Life Sciences Commons^™

Compatibility Of Essential Oils With The Biocontrol Fungus, Beauveria Bassiana, Wanjing Liu

Masters Theses

The tomato seedling damping-off pathogens Rhizoctonia and Pythium have the potential to cause severe loss in the greenhouse and field. Both seed application of Beauveria bassiana and soil amendment with bioactive monarda herbages are sustainable approaches that can play a role in suppressing damping-off of tomato seedlings. The objectives of this research were to determine the compatibility of essential oils and B. bassiana, and to determine the impact of the two when used together as a seed treatment in greenhouse experiments.

Different concentrations of five essential oils that were active against damping-off pathogens (cymene, carvacrol, thymol, borneol, and geraniol) …

Anaerobic Soil Disinfestation: Evaluation Of Anaerobic Soil Disinfestation (Asd) For Warm-Season Vegetable Production In Tennessee, David Grant Mccarty

Masters Theses

Anaerobic soil disinfestation (ASD) is a non-chemical, pre-plant soil treatment recently developed for control of pests such as soilborne plant pathogens, plant-parasitic nematodes, and weeds in specialty crop systems. Soil treatment by ASD includes incorporating a labile carbon (C) source, tarping with plastic, and irrigation of the topsoil to saturation to facilitate the development of strongly anaerobic soil conditions driven by soil microbes. Processes occurring during the anaerobic decomposition of the added C source have been reported control plant pests. The goal of this project was to evaluate and adapt the ASD procedure to environmental conditions and production systems in …

The Epidemiology Of Puccinia Emaculata (Rust) In Switchgrass And Evaluation Of The Mycoparasite Sphaerellopsis Filum As A Potential Biological Control Organism For Switchgrass Rust., Jonathan Allen Black

Masters Theses

Switchgrass (Panicum virgatum L.) is a warm-season, perennial grass, whose native range includes the entire United States and north into Canada, excluding areas along the pacific coast. Recently, symptoms and signs of rust disease (Puccinia emaculata) have been observed on agronomic switchgrass, which include chlorosis of leaf tissue, necrosis, lodging, and plant death.

To evaluate disease progress of switchgrass rust, in four fields, individual leaves of twenty-five switchgrass plants were rated once per week for fifteen weeks over two growing seasons for disease severity. Rust was first observed on Julian day 166 and 152 in 2010 and …

Applicability Of Pigment Compounds For Reducing Light Stress In Bentgrass, Gregory Keith Bartley

Masters Theses

Chlorinated copper phthalocyanine (Signature) and pulverized cells of Chlorella vulgaris (Chlorella) were evaluated in a controlled environment for their ability to act as photoprotectants under supraoptimal levels of ultraviolet (UV) and photosynthetically active radiation (PAR) when applied to plant leaves. Plant pigment changes were documented using High Performance Liquid Chromatography following 1 week of exposure to supraoptimal light in two separate experiments incorporating UV (106.6 μmol m-2 s-1) and PAR (760.6 μmol m-2 s-1) over a 12h photoperiod. Supraoptimal levels of UV and PAR light were found to cause significant reductions in Agrostis palustris chlorophyll and carotenoid leaf pigment levels. …

Investigation Of Phytophthora Species: Phytophthora Colocasiae On Taro And Phytophthora Recovered From Streams In Eastern Tennessee, Sandesh Kumar Shrestha

Masters Theses

Oomycetes, also known as water molds, are morphologically similar to fungi. Unlike fungi, they are diploid and more closely related to plants. Several oomycetes are pathogenic to plants as well as aquatic animals. Members of the genus Phytophthora are a threat to many economically important crops and natural forest systems. The research presented in this thesis addresses intraspecific and interspecific variation in natural populations of Phytophthora. Chapter two summarizes genetic diversity and population structure for Phytophthora colocasiae attacking taro in Hawaii, Vietnam and Hainan Island, China based on novel single nucleotide polymorphism (SNP) markers. Phytophthora colocasiae causes Taro Leaf Blight, …

Abiotic And Biotic Stress Tolerance In Wheat: The Role Of Arbuscular Mycorrhizal Fungi, Marei Mahmoud Abdelkarim

Masters Theses

Rhizospheres of crop plants are complexes of chemical and microbial interactions. Many plants produce allelochemicals, substances that inhibit growth of other plants and microorganisms. In previous research, colonization of Echinacea purpurea by beneficial mycorrhizal fungi appeared to alleviate the effects of allelochemicals on the growth and the development of the medicinal herb (Gualandi, 2010). The overall aims of the work reported here were to determine if colonization by arbuscular mycorrhizal fungi (AMF) alters responses of common wheat (Triticum aestivum) to abiotic [allelopathic effects of sorghum (Sorghum bicolor)] and biotic [bird-cherry oat aphid (Rhopalosiphum padi) …

Prevalence Of Copper Resistance Among Foliar Bacterial Pathogens Of Tomato In Tennessee, Jonathon Thomas Mixon

Masters Theses

Foliar bacterial diseases are among the most important diseases of tomato. Bacterial spot is caused by four species: Xanthomonas euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri, hereafter referred to as Xanthomonas spp. Bacterial speck is caused by Pseudomonas syringae pv. tomato and bacterial canker is caused by Clavibacter michiganensis subsp. michiganensis. Fixed copper products are relied upon extensively for control, due to a lack of effective and economical alternatives. Copper resistance in bacterial spot and speck pathogens has been reported worldwide. Copper resistance quite likely exists in Tennessee, but the extent has never been …