Life Sciences Commons^™

Antibacterial Activity And Chemical Characterization Of Resin From Sciadopitys Verticillata (Thunb.) Siebold And Zuccarini, David Ira Yates

Doctoral Dissertations

Sciadopitys verticillata produces white viscous resin that is unique among the conifers. This research investigated effects of resin on bacteria from different ecological niches and the chemical composition of the resin. Each bacterial species was evaluated separately for response to winter- and summer-collected resins. Exposure to winter-collected resin reduced numbers of colonies of Bacillus cereus, Erwinia amylovora, Agrobacterium tumefaciens, and Escherichia coli and increased numbers of Xanthomonascampestris, Pseudomonas fluorescens, and Pseudomonas syringae. Summer-collected resin affectedpopulation growth of two bacterial species; population counts of E. amylovora decreased and those of P. fluorescens increased. Selected strains of …

Improved Fungicidal Control Of Large Patch Through Optimal Use Of Surfactants And Spray Rate Volume, Jesse J. Benelli

Doctoral Dissertations

Large patch (Rhizoctonia solani AG 2-2LP) epidemics cause significant damage to Japanese lawngrass (JLG; Zoysia japonica) in the transition zone. Large patch primarily affects the stems and sheaths of JLG and is difficult to control using traditional fungicide sprays. Field and growth chamber experiments were conducted during 2015-2016 in TN and GA to evaluate methods to enhance fungicidal control of large patch in JLG landscapes. The 1^st experiment evaluated the most critical application target site that resulted in the greatest amount large patch control. In this experiment, four fungicides (azoxystrobin, flutolanil, tebuconazole, and chlorothalonil) were dispensed as …

Switchgrass Extractives Have Potential As A Value-Added Antimicrobial Against Plant Pathogens And Foodborne Pathogens, Alexander Ian Bruce

Masters Theses

Panicum virgatum (switchgrass), a perennial grass native to North America, is a leading biomass feedstock candidate for the manufacture of cellulosic ethanol. Switchgrass is considered a viable option for biofuel production due to its cheap production cost and ability to grow on marginal land. Biofuel derived from switchgrass has been shown to be very energy efficient, producing 540% more renewable energy versus nonrenewable energy expended. Switchgrass-derived biofuel is also estimated to have greenhouse gas emissions that are 94% lower than emissions from gasoline (Schmer et al 2008). Biofuels are created through biochemical processes that utilize various enzymes and microorganisms for …

Characterization Of Fusarium Species And Alternaria Alternata, And Their Effects On Switchgrass Health And Chemical Components, Sara Beth Collins

Masters Theses

Panicum virgatum L., readily referred to as Switchgrass, is a perennial warm-season bunch grass, used as an alternative energy source for biofuel production. There is insufficient research on switchgrass pathogens, and is expected that an increase in disease pressure will result as more land is reserved for this perennial crop. The purpose of this research was to identify and characterize pathogenic Alternaria alternata and Fusarium species on Switchgrass (Panicum virgatum L.), and to evaluate their impact on stand establishment and plant health. Molecular identifications of fungal isolates obtained from infected commercial switchgrass seed yielded eight species (A. alternata, …

Rapid Molecular Detection And Population Genetics Of Pityophthorus Juglandis, A Vector Of Thousand Cankers Disease In Juglans Spp., Emel Oren

Masters Theses

Thousand Cankers Disease (TCD) is a disease complex involving the fungal pathogen Geosmithia morbida, an insect vector Pityophthorus juglandis, and the hosts, Juglans spp. and Pterocarya spp. Signs and symptoms of TCD include crown thinning due to branch dieback, yellowing and wilting of the leaves, appearance of epicormic shoots, numerous entrance/exit holes, gallery formation by P. juglandis, and the development of small, dark brown cankers underneath the bark. TCD originally described from western U.S., has now expanded to eastern U.S. and northwestern Italy. The disease complex is often difficult to diagnose due to the absence of symptoms …

Anaerobic Soil Disinfestation: Meta-Analysis And Optimization Of Amendment Carbon Rate And C:N Ratio To Control Key Plant Pathogens And Weeds, Utsala Shrestha

Doctoral Dissertations

Anaerobic soil disinfestation (ASD) is an environmentally friendly and cost effective pre-plant soil treatment technique that allows effective control of soilborne pests by creating anaerobic conditions, particularly for specialty and organic crop production under diverse environmental conditions. In spite of being a proven technique, ASD has to be optimized to fit into local production systems with specific pathogen pressure using locally available amendments for successful implementation on a commercial scale. Our meta-analysis study on soilborne pathogens, plant parasitic nematodes, and weeds validated that ASD is an effective approach to control various soilborne pathogens. This study aims to optimize the carbon …

Influence Of Application Technology On Foliar Fungicide Efficacy On Cercospora Sojina Infected Soybean, Shawn Alan Butler

Masters Theses

Due to the constant concern with off-target contamination and application technology requirements associated with future herbicide-tolerant crops, the use of drift-reduction nozzle technology (DRT) may increase. The primary objective of this research was to evaluate the effects of coarse droplets generated by drift-reduction nozzles on foliar fungicide efficacy and residual in soybean infected by frogeye leaf spot caused by Cercospora sojina. No differences in disease control, soybean yield, spray retention, and residual when applying Quadris Top SB, a premix of azoxystrobin and difenoconazole, using nozzles that produce either a medium or ultra coarse droplet spectrum were determined.

Due to …

Evaluation Of Fungicide Efficacy Against Cercospora Sojina And Selection For Qoi-Fungicide Resistance In Soybean, Alicia Mercedes Cochran

Masters Theses

Frogeye leaf spot (FLS) of soybean is caused by Cercospora sojina. In 2010, resistance to the quinone outside inhibitor (QoI) fungicides was reported. Since then, evaluating FLS for QoI-resistance has been of particular interest in Tennessee and other soybean-producing states. In order to determine alternative fungicide options, fungicides with solo and combination mode of action were tested in 2013-2014. The objectives were,1) to evaluate fungicide efficacy for disease control and yield protection, and 2) evaluate selection pressure for QoI-resistance. Treatments included the following fungicide groups: QoI, DMI, MBC, Chlorothalonil, QoI+DMI, SDHI+QoI, SDHI+QoI+DMI, and DMI+MBC. QoI and Chlorothalonil treatments failed …