Plant Pathology Commons^™

Interactions Of Biorational And Synthetic Dmi Fungicides For Control Of Fruit Diseases, Johanna Wesche

All Dissertations

Biological fungicides are increasingly investigated as sustainable alternatives to synthetic fungicides in fruit crop protection. This dissertation examines the interactions between two commercial biological fungicides, Bacillus subtilis AFS032321 (Theia) and metabolites of Pseudomonas chlororaphis AFS009 (Howler EVO); and demethylation inhibitor (DMI) fungicides, with a focus on compatibility, synergistic potential, and resistance implications. In vitro assays revealed that commonly used DMI fungicides difenoconazole, metconazole, tebuconazole, and propiconazole inhibited vegetative growth of B. subtilis at concentrations above 50 µg/ml, whereas mefentrifluconazole promoted colony expansion. Under controlled conditions, lesion development on detached fruit was inhibited synergistically when Theia was combined with the growth-promoting …

Improved Management Strategies For Botrytis Fruit Rot, Macrophomina Root Rot, And Verticillium Wilt In California Strawberry Production, Joseph A. Ramirez

Master's Theses

Strawberry production in California is limited by plant diseases such as Macrophomina root rot (MRR) caused by Macrophomina phaseolina, Verticillium wilt (VW) caused by Verticillium dahliae, and Botrytis fruit rot (BFR) caused by Botrytis cinerea. Current disease management strategies are compromised due to fumigant regulations or ineffective disease management practices. This thesis investigated methods to potentially improve the management of these three diseases. Two host plant resistance evaluations for MRR and VW were conducted for the 2022-2023 and 2023-2024 growing seasons. Sixty-three strawberry genotypes were screened in both years. All plants were exposed to the pathogen via artificial …

Evaluation Of Pierce’S Disease-Resistant Grapevine Cultivars In Upstate South Carolina, Annie Bruno

All Theses

Interest in wine grape production is increasing in South Carolina, but Pierce’s Disease (PD) caused by the xylem-limited bacteria Xylella fastidiosa (Xf) is a major limiting factor. Xf is spread by sap-sucking insect vectors in the Cicadellidae family such as sharpshooters. In the United States, Xf has become endemic to the southeast as global temperatures rise, causing winter temperatures to increase, which allows the bacteria to survive year-round. However, PD-resistant grapevine hybrid cultivars have become available through breeding V. vinifera genes with native American Vitis species that are resistant to Xf. In this study, the PD-resistant grapevine …

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.

Assessment Of Foam Decontamination In Tomato Washing Process, Basim M. Alohali

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The work of the dissertation investigated the efficacy of foam-based decontamination treatments to enhance microbial safety in Roma tomatoes, specifically targeting natural microflora and Salmonella contamination. Growing concerns over foodborne illnesses linked to fresh tomatoes and the limitations of conventional decontamination techniques, such as organic matter built-up and limited microbial reduction, are addressed. The primary objectives were to characterize the physiochemical properties of foams formed using various concentrations of Tween 20 (T20) and sodium dodecyl sulfate (SDS) with and without the addition of sodium hypochlorite (NaOCl) and peracetic acid (PAA), compare the efficacy of foam and traditional dump tank (DT) …

Feeding Behavior Of Sweet Potato Weevil, Cylas Formicarius (Fabricius) (Coleoptera: Brentidae) On Three Sweet Potato, Ipomoea Batatas L. Cultivars Grown In Tarlac, Philippines, Jerah Mystica Novenario, Flor Ceballo-Alcantara

The Philippine Agricultural Scientist

Sweet potato is grown in tropical countries for its edible tubers, which have become an essential food source. It is usually propagated through vine-cutting, which can be obtained from harvested plants or nurseries intended for cutting production only. The recurrent use of vines may cause increased weevil infestation. The crop is known to be infested with insect pests. More importantly, the sweet potato weevil, Cylas formicarius, targets the tubers, thus, causing the economic losses. Sweet potato farmers in Tarlac claim that only one sweet potato cultivar is being attacked by C. formicarius, however, it was found in this experiment that …

Taxonomy Of Cassava (Manihot Esculenta Crantz) Mealybugs (Hemiptera: Pseudococcidae) - 1: Identification And Local Distribution Of The Predominant Species On Witches’ Broom-Diseased Plants In The Philippines, Ireneo L. Lit Jr., Cristian Lucañas, Joanne Langres, Lolita Dolores, Ruby Ana Laude, Merdelyn Caasi-Lit

The Philippine Agricultural Scientist

Samples of cassava (Manihot esculenta Crantz) plants infected with witches’ broom disease were gathered from 13 provinces in the Philippines. Mealybugs were observed to occur in nine out of the 13 cumulative samples. The most predominant among several mealybug species observed was identified as Pseudococcus jackbeardsleyi Gimpel and Miller. P. jackbeardsleyi is not yet known to transmit phytoplasma, especially the one causing cassava witches’ broom (CWB). However, its occurrence in almost 70% of the CWB-infected samples provides circumstantial evidence that it may be related to the spread of the pathogen. This formal report of identification is in support of the …

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …

Identification And Characterization Of Geotrichum Candidum Isolates From Peach With Reduced Sensitivity To Propiconazole, Sara Price

All Theses

Geotrichum candidum Link (1809) is a yeast-like fungus that causes sour rot of stone fruits, including peach (Prunus persica). The disease caused damage between 2021 and 2023 to the peach crop kept in cold storage at a commercial farm in South Carolina despite preharvest and postharvest applications of fungicides. Isolates from 41 symptomatic fruit, from a South Carolina (SC) commercial packing house, as well as other isolates obtained from South Carolina were identified to be G. candidum based on species-specific PCR amplifications of the β tubulin gene. Commonly used postharvest fungicide fludioxonil had no effect on G. candidum mycelial growth …

Disease-Reducing Effect Of Calcium Salts Against Postharvest Diseases Of Mango (Mangifera Indica L. Cv. Carabao) Fruits, Melissa P. Montecalvo, Mary Joy C. Mendoza, Teresita U. Dalisay

The Philippine Agricultural Scientist

Mango fruits (Mangifera indica L. cv. Carabao) are susceptible to fungal infection, resulting in postharvest diseases. Chemical pesticides are used for disease management but may have a health impact and are costly. Therefore, alternatives to chemical control are necessary to minimize health risks and losses due to postharvest diseases. This research presented the disease-reducing effect of calcium salts, calcium chloride (CaCl₂) and calcium carbonate (CaCO₃), against mango stem end rot (SER) (sometimes caused by Lasiodiplodia theobromae) and anthracnose (caused by Colletotrichum gloeosporioides sensu lato). In in vitro assays, mycelial growth of both pathogens …

Genomic Analyses Of A Widespread Blueberry Virus In The United States, Daisy Stainton, Dan E.V. Villamor, Andrea Sierra Mejia, Ashish Srivastava, Dimitre Mollov, Robert R. Martin, Ioannis E. Tzanetakis

Entomology and Plant Pathology Faculty Publications and Presentations

Screening of blueberry accessions using high throughput sequencing revealed the presence of a new virus. Genomic structure and sequence are similar to that of nectarine stem pitting associated virus (NSPaV), a member of the genus Luteovirus, family Tombusviridae. The full genome of the new luteovirus, tentatively named blueberry virus L (BlVL), was characterized and analyzed. Similar to NSPaV, BlVL does not contain readily identifiable movement proteins in any of the seven isolates sequenced. More than 600 samples collected from five states were screened and 79% were found infected, making BlVL the most widespread blueberry virus in the United States.

Understanding The Influence Of Excessive Fertilization And Water Relations On Peach (Prunus Persica (L.) Batsch) Skin Bronzing, Sydney Lykins

All Theses

This project evaluated possible causes of peach skin bronzing, a brown-blotchy skin discoloration on mid to late-season peaches that causes drastic decreases to grower incomes in the Southeastern U.S. It is known that there is no bacterial, insectile, viral, or fungal cause of bronzing; thus, these studies focused on potential nutrient imbalances within the peach. On the ‘PF23’ variety, factors of irrigation, potassium fertilization, and transpiration-inhibiting sprays were tested to see the various effects on the incidence and severity of bronzing. The hypothesis was that excessive irrigation and excessive soil potassium concentrations would induce a higher incidence and severity of …

Distribution And Genomic Diversity Of Pollen-Borne Viruses And Viroids At The Interface Of Peach And Wild Prunus Spp. In The Southeastern United States, Fabian Omar Rodriguez Bonilla

All Theses

Prunus necrotic ringspot virus (PNRSV), prune dwarf virus (PDV), and peach latent mosaic viroid (PLMVd) are important pollen-borne pathogens that affect peach orchards in the southeastern United States. My aim with this research is to identify potential sources of virus/viroid inoculum sources in the wild and determine pathogen movement and interactions between wild Prunus spp. and cultivars of peach (P. persica). In Chapter I, I review the literature on pollen borne viruses and viroids in peach. In Chapter II, I surveyed for these pathogens near peach production areas in South Carolina and Georgia, sampling from three endemic wild …

Proceedings Of The 2022 Passion Fruit Conference: Growing The U.S. Passion Fruit Industry A Strategic Conference For: Growers, Marketers, Researchers, And Stakeholders, Eric T. Stafne

CREC Publications

We are pleased to deliver these proceedings of the passion fruit conference that was held in Homestead, Florida on June 14 and 15, 2022. It was a culmination of a lot of hard work by many people, most of them listed in the previous page. However, it would not have been a success without the attendees who came from various parts of the country to share their experiences growing passion fruit. What follows in these proceedings are the slides of the presentations with by notes taken by attendees along with notes taken of discussion regarding the five priority topic areas: …

Primary Industries Development Research Highlights 2021, Department Of Primary Industries And Regional Development, Tim Scanlon

Books & book chapters

The Primary Industries Development Research Highlights 2021 showcases the breadth and depth of the Department of Primary Industries and Regional Development’s research and development activities over the past several years.

Stories featured in Research Highlights 2021 stem from about 60 (of 140) current and recently-completed projects undertaken by the Department of Primary Industries and Regional Development’s (DPIRD) 1100 scientists, technical experts and economists throughout the State.

Explore our Research Highlights 2021.

The publication demonstrates the innovative and applicable research that DPIRD and its collaborators and investment partners deliver to Western Australia.

Download the Research Highlights 2021 here. Alternatively, …

Characterization, Incidence, And Epidemiology Of Two Novel Strawberry Rhabdoviruses, Ava Wait

Graduate Theses and Dissertations

Strawberry is the most important berry crop, grown in most temperate regions around the world. In the early 2000s and in 2012-2013, viral disease devastated strawberry production in California and Florida respectively; causing multimillion dollar losses. This occurred because viruses were moving in the field undetected. The modern strawberry (Fragaria x ananassa Duch.) is tolerant to single and double infections; yet when several viruses infect plants, symptoms as severe as plant death can occur. To prevent future epidemics, the use of virus-tested planting materials is essential. In 2019, rhabdovirus-like sequences were detected in strawberry using a combination of high-throughput sequencing …

An Evaluation Of Biopesticide Combinations On Yield Performance And Disease/Arthropod Control Of Strawberries Grown In High Tunnel Plasticulture Production Systems In Arkansas., Karlee B. Pruitt

Graduate Theses and Dissertations

This two-year study investigated combinations of biopesticides to determine impacts on strawberry fruit marketable fruit yields, and effectiveness in controlling strawberry pests in a high tunnel production system at the University of Arkansas, Division of Agriculture Research and Extension Center in Fayetteville, Arkansas. Two strawberry cultivars Fragaria × ananassa (Duch.), Camino Real and Sweet Sensation were grown in a high tunnel from early-October to mid-May for two consecutive growing seasons, (2017-18 and 2018-19) with six treatment combinations of biopesticides including an untreated (water) control, nutrient spray and selected biological based fungicides and insecticides, arranged into a split-plot randomized block design. …

Evaluation Of Pheromone Mating Disruption For California Red Scale Control In Commercial California Citrus, Joel Timothy Leonard

Master's Theses

California red scale (CRS), Aonidella aurantii, is an increasingly injurious insect pest for the California citrus industry due to insecticide resistance, changing weather patterns, and shifting trade regulations. The presence of the insect on fruit, damages the rind of the fruit and high populations can cause dieback of branches as well as lower yields. Pheromone mating disruption of CRS has the potential to alleviate population control concerns and reduce insecticide use. The efficacy of the pheromone mating disruption technique for pest management of CRS was determined using the products CheckMate® CRS and Semios CRS Plus. CheckMate® CRS was evaluated …

Evaluation Of Host Resistance And The Utilization Of Organic Amendments To Manage Macrophomina Crown Rot Of Strawberry In California, Jonathan W. Winslow

Master's Theses

The production of strawberries can be severely limited by soilborne plant pathogens, insects and weeds. Macrophomina phaseolina is a problematic soilborne fungal pathogen in California strawberry production inciting the disease Macrophomina crown rot. When established, the pathogen can cause extensive plant decline and mortality. Host resistance will be a critical tool for managing this disease and guiding breeding programs in the post methyl bromide era. Evaluation of host resistance in strawberry germplasm to M. phaseolina was evaluated through phenotypic assessments of disease incidence. A total of 90 strawberry cultivars and elite selections were included in a replicated field trial conducted …

Seasonal Phenology, Distribution And Treatments For Polyphagotarsonemus Latus (Banks) On Primocane-Fruiting Blackberries (Rubus L. Subgenus Rubus) In Arkansas, Jessica Anne Lefors

Graduate Theses and Dissertations

Worldwide, blackberries (Rubus L. subgenus Rubus) are an economically important crop. In 2007, Polyphagotarsonemus latus (Banks) (broad mites), were first reported damaging primocane-fruiting blackberries in Fayetteville, Arkansas. Since this time, broad mite damage to blackberries and yield loss has been reported in many states and countries. Despite the increasing reports of this blackberry pest, little is known about their population dynamics, and few treatments are available. Growers with broad mite populations need a pest management program to minimize yield loss. Therefore, there was a need to develop sampling techniques, describe broad mite seasonal phenology in blackberry fields, and determine efficacy …

Breeding For Resistance In California Strawberry To Verticillium Dahliae, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This article focuses on breeding resistant strawberries to the fungus Verticillium dahliae, common name Verticillium wilt. This is a serious fungal disease that can result in a loss of 50% or more of a strawberry harvest when grown in infested soil. The main goal is to provide an example of how a cultivar can be made more resistant to a plant pathogen with the use of plant breeding methods.

Since 1930 the University of California, Davis, has been developing strawberry cultivars that are adapted to the agricultural industry and regional farms. Developing cultivars that require fewer inputs are of …

Seasonality And Management Of Spotted Wing Drosophila On Berry Crops And Wild Hosts In Arkansas, Lizabeth Rubi Herrera

Graduate Theses and Dissertations

Spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) is a serious invasive pest of small fruit production in North and South America and Europe since 2008. The primary control method is to apply insecticides every 5-7 days. Therefore, it is necessary to develop control tactics that are less chemical dependent to enhance an integrated approach for SWD management. The objectives of this study were to monitor SWD populations in different crop systems and adjacent landscape habitats; identify wild hosts of SWD; evaluate the effectiveness of insect exclusion netting in tunnels to prevent blackberry and blueberry infestations, and compare effects of netted …

Phenotypic Variation And Genetic Purity Of The Original 'Prime-Jim®' X 'Arapaho' Population, Loren M. Luther

Horticulture Undergraduate Honors Theses

In 2013, Castro et al., produced the first linkage map for primocane-fruiting blackberries using the cross ‘Prime-Jim®’ x ‘Arapaho.’ This mapping population has been maintained since the original experiment with the hopes of conducting future studies. Further research was determined to be needed on the population to better characterize additional phenotypic traits, and since nine years had passed since the seedlings were established, there was a need to assess the continued genetic purity of the population using molecular methods. Phenotypic data was collected to analyze the variation of the population including soluble solids content, titratable acidity, average weight, shape, and …

Exploration Of Chemical And Biological Management Strategies For Diaphorina Citri The Primary Vector Of Candidatus Liberibacter Asiaticus, Gretta Marie Sharp

Biology Theses

Diaphorina citri (Hemipteran: Psyllidae), the Asian citrus psyllid, is a phloem-feeding, invasive species endemic to southern Asia that was first identified in the United States in Florida in 1998. Since introduction, D. citri has spread across the major citrus growing regions of the United States. This is of great concern to the citrus industry because D. citri is the primary vector of Candidatus Liberibacter asiaticus the causal agent of Haunglongbing (HLB). Haunglongbing is the most economically devastating disease of citrus causing an estimated 8.92 billion dollars lost in revenue and 4.62 billion dollars lost in gross domestic product between 2006-2007 …

Investigating Novel Approaches For The Integrated Control Of The Soilborne Strawberry Pathogens Macrophomina Phaseolina And Fusarium Oxysporum F. Sp. Fragariae, Mel Carter

Master's Theses

Macrophomina phaseolina (Mp) and Fusarium oxysporum f. sp. fragariae (Fof) are emerging soilborne pathogens causing crown rot and Fusarium wilt, respectively, in commercial strawberry production in California. Fungicides representing eight active ingredients from four different mode of action groups (FRAC groups 1, 3, 7 and 12) were evaluated for their efficacy against each pathogen in vitro and each disease in planta. Fungicide active ingredients were evaluated for their ability to inhibit mycelial growth of both pathogens in vitro. Half-strength potato dextrose agar was amended with six different concentrations (0.01, 0.1, 1.0, 5.0, 10, 50 µg …

Screening Strawberry Clones For Anthracnose Disease Resistance Using Traditional Techniques And Molecular Markers, Melinda A. Miller-Butler

Dissertations

Cultivated strawberry, Fragaria x ananassa Duchesne, is host for many pathogens. One of the most destructive diseases of strawberry is anthracnose, whose symptoms include fruit rot, leaf and petiole lesions, crown rot, wilt, and death. Three species of Colletotrichum are considered causative agents of anthracnose diseases of strawberry. Colletotrichum acutatum causes anthracnose fruit rot, has a broad host range, and occurs in most areas of the world where strawberries are grown. Colletotrichum fragariae, the primary causal fungus of anthracnose crown rot, may infect all aboveground parts of the strawberry plant, and has restricted host and geographic ranges. Colletotrichum gloeosporioides …

Blackberry Virosome: A Micro And Macro Approach, Archana Khadgi

Graduate Theses and Dissertations

Viruses pose a major concern for blackberry production around the world with more than 40 species known to infect the crop. Virus complexes have been identified recently as the major cause of plant decline with blackberry yellow vein disease (BYVD) being the most important disease of the crop in the Southern United States. The objective of this research was to study the blackberry virosome in both the macro and micro scale. The large scale approach involves identification of the major viruses known to be associated with BYVD in the Southern United States as well as the identification of other viruses …

Survey Of Endosymbionts In The Diaphorina Citri Metagenome And Assembly Of A Wolbachia Wdi Draft Genome, Surya Saha, Wayne B. Hunter, Justin Reese, J. Kent Morgan, Mizuri Marutani-Hert, Hong Huang, Magdalen Lindeberg

School of Information Faculty Publications

Diaphorina citri (Hemiptera: Psyllidae), the Asian citrus psyllid, is the insect vector of Ca. Liberibacter asiaticus, the causal agent of citrus greening disease. Sequencing of the D. citrimetagenome has been initiated to gain better understanding of the biology of this organism and the potential roles of its bacterial endosymbionts. To corroborate candidate endosymbionts previously identified by rDNA amplification, raw reads from the D. citri metagenome sequence were mapped to reference genome sequences. Results of the read mapping provided the most support for Wolbachia and an enteric bacterium most similar to Salmonella. Wolbachia-derived reads were extracted using …

Strawberry Growth, Yield, Fruit Nutrition, And Control Of Verticillium Wilt With Pre-Plant Soil Fumigants, Ozone, And Biological Control, Justin J. Scurich

Master's Theses

Verticillium wilt is a widespread soilborne disease of strawberry historically controlled by soil fumigation with methyl bromide (MB). MB was banned by the United Nations in 1995 and will be completely phased out by 2015. Research has concentrated on alternative methods of disease control without finding a single alternative able to replace MB in widespread disease control and yield increase. For the current study, strawberries were greenhouse grown in container pots filled with soil from both infested and non-infested areas of a commercial strawberry field in Watsonville, CA. Treatments included pre-plant soil fumigation with commercially available formulations of methyl bromide, …

Good Agricultural And Handling Practices For Grapes And Other Fresh Produce, Pamela L. Brady, Justin R. Morris

AAES Research Reports and Research Bulletins

In recent years consumption of fresh fruits and vegetables has increased dramatically. This trend has increased the amount of produce being purchased at farmer’s markets, road-side stands, and neighborhood markets since consumers say they feel that the direct contact with growers at these markets makes them better able to assess the quality and safety of the produce. This buying trend has opened new markets to small- and medium-sized farms, which sell at these local outlets.