Plant Pathology Commons^™

Environmental Variables Influencing The Severity Of Pierce's Disease In California Grapevines, Christopher James Boisseranc

Master's Theses

This project was designed to correlate environmental variables with the development of Pierce’s Disease (PD), an infection caused by the gram negative bacterium Xylella fastidiosa (Xf), in grapes (Hopkins et al. 2002). PD is one of the most difficult crop pathogens to manage because it is vectored by insects and its continued presence in the vine is usually fatal. PD is influenced by the interaction of host, disease and vector, and probably many other environmental variables. The general objective was to study and identify the most important variables involved in the expression of Pierce’s Disease.

Over a two year period, …

A Potential Plan Of Action For Emerald Ash Borer In Nebraska, Lee Wheeler

Department of Environmental Studies: Undergraduate Student Theses

Abstract Emerald Ash Borer (Agrilus planipennis) (EAB) is an invasive insect pest. It feeds on the cambium tissues of ash tree species. It was first discovered in the United States in 2002 in Detroit, Michigan. Their effects on ash trees are deadly, and it is quickly spreading across the Midwest. Nebraska has not yet been invaded, but confirmed findings continue getting closer and closer. The major problem facing Nebraskans, with regards to EAB, is how to begin preparations to prevent a dramatic economic loss when an infestation does occur. So, to address this problem, I have conducted street and park …

Heritability Of Latent Period Estimated From Wild-Type And Selected Populations Of Puccinia Triticina, Jeffery S. Lehman, Gregory Shaner

Biology and Earth Science Faculty Scholarship

Durability of partially resistant wheat cultivars to wheat leaf rust depends on the amount of genetic variation in parasitic fitness within populations of the pathogen Puccinia triticina. To assess the durability of partial resistance, selection experiments were used to explore quantitative variation in parasitic fitness of P. triticina. Fungal populations 881-WT and 882-WT were selected for shortened latent period on partially resistant cvs. CI 13277 and Sw 72469-6 for multiple generations. Fitness components were measured for wild-type and selected fungal populations. Responses to selection and selection differentials were calculated, and broad-sense, realized heritabilities for latent period were estimated for wild-type …

Evaluation Of Post-Harvest Disease Resistance In Blackberry Genotypes, John-Paul Kidd, John R. Clark, Patrick Fenn, Barbara Smith

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Forty-nine blackberry genotypes (19 cultivars and 30 breeding selections) were evaluated for post-harvest fruit-rot resistance in June and July 2003. Fully mature, undamaged berries were harvested on two dates for each genotype at the University of Arkansas Fruit Substation, Clarksville. After transporting in chilled coolers back to the Plant Pathology Department in Fayetteville, two replications of 10 berries of each genotype were placed in a high-humidity chamber for 3 d (21-23°C; 16-h daylength). This provided a total of four replications for each entry across the two harvest dates. Natural inoculum from the field provided the post-harvest pathogens, and no additional …

Integrated Weed Management Plan For The Lower Las Vegas Wash, Elizabeth Bickmore

Publications (WR)

The Las Vegas Wash (Wash) is the primary drainage for the metropolitan Las Vegas Valley, eventually finding its way into the Colorado River watershed system. Pursuant to the recommendations of the Water Quality Citizens Advisory Committee, the Las Vegas Wash Coordination Committee (LVWCC) was formed in 1998 to develop a comprehensive plan for the long-term stabilization and management of the Wash. Consisting of representatives from 28 government agencies, businesses, environmental groups and citizens, the LVWCC formulated the Las Vegas Wash Comprehensive Adaptive Management Plan (CAMP) and designated the Southern Nevada Water Authority (SNWA) as the lead agency for the implementation …

Response Of Blackberry Cultivars To Nematode Transmission Of Tobacco Ringspot Virus, Alisha Sanny, John R. Clark, Rose Gergerich

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

A study was conducted on eight cultivars of blackberry (‘Apache’, ‘Arapaho’, ‘Chester’, ‘Chickasaw’, ‘Kiowa’, ‘Navaho’, ‘Shawnee’, and ‘Triple Crown’), of which four plants of each were previously determined in the fall of 2001 to have root, but not leaf, infection with Tobacco ringspot virus (TRSV). The objectives of our study were to determine virus effects on plant vigor and the spread of virus infection in the plants. Eight plants of each cultivar, four infected and four free of infection, were grown in pots on a gravel pad for the 2002 growing season, and samples of primocane and floricane leaves were …

Effects Of Virus Infection On Release Of Volatile Organic Compounds From Insect-Damaged Bean, Phaseolus Vulgaris, Sarah E. Sossamon, Britney K. Jackson, B. Alison Drumwright, Kenneth L. Korth, Gisela F. Erf

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Insects can serve as important vectors of plant pathogens, especially viruses. Insect feeding on plants causes the systemic release of a wide range of plant volatile compounds that can serve as an indirect plant defense by attracting natural enemies of the herbivorous insect. Previous work suggests that the Mexican bean beetle (Epilachna varivestis) prefers to feed on plants infected by either of two viruses that it is known to transmit: Southern bean mosaic virus (SBMV) or Bean pod mottle virus (BPMV). A possible explanation for the preferred feeding on virus-infected tissues is that the beetles are attracted by volatile signals …

Crop Updates 2002 - Oilseeds, David Eksteen, K. Neil Harker, George W. Clayton, Keith Downey, Keith Alcock, Kevin Walden, Beven Addison, Peter Carlton, Kevin Morthorpe, Stephen Addenbrooke, Alex Ford, S. Hasan Zaheer, G. Walton, Imma Farré, Paul Carmody, J. A. Fortescue, D. W. Turner, B. Tan, Margaret C. Campbell, Ian Pritchard, Richard W. Bell, K. Frost, Mike Wong, Ross Brennan, Roger Jones, Jenny Hawkes, Debbie Thackray, Moin U. Salam, Ravjit K. Khangura, Art J. Diggle, Martin Barbetti, Phil Michael, Françoise Berlandier, Christiaan Valentine, Greg Shea, Glen Riethmuller, Rafiul Alam, Greg Hamilton, Jo Hawksley, Patrick Smith, Paul Neve, Felicity Flugge, Amir Abadi, Stephen Powles, Brett Glencross, John Curnow, Wayne Hawkins

Crop Updates

This session covers twenty seven papers from different authors:

1. Forward and acknowledgements, Dave Eksteen, ACTING MANAGER OILSEEDS PRODUCTIVITY AND INDUSTRY DEVELOPMENT Department of Agriculture

PLENARY SESSION

2. GMO canola - Track record in Canada, K. Neil Harker and George W. Clayton,Agriculture and Agri-Food Canada, Lacombe Research Centre, Lacombe, Alberta, R. Keith Downey, Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan

3. GMO canola – Prospects in Western Australia farming systems, Keith Alcock, Crop Improvement Institute, Department of Agriculture

4. Diamondback moth (DBM) in canola, Kevin Walden, Department of Agriculture

CANOLA AGRONOMY

5. Getting the best out of …

Basic Biotechnology, Jennifer Flak, Julie Albrecht

Plant and Soil Sciences eLibrary

An introduction to traditional cross-breeding and genetic engineering of plants, and to biotechnology.

Objectives - Basic Biotechnology

After completing Nutrition Basic Biotechnology, participants should be able to:

• Describe one similarity between traditional cross-breeding and genetic engineering of plants.
• Give two limitations that are encountered with traditional cross-breeding of plants.
• Explain why genetic engineering is not limited in the same way as traditional cross-breeding.
• Define biotechnology in broad terms.
• List three plant applications of biotechnology.
• List the three areas of nutritional profiles that have been improved with biotechnology.

Modules:

• Lesson home
• Objectives - Basic Biotechnology
• Historical Uses of Biotechnology
• Basic Understanding …

Studies On The Biology Of Striga Aspera (Scrophulariaceae) In Nigeria, Emmanuel Izaka Aigbokhan

Biological Sciences Theses & Dissertations

Studies on Striga aspera are few and little information exists on its relationship with the morphologically similar and much studied S. hermonthica. Both species are sympatric in West Africa and if they hybridize, may serve as virulent gene reservoirs for each other.

The primary focus of this study was on the biology of S. aspera in Nigeria. The research focussed on its distribution, phenology, cytology, hybridization, seed dormancy, viability and germination in relation to S. hermonthica. Related studies involving the hybrids include genetic and morphological variability, pathogenicity and the simultaneous dual infection of a maize plant by both species.

In …

Molecular Approaches For Control Of Tomato Bushy Stunt Virus, H. B. Scholthof, M. Borja, Thomas Jack Morris, A. O. Jackson

School of Biological Sciences: Faculty Publications

I N this overview strategies are discussed that are currently being tested in our laboratory in an effort to engineer resistance against tomato bushy stunt virus (TBSV) in plants. TBSV is chosen as a model-system since this is an economically important RNA virus that is well characterized at the molecular level and the virus has some interesting and potentially useful features that can be exploited to produce resistant plants. Moreover, we anticipate that the information derived from our studies with TBSV will be applicable in developing resistance to other plant viruses. Some approaches that we are attempting to apply to …

Germination And Haustorial Development In Orobanche Minor Smith (Orobanchaceae), David L. Spelce

Biological Sciences Theses & Dissertations

Orobanche minor Smith is an introduced root parasite that is known to attack some commercial crops. Germination occurs only after a preconditioning period involving moisture which must be followed by a chemical stimulant produced by the host root. Strigol and strigol analogs (GR-compounds} have been reported to germinate some species of Orobanche. Statistical tests indicate a significant difference between the effectiveness of strigol, GR-7 and GR-45 (P = 0.001).

The embryo is an undifferentiated mass of cells. During germination, the radicular pole of the embryo differentiates into the radicle, while the plumular pole remains undifferentiated. The radicle forms the primary …

Vector Preference Among Varieties Of Lycopersicon Peruvianum And L. Esculentum As Related To Curly Top Virus Resistance, Stanford A. Young

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tests substantiating vector nonpreference as a factor in the ability of certain tomato varieties to escape curly top virus (CTV) infection were conducted and evaluated. Nonpreference is not an effective mode of resistance to CTV in tomatoes under field conditions since leafhoppers feed on and may infect plants before expressing a preference.

Preference of viruliferous leafhoppers was observed on plants of seven tomato varieties arranged both randomly and homogeneously in caged flats. Through observation of curly top symptom development, relative resistance due to vector nonpreference was calculated for each variety.

Up to 23 per cent of the fairly high resistance …

The Action Of Antibiotics And Antimetabolites On The Tobacco Mosaic Virus Infection Process In Bean Leaves, Virendra Nayyar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The action of 28 antibiotics and antimetabolites at varying concentrations was studied in coincidence with the bioassay of tobacco mosaic virus on detached bean leaves by using an ultrasonic method of inoculation developed by Lamborn, Cochran and Chidester.¹ All tested chemicals were classified, in regard to the virus infection process, as inhibitory or stimulatory and their optimal concentrations in the inoculum were determined. Of the 28 antibiotics and antimetabolites studied, eight were found to stimulate while twenty inhibited TMV infection in bean leaves. From the results of these experiments, an attempt was made to characterize the nature of the …

Investigations Of Unusual Curly Top Symptoms In Grafted Tomato Plants And Early Leafhopper Feeding Effects Upon Tomato Seedlings, Donald Eldon Gardner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To determine possible unusual effects of resistant plants upon symptom expression of curly top disease in susceptible tomato plants (Lycopersicon esculentum Mill.), tops of susceptible plants were grafted to lower stems and roots of resistant plants and inoculated. The resistant plants used were wild relatives of L. esculentum: L. peruvianum var. dentatum Dun. and L. peruvianum var. humifusum C. H. Mul. Reciprocal grafts, in which tops of dentatum plants were grafted to lower stems and roots of L. esculentum, were also made and inoculated.

External symptoms in the grafted plant tops were observed and compared with those of nongrafted, …

Observations On The Establishment Of Seedlings Of Phoradendron Californicum On Prosopis Juliflora, Richard L. Null

Dissertations and Theses

The mistletoe Phoradendron californicum is a common parasite on the mesquite plant Prosopis juliflora. Seeds of the parasite are deposited upon the host plant by birds and perhaps other agents. Normally seedlings of the parasite become established when the elongating radicle of the embryo comes into contact with a host branch and forms a holdfast. From the underside of the holdfast the primary haustorium enters the host tissue and establishes the parasitic union. Later the aerial portion of the parasite develops. Some seeds of P. californicum follow a different sequence; they stimulate the host to produce gum in the tissue …

A Rapid Serological Bean Blight Test And Antibiotic Control Measures, Terry Dee Miller

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The detection and identification of bacterial pathogens in bean tissues can be accomplished with relative ease and certainty by utilizing antiserum prepared against specific bean pathogens. This test requires only fifteen minutes to complete, and a minimum amount of equipment. In addition to speed and ease, it eliminates the difficult process of isolating the bacterial pathogens from the many contaminants that will grow in nutrient culture techniques. The advantage of this technique is primarily based on the utilization of the bacterial population already present in the diseased plant tissues.

The effectiveness of this method has been demonstrated by diagnosing beans …

Overwintering Of Erwinia Amylovora Inside Living Host Tissue In Cache Valley, Utah, G. Doyle Morrill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Experiments were conducted to see if Erwinia amylovora (Burrill) Winslow et al. overwinters inside living host tissue in Utah. Bacteria, collected from apple, pear, mountain ash, chokecherry and Pyracantha, were used in the experiment. Isolates taken from buds and inner bark plated on nutrient yeast dextrose agar, we re tested by serological and bacteriophage techniques. Those showing positive tests were then inoculated into Bartlett pear seedlings to test virulence.

Both virulent and avirulent isolates were isolated from each species of plant in the experiment. Pathogenic bacteria were isolated from diseased tissue near cankers, as well as from apparently healthy inner …

Factors Associated With The Penetration And Colonization Of Tomatoes By Verticillium Dahliae, Terry Dee Miller

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Experiments have demonstrated that Verticillium dahliae is capable of direct cortical penetration of roots and of subsequent distribution throughout plants of both resistant (Loran Blood) and susceptible (Meteor) varieties of tomato. Plants were inoculated by the root dip method and planted in sterile soil. After one week the fungus was isolated from the upper portions of both the susceptible and resistant varieties as indicated by growth petiole sections plated on PDA. The distribution of the fungus in the resistant plants was irregular, but in susceptible plants the fungus was isolated regularly from all petiole sections. In experiments using disposable growth …

Northern Corn Leaf Blight (Helminthosporium Turcicum Pass.) On Susceptible And Resistant Corn, Saffet Baydar

Open Access Master's Theses (through 2010)

The objectives of the research reported herein were to (1) become familiar with the technique of inoculating corn with Helminthosporium turcicum, (2) become familiar with a technique of evaluating the susceptibility of corn lines to H. turcicum, (3) become familiar with plant reaction and organism development in the various types of corn and (4) evaluate Turkish corn susceptibility in relation to various types of germ plasm in American corn lines in order to assist in combating the serious disease of Northern corn left blight in Turkey.

Comparative reactions of 10 Turkish, 5 multigenic resistant, 2 heterozygous monogenic …

Supplementary List Of Disease Recorded On Various Hosts In Western Australia, G C. Macnish

Journal of the Department of Agriculture, Western Australia, Series 4

THIS supplement contains the diseases recorded on all hosts during the period July 1, 1961 and June 30, 1963 inclusive.

A few disease records omitted from previous census have been incorporated. A list of previous publications in this series is appended. Also appended is a list of common names of host plants to facilitate reference.

Infrared Spectroscopy As Applied To The Study Of Biochemical Changes Induced By Tobacco Mosaic Virus In Leaf Cells, Banavara Krishnappa Chandrasekhar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The biochemical reactions occurring during the early stages in the infection cycle of a plant virus are still unknown. Many studies involving bacteriophage and animal viruses that have been made in recent years have provided evidence of the nature of virus infection, but these have not been of much value in understanding the nature of plant viruses. Infrared spectroscopy applied to the study of viral infection processes by Chochran and his co-workers (1960, 1962) have given some clues about the nature of biochemical changes taking place in the leaf tissues as a result of infection with cucumber mosaic virus and …

Diseases Recorded On Native Plants, Weeds, Field And Fibre Crops In Western Australia, G C. Macnish

Journal of the Department of Agriculture, Western Australia, Series 4

This list is divided into three sections, the first dealing with native plants, the second with weeds (except grasses) and third with field and fibre crops.

Collecting Plant Specimens. 2. Specimens For Disease Identification, G C. Macnish

Journal of the Department of Agriculture, Western Australia, Series 4

PLANT SPECIMENS submitted to the Department of Agriculture for disease identification are referred to officers of the Plant Pathology Branch, and in most cases a rapid diagnosis can be made.

Use Of The Antibiotics, Streptomycin And Terramycin, As Growth Stimulants For Orchid Seedlings, Margaret W. O'Neill

Biology ETDs

Antibiotics first came to the public's attention in 1945, when penicillin and streptomycin were released by the United States government to fight human diseases. Later, other antibiotics were released and experimental work was done on control of plant and animal diseases. By 1948 plant pathologists found that certain plant diseases such as walnut blight, tomato and pepper bacterial spot, soft rot, cucumber, downy mildew, chrysanthemum bacterial wilt, and lilac bacterial blight could be controlled by antibiotics.

The Effect Of Certain Fluoride Sprays In The Production Of Soft Suture On Peaches, N. V. Narayanamoorthy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pollution of the atmosphere and its potential deleterious effects on health, industry, agriculture and natural resources are causing grave concern in many parts of the world. In the past century there has developed in the fields embraced by physical and biological sciences a considerable knowledge of theoretical and applied information, serving as a versatile tool in combating such problems. Air pollution problems seem to have gained much attention with the rapid development of various industries in major parts of the world. Rural and urban areas adjoining these industrial locales are confronted with the dangerous overall problems of air pollution. Evidently, …

Growth Of The Fungus, Verticillium Albo-Atrum In Resistant And Non-Resistant Strains Of A Tomato Variety And Its Effect On Plant Growth, Robert M. Zundel

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Verticillium wilt, caused by the fungus, Verticillium albo-atrum, is a destructive disease of tomatoes in many areas. Due to the seriousness of this problem, Cannon and Waddoups (1) have developed resistance to this disease in some commercial varieties grown in Utah.

False Smut Of Buffalograss, John L. Weihing

Nebraska Agricultural Experiment Station: Historical Research Bulletins

False smut of buffalograss, Buchloe dactyloides (Nutt.) Engelm., caused by Cercospora seminalis Ell. & Ev. is a disease that destroys the unfertilized ovary. The disease was first reported by J. B. Ellis and B. M. Everhart in 1888. They gave only a brief description of the disease and named the causal fungus Cercospora seminalis. There are no etiological studies of false smut recorded in the literature. The origin of the term "false smut" is unknown to the author, but it so descriptively fits the general appearances of the disease that one readily understands its usage. The following studies were …

Studies Of The Dodder Transmission Of The Western-X Virus From Peach To Herbaceous Plants, Lewis G. Weathers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Western-X disease is considered to be the most serious and destructive virus disease affecting peaches in the northwestern United States. The virus causing this disease in peach also infects chokecherries and most varieties of sweet and sour cherries. There is also evidence (13) that certain varieties of plums and apricots are susceptible. No information now exists to indicate that the virus occurs in plants outside of the genus Prunus. It is found that woody plants such as stone fruit trees are not particularly favorable plants for studying the virus. All attempts to isolate the western-X virus from woody tissue …

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 …