ECOLOGICAL AND GENETIC DIVERSITY OF SOIL-BORNE PATHOGENS AND THE SOIL MICROBIOME

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: EVANS-ALLEN
• Reporting Frequency: Annual
• Accession No.: 1017541
• Project Start Date: Oct 1, 2018
• Project End Date: Sep 30, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
TENNESSEE STATE UNIVERSITY
3500 JOHN A. MERRITT BLVD
NASHVILLE,TN 37209

Performing Department
Agricultural and Environmental Sciences

Non Technical Summary
Agricultural and horticultural crops are produced with an estimated market value of $212.3 billion in the United States each year (USDA, 2014). Soil-borne plant pathogens are diverse and encompass microorganisms such as fungi, oomycetes, bacteria, viruses and nematodes that cause pre- and post-emergence damping-off, root and crown rots, vascular wilts, as well as foliar blight in these crops and amenity plantings. Soil-borne pathogens often survive for long periods on host plant residue, soil organic matter, or as free-living organisms. Soil-borne pathogens may have broad host ranges, and crop species may be susceptible to several different pathogens. Due to the menagerie of plant species produced by growers, and hectares managed, soil-borne disease management is challenging. Interactions with soil texture, chemistry, and environmental conditions make soil-borne disease management challenging.The National Integrated Pest Management (IPM) Road Map has listed "Develop advanced management tactics for specific settings that prevent or avoid pest/disease attack" and efforts to "Improve the efficiency of suppression tactics and demonstrate least-cost options and pest/disease management alternatives" as critical research needs (IPM, 2013). Soil-borne diseases are becoming more difficult to manage because of increased pathogen resistance and restrictions of the use of some chemicals. Conventionally, soil-borne diseases are controlled by using soil fumigants, in-furrow fungicides, or fungicide seed treatment. Once a widely used fumigant, methyl bromide, was phased out of use in 2005 due to its negative effect on the stratospheric ozone layer (Dungan et al., 2003). The loss of methyl bromide has promoted increased interest in alternative methods to control soil-borne diseases.Some soil-borne pathogens have broad host ranges, reducing the effectiveness of crop rotations in soil-borne disease management.Clearly, additional soil-borne disease management strategies suited to the practice of sustainable production are urgently needed.Over the last 15 years there have been surprising and exciting innovative discoveries for natural methods to suppress or eliminate plant pathogens, and/or protect crop plants. Intensive studies of disease-suppressive soils have led to the development of new methods of analysis (Gross et al., 2007; Borneman et al., 2007; Bolwerk et al., 2005; Benitez et al., 2007) and new insights into the nature of soil-borne disease suppression (Hoitink and Boehm, 1999; Han et al., 2000; Krause et al., 2003; Alfano et al., 2007). Such advances indicate that active management of soil microbial communities can be an effective approach to developing natural suppression of diseases and improve crop productivity (Mazzola, 2004). This involves adjusting the types and timing of organic inputs, such as cover crops, animal manures, composts, compost teas, and crop sequencing. Such approaches have been shown to provide site-specific reductions in disease incidence (Abbasi et al., 2002; Rotenberg et al., 2005, Stone et al., 2003; Darby et al., 2006; Larkin et al.,2006; Larkin, 2008). This technology fits the general requirements of sustainable agriculture in that it utilizes natural means to control diseases. However, standardized and reliable techniques for pathogen suppression have not been developed and widely tested on different crop production systems for controlling soil-borne diseases. In part, this is due to the wide variety of organic amendments that are available and their variable effects depending on the chemical makeup of organic substrates, soil types, and/or local climatic conditions.Soil incorporation ofBrassicaor other cover crops has the ability to suppress soil microorganisms through the hydrolysis of glucosinolates (GSL) into isothiocyanate, a natural biofumigant (Kirkegaard et al., 1993, Matthiessen and Kirkegaard, 2006). GSL content and concentration differs amongBrassicacultivars, the development stage of the plant (Bellostas et al., 2007), and the end product formed by hydrolysis of the GSL, so that differentBrassicacultivars may have different levels of potential to control pathogens (Motisi et al., 2009). Therefore, it is important to study the different GSL-hydrolyzed end products produced by differentBrassicacrops and their effect on major soil-borne diseases. Incorporation of biofumigant use in the crop production cycle may provide additional successful and sustainable solutions for improving soil quality and enhancing natural soil-borne disease control. The effective use of biofumigants in crop production appears to be limited by a range of factors, which needs to be examined to provide effective recommendations to growers.Several commercially available biopesticides are composed of specific isolates of soil microorganisms that were selected for their capacity to suppress a range of pathogens. These biopesticides may operate through multiple mechanisms, such as niche exclusion, biocidal/biostatic effects, antibiosis, predation, and parasitism (Handelsman and Stabb, 1996; Fravel, 2005). Some of the most common microbe-based biopesticides contain bacterial isolates ofBacillusspp.,Pseudomonasspp., orStreptomycesspp., or fungal isolates ofGliocladiumspp. orTrichodermaspp. (Fravel, 2005). Many of these organisms suppress disease and associated pathogen populations through multiple mechanisms. Numerous studies and reviews have documented the potential of microbe-based biopesticides to suppress both foliar and root diseases (Doumbou et al., 2001; El-Tarabily and Sivasithamparam, 2006; Emmert and Handelsman, 1999; Fravel, 2005; Jacobsen et al., 2004). However, the general consensus among these reviews is that integration is the key to obtaining consistent activity from biopesticides (Fravel, 2005; Jacobsen et al., 2004).Adoption of biopesticides has increased. But there is a need for biopesticides to provide workable disease management solutions for growers. Demand for biopesticides has continued to expand dramatically in the last 15 years. However, despite substantial growth in the industry and markets, there is still a lack of publicly available data that substantiates efficacy and return on investment for most products. There is a critical need to develop and disseminate science-based informational resources that will promote useful and sustainable adoption by growers that experience significant plant disease pressure.Given the need for sound integrated pest management, approaches coordinating chemical and biological controls are needed. Recently emphasis has been placed on understanding the phytobiome of plants or microbiome of production soils. While metagenomic techniques, in theory, should allow for identification and association with soil-borne diseases, more importantly, these techniques offer the opportunity to understand biological suppressiveness (Weller et al., 2002). However, there are limitations to these methods (Nesme et al., 2016) so evidence must be combined with spatial analysis (Liu, Griffin, and Kirkpatrick, 2014) or analyzed across multiple locations and years to limit sampling error and bias (Paul et al., 2011).Recently, the use of indigenous vs. synthetic microbiomes to control soil-borne diseases was explored (Mazzola and Freilich, 2017). There are clear advantages with respect to survival and likely efficacy when microorganisms adapted to the specific environment or competing for a similar niche in the phytobiome are used.The long-term goals of the proposed project are to investigate the impact of rhizosphere microbial communities on plant health and on the productivity of diverse cropping systems, and to validate and evaluate different soil-borne disease management strategies under different environmental conditions.

Animal Health Component

50%

Research Effort Categories

Basic

30%

Applied

50%

Developmental

20%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	2110	1160	70%
216	2499	1040	30%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 216 - Integrated Pest Management Systems;

Subject Of Investigation
2110 - Ornamental trees and shrubs; 2499 - Plant research, general;

Field Of Science
1040 - Molecular biology; 1160 - Pathology;

Keywords

soil-borne diseases

disease management strategies

cover crops

biopesticides

Goals / Objectives
The long-term goals of the proposed project are to investigate the impact of rhizosphere microbial communities on plant health and on the productivity of diverse cropping systems, and to validate and evaluate different soil-borne disease management strategies under different environmental conditions. In order to provide effective and sustainable recommendations to growers with a useful synthesis of our results, the following objectives will be pursued:Objective 1. Evaluate the biology and diversity of soil-borne pathogens, associated antagonistic microorganisms, and environmental conditions in the context of the whole-system phytobiome. This objective includes traditional, metagenomics, and spatial/temporal methodologies to understand microbial community dynamics that determine soil-borne disease incidence and severity on economically important crops in the U.S.Objective 2. Evaluate the efficacy of soil-borne disease management strategies (chemical, biorational/biological, cultural) and characterize the associations among microbial community profile, soil physicochemical properties, environmental factors and disease suppression.

Project Methods
Objective 1. Evaluate the biology and diversity of soil-borne pathogens, associated antagonistic microorganisms, and environmental conditions in the context of the whole-system phytobiome.?Determination of the fungal community compositions using Illumina sequencing methods.Over the last decade next generation sequencing has become an important tool for conducting culture-independent surveys (Hibbet et al., 2011; Brown et al., 2013).High percentage of the fungal sequences has never been identified or are unknowns since they have never been found in nature or unculturable.Unfortunately, some of the species may be important or critical to understanding agricultural and forest microbial dynamics over time and subsequence impacts of continuous cropping, artificial management and natural inputs being added to cropland and forest health due to environmental changes such as nutrition.Therefore, in order to track changes in the pathogen and mycorrhizal communities associated with environmental causes or specific management practices with those ecosystems, whole-community (Illumina MiSeq) data is most accurate approach for understanding microbiome fluxuations within farm sites and forest habitats. The team members propose to utilize soil samples collected for measurement nutrient levels with the same soil samples, extract fungal DNA from these samples, and determine the fungal community compositions using Illumina sequencing methods.To identify species, community composition and abundance Illumina sequencing will be employed using primers concentration on ITS 2 gene region for sequencing. Potentially for each sample, Illumina sequencing can identify up to 1500 fungal species (Gihring et al., 2011).DNA will be extracted from these soil-litter samples using several protocol including Mo Bio Power® kits and CTAB as needed. The variable region ITS2 rDNA of fungi as stated above will be PCR amplified and analyzed using Illumina sequencing (Illumina Technology, Eurofin MWG). Each sequence will be assigned to its corresponding OTU (operational taxonomic unit) using the rDNA databases (RDP with 292,547 fungal ITS rDNA) for identity analysis. UNITE taxonomy reference database (http://unite.ut.ee/respository.php) will be specifically used to define specific taxa within OTU groupings.Finally, we will perform statistical analyses to examine the relationship between nutrient data and fungal community composition and species diversity measures.All statistical analyses will be carried out in R (version 3.1.1, Development Core Team, 2014) and used the Type 1 error rate of α = 0.05 after post-hoc statistical corrections when appropriate. Kruskal-Wallis rank sum tests and Dunn's post-hoc corrections (posthoc.kruskal.dunn.test) will be carried out in the PMCMR package (Pohlert, 2016). Stepwise regression model selections were performed via the MASS package (Venables and Ripley, 2002). NMDS (metaMDS), perMANOVA (adonis), and environmental vector fitting (envfit) will be conducted in the vegan package (Oksanen et al., 2017) and the pairwise comparisons of sites using Bray-Curtis distances (pairwise.perm.manova) will be conducted in the RVAideMemoire package (Hervé, 2017).Characterization of antimicrobial bacteria.To obtain antagonistic bacteria from crop rhizospheres, soils showing disease suppressiveness will be collected from root systems associated with different soil-borne diseases.Bacteria will be isolated using various selective culture media.Antagonistic bacteria to major fungal and bacterial pathogens of plants will be selected using plate assays(Lu et al., 2002).Initial identification of bacterial genera will be performed as described by Schaad et al.(2001). In addition, the bacterial isolation will be conducted from the fresh vegetable crops, which will be used for searching fresh food-associatedBurkholderiaspp..To further characterize bacterial isolates, routine bacteriological analysis will be performed as described by Schaad et al.(2001), including morphology of bacterial colonies, growth on various media, and Gram staining.Biochemical and physiological analyses will be performed usingthe API kits (bioMérieux, Inc. Durham, NC) as described by the manufacturer.Molecular techniques, such as the 16S rRNA gene sequence analysis, will be conducted as described by Baker et al.(Baker et al., 2003).To characterize the genes dedicated to antagonism, mutagenesis of the antagonistic isolates of interest will be performed using an EZ::TN transposon system (Epicentre Technologies, Madison, WI).Plasmid rescue techniques will be used to clone the transposon-targeted genes from the resulting mutants deficient in antifungal activities as described by the manufacturer.Partial genes associated with antifungal activity will be sequenced.To clone the intact genes of interest, a fosmid library will be constructed using the Copy Control Fosmid Library Production Kit (Epicentre Technologies, Madison, WI) according to the kit manual.Screening the resultant library using the DNA fragments of the targeted genes, as probes will identify the fosmids that carry the intact genes.Complementation of mutant strains will be performed with the identified intact gene carried by appropriate expression vectors(Cardona and Valvano, 2005).Sequence analysis of the targeted genes will provide insights for predicting the possible products contributing to antagonism.Success of cloning the partial genes dedicated to antifungal activities of isolate MS14 demonstrates that the procedures described above work efficiently for obtaining the genes of interest from bacteria. To perform site-direct mutagenesis of the genes of interest, a standard procedure will be used as described previously(Gu et al., 2009b). In brief, the wild-type gene fragment will be disrupted by the insertion of a kanamycin cassette into its open reading frame as described previously(Lu et al., 2002).A 1.1-kbDNAfragment, which carries thenptIIgene without a transcriptional terminator, will be obtained from plasmid pBSL15(Alexeyev, 1995).ThenptIIcassette will be inserted into theappropriatesite of the gene fragment, which will be transferred to pBR325(Prentki et al., 1981).The marker exchange procedure(Gu et al., 2009a) will be employed to generate the corresponding mutant.Objective 2. Evaluate the efficacy of soil-borne disease management strategies (chemical, biorational, biological, cultural) and characterize the associations among microbial community profile, soil physicochemical properties, environmental factors and disease suppression.Chemical and biorational products.In Tennessee, another team member will evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in woody ornamentals.Cover crop.In Tennessee, another team member willassess biofumigant cover crops (arugula, mustard, dwarf essex rape etc.) for soil-borne diseases (PhythophthoraandRhizoctonia) and improved plant growthin woody ornamentals andwill characterize the linkages between microbial community structure and soil-borne disease suppression in woody ornamental nursery systems that employ biofumigant cover crops.Variety/cultivar screening.Cultivar/variety screening for soil-borne pathogens including but not limited toRhizoctoniaspp.andPhytophthoraspp. will be done in natural and artificially infested field/greenhouse environments. Field crops would be planted early season (prior to optimal planting dates) and irrigated to provide conducive environment for disease development. Visual observation of disease and in season/throughout experimental period evaluations will be recorded to determine effects of pathogen on varieties/cultivars.Harvest/plant growth data will be used to determine losses/damage associated with disease.

Progress 10/01/20 to 09/30/21

Outputs
Target Audience:Graduate assistantship:Two M.S. level and 3 PhD level (Advisor) and one M.S. level (co-Advisor) students participated into this project. The students involved in protocol development, experimental design, conducting experiments, data collections for the projects. Extension/Outreach:As woody ornamental plant pathologist, interacted directly with nursery producer, TSU extension agents and TDA regulatory officials toprovide diagnoses of biotic and abiotic problems and management recommendations to support sustainable nursery production in Tennessee. Changes/Problems: Due to Covid 19, we had limited outreach/extension activities in 2021. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Woody ornamental plant pathology lab interacted directly with nursery producer, TSU extension agents and TDA regulatory officials to provide diagnoses of biotic and abiotic diseases and management recommendations to support sustainable nursery production in Tennessee. Our lab diagnosed over 250 woody ornamental samples in spring 2021. Woody ornamental plant pathology lab also participated in the training of nursery growers on soilborne diseases and their management. What do you plan to do during the next reporting period to accomplish the goals?1. Evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in woody ornamentals. We will continueto evaluate chemicals and biorational products for use in soil-borne disease management at greenhouse and field conditions. 2.Develop improved soil-borne disease management strategies based on cultural approaches for suppression of soil-borne pathogens. We will continue to evaluate cultural approaches for use in soil-borne disease managementaton-farms and on-station. 3.Characterize the associations between microbial community profile and soil-borne disease suppression expressed in different soil-borne disease management strategies.Microbial community analyses will be performed on field experiment root and soil samples.

Impacts
What was accomplished under these goals? Evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in ornamentals. The purpose of this study was to evaluate fire ant venom alkaloids and an alarm pheromone analog against several plant pathogens, includingBotrytis cinerea,Fusarium oxysporum,Phytophthora nicotianae, P. cryptogea,Pseudomonas syringae,Phytopythium citrinum,Rhizoctonia solani,Sclerotonia rolfsii,Xanthomonas axonopodis, andX. campestris. All pathogens were tested against red imported fire ant venom alkaloid extract and alarm pheromone compound for growth inhibition in in vitro assay. The venom alkaloid extract inhibited fungal and oomycete pathogens. Neither of the treatments were effective against bacterial pathogens. Three soilborne pathogens,P. nicotianae,R. solani,F. oxysporum, and one foliar pathogen,B. cinereawere selected for further in-vivo assays on impatiens (Impatiens walleriana'Super Elfin XP violet'). Total plant and root weight were higher in venom alkaloid treated plants compared to an inoculated control. The venom alkaloid treatment reduced damping-off, root rot severity, and pathogen recovery in soilborne pathogen inoculated plants. Similarly, venom alkaloid reduced Botrytis blight. However, higher venom rates caused foliar phytotoxicity on plants. Therefore, additional work is needed to evaluate rates of venom alkaloids or formulations to eliminate negative impacts on plants. Overall, these results suggest that red imported fire ant venom alkaloids may provide a basis for new products to control soilborne and foliar plant pathogens. Develop improved soil-borne disease management strategies based on cultural approaches for suppression of Rhizoctonia and (or) Phytophthora spp. and other soil-borne pathogens.? We studied the response of the major cover crops being used by woody ornamental growers in the Southeastern United States toPhytopythium vexans, Phytophthora nicotianae, andRhizoctonia solaniin greenhouse conditions to identify the effective cover crops that can be used in a nursery field production system. Data related to post-emergence damping-off and plant growth parameters (plant height increase and fresh weight) were recorded. Similarly, cover crop roots were assessed for root rot disease severity using a scale of 0-100% roots affected. Among the tested cover crops, the grass cover crops triticale (×Triticosecale Wittm. ex A. Camus.), annual ryegrass (Lolium multiflorumL.), Japanese millet (Echinochloa esculenta(A. Braun) H. Scholz), and the legumes Austrian winter pea (Pisum sativumvar. arvense (L.) Poir) and cowpea 'Iron and Clay' (Vigna unguiculata(L.) Walp.), showed lower root rot disease severity and post-emergence damping-off in the soil inoculated withP. nicotianae, R. solani, orP. vexanscompared to the other crops. Since these cover crops can act as non-host crops and benefit the main crop in one way or another, they can be used in the production system.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Parajuli, M., Panth, M., and Baysal-Gurel, F. 2021. Cover crop usage for the sustainable management of soilborne diseases in woody ornamental nursery production system. 98th Southern division APS virtual meeting. Feb 15-19, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Neupane, S., and Baysal-Gurel, F. 2021. Evaluation of chemical and biocontrol products for the management of Fusarium root and crown rot of oakleaf hydrangea. 98th Southern division APS virtual meeting. Feb 15-19, 2021 (Southern division APS meeting scholarship award and second place- Southern division APS meeting Poster competition).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Neupane, K., and Baysal-Gurel, F. 2021. Efficacy of fungicides, biofungicides, host plant defense inducers and fertilizer to manage Phytophthora root rot of dogwood under flooding condition. 98th Southern division APS virtual meeting. Feb 15-19, 2021 (Southern division APS meeting scholarship award) (Oral presentation).
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Panth, M., Witcher, A., and Baysal-Gurel, F. 2021. Response of cover crops to Phytopythium vexans, Phytophthora nicotianae, and Rhizoctonia solani, major soilborne pathogens of woody ornamentals. Agriculture 11(8):742 DOI: 10.3390/agriculture11080742
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Yang, X., Castroagudin, V.L., Daughtrey, M., Loyd, A., Weiland, J.E., Shishkoff, N., Baysal-Gurel, F., Santamaria, L., Salgado-Salazar, C., LaMOndia, J.A., Crouch, J., Luster. D.G. 2021. A Diagnostic guide for Volutella blight affecting Buxaceae. Plant Health Progress. https://doi.org/10.1094/PHP-02-21-0052-DG.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Bika, R. and Baysal-Gurel, F. 2021. Identification of Fusarium commune, the causal agent of postharvest zinnia meltdown disease in Tennessee. HortTechnology. https://doi.org/10.21273/HORTTECH04795-21
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Dawadi, S., Baysal-Gurel, F., Addesso K.M., Liyanapathiranage, P., and Simmons, T. 2021. Fire ant venom alkaloids: Possible control measure for soilborne and foliar plant pathogens. Pathogens. 2021, 10, 659. https://doi.org/10.3390/pathogens10060659
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Bika, R., Copes, W., Baysal-Gurel, F. 2021. Comparative Performance of Sanitizers in Managing Plant-to-plant Transfer and Postharvest Infection of Calonectria pseudonaviculata and Pseudonectria foliicola on Boxwood. Plant Disease. DOI: 10.1094/PDIS-03-21-0481-RE.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Baysal-Gurel, F. and Bika, R. 2021. Management of powdery mildew on ninebark using sanitizers, biorational products and fungicides. HortScience. Vol 56: Issue 5 p. 532-537. https://doi.org/10.21273/HORTSCI15691-21
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Bika, R., Avin, F.A., Jennings, C., and Simmons, T., 2021. Occurrence of Volutella Blight Caused by Pseudonectria foliicola on Boxwood in Tennessee. Plant Disease. https://doi.org/10.1094/PDIS-01-21-0109-PDN
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Baysal-Gurel, F., Bika, R., Jennings, C., Palmer, C., and Simmons, T. 2020. Comparative performance of chemical and biologically-based products in management of algal leaf spot on magnolia. HortTechnology. https://doi.org/10.21273/HORTTECH04692-20.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Bika, R., Palmer, C., Alexander, L., and Baysal-Gurel, F. 2020. Comparative performance of reduced-risk fungicides and biorational products in management of post-harvest Botrytis cinerea on hydrangea cut flowers. HortTechnology. https://doi.org/10.21273/HORTTECH04656-20.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Bika, R., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for the control of Volutella blight of boxwood, 2020. Plant Disease Management Report No. 15:OT001. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for control of Cercospora leaf spot on Hydrangea, 2020. Plant Disease Management Report No. 15:OT005. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for control of powdery mildew and spot anthracnose of dogwood, 2020. Plant Disease Management Report No. 15:OT006. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for control of powdery mildew on crapemyrtle, 2020. Plant Disease Management Report No. 15:OT007. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for control of powdery mildew of Hydrangea, 2020. Plant Disease Management Report No. 15:OT013. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Parajuli, M., and Panth, M. 2021. Evaluation of fungicides, biofungicides, host plant defense inducers and fertilizer for the control of Phytopythium root rot of red maple, 2020. Plant Disease Management Report No. 15:OT014. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Oksel, C., Simmons, T, and Jennings, C. 2021. Evaluation of bactericides for control of Pseudomonas leaf spot on Magnolia, 2020. Plant Disease Management Report No. 15:OT016. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Parajuli, M., and Panth, M. 2021. Evaluation of fungicides, biofungicides, host plant defense inducers and fertilizer for the control of Phytopythium root rot of ginkgo, 2020. Plant Disease Management Report No. 15:OT017. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Neupane, S., and Simmons, T. 2021. Evaluation of fungicides, biofungicides, host plant inducers and fertilizer for the control of Phytophthora root rot of boxwood in field conditions, 2020. Plant Disease Management Report No. 15:OT018. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for the control of boxwood blight, 2020. Plant Disease Management Report No. 15:OT002. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of different rates of Postiva for the control of Cercospora leaf spot, black leaf spot and powdery mildew of rose, 2020. Plant Disease Management Report No. 15:OT003. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for control of Entomosporium leaf spot on Indian hawthorn, 2020. Plant Disease Management Report No. 15:OT004. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Neupane, K. and Baysal-Gurel, F. 2021. Fungicides for Phytophthora Root Rot in Containerized Dogwood. Chase Digest June 2021 Issue Volume 9(6).
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., and Neupane, K. 2021. Evaluation of fungicides and host plant defense inducers for the control of Phytophthora root rot of dogwood, 2020. Plant Disease Management Report No. 15:OT019. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F., Simmons, T, and Jennings, C. 2021. Evaluation of fungicides for control of Cercospora leaf spot on crapemyrtle, 2020. Plant Disease Management Report No. 15:OT020. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F. 2021. Phytophthora Root Rot Control on Field-Grown Boxwood. Chase Digest August 2021 Issue Volume 9(8).
• Type: Other Status: Published Year Published: 2021 Citation: Bika, R. and Baysal-Gurel, F. 2021. Comparative Performance of Sanitizers in Managing Boxwood Blight and Volutella Blight BBIG Newsletter Volume 2, Issue 2, released May 28, 2021 and also at https://irp.cdn-website.com/217658e5/files/uploaded/BBIG%20Newsletter%20Vol%202%20Issue%202.pdf
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F. 2021. Control of Fusarium Root Rot on Oakleaf Hydrangea. Chase Digest May 2021 Issue Volume 9(5).
• Type: Other Status: Published Year Published: 2021 Citation: Parajuli, M., Baysal-Gurel, F., Avin, F., and Panth, M. 2021. Phytopythium Root Rot Prevention on Maple. Chase Digest April 2021 Issue Volume 9(4).
• Type: Other Status: Published Year Published: 2021 Citation: Baysal-Gurel, F. 2021. Control of Phytophthora Root Rot on Field-grown Boxwood with Fungicides and Biologicals. Chase Digest April 2021 Issue Volume 9(4).
• Type: Other Status: Published Year Published: 2021 Citation: Panth, M., Baysal-Gurel, F., Avin, F., and Simmons, T. 2021. Phytopythium Root Rot Prevention on Gingko. Chase Digest February 2021 Issue Volume 9(2).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Neupane, S., Alexander, L., Baysal-Gurel, F. 2021. Response of Hydrangea quercifolia cultivars to Fusarium root and crown rot. 2021 ASHS Annual Meeting. Denver, CO. August 5-9, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Ghimire, B., Avin, F. A., Waliullah, S., Ali, Md E., Baysal-Gurel, F. 2021. Detection of Phytopythium vexans in different sources using loop-mediated isothermal amplification. Annual Meeting of the American Phytopathological Society  Plant Health 2021 online. August 2-6, 2021 (Poster presentation) (complimentary registration award from APS Foundation ($269)).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Parajuli, M., Panth, M. and Baysal-Gurel, F. 2021. Effect of solitary and combined use of cover crops on soilborne disease suppressiveness in woody ornamental nursery production systems. Plant Health 2021 online. August 2-6, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Bika, R. and Baysal-Gurel, F. 2021. Dip application of sanitizers in managing postharvest infection of Calonectria pseudonaviculata on boxwood cuttings. Annual Meeting of the American Phytopathological Society  Plant Health 2021 online. August 2-6, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Neupane, S. and Baysal-Gurel, F. 2021. Performance of fungicides, biofungicides, fertilizers, and host plant defense inducers in managing Phytophthora root rot of boxwood in greenhouse. Annual Meeting of the American Phytopathological Society  Plant Health 2021 online. August 2-6, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Neupane, S., Simmons, T., and Baysal-Gurel, F. 2021. Management of Phytophthora root rot of boxwood using fungicides, biofungicides, fertilizers and host plant defense inducers in field conditions. The 43th Annual University-Wide Research Virtual Symposium, 2021. March 22-26, 2021 (Oral presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Parajuli, M., Panth, M., and Baysal-Gurel, F. 2021. Cover crop usage for the sustainable management of soilborne diseases in woody ornamental nursery production system. The 43th Annual University-Wide Research Virtual Symposium, 2021. March 22-26, 2021 (Oral presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Parajuli, M., Panth, M., and Baysal-Gurel, F. 2021. Efficacy of fungicides and biofungicides in controlling root and crown rot disease of woody ornamental plants caused by Phytopythium vexans. The 43th Annual University-Wide Research Virtual Symposium, 2021. March 22-26, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Ghimire, B., Avin, F., and Baysal-Gurel, F. 2021. Development of loop-mediated isothermal amplification method for detection of Phytopythium vexans in different sources. The 43th Annual University-Wide Research Virtual Symposium, 2021. March 22-26, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Panth, M., Witcher, A., and Baysal-Gurel, F. 2021. Response of different cover crops against Phytophthora nicotianae. 98th Southern division APS virtual meeting. Feb 15-19, 2021 (Poster presentation).
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Bika, R. and Baysal-Gurel, F. 2021. Comparative Performance of Sanitizers in Reducing the Plant-to-plant Transfer of Calonectria pseudonaviculata in Boxwood Using Cutting Tool. Northeastern plant, pest, and soil conference. Jan 4-7, 2021 (Graduate student travel award).

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Graduate assistantship:Four M.S. level and 1 PhD level (Advisor) and two M.S. level (co-Advisor) students participated into this project. The students involved in protocol development, determining inoculation methods, experimental design, conducting experiments, data collections for the projects. Extension/Outreach:As woody ornamental plant pathologist, I interacted directly with nursery producer, TSU extension agents and TDA regulatory officials toprovide diagnoses of biotic and abiotic problems and management recommendations to support sustainable nursery production in Tennessee. Changes/Problems:Due to Covid 19, we had limited outreach/extension activities in Summer and Fall 2020. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Woody ornamental plant pathology lab interacted directly with nursery producer, TSU extension agents and TDA regulatory officials to provide diagnoses of biotic and abiotic diseases and management recommendations to support sustainable nursery production in Tennessee. Our lab diagnosed over 200 woody ornamental samples in fall 2020. Woody ornamental plant pathology lab also participated in the training of nursery growers on soilborne diseases and their management. What do you plan to do during the next reporting period to accomplish the goals?1. Evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in woody ornamentals. We will continueto evaluate chemicals and biorational products for use in soil-borne disease management at greenhouse and field conditions. 2.Develop improved soil-borne disease management strategies based on cultural approaches for suppression of soil-borne pathogens. We will continue to evaluate cultural approaches for use in soil-borne disease managementaton-farms and on-station. 3.Characterize the associations between microbial community profile and soil-borne disease suppression expressed in different soil-borne disease management strategies.Microbial community analyses will be performed on field experiment root and soil samples.

Impacts
What was accomplished under these goals? Evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in ornamentals.? Soilborne diseases caused by pathogens such asPhytophthora,Rhizoctonia,Fusarium,Verticillium, andPythiumspecies are the most important diseases of woody ornamentals. Gingko (Gingko biloba) and red maple (Acer rubrumL.) 'October Glory' plants grown in containers and fields in Tennessee have shown root and crown rot symptoms with dark brown to black lesions in 2017 and 2018.The objective of this research was to isolate and identify pathogens affecting gingko and red maple plants in nurseries of Tennessee and develop fungicide/biofungicide management recommendations for nursery producers.Isolations were made from the infected roots. SeveralPhytophthora-like colonies with spherical zoospores, filamentous to globose oogoni, and whitish mycelium, were isolated on V8-PARPH medium. For confirming identity,total genomic DNA was extracted followed by thesequence analysis of the internal transcribed spacer (ITS) regions, andlarge subunit (LSU) of the nuclear ribosomal RNA (rRNA) as well ascytochrome c oxidase subunit I (Cox I) and cytochrome c oxidase subunit II (Cox II) of mitochondrial DNA (mtDNA). Based on morphological and molecular analysis,Phytopythium vexanswas described as a causal agent of crown and root rot from the infected gingko and red maple plants. To complete Koch's postulates, a pathogenicity test was performed by drenching 100 ml V8 agar medium slurry ofP. vexansinoculum on 1-year-old potted ginkgo plant root systems as well as red maple 'October Glory'. Necrotic lesion development was observed in the root system 45 days after inoculation andP. vexanswas re-isolated from the roots of both gingko and red maple. All control gingko and red maple plants remained disease-free and no pathogen was re-isolated. In addition, the efficacy of fungicides, biofungicides, fertilizer and host-plant defense inducers (traditionally recommended for management of oomycete diseases) for control of Phytopythium crown and root rot was evaluated on gingko and red maple 'October Glory' seedlings in greenhouse and field trials. In both greenhouse and field trials, the fungicides such as Empress Intrinsic, Pageant Intrinsic, Segovis andSubdue MAXXwere effective, and biofungicide such as Stargus was promising to reduce the disease severity caused by pathogenP. vexanson gingko and red maple plants. This comparative study will help nursery producers to make proper management decisions for newly reported Phytopythium crown and root rot disease of gingko and red maple plants. Characterize the associations between microbial community profile and soil-borne disease suppression expressed in different soil-borne disease management strategies. Phytophthora nicotianaeis a soilborne plant pathogen which can infect 255 genera in 90 families and is one of the most devastating soilborne pathogens in the south-eastern United States. This pathogen can affect a diverse group of plants, including woody ornamentals, causing wilting and chlorosis of leaves, stem and crown necrosis, while below ground symptoms comprise root necrosis. The objective of this research experiment was to evaluate the impact of cover crops on the soilborne diseases in field nursery production. Winter cover crops (triticale or crimson clover) were seeded at the manufacturer recommended rates in September - October (optimal timing for each cover crop species) in 2.4 x 14.6 m field plots with four replicates per treatment at Pleasant cove nursery, Rock Island, TN USA (Warren Co.). Plots were prepared by disk harrow and cover crop seeds broadcast, followed by a cultipacker to incorporate seed into the soil. Plots with no cover crop (bare soil) were used as control. A preemergent herbicide(Sureguard (Valent BioSciences LLC.,Libertyville,IL USA))was applied post-transplant within tree rows to prevent weed/cover crop competition at the base of the trees. Each plot was sampled randomly at four locations each within rows and within middles, mixed in situ with a spade, and placed in a plastic bucket. The soil was stored for one week, at an ambient temperature in a greenhouse before use. The greenhouse bioassays were conducted at the Tennessee State University Otis L. Floyd Nursery Research Center (TSUNRC) in McMinnville, TN, USA. The soil sample from each field treatment -1) cover crop- triticale, 2) cover crop- crimson clover, and 3) bare soil (control); and replication was divided into round plastic containers (top diameter-16 cm, bottom diameter-13.5 cm and height-16 cm) with 3 kg of soil per container. Those soils were then used as either inoculated (withP. nicotianae, the rice grain method [6]) or non-inoculated. Isolate FBG201507 ofP. nicotianaewas obtained from the culture collection of Dr. Fulya Baysal-Gurel at the TSUNRC. For each bioassay, ten single-pot replications per treatment were arranged in a randomized complete block design. Rooted cuttings of red maple were transplanted into the containerized field soil, and disease severity was assessed 2 months later. Drip irrigation system was used once per day for 1 min during the experiment. The severity of root rot was assessed using a scale of 0-100% at the end of the experiment.Plant width and height were recorded at the beginning and end of the experiment to be able to calculate the difference. Total plant fresh weight and root weight were recorded at the end of the experiment. The presence ofPhytophthorawas confirmed by plating root samples on PARPH-V8 selective medium. Disease severity, pathogen recovery, total plant weight, root weight and increase in plant height were analyzed with a one-way analysis of variance (ANOVA) using Proc GLM in SAS, and means were separated using Tukey test (α=0.05). In the greenhouse bioassay without the addition of pathogen inoculum,Phytophthoradisease severity was significantly lower in soil collected from the cover crop treatments compared to the bare soil treatment. But there were no significant differences between triticale and crimson clover cover crops in disease severity. The pathogen recovery was significantly lower in triticale cover crop treatment compared to the bare soil treatment. There were no significant differences between crimson clover cover crop treatment and the bare soil treatment in pathogen recovery. There were no significant differences between the cover crop treatment and the bare soil treatment in total plant weight and height increase with no pathogen inoculum introduction. In the greenhouse bioassay with the addition ofP. nicotianaeinoculum,Phytophthoraroot rot severity and pathogen recovery was significantly lower in soil collected from the cover crop treatments compared to the bare soil treatment. Disease severity was lower in triticale cover crop treatment compared to crimson clover cover crop treatment. There were no significant differences between triticale cover crop treatment and crimson clover cover crop treatment inPhytophthorapathogen recovery. Total plant weight was significantly greater in the cover crop used soil compared to the bare soil. Increase in maple plant height was significantly greater when the crimson clover cover crop was used compared to the bare soil. Overall, the cover crops were effective in reducingPhytophthorapressure in maple production system, however, longer period of cover cropping might be required to see the prolonged effect of cover crops. Growers can get benefit of incorporating these cover crops into production by reducing the need for synthetic crop protection materials.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Panth, M., Hassler, S., and Baysal-Gurel, F. 2020. Methods for management of soilborne diseases in crop production. Agriculture. (Baysal-Gurel-corresponding author). Agriculture 10(1), 16; https://doi.org/10.3390/agriculture10010016
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Tekin, N.T., Kaplanoglu, E., Erdemir, E., Baysal-Gurel, F., Uyanik, C., and Hargrove, S. K. 2020. Modeling and Testing of Magnetic Speed Controlled Submersible Robot for Hydroponic Production. 2019 SoutheastCon. IEEE pp. 1-4. DOI:10.1109/SoutheastCon42311.2019.9020356.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Ojha, V., Oliver, J., Addesso, K., Baysal-Gurel, F., Youssef, N., and Simmons, T. 2020. Optimization of Phytophthora effective systemic fungicides for ambrosia beetle management. SNA Research Conference Vol; 64 2020. Entomology section.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Neupane, S., Simmons, T., and Baysal-Gurel, F. 2020. Management of Phytophthora root and crown rot using biofumigation on field grown boxwood. SNA Research Conference Vol; 64 2020. Pathology and Nematology Section.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Panth, M. and Baysal-Gurel, F. 2020. Impact of cover crop usage on soilborne disease suppressiveness in field nursery production. SNA Research Conference Vol; 64 2020. Pathology and Nematology Section
• Type: Other Status: Published Year Published: 2020 Citation: Baysal-Gurel, F. Brown, M.S., Oliver, J., Addesso, K. 2019. Evaluation of fungicides and biofungicide to control Phytophthora root rot and ambrosia beetles on flood-stressed flowering dogwoods. Ambrosia beetle working group meeting proceeding. October 15, 2019. Griffin, GA.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Baysal-Gurel, F., Liyanapathiranage, P., Panth, M., Avin, F.A., and Simmons, T. 2020. First report of Phytopythium vexans causing root and crown rot on flowering cherry in Tennessee. Plant Disease. https://doi.org/10.1094/PDIS-06-20-1166-PDN
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Panth, M., Baysal-Gurel, F., Simmons, T., Addesso, K., and Witcher, A. 2020. Impact of winter cover crop usage in soilborne disease suppressiveness in woody ornamental production system. Agronomy 10(7), 995; https://doi.org/10.3390/agronomy10070995
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Hudson, O., Walilullah, S. Hand, J. Gazis-Seregina, R., Baysal-Gurel, F., and Ali, E. 2020. Novel method for detection of Phytophthora capsici in irrigation water using loop-mediated isothermal amplification. J. Vis. Exp., e61478, doi:10.3791/61478.
• Type: Other Status: Published Year Published: 2020 Citation: Baysal-Gurel, F. 2020. Phytophthora root and crown rot of boxwood. Tennessee Greentimes. Volume 21/No. 1 Spring 2020.
• Type: Other Status: Published Year Published: 2020 Citation: Baysal-Gurel, F. 2019. Control of Phytophthora on boxwood. Chase Digest August 2019 Issue Volume 7(8).

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Graduate assistantship:Three M.S. level (Advisor) and two M.S. level (co-Advisor) students participated into this project. 2 M.S. students successfully completed their proposal defenses in December 2018 and 2 M.S. students (co-advisor) successfully completed their proposal defenses in February and March 2019. The students involved in protocol development, determining inoculation methods, experimental design, conducting experiments, data collections for the projects. Extension/Outreach:As woody ornamental plant pathologist, I interacted directly with nursery producer, TSU extension agents and TDA regulatory officials toprovide diagnoses of biotic and abiotic problems and management recommendations to support sustainable nursery production in Tennessee.We diagnosed 210 plant, water and soil samples in 2018. The TSU Nursery Research Center woody ornamental pathology lab confirmedthree new diseases in Tennessee in 2018:Phoma leaf spot on orchid and Zonate leaf spot on Cardinus. inOur lab also confirmed boxwood blight in Summer 2018 at sales yard inSmithnville, TN.I worked closely withnursery producer, TSU extension agents and TDA regulatory officials, providing recommendations regarding this important disease and its management. Lead researcherattended to seven national meetings/conferences, oneInternational Congress in Turkey, one International Conference in Florida,three extension activities, and thirty-one extension trainings (includingMaster Gardener Class, TDA inspectors training and Job Shadow)during this period.Lead researcherorganized one seminar and invited Dr. Brian McSpadden Gardener as a seminar speaker on at TSUNRC Conference room in McMinnville, TN. The title of his seminar was "Getting the Most from Composts- Nutrients, Humates, and Microbes, and More for Nursery Professionals".Growers, master gardeners, undergraduate and graduate level students, researchers and the general public attended to this educational event. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Woody ornamental plant pathology lab interacted directly with nursery producer, TSU extension agents and TDA regulatory officials to provide diagnoses of biotic and abiotic diseases and management recommendations to support sustainable nursery production in Tennessee. Our lab diagnosed over 200 woody ornamental samples in 2018. Woody ornamental plant pathology lab also participated in the training of nursery growers on soilborne diseases and their management. Student Count Lead researcher isfaculty advisor for Mary Holden, Milan Panth and Ravi Bika, M.S. She is serving as a member at the committee of Victoria Deren and Vivek Ojha since fall 2018, M.S.Lead researcherwill be mentoring four undergraduate interns from Tennessee Tech in 2019.The project allowed three students and PI to presentproject results at five International, regional or national meetings (five oral presentations). What do you plan to do during the next reporting period to accomplish the goals?1. Evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in woody ornamentals. We will continueto evaluate chemicals and biorational products for use in soil-borne disease management at greenhouse and field conditions. 2.Develop improved soil-borne disease management strategies based on cultural approaches for suppression of soil-borne pathogens. We will continue to evaluate cultural approaches for use in soil-borne disease managementaton-farms and on-station. 3.Characterize the associations between microbial community profile and soil-borne disease suppression expressed in different soil-borne disease management strategies.Microbial community analyses will be performed on field experiment root and soil samples.

Impacts
What was accomplished under these goals? Evaluate the efficacy of chemical and biorational products for controlling soil-borne diseases with different application methods, intervals and reduced-rate applications in ornamentals.Boxwood 'Green Velvet' cuttings were taken from the mother plants at commercial nursery in Smithville, TN. Cuttings were 4-inch in height and three leaves were kept remaining. A slant cut was made at the end of the stem and from the remaining leaves; half of the leaves were cut and removed. Cuttings were dipped in 1% 3-Indole Butyric Acid(IBA) (Harmodin®3, OHP Inc, Mainland, PA) and the cuttings were stacked with wet clothes until transplant. Boxwood cuttings were planted in 2-inch nursery containers on 7 Nov, 2018.The 2-inch nursery containers contain Morton's Pine Bark Nursery Mix were inoculated withP. nicotianaegrown on rice grains for 10 days. Two rice grains were placed 1-inches below the surface potting mix on 31 Oct, 2018. Non-treated, non-inoculated and non-treated, inoculated containers served as controls. Twenty single-boxwood cuttings per treatment were arranged in a completely randomized design in a greenhouse at the Otis L. Floyd Nursery Research Center in McMinnville, TN. Boxwood cuttings were watered with overhead irrigation system one time per day for 1 minute. The standard treatment included only Subdue Maxx drench application at 10 weeks interval, and the rotation program included Pageant spray at transplanting, Pageant spray 2 weeks after first application, Chipco 26019 spray application 3 weeks after second Pageant spray application, and Empress drench application 3 weeks after Chipco 26019 spray application. Spray applications of fungicides was applied to run-off using a backpack CO2-pressurized sprayer at 40 psi. The boxwood cuttings were re-potted from 2-inches to 4-inches nursery containers in Morton's Pine Bark Nursery Mix on 28 Nov, 2018 and from 4-inches to 1 gal nursery containers on 9 Jan, 2019. Five plants were pulled and cleaned on 28 Nov 2018, 9 Jan, 6 Feb and 6 Mar 2019 for assessment of root development using 1-5 scale where 1 is unrooted cutting not callused, no roots developed; 2 is callus with root bumps; callus with first true root; 3 is at least 3 -5 roots ¼ -½" in length; 4 is 5-7 or more roots at least 1" in length; 5 is fully rooted liner and assessment of Phytophthora root rot severity using a scale of 0-100% roots affected. Plant height, total fresh weight and root weight were also recorded on 6 Mar and plant marketability was evaluated using a scale of 1-5 where 1 is dead, 3 is commercially acceptable and 5 is a perfect plant. Phytophthora root rot disease pressure was high in this trial with non-treated, inoculated control rooted boxwood cuttings showing 53.0% disease severity by 6 Mar. Fungicide rotation program (Pageant Intrinsic, Chipco 26019 and Empress Intrinsic) and Subdue Maxx alone significantly reduced Phytophthora root rot severity compared to non-treated, inoculated control. Phytophthora root rot severity was numerically higher in Subdue Maxx treated rooted boxwood cuttings compared to fungicide rotation program. Fungicide rotation program and Subdue Maxx significantly increased the plant height, total fresh weight and root weight compared to non-treated, inoculated control. The rotation program resulted numeric increase on the percent plant height compared to Subdue Maxx; but resulted significant increase on the percent plant height compared to non- treated, inoculated and non-inoculated controls. Phytotoxicity and defoliation were not observed in any of the rooted boxwood cuttings. Non-treated, inoculated control rooted boxwood cuttings were not commercially acceptable due to the level of Phytophthora root rot at the end of the experiment (data not shown). Bare root boxwood 'Green Velvet' plants were potted in no. 1 nursery containers in Morton's no. 2 Grow Mix on 3 Oct.Eight single-plant replications per treatment were arranged in a completely randomized design in a greenhouse at the Otis L. Floyd Nursery Research Center in McMinnville, TN. Each plant was top dressed with 5 g of 18-6-8 Nutricotecontrolled-releasefertilizeron 5 Oct. Boxwood plants were watered with overhead irrigation system two times per day for 2 minutes.Plants were inoculated withP. nicotianaegrownon rice grains for 10 days. Four rice grains were placed 2 in below the surface potting soil on 26 Oct.Non-treated, non-inoculated and inoculated containers served as controls.Spray applications of Orkestra Intrinsic were applied to run-off using a backpack CO2-pressurized sprayer at 40 psi beginning on a 14-day schedule. Empress Intrinsic, Orvego, Segovis and Subdue Maxx were applied as drench application on a 14-day schedule. Defoliation due to disease was assessed by using a scale of 0-100% on 16 and 30 Nov; and 15 Dec. On 14 Dec, total fresh weight, root weight and root length were recorded and severity of Phytophthora root rot was assessed using a scale of 0-100% roots affected. All fungicide treatments significantly reduced disease severity and the defoliation percentage due to Phytophthora root rot compared to non-treated, inoculated control boxwood plants, but there were no differences among treatments on the defoliation percentage. Empress Intrinsic and Orvego program, Orvego and Orkestra Intrinsic program, and Segovis and Subdue Maxx program and Empress Intrinsic alone most effectively reduced Phytophthora root rot disease severity. Total fresh weight was significantly different among Empress Intrinsic and Orvego program, Orvego and Orkestra Intrinsic program, and Segovis and Subdue Maxx program, Empress Intrinsic alone, Orkestra Intrinsic alone treated and Orvego alone treated, non-treated, inoculated control boxwood plants. Plants treated with Empress Intrinsic and Orvego program and Orvego and Orkestra Intrinsic program had the highest and statistically similar root weight values. The root length was significantly different among treated and non-treated, inoculated control boxwood plants. Phytotoxicity was not observed in any of the treated boxwood plants. Characterize the associations between microbial community profile and soil-borne disease suppression expressed in different soil-borne disease management strategies.Soilborne diseases are the most economically important problem of Southern region nursery producers. The goal of this research was to improve Rhizoctonia root rot disease management through the use of soil solarization alone and in combination with biofumigant cover crops- arugula 'Astro' (Eruca vesicariassp.sativa), mustard green 'Amara' (Brassica carinata) and turnip 'Purple top forage' (B. rapa); good quality compost and mustard meal amendment. The experiments were established as on-farm trials with prevalentRhizoctonia solanipopulation in propagation beds. All three biofumigant cover crops, arugula 'Astro', mustard green 'Amara' and turnip 'Purple top forage' in combination with solarization were able to reduce the Rhizoctonia root rot in flowering cherry 'Kwanzan' plants in nursery propagation beds. Compost amendment numerically or significantly increased the flowering cherry rooted cuttings growth (plant weight, root weight and plant height) compared to other treatments. Soil solarization in combination with cover crops and organic inputs could be used as part of an integrated approach to manage Rhizoctonia root rot in nursery crop propagation beds.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Brown, M., Baysal-Gurel, F., Oliver, J., and Addesso, K. 2019. Comparative performance of fungicides, biofungicides, and host plant defense inducers in suppression of Phytophthora root rot in flowering dogwood during simulated root flooding events. Plant Disease. First look https://doi.org/10.1094/PDIS-09-18-1597-RE.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Pandey, M., Addesso, K. M., Archer, R. S., Valles, S. M., Baysal-Gurel, F., Ganter, P. F., Youssef, N. N., and Oliver, J. B. 2019. Worker Size, Geographical Distribution, and Introgressive Hybridization of the Invasive Solenopsis invicta and Solenopsis richteri (Hymenoptera: Formicidae) in Tennessee. Environmental Entomology.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Baysal-Gurel, F., and Simmons, T. 2019. Evaluation of fungicides for the control of black spot of rose, 2018. Plant Disease Management Report. Online publication. The American Phytopathological Society, St. Paul, MN.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Baysal-Gurel, F., and Simmons, T. 2019. Management of Cercospora Leaf Spot of Hydrangea with Fungicides and Biorational Products. SNA Research Conference Vol. 63 2019. Pathology and Nematology Section.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Baysal-Gurel, F., and Simmons, T. 2019. Evaluation of Fungicide Rotations at Different Application Intervals for the Control of Powdery Mildew of Dogwood. SNA Research Conference Vol. 63 2019. Pathology and Nematology Section.
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Baysal-Gurel, F. 2019. Track and Trace: Plant Pathogen Detection. 1st International Molecular Plant Protection Congress. April 10-13, 2019. Adana, Turkey.
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Holden, M., Simmons, T., Baysal-Gurel, F. 2019. Occurrence of Fusarium Crown Rot on Oakleaf Hydrangea (Hydrangea quercifolia). The 41th Annual University-Wide Research Symposium, 2019. April 1-5, 2019. Nashville, TN.
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Panth, M. Simmons, T., Baysal-Gurel, F. 2019. Occurrence of Phytopythium disease on woody ornamentals. The 41th Annual University-Wide Research Symposium, 2019. April 1-5, 2019. Nashville, TN.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Baysal-Gurel, F., Liyanapathiranage, P. 2019. Pathogenicity of Rhizoctonia solani and Phytophthora nicotianae to Brassicaceae cover crops. Archives of Phytopathology and Plant Protection. DOI: 10.1080/03235408.2019.1617499
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Holden, M., Simmons, T., Baysal-Gurel, F. 2019. First report of Fusarium crown rot of oakleaf hydrangea in Tennessee. Association of Research Directors, Inc. 19th Biennial Research Symposium. March 30 - April 3, 2019, Jacksonville, FL
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Baysal-Gurel, F., Brown, M., Oliver, J., Addesso, K. 2019. Control of Phytophthora root rot and ambrosia beetles on flowering dogwood trees during simulated flood events. 96th Southern division APS meeting. Feb 7-9, 2019. Gainesville, FL.
• Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Baysal-Gurel, F., Brown, M., Oliver, J., Addesso, K. 2018. Comparative performance of fungicides, biofungicides, and host plant defense inducers in suppression of Phytophthora root rot in flowering dogwood during simulated flood events. International Soilborne Oomycete Conference. December 4-6, 2018. Islomorada, FL.