Alan S. Windham

Plant Pathology Concepts and Laboratory Exercises

Introductory Concepts Plant Pathology and Historical Perspectives, M.T. Windham and A.S. Windham What Is A Disease? M.T. Windham and A.S. Windham Introduction to the Groups of Plant Pathogens, M.T. Windham Groups of Plant Pathogens Plant Pathogenic Viruses, M.A.C. Langham Mechanical Inoculation of Plant Viruses, M.A.C. Langham Plant-Parasitic Nematodes, J.P. Noe Pathogenicity and Isolation of Plant Parasitic Nematodes, J.P. Noe Plant Pathogenic Fungi and Fungal-like Organisms, A. Brooks Gould Slime Molds and Zoosporic Fungi, S.E. Mozley-Standridge, D. Porter, and M.A. Cubeta Laboratory Exercises with Zoosporic Plant Pathogens, M.A. Cubeta, D. Porter, and S.E. Mozley-Standridge Archiascomycete and Hemiascomycete Pathogens, M. L. Daughtrey, K. T. Hodge, and N. Shishkoff The Powdery Mildews, M.L. Daughtrey, K.T. Hodge, and N. Shishkoff Ascomycota: Pyrenomycetes, Discomycetes, and Loculoascomycetes, K.J. Curry and R.E. Baird Deuteromycota: An Artificial Assemblage of Asexually Reproducing Fungi, R.E. Baird Laboratory Exercises with Selected Asexually Reproducing Fungi, R.E. Baird Smut and Rust Diseases, L.J. Littlefield, Y.H. Li, and D. Hensley Basidiomycota: Fleshy Mushrooms and Other Important and Symbiotic Associations, R.E. Baird Oomycota: The Fungi-like Organisms, R.N. Trigiano, M.H. Ament, and K.H. Lamour Laboratory Exercises with the Oomycetes, R.N. Trigiano, R. E. Baird, and S. N. Jeffers Soilborne Plant Pathogens, B.H. Ownley and D. Michael Benson Laboratory Exercises with Soilborne Plant Pathogens, D M. Benson and B.H. Ownley Parasitic Seed Plants, Protozoa, Algae, and Mosses, M.T. Windham and A.S. Windham Abiotic Diseases, A.S. Windham and M.T. Windham Molecular Tools for Studying Plant Pathogens Molecular Tools for Studying Plant Pathogens, T.A. Rinehart, X.W. Wang, and R.N. Trigiano Molecular Techniques Used for Studying Systematics and Phylogeny of Plant Pathogens, R.N. Trigiano, M.H. Ament, S.L. Finley, R.E. DeVries, N.R. Rowland, and G. Caetano-Anolles Plant-Pathogen Interactions Plant-Fungal Interactions at the Molecular Level, R.B. Ferreira, S. Monteiro, R. Freitas, C.N. Santos, Z. Chen, L.M. Batista, J. Duarte, A. Borges, and A.R. Teixeira Testing Blad, a Potent Antifungal Polypeptide, S. Monteiro and R. Boavida Ferreira Detecting and Measuring Extracellular Enzymes Produced by Fungi and Bacteria, R.N. Trigiano and M.H. Ament Host Defenses: A Physical and Physiological Approach, K.D. Gwinn, S.E. Greene, J.F. Green, and D. Trently Disruption of Plant Function, M.B. Riley Epidemiology and Disease Control Plant Disease Epidemiology, K.L. Bowen Host Resistance, J.K. Pataky and M.L. Carson Cultural Control of Plant Diseases, G. Moorman and K.D. Gwinn Chemical Control of Plant Diseases, A.S. Windham and M.T. Windham Biological Control of Plant Pathogens, B.H. Ownley and M.T. Windham Integrated Pest Management, C.A. Hollier and D.E. Hershman Plant Disease Diagnosis, J.M. Mullen Diagnostic Techniques and Media Preparation, J.M. Mullen Special Topics In Vitro Plant Pathology, J. Subramanian and D.J. Gray Proper Use of Compound and Stereo Microscopes, D.T. Webb Appendix 1: Careers In Plant Pathology, A.S. Windham and M.T. Windham Glossary Index

Stakeholder Vision of Future Direction and Strategies for Southeastern U.S. Nursery Pest Research and Extension Programming

Extension and research professionals worked with a focus group of 10 nursery owners and managers across a five-state region (Georgia, Kentucky, North Carolina, South Carolina, Tennessee) in the southeastern United States to prioritize diverse nursery pests and production issues that are related to container and field production. A second focus group meeting, focused on technology, was followed by a survey that asked nursery growers to prioritize potential inputs and uses of information technology and the features they most valued, for example, that might be included within a nursery-specific mobile device application. The resulting prioritization highlights common challenges faced by growers across the southeastern United States in managing major plant diseases, arthropod pests, and weeds; as well as documenting emerging critical issues of nonpest related production issues, regulatory constraints, and technological needs. The focus group and survey format effectively identified grower needs that will help inform nursery producers and guide university Extension and research professionals, university administrators, industry associations, and state and federal government officials toward efficient resource allocation. These prioritizations explain the current state-of-need across a diverse agricultural industry segment and will help further refine future strategic action plans for nursery integrated pest management (IPM) and emerging critical nursery crop pest issues.

Assessing the integrated pest management practices of southeastern US ornamental nursery operations

BACKGROUND The Southern Nursery Integrated Pest Management (SNIPM) working group surveyed ornamental nursery crop growers in the southeastern United States to determine their pest management practices. Respondents answered questions about monitoring practices for insects, diseases and weeds, prevention techniques, intervention decisions, concerns about IPM and educational opportunities. Survey respondents were categorized into three groups based on IPM knowledge and pest management practices adopted. RESULTS The three groups differed in the use of standardized sampling plans for scouting pests, in monitoring techniques, e.g. sticky cards, phenology and growing degree days, in record-keeping, in the use of spot-spraying and in the number of samples sent to a diagnostic clinic for identification and management recommendation. CONCLUSIONS Stronger emphasis is needed on deliberate scouting techniques and tools to monitor pest populations to provide earlier pest detection and greater flexibility of management options. Most respondents thought that IPM was effective and beneficial for both the environment and employees, but had concerns about the ability of natural enemies to control insect pests, and about the availability and effectiveness of alternatives to chemical controls. Research and field demonstration is needed for selecting appropriate natural enemies for augmentative biological control. Two groups utilized cooperative extension almost exclusively, which would be an avenue for educating those respondents.

Powdery Mildew of Dogwoods: Current Status and Future Prospects

Cornus is a large genus of trees and shrubs that are collectively referred to as dogwoods. Flowering dogwood (C. florida L.) and kousa dogwood (C. kousa (F. Buerger ex Miq.) Hance) and interspecific hybrids of these species are popular ornamental trees that are known for their showy bracts, red berries (drupes), and/or fall color. Other species that are commercially grown for specialty markets include the pagoda dogwood (C. alternifolia L.), giant dogwood (C. controversa Hemsl.), cornelian cherry (C. mas L.), Pacific dogwood (C. nuttallii Aud.), and redosier dogwood (C. sericea L.). The foliage of native species, such as flowering dogwood and pagoda dogwood, is high in calcium (12) in quantities above what is needed for skeletal growth of wildlife; it is the preferred browse material for lactating does in late spring while many other trees are still leafless (13,22). The berries of flowering dogwood have high oil content and provide mast for numerous species of migrant songbirds, wild turkeys, and large and small mammals (22). For many years, nurseries that produced flowering and kousa dogwoods had the luxury of working with relatively diseasefree crops. Disease management and control costs were minimal and estimated at approximately

Genetic variability and phylogenetic analysis of hosta virus X

120/ha/year. In the late 1970s, flowering and kousa dogwoods were threatened by a new disease, dogwood anthracnose, caused by Discula destructiva (39), which was reviewed by Daughtrey et al. (3). In 1994, another disease, powdery mildew, reached epiphytotic levels in flowering dogwoods. Tens of millions of dollar’s worth of dogwoods were destroyed and millions of cultivated seedlings lost their commercial value because formal management strategies were not formulated. In subsequent years, fungicide management costs were estimated to be

Genetic analysis of fungicide-resistant Sclerotinia homoeocarpa isolates from Tennessee and northern Mississippi

1,975/ha/year. Many small producers of dogwoods terminated production of the tree because they could not afford the additional overhead or were not inclined to continue routine fungicide sprays every 2 weeks from May to October. Powdery mildew on C. florida was first reported in 1887 by Burrill and Earle (1), but this disease was rarely reported on flowering dogwood in the United States before 1994. However, the disease appeared simultaneously in forest, landscape, and nursery plantings statewide in Alabama in 1994 (8). Similar outbreaks of powdery mildew were observed in Tennessee, where many nursery fields of flowering dogwood were abandoned (Fig. 1). Powdery mildew has emerged as a nationwide disease of flowering dogwood (2). Although the host side of the disease triangle remained constant, we do not know whether the change of frequency and severity of powdery mildew in flowering dogwood was due to a change in the pathogen or a change in the environment.

Development of an RT-PCR/RFLP assay to detect Hosta virus X in hosta (Hosta spp.)

Triple gene block 1 (TGB1) and coat protein (CP) sequences of 30 hosta virus X (HVX) isolates from Tennessee (TN), USA, were determined and compared with available sequences in GenBank. The CPs of all known HVX isolates, including those from TN, shared 98.3–100% and 98.2–100% nucleotide and amino acid sequence identity, respectively, whereas TGB1 shared 97.4–100% nucleotide and 97–100% amino acid sequence identity. TGB1 of TN isolates were all longer by one codon from that of a Korean isolate, which is the only sequence publicly available. Phylogenetic analysis of nucleotide and amino acid sequences of TGB1 and CP of all known HVX isolates, separately or combined, revealed a close relationship, suggesting that all of them are derived from a common ancestor. Phylogenetic analysis with the type member of each genus of the family Flexiviridae confirmed that HVX is a member of a distinct species of the genus Potexvirus.

Experiential Nursery Integrated Pest Management Workshop Series to Enhance Grower Practice Adoption

Sclerotinia homoeocarpa is the causal agent of dollar spot disease that reduces the uniformity and aesthetic value of golf putting greens. Fungicide-resistant isolates of S. homoeocarpa were collected from putting greens at 10 locations across Tennessee and northern Mississippi. Genetic diversity among the 60 isolates was investigated using vegetative compatibility, conserved gene sequences, and amplified fragment length polymorphism (AFLP). Six tester strains were paired with Tennessee and northern Mississippi isolates on potato dextrose agar. Some of the 60 isolates were delineated into vegetative compatibility groups, but fungicide resistance could not be associated with a particular vegetative compatibility group. Genetic similarities of isolates at the vegetative compatibility level could be attributed to founder effects. Sequencing the regions of CAD, EF1-α, β-tubulin, and internal transcribed spacers revealed 100% homology among isolates. Capillary gel electrophoresis and analysis of AFLP fragments indicated 86 to 100% similarity between the isolates. Vegetative compatibility and molecular data indicate that the populations of the pathogen are clonal. Isolates did not cluster according to fungicide resistance during unweighted pair group with arithmetic means analysis, but did appear to cluster according to vegetative compatibility group and location. Although associations could not be made between molecular markers and fungicide resistance, links between vegetative compatibility and AFLP markers may provide a foundation from which other studies could be performed.

Resistance of Sclerotinia homoeocarpa to Iprodione, Propiconazole, and Thiophanate-Methyl in Tennessee and Northern Mississippi

Summary Hosta virus X (HVX) is the most damaging virus of hosta (Hosta spp.). By taking advantage of the conserved coat protein (CP) sequences of characterised isolates of HVX, a reliable and sensitive diagnostic assay, based on RT-PCR, was developed. The conserved, single Hind II recognition site within the CP sequences was also exploited for restriction fragment length polymorphism (RFLP)-based verification of the amplicons. The reliability of the assay was demonstrated by successful amplification of 30 HVX isolates from 20 cultivars of hosta. The effectiveness of the assay was demonstrated by detecting several distinct isolates of HVX in a mechanically-inoculated hosta cultivar containing a low virus titre. The assay was capable of detecting HVX in composite samples consisting of a single HVX-infected leaf disc, approx. 1 cm in diameter, combined with up to 200 virus-free leaf discs of similar size, which demonstrated its potential for large-scale screening. The sensitivity of the assay was not affected by genetic variation in the hosta cultivars or in the virus isolates. We conclude that RT-PCR/RFLP is reliable, sensitive, and efficient for large-scale screening of hosta for HVX infection.

First Report of Geosmithia morbida in North Carolina: The Pathogen Involved in Thousand Cankers Disease of Black Walnut

Three, 2-day hands-on experiential learningworkshopswere presented in three southeastern United States cities in June 2014, by the Southern Nursery Integrated Pest Management (SNIPM) working group. Attendees were provided 4 hours of instruction including hands-on demonstrations in horticultural management, arthropods, plant diseases, and weeds. Participants completed initial surveys for gains in knowledge, skills, and abilities as well as their intentions to adopt various integrated pest management (IPM) practices after the workshop. After 3 years, participants were again surveyed to determine practice adoption. Respondents changed their IPM practice behavior because of attending the workshops. Those returning the survey set aside more time to scout deliberately for pests, plant diseases, and weeds; used a standardized sampling plan when scouting; and adopted more sanitation practices to prevent plant disease. Fewer horticultural management practices were adopted than respondents originally intended. Future emphasis should be placed on using monitoring techniques to estimate pest emergence, for example, traps and pheromone lures, as well as plant phenology and record keeping. However, more work is needed to highlight both the immediate and longterm economic benefits of IPM practice adoption in southeastern U.S. nursery production.