Plant Pathology Commons^™

Cherry Powdery Mildew In Utah, Marion Murray, Christina Lilligren, Megan Kast

All Current Publications

This fact sheet provides information on powdery mildew, a common problem in commercial tart and sweet cherry orchards in Utah and throughout the western U.S. Hosts, disease biology, symptoms and signs, and management are covered.

Providing Pest Management Education For Home Gardeners In Utah, Nick Volesky, Marion Murray

Outcomes and Impact Quarterly

In January 2024, Utah State University (USU) Extension's Integrated Pest Management (IPM) program launched a three-part class series targeting Utah's home gardeners. The goal was to enhance their abilities in identifying and managing insect and plant diseases. With over 200 participants, the series notably increased the knowledge of attendees. This initiative aligns with the USU Extension IPM program's mission to promote sustainable pest management practices across Utah, evidencing its commitment to environmental stewardship and community education.

Dwarf Bunt In Winter Wheat, Justin Clawson, Claudia Nischwitz, Margaret Krause, Will Krause

All Current Publications

Dwarf bunt or stinking smut is a disease that impacted Utah winter wheat production in the 1930s, resulting in fields with 95% infections. Breeding and selection of resistant varieties has irradiated the disease. As organic production of winter wheat increases, selecting resistant varieties will become of utmost importance to prevent crop loss.

Demonstration Farm Provides Educational Opportunity For Ipm, Nick Volesky, Mair Murray

Outcomes and Impact Quarterly

The mission of USU Extension’s Integrated Pest Management (IPM) program is to increase the use of sustainable pest management practices within urban and rural landscapes to provide economic, human, and environmental health in Utah. In the spring of 2022, the IPM program established a vegetable farm to test and demonstrate IPM practices. The farm served as an experiential learning classroom for almost 50 farmers and home gardeners.

The Backyard Garden - Tomato Pests, Nick Volesky, Marion Murray

All Current Publications

This fact sheet contains information about pests and diseases that affect tomatoes. It includes general information and guidance on severity, other hosts, symptoms, and management.

The Backyard Garden - Leafy Greens Pests, Nick Volesky, Marion Murray

All Current Publications

This fact sheet provides information about the diseases that affect leafy greens. It includes general information, other hosts, disease symptoms to watch for, and management options.

The Backyard Garden - Cole Crops Pests, Nick Volesky, Marion Murray

All Current Publications

This fact sheet contains information about pests and diseases that affect cole crops. Cole crops are plants that belong to the mustard (Brassica) family, including hardy, cool-season crops such as broccoli, kohlrabi, cabbage, rutabaga, cauliflower, kale, Brussels sprouts, and turnips. The fact sheet offers general information and guidance on severity, other hosts, symptoms, and management.

Helping Utah Landowners Reduce Pesticide Use Through A Statewide Ipm Program, Nick Volesky, Mair Murray

Outcomes and Impact Quarterly

The Utah Integrated Pest Management (IPM) program provides outreach and education to Utahns to reduce pesticide use and ultimately protect human and environmental health. In 2022, the IPM program responded to stakeholders’ needs by partnering with county Extension offices to deliver eight (8) in-person workshops across the state. The workshops connected Extension specialists and county faculty with managers of home landscapes and farms. The objective of the workshops was to provide participants with IPM skills to identify, monitor, and manage pest problems in preparation for the upcoming growing season.

Abiotic Disorders Of Tomatoes, Nick Volesky, Marion Murray, Sheriden M. Hansen, Maegen A. Lewis

All Current Publications

Monitoring tomato plants regularly from seedling to harvest allows for early detection of abnormal conditions. Although tomato plants can be attacked by a variety of living organisms (insects, mites, pathogens, vertebrates), nonliving (abiotic) conditions can cause just as much damage. Abiotic diseases in tomato plants can arise from nutrient deficiencies, temperature extremes, abnormal lighting, chemical application, changes in water uptake, mechanical damage, genetic mutations, and more. This guide will cover most of the abiotic disorders and diseases that can affect tomatoes in Utah.

Big Bud Disease In Tomatoes And Peppers, Claudia Nischwitz, Erin Petrizzo

All Current Publications

This fact sheet provides information on the symptoms of big bud on tomatoes and peppers. It reviews the disease cycle and recommendations on controlling beet leafhopper and managing big bud disease in Utah.

Fusarium And Verticillium Wilts Of Vegetables, Nick Volesky, Marion Murray, Claudia Nischwitz

All Current Publications

Fusarium wilt and Verticillium wilt are soilborne plant diseases that attack vascular tissue. They cause similar symptoms in their hosts and are difficult to manage as they can survive in the soil for many years. Once a plant is infected, there is no treatment or cure. Therefore, management should focus on preventive and cultural control practices. This fact sheet identifies the many vegetables susceptible to these pathogens in Utah and reviews symptoms, diagnosis, and ways to prevent these diseases.

Vegetable Diseases Of Utah, Claudia Nischwitz, Marion Murray, Nick Volesky

All Current Publications

This guide provides a list of vegetable crop diseases that have been documented in Utah along with some that are likely to occur. Plant diseases are caused by pathogens such as fungi, bacteria, viruses, and fungal-like organisms. Diagnosing specific plant diseases takes careful observation of signs, symptoms, and sometimes culturing and molecular testing in a laboratory setting.

Lily Leaf Beetle, Ann Mull, Lori R. Spears

All Current Publications

The lily leaf beetle (LLB) (Coleoptera: Chrysomelidae) is an important pest from Eurasia that threatens native and cultivated true lilies (Lilium spp.) and fritillaries (Fritillaria spp.). It is also known as the red lily leaf beetle or scarlet lily beetle. LLB was first reported in North America in Montréal, Canada, in 1945 and in the U.S. in 1992 in Massachusetts, likely arriving via European shipments of lily bulbs. LLB has been detected in nine of the 10 Canadian provinces and 14 U.S. states, including the New England states, Pennsylvania, Wisconsin, Minnesota, and Washington (EDDMapS, 2021). Based on LLB’s native distribution …

Powdery Mildews On Vegetables, Nick Volesky, Marion Murray, Claudia Nischwitz

All Current Publications

Powdery mildew is one of the most easily recognized fungal plant diseases. It is categorized by spots or patches of white-to-gray powder-like growth on foliage, stems, or fruit. Roughly 700 species exist that infect grasses, ornamentals, weeds, fruit trees, landscape trees, shrubs, and vegetables. The closely related species of fungi that cause powdery mildew are host-specific, meaning they cannot survive without the proper host. Powdery mildew fungi spread in conditions of low rainfall and hot temperatures, making Utah’s climate the perfect environment. This fact sheet provides information on powdery mildew and its management.

Corn Smut (Ustilago Maydis), Kalen Taylor, Nick Volesky, Claudia Nischwitz, Marion Murray

All Current Publications

Corn smut is caused by the fungus Ustilago maydis. Smut rarely occurs in Utah and is not considered economically important for grain production. For home gardeners and small farms, serious smut infections on sweet corn can cause ears to be inedible. U. maydis spreads from plant to plant by wind-borne or water-splashed spores onto silks or through existing wounds. Therefore, keeping corn plants insect- and disease-free reduces the number of entry points for infections. This fact sheet reviews the disease cycle, identification, and management.

Mancha Anular Necrótica Y Mancha De Verano Del Césped, Claudia Nischwitz, Kelly Kopp, Jaydee Gunnell, Kent Evans, Erin Frank, Celina Wille

All Current Publications

La mancha anular necrótica y mancha de verano del césped son enfermedades fúngicas que infectan los pastos de estación fría y causan síntomas similares. Los síntomas comienzan como un crecimiento deficiente y marchitez de las hojas, que se convierten en parches marrones obvios que varían de 1 a 3 pies de diámetro. Debido a los síntomas similares que se observan en la infección por ambos patógenos, se necesita un microscopio para diagnosticar adecuadamente cada enfermedad. El manejo de ambas enfermedades puede ser difícil y frecuentemente requiere una combinación de técnicas de control cultural, químico y varietal.

Expression Analysis Of Plant Defense Responses During The Establishment Of Biotrophy And Role Of Abiotic Stress In The Infection Of Dyer’S Woad (Isatis Tinctoria) By Puccinia Thlaspeos, Elizabeth Thomas

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The kinetics and amplitude of the salicylic acid-responsive pathogenesis-related (PR) genes and the cytochrome P450 gene ItCYP79B2 in the compatible interaction between Puccinia thlaspeos and dyer’s woad (Isatis tinctoria) during the first 72 hours of inoculation were examined. Immediately following penetration of the host by the rust pathogen, there was a modest up-regulation of PR genes but a significant down-regulation of ItCYP79B2 expression. During haustoria formation, a significant pathogen-mediated suppression of PR genes was observed with a corresponding up-regulation of ItCYP79B2. This potentially facilitates haustoria formation by P. thlaspeos. After haustoria formation, a more …

The Isolation, Property Analysis And Determination Of In Planta Growth Ability Of Extracellular Polysaccharide Mutants Of Corynebacterium Michiganense Pv Insidiosum, Mary C. Paschke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Corynebacterium michiganense pv insidiosum, the organism responsible for bacterial wilt of alfalfa, produces an extracellular polysaccharide (EPS) that has been linked to its virulence. The EPS is composed of three different-sized molecules (components I, II and III). It has been demonstrated that this EPS accumulates in the vascular system of infected plants and causes disruption of the flow of water.

The importance of EPS to the survival and pathogenicity of C.m. pv insidiosumis not known. In order to begin assessing the value of EPS, mutant strains that are EPS-deficient were isolated after UV mutagenisis. Analysis by gel filtration …

Source Of Inoculum, Yield And Quality Of Tomato As Affected By Leveillula Taurica, Wayne B. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tomato transplant stock from southern Nevada served as a source of inoculum and developed disease symptoms of tomato powdery mildew approximately three weeks before Utah-grown transplants. Plants from Nevada and Utah were equally infected seven weeks after planting and no differences in severity or yield were detected at the end of the season due to rapid spread of the fungus. Tomato yields were reduced ca 40% in check plots when compared to plots treated with triadimefon, propiconazol or sulfur. The amount of sunburned fruit in check plots was three to four times greater than in plots where the disease was …

Impact, Epidemiology And Control Of Crown And Root Rot Of Spring Barley In Utah, Rastri Dey Kidambi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A three year study was initiated to study impact, epidemiology and control aspects of crown and root rot of irrigated and dryland spring barley in Utah. Isolations from leading edges of necrotic lesions of infected plants showed Cochliobolus sativus to be most frequently isolated. Yield loss studies showed that the disease had it's greatest effect in kernel weight reduction.

Time course studies of disease initiation, development and progress were made throughout two consecutive growing seasons. Disease initiation began 25-30 days after planting and reached maximum levels at approximately 60-80 days. Soil inoculum levels were determined by the flotation viability method …

Crown And Root Rot Of Alfalfa In Utah, Victoria Allard Turner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Symptoms of dark crown necrosis were found in all fields and varieties of alfalfa examined throughout the state. No significant differences were noted among varieties in 1 year old test plots in the amount of disease (Disease Index = D.I.) present in crown tissue. Significant differences were noted in plots 2.4 years and older among the different varieties. Varieties common to all plots did not differ overall; however, varieties responded differently according to location.

Fusarium spp. were most frequently isolated from affected crowns throughout the state, yet, differences in occurrence of species among the different aged plots and fields were …

In Vitro Morphogenesis And Mutation Of Glycine Max L., Thomas Daniel Wilson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Soybean (Glycine max L. c.v. Consoy) tissue cultures were grown in synthetic media containing various concentrations and combinations of minerals, auxins, cytokinins, pH levels, and inorganic growth factors in a systematic procedure to establish optimum media for initiation and maintenance of callus. Further modification of the hormone level was employed to initiate callus morphogenesis. Normally toxic levels of atrazine were established in soybean calli media, and ethyl methanesulfonate (EMS) and X ray-induced mutant calli were selected for atrazine tolerance.

Optimal media for initiation and maintenance of soybean calli were developed and a defined medium was determined that consistently yields …

Multiple Forms Of Deoxyribonucleic Acid-Dependent Ribonucleic Acid Polymerase In Barley Leaves (Hordeum Vulgare L.), Sachchidananda Javali

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Ribonucleic acid polymerases (E.C. 2.7.7.6) have been solubilized form whole green leaves of barley (Hordeum vulgare L.). Three major forms of the solubilized enzyme have been isolated by sonication in high ionic strength buffers, cation and anion exchange chromatography, and agarose gel permeation chromatography and designated I, II, and III. The enzyme fractions appear analogous to the Class I, II, and III ribonucleic acid polymerases defined in other eucaryotic systems. The ionic strength optima, amatoxin sensitivity, and relative activities with denatured calf thymus deoxyribonucleic acid were different for Class I, II, and III polymerases.

A simple, rapid, reproducible method …

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, …

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 …

Effects Of Two Pathogenically Differing Isolates Of Verticillium Albo-Abrum On Tomato Growth, Leonidas Berry Camp

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A study was performed using isolates of Verticillium albo-atrum which were reported as varying in their pathogenicities to a susceptible and resistant tomato variety. Also included as objectives in this undertaking were cross-protection and effects of spore density in the inoculum on the development and severity of Verticillium wilt of tomatoes.

After retesting the strains which were reported as pathogenic variants, results suggested that reported variabilities were non-existent in most of the isolates and instead there were only two pathogenic type-categories: (a) strains pathogenic to both resistant and susceptible tomato varieties; and (b) strains pathogenic only to the susceptible variety. …

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 …