peach puree variables over a 6-week accelerated shelf-life test (35°C) were evaluated. The variables of interest were three color measures [ L* (lightness), a* (redness), and b* (yellowness)]; two brown pigment measures [spectrophotometric absorption at 420 nm (Browning Index) and 443 nm (Hydroxymethylfurfural)]; °Brix; and pH). Puree was collected from three different cultivars (2 freestone and 1 clingstone) and puree samples from each cultivar were subjected to 20 combinations of pasteurization temperatures (70°C, 80°C, 90 °C, 100°C) and same hold times (0 minutes, 1 minute, 3 minutes, 5 …

Elucidating The Cellular Physiology Of Glyphosate Resistance In Palmer Amaranth (Amaranthus Palmeri) Using Integrated Omics Approaches, Pawanjit Kaur Sandhu

All Theses

The evolution of resistance to herbicides in weeds poses a major threat to agricultural production systems. To date, herbicide resistance has been reported against 21 modes of action in 266 weed species across 71 countries. More than 50 weed species have developed resistance against glyphosate, the most widely used herbicide worldwide. Although several mechanisms of glyphosate resistance have been discovered, our understanding of alterations in the cellular physiology of glyphosate-resistant weed biotypes, and the induction of the resistance mechanisms remains limited. This knowledge is critical to developing sustainable weed management practices and for a comprehensive understanding of plant stress adaptations. …

An In Vitro Approach To Identify Sources Of Resistance To Fusarium Wilt Caused By Fusarium Oxysporum F. Sp. Vasinfectum Race 4 In Domesticated Cotton, Stephen Parris

All Theses

Cotton lint produced by the plants Gossypium barbadense L. (pima cotton) and Gossypium hirsutum L. (upland cotton) is the world’s leading source of renewable textiles. The fibers of the cotton plant have been woven so intricately into our society that it would be hard to imagine life without their products. Cotton breeders must then not only continue to work to improve the quality of cotton fibers (fineness, strength, dyability, etc.) but also to improve the resilience of the plant against biotic and abiotic factors. Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) is an aggressive fungal pathogen, which causes Fusarium …

Enabling Breeding For Targeted Heat Requirement In Peach, Omer Atagul

All Theses

Peach [Prunus persica (L.) Batsch] germplasm varies in heat requirement and bloom time. This variability can be utilized in breeding for targeted environment or overall climate resilience. Development of molecular tools to aid in targeted selection of dormancy related traits is needed to support breeding for these traits. This project furthers our understanding of heat requirement accumulation diversity and genetic control in peach.

Peach bloom date (BD) is determined by the dynamic relationship of temperature requirements, from the sequential fulfillment of chill requirement (CR) and heat requirement (HR). Knowledge of HR and its influence on BD would provide deeper …