Plant Pathology Commons^™

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 ...

Efficacy Of Biopesticides For Organic Management Of Cucumber Beetles, Mary A. Rogers

Doctoral Dissertations

Organic growers are limited in crop protection techniques for cucumber beetle management. Spotted (Diabrotica undecimpunctata howardi) and striped (Acalymma vitatta) cucumber beetles and are significant pests of cucurbits in the U.S. Feeding results in aesthetic damage and reduction in marketable yields as well as transmission of bacterial wilt that can result in plant mortality. Biopesticides are products formulated from naturally occurring organisms such as fungi and bacteria that are pathogenic or toxic to insect pests. Advantages to these products are that they have low environmental risk, low risk to non-target organisms including mammals and beneficial insects, and can help ...

Brassica Variety Trials 2012, Rebecca Brown

Rhode Island Agricultural Experiment Station Bulletin

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

Alternative Methods Of Control For Phytophthora Nicotianae Of Tobacco, Anna M. Holdcroft

Theses and Dissertations--Plant Pathology

Kentucky is the nation’s leading producer of burley tobacco and the crop’s most economically important disease is black shank, caused by Phytophthora nicotianae (Pn). Current management is effective, however, problems with expense and pathogen persistence are issues. Two alternative methods for control of Pn were examined: biofumigation and soil application of an organic, yeast fermentation‐derived product (Soil‐Set). Field studies in 2009 and 2010 found no effect on populations of fungi, disease severity of Pn, and yield between mustard‐ and wheat‐amended plots. Experiments in the greenhouse suggested that survival of Pn was impacted by biomass rather ...

Characterization Of Chemotype And Aggressiveness Of Nebraska Isolates Of Fusarium Graminearum, Anita Panthi

Theses, Dissertations, & Student Scholarship: Agricultural Leadership, Education & Communication Department

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is a devastating disease of wheat and other small grain cereals. FHB lowers grain yield and quality and contaminates grain with mycotoxins, predominantly deoxynivalenol (DON) and its acetylated derivatives 3-ADON and 15-ADON. Forty one Fusarium isolates collected from grain elevators and wheat fields in Nebraska in 2009 and 2010 were sequenced for molecular identification. Forty isolates were identified as F. graminearum and one isolate was identified as F. culmorum. Seventy seven F. graminearum isolates collected from grain elevators and wheat fields in Nebraska from 2007 to 2010 were tested for DON ...

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

Theses, Dissertations, and Student Research in Agronomy and Horticulture

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 important soybean ...

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 ...

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 ...

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 2011, respectively. Ninety-five ...

Improved Understanding Of Factors Influencing The Re-Emergence Of Goss's Bacterial Wilt And Blight Of Corn, Craig B. Langemeier

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Goss’s bacterial wilt and blight (Goss’s wilt) is a serious and sometimes severe disease of corn. Goss’s wilt was first identified in Dawson County Nebraska in 1969. Today Goss’s wilt can be found in two countries including the U.S. and Canada, and twelve states including Nebraska, Iowa, North Dakota, South Dakota, Minnesota, Illinois, Indiana, Texas, Kansas, Colorado, Wisconsin and Wyoming. Goss’s wilt was observed in Nebraska throughout the 1970’s, and from the early 1980’s until recently developed only sporadically. Around 2006, a re-emergence of the disease was observed in western Nebraska, northeast ...

High School Horticulture Curriculum, Margaret Maratsos

Horticulture and Crop Science

Horticulture is just one of the many topics covered in a high school agriculture curriculum, and yet, there are very few lesson plans or resources available to teachers for these classes specifically. The objectives of this project were to compile a set of lesson plans, lab plans, and tests that would emphasize interactive and investigative learning. The lesson plans were written in such a way that they reflected a certain set of standards, set down by the state of California, and were meant to serve as a bare outline of topics that would be discussed within a week’s worth ...

Towards Defining Nutrient Conditions Encountered By The Rice Blast Fungus During Host Infection, Richard A. Wilson, Jessie Fernandez, Cristian Fernando Quispe, Julien Gradnigo, Anya Seng, Etsuko Moriyama, Janet D. Wright

Papers in Plant Pathology

Fungal diseases cause enormous crop losses, but defining the nutrient conditions encountered by the pathogen remains elusive. Here, we generated a mutant strain of the devastating rice pathogen Magnaporthe oryzae impaired for de novo methionine biosynthesis. The resulting methionine-requiring strain grew strongly on synthetic minimal media supplemented with methionine, aspartate or complex mixtures of partially digested proteins, but could not establish disease in rice leaves. Live-cell-imaging showed the mutant could produce normal appressoria and enter host cells but failed to develop, indicating the availability or accessibility of aspartate and methionine is limited in the plant. This is the first report ...

Aloe Striata Plant Defense Compounds Produced In Response To Jasmonic Acid, Salicylic Acid, And Eriophyid Mite Salivary Extract Elicitor Compounds, Fritz Light

Master's Theses and Project Reports

Aloe mites are herbivores of the genus Aloe (ALOACEAE) and are associated with hyperplastic growth in various aloe species, but the biochemistry of this interaction is poorly understood. In an effort to characterize plant defense responses to herbivory in the genus Aloe, a salivary extract was isolated from aloe mites (Aceria aloinis Keifer) and its bioactivity was tested using a hypocotyl elongation assay. Subsequently, Aloe striata plants were treated with jasmonic acid (JA), salicylic acid (SA), and the mite salivary extract. Using water and methanol, compounds of different polarity were extracted from aloe tissues that had been frozen and crushed ...

Hairy Roots As A Model To Investigate The Role Of Suberin In The Phytophthora Sojae-Soybean Pathosystem, Pooja Sharma

University of Western Ontario - Electronic Thesis and Dissertation Repository

Part of the resistance mechanism of soybean (Glycine max [L.] Merr.) to Phytopthora sojae Kauf. & Gerd. involves pre-formed root suberin. In order to investigate the role of suberin in this host-pathogen interaction, I characterized hairy roots, formed as a result of Agrobacterium rhizogenes (Riker et al.) Conn infection, as a model to be used as a reliable soybean transformation system. I established hairy root cultures and demonstrated that they were a result of A. rhizogenes infection. The anatomy and suberin deposition in soybean hairy roots was examined, and found to be very similar to that of wild-type roots. In hairy ...

The Pseudomonas Syringae Type Iii Secretion System: The Translocator Proteins, Their Secretion, And The Restriction Of Translocation By The Plant Immune System, Emerson Crabill

Dissertations and Theses in Biological Sciences

Pseudomonas syringae is a Gram-negative plant pathogen whose virulence is dependent upon its type III secretion system (T3SS), a nanosyringe that facilitates translocation, or injection, of type III effector (T3E) proteins into eukaryotic cells. The primary function of P. syringae T3E proteins is suppression of plant immunity. Bacterial proteins called translocators form a translocon that forms a pore in the host plasma membrane which is traversed by T3Es. HrpK1, a putative P. syringae translocator, is a type III-secreted protein important for virulence and T3E injection, but not secretion of T3Es. Harpins are a group of proteins specific to plant pathogens ...