Brief Summary of Minutes of Annual Meeting

Minutes of the Annual Meeting of the Technical Committee of MRP Project S-1028 Nov. 4 to 5, 2011, Oklahoma City, Oklahoma Attendees: C. Garzon (OK), C. Canaday (TN), C. Rothrock (AR), K. Broders (NH), H. Scherm, (Adm. Advisor). Other participants Luisa Santamaria (OR) The meeting was held at the Hilton Garden Inn Quail Springs in Oklahoma City, Oklahoma. The meeting was called to order by Carla Garzon, Chair, at approximately 8:30 A.M. Carla welcome the participants. Harald Scherm introduced himself as the new administrative advisor and talked about multi-state projects and the status of the current project. He also reviewed the steps involved in rewriting the project and his feeling regarding a multi-state projects and information exchange groups. The members discussed their interests in developing a new project and the focus of the project. The general consensus of the participants was that there were advantages to developing a collaborative research project and that we should explore a new multi-state project. The project would focus more on specific pathogens. The genera suggested were Pythium, Rhizoctonia, and/or Verticillium. Areas of research suggested were diversity, IPM, metagenomics, and development of methodologies for sampling, detection, statistical data analysis, and education. Presentations relating to the projects research objectives and current research of participants were then started. Craig Rothrock presented research on Brassica cover crops as part of objective 2 (examining the effect of cultural practices on soilborne pathogens and plant growth). Cover crop establishment in the winter of 2010 was poor and results did not show much benefit in growth or disease suppression. The greatest effects on pathogen suppression in past years had been on nematodes. In addition, he presented evidence of shifts in microbial populations from the use of Brassica cover crops using DGGE analysis. Research examining the genetic diversity of Rhizoctonia solani between natural ecosystems and agricultural ecosystems (objective 3) included surveys in 2011 to collect samples from diverse crops in the Southeast. Isolates are being characterized. The sampling protocol involves baiting populations of Rhizoctonia from soil using toothpick baits and selective media, as well as seedling isolations Craig Canaday presented data on the role of chloride in enhancing Phytopthora sojae on soybean and recent parallel research on snap bean production and potassium fertilizers. He showed significant yield response from the use of K2SO4 versus KCL. He also presented information for soybean and snap bean on mechanisms of plant response from Cl amendments on Ca micropartitioning. Carla Garzon gave an overview of her research on diversity of Pythium spp. and species characterization (objective 3). Additional research presentations involved graduate students in her laboratory. Andres Espindola presented information on development of specific primers for identification of Sclerotinia spp. and a novel massive parallel sequencing based diagnostic tool. Francisco Flores presented research on chemical hormesis caused by subinhibitory levels of fungicides and methods of modeling hormetic effects. Kirk Broders presented research related to the project on diversity (objective 3). He presented a review of a large project characterizing Pythium spp. on soybean. In addition to characterizing species associated with soybean he presented information collected to examine the role of soil physical or chemical factors on importance of Pythium seed and root rot in fields and species composition. He also presented information on his recent research on the diversity of Butternut pathogen, Ophiognomonias clavigignenti-juglandacearum. He gave an overview of his current research interests. Luisa Santamaria introduced her research with the nursery industry in Oregon on Verticillium dahliae. Her research has focused on sources of inoculum of the pathogen as influenced by cultural practices used in the industry. In addition, she discussed her education efforts with workers in the horticultural industry to increase awareness of plant pathology and improve management practices. Business Meeting. C. Garzon, chair, called the business meeting to order following a break after the presentations by participants. The members present discussed a location for next year's meeting and Carla volunteered to host the group in Oklahoma City again in 2012. Participants agreed that the location was convenient and with Carla's role in rewriting the project the site would be best. Craig Rothrock will become chairman for next year's meeting. Kirk Broders was nominated for secretary for 2012, and the nomination was seconded and passed unanimously. The writing committee for a new project will consist of Carla Garzon and Kirk Broders and will be chaired by Carla Garzon. Research objectives will be identified by present and potential members of the project. The committee with then involve participants in writing the new project. A possible timeline for activities to receive approval was discussed. Craig Canaday put forth a resolution thanking Carla for organizing the meeting and her efforts as host during the meeting. The resolution was endorsed by all present. The meeting was adjourned at 5:00 p.m. Respectfully submitted, C. Rothrock, Secretary

Objective 1. Examine commercial and non-commercial biocontrol agents for use as seed treatments, in-furrow treatments or as potting mix amendments. Kentucky: Biological control of Phytophthora Blight of Summer Squash with Trichoderma was studied. A trial was conducted in the summer of 2011 to evaluate Tenet, a commercial formulation containing Trichoderma harzianum and T. viride, for suppression of Phytophthora blight, caused by Phytophthora capsici, on summer squash when applied to seedlings prior to transplanting or to soil via drip irrigation, alone or in conjunction with fungicide programs. Earlier results showed that Tenet-containing treatments reduced the severity of Phytophthora blight by 25% over the untreated control; however, results from the 2011 study differed. Tenet, when applied to squash seedlings one week prior to transplanting, reduced overall severity of Phytopthora blight compared with the untreated control. Treatments applied in the field had no effect  a departure from the trial conducted in 2009. Mississippi: Recent research in the Plant Bacteriology laboratory of Mississippi State University continued understanding the mechanisms of antifungal bacteria present in soil-borne disease systems. Further characterization was conducted to understand functions of the genes in the 56-kb occ gene cluster that is essential for production of occidiofungin production by Burkholderia contaminans strain MS14. A biosynthesis pathway was proposed based on genetic and biochemical analysis. Occidiofungin was evaluated regarding its stability and efficacy as a antifungal compound. Interestingly, disruption of the ocfC gene in the ocf gene cluster by the insertion of the nptII cassette resulted in xylose-free occidiofungin production and reduction of antifungal activity against the indicator fungus Geotrichum candidum. However, the antifungal activity of the xylose-free occidiofungin was significantly increased against Candida species as compared with the wild-type occidiofungin. These results are significant for development of agricultural biofungicides and medical parametrical drugs. In addition, more than 60 bacteria obtained from Mississippi soils exhibited significant antifungal and/or antibacterial activities against pathogenic fungi and bacteria. The mechanisms of antifungal and antibacterial activities of the isolates are under investigation. Oklahoma: A study of bacterial communities present in Andean soils from Ecuador suppressive to Phytophthora infestans was conducted. Serial dilutions of soils were performed and plated on differential and selective media following standard protocols. Approximately 3,000 bacterial strains of Bacillus, Pseudomonas, and Actinobacteria (including Streptomyces) were isolated, evaluated for their ability to inhibit P. infestans and Rhizoctonia solani. Strains with stronger inhibitory effects were selected for further characterization, and 200-300 strains of each bacterial group were sequenced (16S rDNA). Currently, the microbial communities in these soils are under further examination using metagenomic methods. Finally, analyses of the physical and chemical properties of the soils are being assessed, since the soils studied preserved suppressive qualities (about 30% of the observed suppression) after removal of microbial populations by tyndallization at 80ºC. South Carolina: A new commercial formulation of Bacillus subtilis (Serenade Soil) was evaluated for control of root diseases on cabbage and spinach. Two field experiments are in progress in which three rates of Serenade Soil are compared with water-treated and a fungicide-treated controls. Objective 2. Examine the effect of cultural practices on soilborne pathogens and plant growth. Arkansas: Research was repeated to characterize changes in plant pathogen and general microbial populations in soils following a summer Brassica cover crop, mustard seed meal amendment, solarization or a combination of the cover crop and solarization, compared with no soil treatment prior to establishing an annual strawberry crop at two locations in Arkansas. General microbial and suspect pathogen populations from soils were quantified by plate count methods. Additional soil samples were taken after cover crop incorporation to generate denatured gradient gel electrophoresis (DGGE) profiles for bacterial (including actinobacteria) and fungal populations. Soil treatments affected the level of bacterial and fungal populations in the soil at the time of treatment and at strawberry transplant. In all cases, there was a trend for higher bacterial and fungal populations in Brassica, Brassica plus solarization, and mustard seed meal-amended soils compared with solarized only and control soils. Total culturable bacterial populations were significantly higher in soils that had been planted with a Brassica cover crop followed by solarization and soils receiving mustard seed meal amendments at both locations at the time of strawberry transplanting. DGGE produced unique profiles of bacteria and fungi compared with that of control soils. Bacteria profiles were still present at the time of strawberry transplanting. This project has successfully proven how including soil treatments such as a Brassica cover crop, solarization or mustard seed meal application as a practice in annual strawberry production can enhance the soil microflora, especially the bacterial community. Cover crop establishment of Brassica crops in the winter of 2010 was poor and results did not show much benefit in growth or disease suppression for the subsequent summer cotton crop. The greatest effects on pathogen suppression in past years for the subsequent cotton crops have been on nematodes. Mississippi: The Sweet Potato Rot research project is a survey comparing microbial flora between damaged and control roots to identify possible pathogen or other cause such as specific management practices. The research is divided into three main areas of study including: 1) sampling of sweet potato plant and root tissues from fields with a history of the rot complex for culturing of fungal and bacterial strains present in plant and root tissues; 2) identification of each fungal and bacterial isolate based on both morphological characteristics and gene fragment (ITS, 16s rDNA, EF1-alpha) sequences; and 3) determining pathogenicity of fungal and bacterial isolates on storage root tissue in the laboratory and on intact plants in the greenhouse under field conditions. We hope to determine which of the pathogenic isolates are capable of infecting a plant under field conditions and, using this information, work with collaborating extension research groups to improve sweet potato resistance to the identified pathogen(s). Roots and stem tissues have been sampled throughout the year, beginning with seed stock, at the time slips are transplanted into the field, pre- and post-harvest, and during storage. The study has been repeated over two years, with the second year of sampling nearing completion. To date, over 4,500 fungal isolates and over 4,600 bacterial isolates have been cultured, and many have been identified using morphological techniques for fungi and molecular techniques for bacteria. The bacterial community is primarily composed of members of Bacillus spp., Paenibacillus spp., and Stenotrophomonas maltophilia. Predominant species of fungi include Fusarium spp., Macrophomina spp., Botryodiplodia theobromae, and Aspergillus niger. A portion of these isolates are being tested for pathogenic characteristics on sweet potato storage root tissue, and several potential fungal pathogens have been tentatively identified. Between management period 7 and 8, when end-rot symptoms become visible, the distribution and total number of fungal species changed significantly. Botryodiplodia theobromae, Fusarium spp. and Macrophomina spp. increased in number in the Site 1 field, while the dominant Aspergillus niger from the previous sampling period was not detected. Storage roots taken from the Site 2 field showed an increased occurrence of Fusarium spp. at management period 8. We also detected a greater variety of isolates in samples from management period 8 (Site 1 n=36; Site 2 n=25) than we did in samples from management period 7 (Site 1 n=16; Site 2 n=15). Fungal isolates were found in all tissue types that were sampled, and there was no statistical difference in the frequency of isolate occurrence between tissue types (parenchyma, stem end, root end). Currently, pathogenic trials are underway in the greenhouse to determine the effects of individual fungal pathogens on transplanted sweet potato slips. North Carolina: Phytophthora root rot of Fraser fir, caused by several Phytophthora spp., is a severe problem in Christmas tree production. Since fungicides are not economically viable for disease management in field plantings and host resistance is not available, cultural control methods were investigated. Mulches, dairy compost, and soil pH adjustment were tested at five field sites in North Carolina. Treatments included wood chips, wood chips plus compost, or pine bark as raised beds, and compost or sulfur tilled into soil. Soil and mulch microbial populations were characterized by dilution-plating and calculation of a log series diversity index and by enzyme analyses at 5, 12, 17, and 24 months after planting. Bacterial and fungal counts, and microbial activity were higher in mulch than in soil at all sites and times (P<0.01), and generally did not differ among mulch types or among soils. Treatments significantly affected disease ratings and tree survival at three of five sites, with one or more mulch treatments yielding lower disease ratings and greater survival than controls. Tree mortality at each time point varied significantly with cellulase activity in the upper root zone (P=0.005). Other biological variables did not show significant relationships with disease ratings or mortality. Wood-based mulches were tested on Fraser fir for reduction of Phytophthora root rot to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml-1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10-50 U ml-1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml-1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1000 U ml-1 with three timings. Activity diminished by 47% between one and 15 days after application. Cellulase applied at 100 U ml-1 two weeks before planting yielded activity of 20.08 µmol glucose equivalents per gram soil water (GE g-1 aq) at planting, a level equivalent to mulch samples. Activity at planting ranged from 3.35 to 48.67 µmol GE g-1 aq, but no treatment significantly affected disease progress. South Carolina: Two research projects were conducted. The objective of the first project was to evaluate the susceptibility of Lagenaria, Cucurbita and Citrullus rootstocks to Fusarium wilt of watermelon.The rootstocks Emphasis, Macis, and WMXP 3945 (Lagenaria siceraria), Shintosa Camel and Strong Tosa (Cucurbita moschata x Cucurbita maxima), and Ojakkyo (Citrullus lanatus var. citroides) were evaluated in a field experiment. The rootstocks were grafted with seedless watermelon Tri-X 313 (Citrullus lanatus var. lanatus). Tri-X 313 not grafted or grafted to itself served as controls. Plants were transplanted to a field naturally infested with a mixture of races 1 and 2 of Fusarium oxysporum f. sp. niveum, the causal agent of Fusarium wilt of watermelon. Wilt incidence was highest in the nongrafted Tri-X 313 and moderate in the self-grafted Tri-X 313 and those grafted onto Ojakkyo citron. All five other rootstocks had less than 2% wilted plants and did not differ from each other, but differed from the other three treatments. Fruit weight was greater with Lagenaria and Cucurbita rootstocks than with Tri-X 313 (mean of not grafted and self-grafted). Lagenaria rootstocks also increased fruit number. In the second project oilseed radish (Raphanus sativus), mustard (Brassica juncea cv. Pacific Gold), and winter rapeseed (B. napus cv. Dwarf Essex) were sown in fall 2010 and spring 2011 before incorporation as biofumigation cover crops. After incorporation in February and April, plots were covered with white-on-black virtually impenetrable film (VIF). Control treatments were fallow with and without VIF. Isothiocyanate concentrations (ITCs) in soil were higher after incorporating fall-planted vs. spring-planted Brassicas. Mustard produced the most ITCs and oilseed radish produced the least. Five weeks after incorporation, populations of Pythium spp. and Sclerotium rolfsii did not differ among treatments. Populations of Rhizoctonia solani were higher in fallow without VIF than in all mulched treatments, indicating that the VIF reduced populations of R. solani. Pepper plants transplanted into the plots were stunted due to infection of the roots in all plots by Pythium aphanidermatum but particularly in the fallow plots without VIF. Pepper yields were consistently highest in Brassica treatments compared with fallow with VIF, and yields in fallow with VIF yields were higher than yields in fallow without VIF. Tennessee (Canaday): A laboratory study on the effects of chloride salts on the micro-partitioning of root Ca was conducted using energy-dispersive analysis of x-rays to measure the relative changes in the root nutrients. Detectable levels of calcium in the outer cell layers of 10 to 13 day-old soybean taproots were significantly lower when plants were grown in soil treated with potassium chloride, sodium chloride, or magnesium chloride than when the plants were grown in untreated soil or soil treated with potassium sulfate. Tennessee (Ownley): Anaerobic soil disinfestation (ASD) treatments were applied to soil in growth chamber pot studies to determine effects on populations of Rhizoctonia solani, and growth and disease of a subsequent broccoli crop. Cover crops were hairy vetch, arugula, wheat, cereal rye, crimson clover, and mustard. A fallow control was included; due to lack of organic matter incorporated into the control, it was anticipated that R. solani populations would be low. Cover crops were grown for 4 weeks, and then chopped and incorporated into soil. Inoculum of R. solani grown on cornmeal:sand was added to all pots at 2% w/v. Half the pots were irrigated (ASD treatment) after incorporation of the cover crops, and half received no water. After 4 weeks, toothpicks were inserted into soil as baits for R. solani and Packman broccoli seed were planted into the pots to determine pathogenicity of R. solani populations. The toothpick bait method was used to determine populations of R. solani per gram of soil. Two trials were conducted. Choice of cover crop incorporated into soil had a significant impact on plant growth, Rhizoctonia disease rating of broccoli, and number of propagules of R. solani in soil, with and without irrigation. Irrigation following cover crop incorporation is an important component of the ASD method in order to achieve anaerobic soil conditions. Without irrigation, the largest broccoli seedlings with lowest disease ratings and lowest numbers of R. solani propagules in soil were found in the fallow control for both trials. In trial 1, broccoli seedlings from pots treated with the hairy vetch cover crop were also large and not different from the fallow control. However, disease rating and populations of R. solani in soil were higher. In trial 2, there were no differences in number of R. solani propagules in soil or plant disease rating among the cover crops; but crimson clover resulted in larger broccoli seedlings than the mustard treatment. in trial 1 (with irrigation, ASD treatment), broccoli from soil mixed with chopped hairy vetch were twice as large (weight) as the fallow control, and were equally low in disease rating and propagule counts of R. solani in soil as the control. In trial 2 (with irrigation), crimson clover, wheat, and hairy vetch resulted in broccoli shoot height that was the same as the fallow control plants. Rhizoctonia populations were equally low in the fallow and wheat soil treatments, while disease rating of broccoli was lowest, and not different from the fallow control, with hairy vetch, wheat, crimson clover, and cereal rye ASD treatments. Texas: Three studies were conducted. In the first study, laboratory assays were conducted to determine the impact of oilseed meals and isothiocyanates (ITCs) on Phymatotrichopsis omnivora, the causal agent of cotton root rot. The effect of oilseed meals from both Brassicaceous plants, including mustard (Brassica juncea) and camelina, as well as non-Brassicaceous plants, including jatropha, flax, and Chinese tallow, on P. omnivora sclerotial germination and hyphal growth in Branyon clay soil were investigated. Also, the effects of four types of individual ITCs, including allyl, butyl, phenyl, and benzyl ITC, on P. omnivora growth on potato dextrose agar (PDA) were assessed. Oilseed meals were added to soil at rates of 0, 1, and 5% (w/w). The results showed that all tested brassicaceous and jatropha seed meals were able to inhibit P. omnivora sclerotial germination and hyphal growth at 5% and 1% application rates, respectively, with mustard seed meal being the most effective. Neither flax nor Chinese tallow showed any inhibitory effects on sclerotial germination. All tested ITCs inhibited P. omnivora OKAlf8 hyphal growth, although the level of inhibition varied with concentration. The IC50 values were 0.62 ± 0.19, 4.47 ± 0.08, 5.67 ± 0.10, and 20.48 ± 0.30 µg cm-3 for allyl, butyl, phenyl, and benzyl ITC respectively. In the second study, a laboratory study was conducted to examine the impact of various oilseed meals on soil C, N, bacteria, and fungi. Mustard (B. juncea) and flax seed meals and sorghum-sudangrass were added to Weswood loam soil at levels of 0, 1, 2.5, and 5% (w/w). Both the type of amendment and application rate affected soil organic C, total C & N, and C & N mineralization. Mustard meal amendment initially inhibited C mineralization as compared to flax, but >50% of mustard and flax organic C was mineralized within 51 days. Nitrogen mineralization was similar for flax and mustard, except for the 2.5% rate at which a lower proportion of mustard N was converted to nitrate. Soil bacterial and fungal community responses to the 2.5% amendment rate were characterized using 16S rRNA and fungal ITS gene sequences at four time points over the course of the experiment. Distinct bacterial and fungal communities occurred among amendment-type lines, with mustard inducing large increases in the abundance of bacterial groups known to include many fungal disease-suppressing bacteria (e.g., Bacillus, Pseudomonas, and Streptomyces spp.), while other amendments increased Actinobacteria or Bacteroidetes abundances. Shifts in bacterial community composition slowed after 14 days but all biomass treatments still contained unique communities after 28 days. Dramatic shifts were also seen among fungi, with fungal phylotype richness decreasing by > 60% following mustard seed meal addition. Changes among the fungi, especially for the mustard treatment, persisted throughout the entire study. Finally, a third laboratory study was conducted to determine soil microbial community responses to four types of ITCs (allyl, benzyl, phenyl, and butyl) in a microcosm study using Weswood loam soil. Microcosms were amended with 50 µg g-1 of an individual ITC and incubated at 25°C for 28 days. Community qPCR assays were used to evaluate relative abundances of soil microbial populations after 2, 7, 14, 21, and 28 days. Soil microbial community composition after 2, 7, and 28 days was determined through tag-pyrosequencing using 454 GS FLX titanium technology, targeting ITS and 16S regions for fungal and bacterial communities respectively. Our results showed that the application of ITCs altered soil microbial community composition by suppressing either soil fungal or bacterial abundance, depending upon the ITC applied. Allyl ITC greatly decreased soil fungal abundance by >6 times compared with the unamended control, and significantly changed both fungal and bacterial communities composition. In contrast, butyl ITC had a larger impact on bacterial rather than fungal abundance and composition. Objective 3. Examine the genetic diversity of Rhizoctonia solani between natural ecosystems and agricultural ecosystems. Arkansas: Populations of Rhizoctonia solani were examined using the protocol previously developed by the regional project members. The sampling protocol involved baiting populations of Rhizoctonia from soil using toothpick baits and the TS selective media, as well as seedling isolations. In 2011, isolations included surveys to collect samples from diverse crops in the Southeast. In addition, a long-term rotation study including rice, soybean, corn, and winter wheat was used to examine shifts in soil populations of Rhizoctonia spp. as a result of cropping history. Isolates are currently being characterized. Soybean and rice rotations are being assessed for spatial distribution of Rhizoctonia populations. The diversity of Rhizoctonia spp. in these cropping systems included R.solani (AGs 11, 1-1A, 4 and 2-1), Rhizoctonia oryzae, and bi-nucleate Rhizoctonia species. A new selective medium TS was developed for improved recovery of Rhizoctonia spp. from soil. The medium is an improvement over the previous selective media used as part of the project as a result of better suppression of Trichoderma spp. and Mucorales. Kentucky: Isolates recovered in 2010 were stored improperly and could not be shipped to C. Rothrock for identification. We were unable to work on this objective in 2011, but plan to re-do the 2010 sampling and isolation to provide comparisons of isolation methods for R. solani and for diversity of R. solani. Louisiana: A study was conducted at the Macon Ridge Research Station near Winnsboro, LA to assess the diversity of Rhizoctonia spp. in fields planted to cotton, grain sorghum, and soybean fields. A standardized protocol developed by the S-1028 group was used. Thirty random soil samples per crop were taken from two locations (15/location). Within each location five sample sites were randomly chosen. When possible, one location was in a field where conventional tillage practices were utilized and the other location was from a field where minimum tillage practices were utilized. Soil was transported to the lab for further processing. Soil was placed in plastic pots. Moisture was supplemented to soil to saturation and toothpicks were placed in soil and left for a predetermined time according to the protocol. Toothpicks were plated onto ethanol-potassium nitrate medium. Plates were monitored for growth of Rhizoctonia 24 hours after plating and colonies were quantified. Colonies were then transferred to antibiotic-amended water agar plates. Number of colonies per treatment is presented in the table below. Attempts were made to transfer Rhizoctonia colonies to water agar, but fungal contaminants interfered with this process. 2011 Rhizoctonia solani Diversity Study Tillage Crop # Colonies Minimum CT 15 Conventional GS 24 Conventional CT 16 Minimum SB 21 Minimum SB 36 Conventional GS 15 An additional study was conducted on the Macon Ridge and Red River Research Station in collaboration with Dr. Craig Rothrock at the University of Arkansas. Each station served as a sampling site. Soil and seedling samples of cotton and soybean were taken at these sites. Samples were then shipped to Dr. Rothrock's lab for further processing. Additional Ecological and Genetic Diversity of Soilborne Pathogens and Indigenous Microflora Outcomes Iowa: Activities included conducting and analyzing studies on the effects of biochar on soil respiration and soil microbial populations. Biofuels are being carefully evaluated for their efficacy to replace hydrocarbons. Pyrolysis of plant materials leaves behind residues (biochars) that may impact soil cultural practices and affect soilborne organisms and plant growth. We studied corn stover and three biochars (pyrolysis products made from corn stover) and their decomposition in soil. The study revealed that the percentage of carbon lost from the amendments after eight weeks was greatest for corn stover (44% by weight), followed by the two less completely pyrolyzed biochars (9 and 10%), and least (4%) from the biochar made by fast pyrolysis at 500C. Thus, all biochars contained at least some readily bioavailable carbon that could be measured as CO2 emissions over 8 weeks. Microbial availability roughly correlated inversely with the degree of pyrolysis completeness. There was an apparent shift in microbial communities from bacteria and actinomycetes to fungi with increasing degree of pyrolysis. A soil biology educational website containing video of important soil organisms including fungi, ectomycorrhizae, endomycorrhizae, and their activities in the soil food web is maintained at (http://www.agron.iastate.edu/~loynachan/mov/). Oklahoma: A study of the genetic diversity of populations of Sclerotinia minor in agricultural soils in Stillwater, OK, was completed. Sclerotia collected from five experimental peanut plots (two breeding, two variety disease resistance assessment, and one chemical trial) were sterilized, germinated, and strains were characterized to species morphologically. Species identification was verified by sequencing the ITS region (including the small subunit of the rDNA). Most of the strains recovered (n=130) were verified as S. minor, however a few (n=15) produced sequences with higher similarity to S. sclerotiorum than S. minor, but not 100% similar. The population structure of S. minor was examined and it was determined that strains from breeding and disease resistance assessment were not significantly different. However, significant differentiation was found between S. minor populations from chemical trial plot and all other plots. Currently, 15 strains representing the genetic diversity of the studied sample are being evaluated for pathogenicity and fungicide sensitivity. A second study is currently underway to evaluate the effects of sublethal fungicide concentrations on populations of oomycete (Pythium and Phytophthora) and fungal (S. homeocarpa, Botrytis cinerea, and R. solani), plant pathogens.

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Cubeta, M.A., Burpee, L.L. Fonash, E.G. Csinos, A.S., and Ji, P. 2011. First report of root rot caused by binucleate Rhizoctonia anastomosis group F on Musa spp. Plant Disease 94:490. Abstracts Abd-Elmagid A, Garrido P, Hunger R, Melouk H, and Garzon, CD. 2011. Multiplex PCR for diagnosis of four Sclerotinia species. 8th Annual Graduate Research in Biological Sciences Symposium. Stillwater, OK, September 22-23, 2011. Canaday, C. H., Donald, P., and Mengistu, A., 2011, Increases in snap bean and soybean seedling diseases associated with a chloride salt and changes in the micro-partitioning of tap root calcium. Phytopathology101:S26. Dobhal, S, Garrido, P, Melouk, H, Garzon, CD. 2011. Strain discrimination and genetic diversity assessment of the fungal plant pathogen Sclerotinia minor from neighboring agricultural fields in Oklahoma. Chemical and Biological Defense Science and Technology Conference. Las Vegas, NV, November 14-18, 2011. Espindola A., Daniels J., Stobbe A., Schneider W., and Garzon, C.D. 2011. Design and validation of queries for the detection of Phytophthora ramorum in simulated metagenomes. American Phytopathological Society 2011 National Meeting, Honolulu, Hawaii. Phytopathology. 101: S50 Flores, F., Garzon, C. D. Evaluation of hormesis on the response of soilborne plant pathogens to pesticides in vitro. 8th Annual Graduate Research in Biological Sciences Symposium. Stillwater, OK, September 22-23, 2011 Flores, F., Garzon, C. D. 2011. Evaluation of hormesis on the response of soilborne plant pathogens to pesticides in vitro. 8th Annual Graduate Research in Biological Sciences Symposium. Stillwater, OK, September 22-23, 2011 Garrido P., Melouk H, and Garzon, C.D. 2011. Population structure and genetic diversity of Sclerotinia minor from peanut research plots in Oklahoma. American Phytopathological Society 2011 National Meeting, Honolulu, Hawaii. Phytopathology. 101: S59 Hollister, E.B., P. Hu, A.S. Wang, F.M. Hons, and T.J. Gentry. 2011. Soil bacterial and fungal community responses to oilseed meal addition. In Abstracts, 111th General Meet., ASM, New Orleans, LA. 21-24 May 2011. ASM, Washington, D.C. Hu, P., E. Hollister, A. Wang, F. Hons, and T. Gentry. 2010. Soil microbial community changes after oilseed meal application. In Abstracts, ASA-CSSA-SSSA Annual Meet., Long Beach, CA. 31 October - 3 November 2010. Orquera, G., Mogrovejo, C., Villamarin, D., Jarrin, F., Garzon, C.D., Molineros, J., Forbes, G., Koch, A., Benitez, M.S. 2011. Characterization of microbial populations from P. infestans suppressive Andean soils in Ecuador. American Phytopathological Society 2011 National Meeting, Honolulu, Hawaii. Phytopathology. 101: S133 Spurlock, T., Rothrock, C., and Monfort, W. 2011. A new selective medium for isolation of Rhizoctonia spp. from soil. (Abstr.) Phytopathology 101:S170. Villamarin D, Orquera G., Mogrovejo, C., Garzon, C.D., Molineros, J., Forbes, G., Koch, A., Benitez, M.S. 2011. Supressiveness to Phytophthora infestans infection in potato tubers by Andean soils from three provinces of Ecuador. American Phytopathological Society 2011 National Meeting, Honolulu, Hawaii. Phytopathology. 101: S183 Other Publications Canaday, C.H., 2011, Effects of seed treatment fungicides, biological agents, and potash fertilizers on snap bean seedling diseases, 2010. Plant Disease Management Reports 5:ST002. Dau, L. 2010. The promise of biochar. M.S. creative component, Iowa State University, Ames, IA. Flores, FJ. 2010. Effect of Low Doses of Pesticides on Soilborne Pathogens  An Approach to the Hormetic Response. M.S. Thesis. Oklahoma State University Hansen, Z. R. 2011. Potential of three brassica cover crops for biofumigation in the field and the relationship between soil myrosinase and biofumigation efficacy. M.S. Thesis, Clemson University. 136 pp. Hansen, Z. R., Keinath, A. P., Baccari, G. V., and DuBose, V. B. 2011. Evaluation of Brassica cover crops for control of root rot in peppers, 2010. Plant Disease Management Reports 5:V073. Online publication. doi: 10.1094/PDMR05. Keinath, A. P., Baccari, G. V., and DuBose, V. B. 2011. Evaluation of biofungicides to prevent damping-off of organic arugula, 2010. Plant Disease Management Reports 5:ST010. Online publication. doi: 10.1094/PDMR05. Grants awarded Backman PA, Stehouwer R, and Gugino B. Conservation Agriculture as a potential pathway to better resource management, higher productivity, and improved socio-economic conditions in the Andean Region. USAID SANREM CRSP, $340,000; 5 years. Backman PA and Gugino B. Integrated Pest Management: Science for Agricultural Growth in Latin America and the Caribbean. USAID IPM CRSP $190,000; 5 years. Baird, R. Participatory modeling and decision support for improving sweet potato production efficiency, quality, and food safety. USDA-CSREES-SCRI. $ 32,500; 1 year. Baird, R. Baseline data on sweetpotato root microorganisms and the determination of the causal agents associated with a newly emerging rot diseases complex. SRI $37,000; 1 year. Koch AR, Benitez MS, Garzon CD, Molineros JE. Population dynamics of Phytophthora infestans in potato producing soils in the Carchi and Chimborazo provinces, and inoculum infection potential. Politechnic School of the Army, Ecuador. $38,000; 1 year. Keinath, A. Development of Grafting Technology to Improve Sustainability and Competitiveness of the US Fruiting Vegetable Industry. USDA, NIFA, SCRI, $286,403; 3 years. Lu, S. Genetic and Chemical Characterization of Novel Antibiotics Produced by Plant Disease-Suppressive Bacteria. MAFES-SRI. $79,300; 1 year.