Brief Summary of Minutes of Annual Meeting

1. Evaluate the population genetic diversity of soilborne pathogens and antagonistic microorganisms in different growing systems and regions using traditional and metagenomic approaches.

Members of this multistate research project have continued to provide new insight into the genetic diversity of a number of soilborne pathogens in a variety of production systems.

A disease dissimilar to other reported diseases of soybean has been found in the Mississippi River Delta. In fields where soybeans are R5, plants appear chlorotic, stunted, and when extracted from the soil, have a malformed and necrotic taproot that is often black. The estimated yield loss from affected plants was approximately 30% in 2014. The occurrence of symptomatic plants was sporadic and it was estimated that the impact to overall yield was less than 1%.  However, in 2015, disease was more severe in some fields and widespread regionally. Additionally, in areas of symptomatic plants, gaps in stand were evident with dead plants between the chlorotic plants. When dead plants were extracted from the soil, the taproot was malformed and black if present.  Symptoms were similar in Mississippi and Louisiana. Recently, a team of scientists from the University of Arkansas, Mississippi State University, and Louisiana State University have named the new disease of soybean prevalent in those three states, taproot decline (TRD). The regional distribution of disease occurrence and yield loss is unclear at this time.  However, as of harvest in 2016, it has been found as far north as Jonesboro, Arkansas and some farmer and consultant reports indicate losses could be as high as 10 bu/acre. In 2016, fields in Mississippi and Louisiana suffered substantial yield losses from this disease.  Currently, seed treatment fungicide or varietal recommendations for growers are unavailable. Further, understanding the regional distribution, commercially available seed treatment efficacy, and varietal susceptibilities are necessary for successful management of this disease. Two fields were chosen and 100 positions marked by GPS encompassing 0.70 and 0.67 ha in 2014 and 2015 respectively. Yellow plants were counted within 3 m of the GPS position in both years. In 2015, the number of dead plants and overall stand within 3 m was determined for each GPS position.  Data were analyzed spatially using Moran’s I in GeoDa.  In both years, chlorotic plants were aggregated (P=0.05) indicative of a soilborne disease. The major ranges for yellow plants were 61.5 m and 128.4 m in 2014 and 2015, respectively. In 2015, the spatial distributions of yellow chlorotic plants and dead plants were related (P=0.004) and the relationship of yellow and dead plants was inversely related to overall healthy stand (P<0.0001). These findings indicate the cause of the disease is likely soilborne and symptoms range from plants dead in the vegetative stages to plants chlorotic and stunted in the reproductive stages, likely due to timing of infection and colonization. Repeatedly, similar fungal isolates were being isolated from infested plant material in all three states. These isolates were used in each laboratory to complete Koch’s postulates, essentially confirming this fungus as the cause of the disease by recreating the disease symptoms as they are observed in the field. Molecular methods were used in addition to observation of morphological characters to confirm these fungi were in fact similar to other fungi in the genus Xylaria. However, similarity with a particular species could not be determined. Through phylogenetic analysis of isolates collected from Arkansas, Louisiana, and Mississippi, as well as other known species of Xylaria, it has been determined that this fungus is previously undescribed and that the causal agent of TRD is a member of the Xylaria arbuscula species aggregate and strongly related in the phylogeny to Xylaria striata.

Isolates of Rhizoctonia solani recovered from major row crops in the southern United States as part of a Rhizoctonia survey, representing anastomosis groups (AG) 2, 4, 7, and 11, were evaluated for virulence using stand and hypocotyl/coleoptile ratings on soybean, corn, rice and cotton. At planting isolates of AG2 caused significant stand loss and brown-reddish discoloration of coleoptiles in corn, and AG4 isolates were highly virulent caused significant stand loss on cotton. In all four crops, AG4 and AG11 isolates caused reddish brown lesions on hypocotyls or coleoptiles. When AG4 isolates were used to infest soil that contained isolates of other AGs the severity of symptoms were reduced compared with soils infested only with AG4, even with isolates that demonstrated some level of virulence.

Mycovirus epidemiology in Rhizoctonia solani on important row crops was examined using 190 geotagged isolates from five different fields in Arkansas using cellulose affinity chromatography. The cDNA from double-stranded RNA enriched material was sequenced and sequences analyzed to determine whether they belong to known or undescribed viruses. Detection primers were designed for each virus and then used in all geotagged isolates. Results indicate mycoviruses are commonly found in isolates of R. solani. More than 20 new viruses, belonging to at least three different virus families have been discovered. Future experiments will determine the effects of mycovirus presence on growth and virulence of the fungus. Spatial analysis should help reveal whether interactions exist between Rhizoctonia spp., AGs, and mycovirus distribution in fields, as well as cropping and soil properties.

Work in Mississippi has focused on characterization of endophytic microbial communities associated with the soybean charcoal rot disease system. Symptomatic and asymptomatic soybean plants in a field known to be affected by charcoal rot were collected in 2013 and 2014. Final identification of the fungi was conducted in 2015 using traditional morphological methods and supported by molecular ITS sequence data and TEF-1α² for Fusarium spp. Fourteen common fungi either pathogenic, endophytic or saprophytic were identified in over 77% of isolations.  The most commonly occurring species from soybean tissues in order of frequency were Alternaria spp, Fusarium solani (species complex with two taxa), Penicillium chryseogenum, Cladosporium sphaerospermum, Fusarium chlamydosporum, Clonostachys rosea (teleomorph=Bionectria ochroleuca), Trichoderma harzianum (= Hypocrea lixii), Fusarium oxysporum, Fusarium sp. (=Fusarium proliferatum) and Trichoderma sp.  Using the common isolates obtained in the study, bioassays were conducted using Macrophomina phaseolina 151 (charcoal rot pathogen). Select species isolates were evaluated in preliminary bioassays to determine which isolates may be involved in charcoal rot disease suppression. From those studies Clonostachys rosea (=Bionectria ochroleuca) and Fusarim solani (two taxa within complex) showed some level of antifungal activity. In another research project, the Mississippi researchers focused on development of baseline data on sweetpotato root microorganisms and determination of the causal agent(s) associated with a newly emerging rot disease complex. Tissue samples from select plant parts (e.g. storage roots) across 2 years and eight growth stages were collected to determine variations in fungal populations. These results attempted to provide indication of potential timing and causes of tip/end rot disease of sweetpotato. Results for fungal diversity analysis show a wide distribution of species across many management periods, but the harvest and post-harvest sampling periods show the greatest species richness over both years. Macrophomina phaseolina, Aspergillus flavus, A. niger, A. tubingens, A. japonicus, and six species of Fusarium were pathogenic in trials on disease-free sweetpotato root tissue. In addition, F. oxysporum and F. solani consistently produced necrotic lesions in root tissue. These two species accounted for nearly 78% of the overall isolates from early season seed stock and bedding plant samples. Microbial populations in post-harvest tissues also differed in relative abundance from prior sampling dates. M. phaseolina increased to 30% occurrence and F. oxysporum and F. solani decreased to 15.5% isolation frequencies between 60 and 90 days post-harvest. During a previous study, a possible interaction between M. phaseolina and high populations of the reniform nematode, Rotylenchulus reniformis, was discovered. Three-year studies evaluating both organisms separately and together in greenhouse and field trials did not show any direct correlations to levels of tip/end rot in field or later in stored storage roots.  It was determined that other management practices should be considered as cause of the increase in tip/end rot of sweetpotato. Other research and preliminary results showed that biochar, a byproduct of the fast pyrolysis of organic matter to create biofuels, may have disease control potential and support plant growth. Using M. phaseolina as the tester pathogen, chitosan and biochar preliminary culture plate studies confirm that the pathogen had decreased mycelial growth compared with the control cultures in vitro. Chemical signatures or MVOCs (Microbial Volatile Organic Compounds) of M. phaseolina and other tip/end rot studies are being determined to develop equipment for sensory detection of infected soybean seeds and sweetpotato roots held in storage. Initial studies center on pure cultures of the pathogen and various forms to confirm results contain consistent compounds. In spring 2017, sterile storage roots will be available and the MVOCs will be compared from those microbial clean tissues and with the fungal pathogen. To ensure that MVOC data is unique to M. phaseolina from the pure culture studies, we are now looking at closely related fungal species (Botrysphaeriaceae) common to tip/end rot and soybean diseased necrotic tissues, and other Phyla of fungi common to sweetpotato and soybean plants. Further research has focused on detection of pre-storage and packing identifications of fungi infecting tip/end rot sweet potato roots using portable MVOC detection machinery within warehouses. The researchers collected new M. phaseolina isolates from identical hosts of sweet potatoes. The isolates were separated, verified, and prepared for MVOC analysis. The MVOC results from the GC/MS were unexpected due to high background noise. Therefore, further work is planned to reduce the analytical noise and improve the accuracy of MVOC identification. 

Additional research conducted at Mississippi State under this project include the folowing. (1) Identification of antagonistic bacteria associated with plant diseases. More than 200 bacterial isolates were obtained from soils and plant samples, and tested for antimicrobial activities using the standard bioassay procedures. Approximately 30 isolates showed significant antifungal activities against Geotrichum candidum and more than 20 isolates exhibited significant antibiotic activities against Erwinia amylovora. These isolates were further purified and preserved at -80^oC. The isolates were preliminarily identified to be Bacillus spp., Paenibacillus spp., Burkholderia spp., Enterobacter spp. and Pseudomonas spp. using 16S rDNA sequence analysis. (2) Investigation of the genes associated with production of the antibacterial activities. RNAseq analysis was employed to understand the regulation network of Burkholderia contaminans strain MS14. In addition to the LuxR gene and non-ribosomal biosynthesis gene (NRPS) for siderophore biosynthesis, we have identified an additional two genes predicted to synthesize bactericidal compound(s). Confirmations of their functions is underway. We have confirmed that occidiofungin is an important component responsible for the antifungal activity of Burkholderia pyrrocinia strain Lyc2. In addition, strain MS586 possesses significant antibacterial activity against the plant-wilting bacterium Ralstonia solanacearum, and was proposed as a novel species of the genus Pseudomonas. Two genes were confirmed to be critical for its antibacterial activity. (3) Genome sequencing of Burkholderia contaminans strain MS14 and Pseudomonas chlororaphis strain UFB2 were completed and the findings have been published. The genome sequence data provide important insights into understanding antimicrobial activities of these bacteria. (4) Evaluation and characterization of endophytic bacteria of soybean associated with charcoal rot disease. More than 20 isolates of endophytic bacteria that show strong antimicrobial activities against the charcoal rot pathogen have been isolated. Population analysis of the bacteria in plants by Illumina sequencing is underway.

At Oklahoma State University, the genetic profiles of Pythium and Globisporangium isolates resistant and sensitive to mefenoxam were completed. Monophyletic groups with high risk of developing mefenoxam resistance were identified within Globisporangium cryptoirregulare, as well as low-risk phylogenetic groups. The phylogenetic relationships of four clades within Globisporangium irregulare, identified in 2014, were confirmed. The SSR protocol developed for Fusarium proliferatum was published. Strains isolated from onion in Oklahoma, transformed to express fluorescent proteins, were used to examine the infection process in onion and the patterns were compared microscopically between species. A draft of the genome of Sclerotinia minor was annotated and compared with the genomes of sister taxa. A bioinformatics tool for metatranscriptomic analysis for detection of soilborne fungi and oomycetes and functional analysis was developed. The population biology analysis of Ophiosphaerella herpotricha was conducted and a manuscript is in progress. The manuscript describing a multiplex PCR assay for discrimination of three Ophiosphaerella species was submitted for publication.

2. Examine the effect of traditional or newly developed management strategies (chemical, cultural, and biological), soil physicochemical properties, or introduced biological control agents on the microbial community and its ability to suppress soilborne pathogens.

A project established in Tennessee focused on evaluation of chemical and biorational products for controlling soilborne diseases with different application methods, intervals and reduced-rate applications in woody ornamentals. The project has resulted in development of inoculation protocols for Rhizoctonia solani. This evaluation (inoculation methods and inoculum level) was a necessary first step to the screening of chemical and biorational products and cultural approaches (such as biobiofumigant cover crops, solarization). Chopped potato medium, agar plugs and agar slurry inoculation methods with three inoculum levels were evaluated to determine the disease response of Rhizoctonia solani on Viburnum plants. Plants were evaluated 1 month after inoculation for disease severity on root using a 1-5 ordinal scale. All inoculum levels of the agar slurry method showed significantly higher disease severity compared with the other methods. Agar slurry prepared with 7-day-old R. solani cultures can be used as an inoculation method which gives higher disease response in Viburnum and has the potential to be useful in future research on Rhizoctonia disease on other woody ornamentals as well. 

Chemical and biorational products were evaluated for ability to control Phytophthora root rot in oak leaf hydrangea cvs. Queen of Hearts and Munchkin in greenhouse conditions. Treatments were RootShield WP (Trichoderma harzianum Rifai strain KRL-AG2), RootShield Plus (T. harzianum Rifai strain T-22 and T. virens strain G-41) and Subdue Maxx (Mefenoxam). All treatments reduced root rot disease severity compared with the inoculated, non-treated controls in both cultivars. There were no significant differences between the treatments. Root rot disease severity was significantly higher in the cultivar Queen of Hearts than cultivar Munchkin. This study shows that biopesticides, RootShield WP and RootShield Plus, should be considered to reduce the risk of Phytophthora root rot on container-grown oak leaf hydrangeas in the nursery.

Chemical and biorational products (including Subdue Maxx, Empress, Segovis, OxiPhos, Terraclean, TerraGrow, MBI110, RootShield Plus and IT-1503 for Phytophthora nicotianae in Hydrangea; Paegant, Mural, Empress, Terraclean, TerraGrow, MBI110, RootShield Plus, Soilgard and IT-1503 for Rhizoctonia solani in Viburnum) were evaluated in field conditions. The experiment was set up at the Tennessee State University, Otis Floyd Nursery Research Center in McMinnville, TN as a randomized complete block design with four replications. Experiments are underway and plants will be evaluated for root development and disease severity on root at the end of the trial using an 1-5 ordinal scale. Also at TSU, researchers are focusing on development of improved soilborne disease management strategies based on cultural approaches for suppression of Rhizoctonia and (or) Phytophthora spp. and other soilborne pathogens. An agar slurry method was used to screen 15 biofumigant cover crops' susceptibility (belonging to the Brassicaceae family) to this disease under greenhouse conditions. Phytophthora infested rice grains were used to inoculate soil based on established protocols. Untreated biofumigant cover crops were sown in 10-cm pots containing infested soil. Non-infested sterilized soil was used as a control. Stand data and fresh weight were recorded at the end of experiments. According the analysis of germination data taken from both Phytophthora and Rhizoctonia experiments, eight cover crops having the highest germination under seedling disease pressure were selected. Oilseed radish, Mustard, Purple top forage turnips, Astro Arugula seeds, Mighty Mustard pacific gold, Amara Mustard, Rape and oriental Mustard were selected to use for field experiments. Cultural approaches including biofumigant cover crops, compost amendment, and solarization were evaluated under field conditions at two sites. Experiments are underway and plants will be evaluated for root development and disease severity on roots later in 2017.

During 2016, at Oregon State University – NWREC, efforts to establish guidelines for developing and implementing disease control strategies in managing Phytophthora root rot on ornamental plants continues. Ongoing trials determine the effectiveness of varying concentrations of calcium amendments, in the form of gypsum, against inoculum of two soilborne pathogens, Phytophthora cinnamomi and P. plurivora.

At Oklahoma State University, strains of Fusarium spp. were tested for hormetic effects at low doses of fungicides. Low-dose growth stimulation was observed suggesting that fungicides at low doses could enhance Fusarium spp. epidemics. New protocols for testing the effects on mycotoxin production of exposure of Fusarium spp. to hormetic doses of fungicides were developed. Differences in the patterns of infection of strains of Fusarium oxysporum and Fusarium proliferatum were identified by fluorescence microscopy. The protocols developed for this study will be applied to analysis of fungicide hormesis on fungal growth in planta.

In soybean-producing areas of Arkansas, root damage caused by southern root knot nematode (Meloidogyne incognita) and defoliation caused by frogeye leaf spot (a fungus, Cercospora sojina) are two of the most economically important soybean diseases. It is not uncommon for these diseases to be found in the same field (along with many other diseases) during the same growing season. Many times, soybean varieties are planted that are susceptible to both requiring nematicide and fungicide inputs to protect yields and minimize additional expense. Collecting data in space (yield maps, soil textural maps, and digital imagery captured by UAS or satellites) allows comparisons between multiple diseases and field characteristics. The objective of this work was to determine how two commonly occurring diseases, root damage caused by root-knot nematode (RKN) and defoliation caused by frogeye leaf spot (FLS) affected each other and overall yield using spatial data collection and analysis. Two fields, ca. 10 acres, at the Rohwer Branch of the Southeast Research and Extension Center near Rohwer, AR were split in 2014 and planted to half corn and half grain sorghum.  In 2015, these fields were planted to Armor DK 4744 soybean and test areas were assigned 200 points (20 rows of 10 points in a row, GPS-marked) in each field with 100 in the half of the fields from corn and 100 in the half with grain sorghum in 2014. These points were untreated and served as controls. Multiple randomized treatment strips were placed between rows of points with 10 points adjacent to the untreated points in each strip (and also GPS marked). In one field, Telone II was applied in the strips between the 200 rows of points, 18 strips total with 9 strips within each set of 100 points prior to planting.  In the other field, seed treated with Ilevo was planted in 18 strips with 9 strips in each set of 100 points. Three replications of three different fungicides (Topsin XTR, Quadris Top SB, and Stratego YLD) were applied in both fields within and adjacent to Telone II and Ilevo strips for comparisons. Fields were scouted throughout the season for FLS and root galling. When FLS occurred, it was rated as a percentage within a 10-ft length of row at each point. Soil samples were taken at harvest at the 200 points assigned in each field and submitted for analysis of populations of RKN (and other nematodes) as well as soil fertility and chemistry analyses. All variables from all points were spatially interpolated and analyzed after harvest and disease differences, product efficacy, and yield compared. Points within areas of fields determined to have the greatest disease pressure were extracted using the query function in ArcMap 10.1 (ESRI, Redlands, CA) and treatment groups compared to untreated using a two-sample t-test.  

Root-knot nematode was found in both fields along with stunt, spiral, soybean cyst, and stubby-root nematodes. Frogeye leaf spot was severe and RKN populations negatively correlated with FLS in the field where Ilevo was applied but not the field where Telone II was applied. Little galling was observed on the roots. Populations of RKN did not aggregate on the areas of each field rotated with corn, but the populations in those areas were slightly higher. In the Ilevo field, the areas with the greatest amount of disease were related to areas with the lowest soil potassium levels (P=0.01). Within these areas, strips of Ilevo had less overall FLS than the untreated strips. Due to the correlation between FLS and K, points below optimal levels of K were separated from points with K levels within optimal levels, above and below 130 ppm. When product efficacy was compared between K levels, the FLS percentage was significantly less for all treatments applied across areas with optimal K except Ilevo+Stratego YLD compared to the areas of below optimal K. The direct comparison of Ilevo without fungicide to the untreated checks, indicated Ilevo lowered FLS in both comparisons but was only significant in the areas of below optimal K (P<0.0001). 

In the Telone II field, again, the areas with the greatest amount of FLS correlated with areas of lower soil K (P=0.01). The addition of Telone II resulted in significantly less FLS from the untreated control in areas of the field with K levels below 130 ppm. Fungicides all performed similarly whether Telone II was applied or not when compared with the untreated control or each other. When yield within the Telone II strips was compared with that of the control, the addition of a nematicide increased yield by approximately 7 bu/acre in areas with less than 130 ppm K (P=0.05). Over the entire field, however, the addition of Telone II only resulted in a 2 bu/acre gain.

One of many crop management practices being adopted by cotton growers is site-specific management, which involves observing, measuring, and responding to field variables as they change across a field in order to optimize crop inputs for specific sites to maximize yield potential. Predicting and preemptive management for cotton seedling diseases could provide more uniform stand establishment. In a spatial research field trial using a range of fungicide seed treatments at the Judd Hill Plantation, stand improvement from fungicide seed treatments increased where minimal soil temperature decreased across this field in both years. Seedling disease indices increased as minimal soil temperature decreased across this field both years of this study. Thilaviopsis basicola soil inoculum levels and incidence on seedlings also increased as minimal soil temperature decreased across this field both years. These results show that seedling disease pressure varied spatially across this field based on predictable soil factors. This information could be used for creating prescription maps for variable rate management.

Scientific articles

Pradhan S, Flores F, Molineros JE, Melouk H, Walker NR, and Garzon CD. 2016. Improved assessment of mycelial growth stimulation by low doses of mefenoxam in plant pathogenic Globisporangium species. European Journal of Plant Pathology. DOI 10.1007/s10658-016-1016-5

Moncrief IR, Garzon CD, Marek SM, Stack JP, Gamliel A, Garrido P, Proaño MF, Gard M, Dehne H,  Fletcher J. 2016. Development of simple sequence repeat (SSR) markers for discrimination among isolates of Fusarium proliferatum. Journal of Microbiological Methods. 126: 12-17.

Abd-Elmagid A, Hunger R, Garzon CD, Jub H, Payton M, and Melouk H. 2015. Effect of osmotic and matric potentials on Sclerotinia minor and Sclerotinia sclerotiorum virulence on peanut. Int. J. Phytopathol. 04: 147-158.

Spurlock, T. N., Rupe, J. C. 2016. Aerial blight. Compendium of Soybean Diseases and Pests, Fifth Edition.  APS Press, St. Paul, MN.

Spurlock, T. N., Rothrock, C. S., Monfort, W. S., Griffin, T. W. 2016. The distribution and colonization of soybean by Rhizoctonia solani AG11 in fields rotated with rice.  2016. Soil Biology & Biochemistry 94:29-36.

Allen, T., Bluhm, B., Conner, K., Doyle, V., Price, T., Sikora, E., Singh, R., Spurlock, T., Tomaso-Peterson, M., Wilkerson, T. 2016. First report of taproot decline, a previously undescribed soybean disease, in the southern United States.  Plant Health Progress. (submitted)

Spurlock, T. N. 2016. Using spatial data layers to understand soybean diseases.  Crop & Soil 49:12-15.

Tomaso-Peterson, M., Allen, T., Singh, R., Spurlock, T., Price, P. 2016. Characterization of taproot decline in southern soybean. Proceedings of the 43^rd Annual Southern Soybean Disease Workers, Pensacola, FL.

Wilson, K., Rothrock, C., and Spurlock, T. 2016. Spatial examination of soil factors on cotton seedling disease pressure. Page 593 in: Proceedings of the 2016 Beltwide Cotton Conferences.

Extension publications:

Espindola AS, Garzon CD, Marek SM, Melouk H, Schneider W. 2016. Genome (DNA) Sequencing of Sclerotinia minor.  Partners in Progress - Peanuts. Peanut Research. Oklahoma State University, P-1047. P. 19-22.

Baysal-Gurel, F., Liyanapathiranage, P., Blalock, A. 2015. Southern blight management for woody ornamentals. ANR-PATH-02-2015. TSU-16-0191(A)-15-61065.

Baysal-Gurel, F., Kabir, Md N., Blalock, A. 2016. Root diseases of hydrangeas. ANR-PATH-4-2016. TSU-16-0237(A)-15-61065.

Abstracts/Posters

Iturralde JF, Flores FJ, Koch AR, Garzón CD, Walker NR. 2016. A Multiplex end-point PCR assay for the detection and identification of three species of Ophiosphaerella that cause spring dead spot of bermudagrass. 5th European Turfgrass Society, Jun. 5-8, Albufeira, Portugal.

Presentations / Professional Meetings

Proaño MF, Ayala C, Chiriboga A, Daughtrey M, Garzon CD. 2016. Characterization and identification of Pythium and Globisporangium species present in ornamental greenhouses from Long Island, New York. APS Annual Meeting. Jul. 30- Aug. 3, Tampa, FL. 60-O

Kabir, Md N., Liyanapathiranage, P., Simmons, T., Baysal-Gurel, F. 2016. Effect of biopesticides on Phytophthora root rot disease of oakleaf hydrangea. APS Annual Meeting. Jul. 30- Aug. 3, Tampa, FL.

Kabir, Md N., Simmons, T., Liyanapathiranage, P., Curry, C., Alexander, L., Baysal-Gurel, F. 2016. Evaluation of stem inoculation technique for assessing resistance to Phytophthora nicotianae in hydrangea cultivars. APS Annual Meeting. Jul. 30- Aug. 3, Tampa, FL.

Spurlock, T., Rothrock, C., Urrea-Romero, K., Tolbert, A. 2016. Spatial distribution of taproot decline of soybean. Phytopathology 106:S2.14.

Urrea, K., Rothrock, C., and Winters, S. 2016. Virulence of Rhizoctonia solani anastomosis groups on cotton, corn, rice, and soybean. Phytopathology 106:S4.30

Stetina, T., Rothrock, C., Spurlock, T., and Tzanetakis, I. 2016. The virosome of Rhizoctonia solani and its effect in fungal pathogenicity. Phytopathology 106:S4.43.

Theses

Espindola, AS. 2016.  Eukaryotic Plant Pathogen Detection through High Throughput DNA/RNA Sequencing Data Analysis. Doctor of Philosophy in Plant Pathology, Oklahoma State University.

Proaño, MF. 2016. Temporal and Host Related Variation of Pythium and Globisporangium Species in Floricultural Crops. Master of Science in Entomology and Plant Pathology, Oklahoma State University.