Brief Summary of Minutes of Annual Meeting

The last meeting of the entire committee was held in Wooster, OH on month/date of 20034. A. Westphal was nominated as committee secretary and agreed to act as chair in 2004. Committee members reintroduced themselves and briefly described their research expertise and committee related activities. Written state reports were passed to the group by several attendees. New project proposal for NC-125: The committee focused most of its time on the development of the renewal project. S. Pueppke discussed the history of the committee, funding allocations, and the nature of collaborations under the MSRP structure. B. McSpadden Gardener presented an overview of the renewal process including a timeline for submission, the review process, and related information described by materials available on the NIMSS web site. Discussion ensued as to the draft version of the renewal project prepared by the writing committee. Suggestions for additions and revisions followed. Particular emphasis was put on developing collaborations and planning extension-related activities. D. Eastburn led the writing activities that led to a nearly complete revision by the end of the meeting. The writing committee applied refinements following the meeting and review by the entire committee. The final renewal proposal was submitted. Renewal was not granted. A subgroup of the committee met at the APS meetings at Charlotte, NC in 2004.

Objective I. Compare efficacy of biocontrol systems on economic plants in the North Central Region. Objective IA. Compare methods of production, delivery and enhancement of applied and indigenous biocontrol agents. Three commercially produced biological seed treatments were evaluated for their effects on the development of sudden death syndrome of soybeans (SDS), caused by Fusarium solani f. sp. glycines, in an inoculated field setting. Seed of a soybean variety with known susceptibility to SDS was treated with formulations of Yield Shield WP (Bacillus pumilus GB34, 0.1 oz per 100 lbs seed), Bio Yield F (Bacillus amyloliquefaciens GB 99, and Bacillus subtilis GB 122, 0.5 fl. oz. per 100 lbs seed), Kodiak F (Bacillus subtilis GBO3, 0.5 fl. oz. per 100 lbs seed) prior to planting. Treated seed, as well as non-treated control seed, were planted in 25 ft. rows with 30 inch row spacing into plots that were inoculated or non-inoculated with Fusarium solani f. sp. glycines. Inoculum was applied as colonized sorghum seed at a rate of 300 lbs/acre, using a seed drill to a depth of six inches seven weeks prior to planting. Plots were monitored for foliar symptoms of SDS throughout the season, and yield data were recorded for each plot. Only very mild foliar symptoms were observed on a few plants in late August. Most of the plants showed no foliar symptoms during the season. Analysis of yield data showed no significant differences between any of the seed or inoculation treatments. Hot weather conditions at the beginning of August may have disrupted the disease development process. Very little SDS was observed in Illinois this season. We determined if tomato transplants treated with BioYield" or DAPG-producing bacteria native to Ohio soils have the ability to promote plant growth or induce host resistance. The bacteria tested were present in a commercialized biological product or rhizobacteria isolated previously from tomato or soybean rhizosphere. Bacteria treatment of tomato seeds did not alter germination. However, all three of the bacteria treatments significantly decreased the root-to-shoot ratio of treated plants compared to water treated plants. The bacteria treatments resulted in plants with greater shoot tissue than those treated with water. Therefore, we concluded that all three of these bacteria treatments were capable of promoting plant growth. This is a novel finding that DAPG-producing P. fluorescens strains from tomato and soybean rhizosphere are capable of promoting plant growth in the absence of root disease pressure. The enzyme activity in green tissue from these treated seedlings was not significantly different from plants treated with water. This is an indication that these bacteria treatments do not induce defense related enzyme activity. It may be interesting to further investigate the ability of DAPG-producing P. fluorescens strains to promote plant growth of transplant tomatoes and other vegetables. In greenhouse studies, Trichoderma sp and mycorrhizal inoculation protected plants from infection by Fusarium oxysporum. Field results in 1999-2000 suggested that both formononetin and arbuscular mycorrhizal inoculation can increase plant height of asparagus and reduce Fusarium root lesions. A cooperative effort with S. Gage, Director of the Computational Ecology and Visualization Laboratory at MSU was initiated in 2001 to determine the effects of environment and biocontrol organisms at larger than field scales. A modeling applications systems integrative framework (MASIF) was developed to expand crop models (corn and soybean) from field to multicounty and regional use. This framework allows information derived from crop models to be shown in visual form and links an array of existing visualization, data management, and analytical software to manage the large volumes of model inputs and outputs as well as model execution. The MASIF framework also allows the incorporation of environmental databases, independent of the use of crop models, for biocontrol options at expanded scales. We have studied the effect of crop sequence and tillage, over time, on Mn transition states in soil as this might affect biological control activity and predispose plants to disease. There were interactions between tillage (Fall Chisel and No Till) and Crop rotation/sequence (continuous corn, continuous soybean, corn-soybean-wheat rotation in various combinations). Manganese availability was highest in the continuous corn rotation and lowest in the continuous soybean rotation, which might explain the limited practice of continuous soybean compared to continuous corn. Manganese was not as available with crop rotations of corn and soybean with wheat as with continuous corn, but better than continuous soybeans (Table 1). The order of highest Mn availability was continuous corn > corn in a corn-soybean-wheat sequence > soybeans in a corn-soybean-wheat rotation > wheat in a corn-soybean-wheat sequence > continuous soybean Manganese was generally more available in a Fall chisel than no-till system. Since some soilborne plant pathogens oxidize Mn+2 to the non-available oxidized Mn+4 form, effects of the crop on Mn valence states in the soil could predispose to disease and enhance pathogen virulence. Many proposed biocontrol agents are Mn reducers and could off-set the effects of reduced availability induced by the pathogen or crop rhizosphere effects. The basis for increased take-all of wheat commonly observed after glyphosate burn-down herbicide treatments or following glyphosate-resistant crops was evaluated on a low and sufficient Mn soil. The increase in take-all following glyphosate-resistant soybeans indicates that the effect is indirect through soil microbial interactions influenced by root exudates or residue decomposition. Presence of the glyphosate-resistant gene in corn and soybeans quite specifically reduced the uptake efficiency of Mn (tissue concentrations). Application of glyphosate further reduced Mn uptake and utilization efficiency. Manganese applied + or ? four days around the glyphosate ?event? was not translocated to new tissue. Initial data suggests that application 8-10 days after glyphosate may avoid the glyphosate-immobilization and reduced physiological efficiency. Tank-mixing the micronutrients (Cu, Mn, Zn) as well as P and Ca not only reduces their uptake by plants, but also reduces the herbicidal efficacy of the glyphosate. Roundup formulation influenced the effect on micronutrient efficacy with the weathermax formulation having less interaction than the Roundup Ultramax formulation. Amplification of phylogenetically significant sequences (i.e. ribosomal and actin genes) was attempted using a mix of previously described and newly designed oligonucleotide primers. The complexity of soil and rhizosphere DNA used as template precluded clean amplification of DNA fragments of the expected size for several of the tested primer sets. Nonetheless, positive results were obtained for previously published primers targeting the ribosomal sequences of Archaea, Fungi, Bacteria, and Pseudomonas spp., as well as the nitrogenase gene, nifH, from rhizobia. Success was also achieved with primers designed in our laboratory targeting the ribosomal genes of Bacillus, Burkholderia, Trichoderma, and the actin genes of Pythium and Phytophthora spp. The phylogenetic origin of amplified sequences was determined by cloning and sequencing multiple products from each reaction set. These results provided us with a significant improvement in our ability to characterize the abundance and diversity of the many different microbial taxa inhabiting agricultural soils. We used these primer sets to characterize microbial diversity across different environments. DNA was isolated from soils and rhizospheres sampled at multiple sites throughout the state of Ohio. Microbial community profiles were generated that allowed for comparisons between crops, sites, and treatments. Microbial community structure was found to differed dramatically with microhabitat (e.g. soil vs rhizosphere), but also with crop (corn vs. soybeans). In contrast, fewer differences were observed between sites despite significant variation in soil types and prevailing weather conditions. These results indicate the relative importance of plant species in determining the active fraction of soil microbial communities. Such species-dependent variation indicates: (i) A comprehensive evaluation of microbiotic contributions to plant health across large geographic areas can be achieved. (ii) The relative contributions of different microbial populations to plant health can be calculated using a combination of community profile and disease assessment data. (iii) Crop selection is a major controlling factor for microbial processes at the field scale. We have completed two projects that have quantified the influences of biocontrol agents in rhizosphere bacterial population structure in two different collaborative efforts. In the first, we examined the effects of a wild-type DAPG producer and a near isogenic strain that was genetically modified to produce phenazine-1-carboxylic acid (PCA). In the second, we examined the influences of Trichoderma harzianum T382 as compared to the composition of various potting mixes. In both instances, colonization of the rhizosphere by the biocontrol agents was verified. Using T-RFLP analyses, we determined that shifts in bacterial populations occurred following applications of the different biocontrol agents. However, the magnitude of such changes was generally small and the effects were inconsistent over time in independent replicates. These data indicate that application of these biocontrol agents is, like other farming practices, a disturbance, but one with no consistent impact on the phylogenetic composition of root colonizing bacterial populations. We further determined the abundance of DAPG-producing pseudomonads, native biocontrol populations with the capacity to inhibit the growth of diverse root pathogens. This past year, we evaluated the effects of rotation and compost addition in additional controlled experiments. DAPG producers were found to be most abundant in compost amended plots as compared to non-amended plots, indicating that applied organic matter can stimulate their populations and biocontrol activities. We also observed that the soil conditions altered by rotations significantly affected rhizosphere colonization. These data also indicate that there is a high degree of metabolic redundancy among hylogenetically distinct bacterial populations. These results further indicate that the abundance of native DAPG-producing pseudomonad populations can be managed to some degree. We have characterized the susceptibility of perennial grain accessions to the important diseases tan spot, take-all, barley yellow dwarf, and wheat streak mosaic. We have characterized the differences in timing requirements for eradication of volunteer wheat harboring wheat streak mosaic virus vectors as a function of the method of eradication. We have demonstrated that the tan spot pathogen is more competitive than the leaf rust pathogen, to the extent that the presence of the leaf rust pathogen can facilitate greater tan spot infection under some circumstances. We have described the likely challenges due to disease in perennial grain systems. We have demonstrated that cultivar mixtures can reduce disease for both tan spot and leaf rust, though the effect is greater for leaf rust as predicted by the life history characteristics of the leaf rust pathogen. We have proposed a novel method for managing take-all through simple changes in planting patterns that we predict can have a substantial impact to reduce yield losses. In the study of plant disease ecology of tallgrass prairie systems, we have determined that seven dominant tallgrass prairie species are slightly susceptible to tan spot pathogens from wheat and three of seven are highly susceptible to take-all pathogens from wheat. We have demonstrated that a common rust pathogen of the tallgrass prairie dominant big bluestem is more abundant in midslope positions. We have shown that three dominant tallgrass prairie species are commonly infected with barley yellow dwarf virus, though the dominant strains are not the same as in Kansas wheat. The non-target effects of Dutch Trig, a fungal biocontrol agent used to protect elm trees against Dutch elm disease were evaluated in a greenhouse based experiment. Dutch Trig is a Verticillium sp. originally isolated from potato. We have been evaluating the pathogenicity of the Dutch Trig fungus on a number of vegetable crops to determine if this biocontrol agent is pathogenic on commonly grown vegetable species known to be susceptible to Verticillium wilt. Greenhouse inoculations with the Dutch Trig organism resulted in typical Verticillium wilt symptoms on tomatoes and eggplant. However the symptoms on Dutch Trig inoculated plants were not as severe as those on plants inoculated with a virulent isolate of Verticillium dahliae isolated from pepper. Peppers inoculated with the Dutch Trig organism were stunted compared to the non-inoculated control plants. Some mild leaf vein necrosis was observed on inoculated broccoli, but no symptoms were observed on horseradish plants inoculated with the Dutch Trig organism. The biocontrol agent Sporodesmium sclerotivorum is a mycoparasite of sclerotia. Infestation of S. sclerotivorum into research plots on several Iowa farms reduced the incidence of Sclerotinia stem rot by an average of 73% in 2000. Biocontrol efficacy was not strongly influenced by the inoculum dosage, i.e., by the density at which the fields were infested with S. sclerotivorum macroconidia. Furthermore, the antagonist was shown to control disease under no-till conditions as well as following incorporation into soil. The effectiveness of S. sclerotivorum at controlling Sclerotinia wilt in sunflower in North Dakota was examined, and although little disease occurred, the fields were found to have been heavily infested with natural S. sclerotivorum strains prior to introduction of the biocontrol strain. The optimal method for mass production of S. sclerotivorum inoculum was found to be the preparation of alginate pellets, with S. sclerotivorum mycelia either inside or outside the pellets. Objective I B. Determine the influences of host and environment on biocontrol efficacy A four-year, multidisciplinary research effort to study the biological effects of transitioning from conventional cash grain production to an organic production system at the University of Illinois research farm continued in the 2004 growing season. Plots of three organic production systems (pasture, cash grains, and vegetable crops) were established on a six acre field site that has been designated for research on organic agriculture. Three amendment treatments (no amendment, manure amendment, and composted plant material amendment) were established as sub-plots within each of the production system plots, applied in the Spring of 2004. In 2004 the cash grain plots were planted to wheat, and the vegetable crop plots were planted to cabbage and broccoli. Soil samples were taken during the growing season, and they will be evaluated for differences in disease suppressiveness to three pathogens, Rhizoctonia solani, Fusarium solani f. sp. glycines, and Phytophthora sojae in greenhouse assays this winter. Soil samples were taken from all plots this summer to establish baseline disease suppression levels. We examined the effects of tillage on soil suppressiveness against Heterodera glycines and conducted a survey for soil suppressiveness against this pathogen in soybean production systems. Further studies on the dynamics of native pathogen antagonists were performed in prairie and agricultural soils. Specifically, comprehensive analyses of the genetic and phenotypic diversity of streptomycetes were continued, focusing on 16S sequences, rep-PCR fingerprints, nutrient utilization, and antibiotic inhibition and resistance profiles. Hypotheses of local adaptation and fitness tradeoffs were tested for native prairie streptomycete communities. Studies of the impacts of green manures on disease intensity on newly established alfalfa stands were established in field plots at Becker, MN and in St. Paul, MN. A major factor that limits biocontrol of foliar diseases is often the poor ability of the antagonists to establish and maintain populations following inoculation onto leaves. Studies addressing the factors influencing bacterial leaf colonization used the species Pantoea agglomerans (previously Erwinia herbicola), which is a species that includes several strains with antagonistic activity against phytopathogens. Bacterial adherence to leaf surfaces was shown to be advantageous to leaf colonization, and P. agglomerans was strongly superior to at least two phytopathogens in the proportion of the population that adhered to leaves. P. agglomerans was found to localize exclusively to leaf surface sites, rather than to endophytic sites like the phytopathogen examined, and thus as a biocontrol agent, P. agglomerans must have mechanisms for tolerating the fluctuating environmental conditions characteristic of leaf surfaces. Although studies with whole-cell water deprivation-responsive biosensors indicated that P. agglomerans cells were not strongly deprived of water on leaves under controlled conditions, P. agglomerans was more tolerant to water deprivation than two phytopathogenic bacterial species. These results suggested that under field conditions, where the fluctuations in water availability on leaves are particularly pronounced, water deprivation tolerance of P. agglomerans may be one factor required for successful population development on leaves. Objective II. Determine mechanisms of action of North Central region biocontrol systems. Objective IIA. Determine the nature of biocontrol agent-crop-pathogen association. Further work was conducted using the phylogenetic markers developed in our laboratory. The complexity of soil and rhizosphere DNA used as template resulted in a mixture of amplification products of diverse phylogenetic origin. This was particularly apparent with the genus-specific probes when relatively few cycles were used in the amplifications. These results, while representing a significant improvement in our ability to characterize the abundance and diversity of the many different microbial taxa inhabiting agricultural soils, indicate that subdominant microbial populations are often obscured in such culture-independent assays. Overall, our results indicate that: (i) A comprehensive evaluation of microbiotic contributions to plant health across large geographic areas will be limited to the numerically dominant populations. (ii) The relative contributions of different microbial populations to plant health can be calculated using a combination of community profile and disease assessment data. (iii) Crop selection is the single most important major controlling factor for microbial processes in the rhizosphere. Evaluation of the biocontrols for the induction of host resistance in vegetables: We set out to determine if Actigard" can induce host resistance in fruit by foliar application. Four and ten days after treatment, fruit tissue from plants treated with Actigard tended to have lower enzyme activity than those of control plants. To contrast, leaf tissue from plants treated with Actigard tended to have higher enzyme activity than the control plants. This is an indication that Actigard treatment induces defense-related enzymes in green tissue but not in fruit tissue. The plants in this investigation were heat stressed for at least 24 hours. This stress resulted in the inability of the experiment to be fully replicated, so, the results are not entirely conclusive. However, the activation of defense related enzymes in green tissue indicates the ability of Actigard treatment to induce host defenses in tomato leaves. It would be interesting to investigate the ability of Actigard treatment to reduce disease severity caused by foliar fungal pathogens common in Ohio. It has already been illustrated that this product is capable of reducing disease severity caused by bacterial diseases of tomato. Mycoviruses, viruses that infect fungi, have been studied in several plant pathogen systems, and in some cases they have been found to affect the pathogens ability to cause disease. We are currently studying the presence of mycoviruses in Fusarium solani f. sp. glycines, causal agent of sudden death syndrome of soybeans, and evaluating their effects on the pathogens ability to cause disease. In other disease systems mycoviruses have been used to develop biological control systems based on the use of hypovirulent isolates. The presence and effects of mycoviruses also may provide insight into a source of variation in characteristics within a pathogen population, giving us more information on basic pathogen biology. Additional virulence assays and reanalysis of data from previous experiments have demonstrated that FSG isolates containing dsRNA mycoviruses are generally less virulent than are isolates which are free of mycovirus infection, although the presence of mycoviruses is not the only factor affecting virulence. Assays comparing virulence levels of mycovirus cured strains with those of their infected parental strains indicate an increased level of virulence in isolates that have been cured of the 10 to 11 kb dsRNA fragments. Based on initial evidence, the 10 to 11 kb dsRNA fragments are believed to be mycoviruses in the Hypoviride group of viruses. Efforts to sequence the dsRNA fragments and further characterize the viruses continue. We have reviewed a number of statistical advances that can be applied to improve plant pathology research. We have introduced meta-analysis to plant pathologists with an example of application in comparative studies of yield loss to disease. IIB. Elucidate biochemical and genetic basis for the interactions. This research has established that manganese oxidation is a virulence factor for the wheat take-all pathogen, Gaeumannomyces graminis, and other plant pathogens. Since manganese is physiologically available to the plant for defense reactions (shikimate pathway) only in the reduced form, oxidation of manganese by the pathogen in the infection court reduces the plants ability to respond to infection. Manganese oxidation occurs through a pathogen produced extracellular enzyme(s) similar to manganese peroxidase. Some pathogen-produced laccases also can oxidize manganese to the non-available form. Culture assays and spectrophotometric analysis of crude culture extracts derived from Gaeumannomyces support the involvement of a multi-copper oxidase such as laccase, and possibly other extracellular oxidative enzymes, in manganese oxidation. Twelve putative laccase genes were found in Magnaporthe grisea, a fungus closely related to Gaeumannomyces graminis and we found strong expression of lcc 15 under manganese oxidizing conditions. Two genes with homology to manganese peroxidase also were identified in Magnaporthe grisea, and targeted deletion of these two genes resulted in greatly reduced virulence. It appears that there are at least two separate enzymes involved in manganese oxidation by these fungi that could influence their virulence and rhizosphere interactions via biological control. Efforts to further characterize metabolites produced by L. enzymogenes C3 that might be involved in biological yielded factors that have positive and negative effects on biocontrol efficacy. Strain C3 produces three ²1,3-glucanases and two chitinases, the production of which is regulated by a clp gene homologue belonging to the crp gene family. Using mutants deficient in either ²1,3-glucanase or chitinase activity or deficient in both groups of enzymes, ²1,3-glucanase was found to be involved in biocontrol of damping off of sugarbeet, caused by Pythium ultimum and leaf spot of tall fescue, caused by Bipolaris sorokiniana, while chitinase activity was shown to contribute to control of Bipolaris leaf spot. These enzymes, however, did not account entirely for biocontrol activity by C3. A small molecular weight, heat-stable antifungal factor, presumably involving a family of lipopeptide antibiotics, was found to cause abnormal hyphal growth in which hyphal polarity was disrupted. The factor was effective in vitro against all plant pathogenic fungi tested, as well as oomycetes. Using a mutant strain of C3 with reduced antibiotic excretion, evidence was found that the antifungal factor might have a role in biocontrol. Strain C3 induced systemic resistance in tall fescue against B. sorokiniana when the bacterium was applied to roots, while localized resistance was induced when C3 was applied to leaves. The same spatial phenomenon was found other strains of bacterial species were tested on tall fescue. Induced resistance by C3 can be elicited in wheat as well, being active against B. sorokiniana and Fusarium graminearum, but no evidence has been for induction of resistance in dicots by C3. Strain C3 produces a phytotoxic factor when grown in vitro or when applied to seed. The factor inhibits seed germination and reduces root growth in all graminaceous plants tested; some dicots (soybeans, tobacco) are sensitive to the factor, but sugarbeet is not. While the factor does not affect plants when it is applied to foliage, its effect on root growth is a concern when C3 is applied as a seed or root treatment.

Al-Naimi, F.A., K. A. Garrett, and W. W. Bockus. Competition, facilitation, and niche differentiation in foliar pathogens. Oecologia, In Press. Arriola, L., M.K. Hausbeck, J. Rogers, and G.R. Safir. 2000. The Effect of Trichoderma-harzianum and Arbuscular Mycorrhizae on Fusarium Root Rot in Asparagus. 2000. Hort. Tech. 10:141-144 Beattie, G. A. and L. M. Marcell. 2002. Comparative dynamics of adherent and non-adherent bacterial populations on maize leaves. Phytopathology 92:1015-1023. Blouin-Bankhead, S., Landa, B.B., Lutton, E., Weller, D.M., McSpadden Gardener, B. 2003. Minimal changes in rhizobacterial population structure following root colonization by wild type and transgenic biocontrol strains. FEMS Microbiol Ecol. submitted 12/18/03. Cox, C. M., K. A. Garrett, W. W. Bockus, and L. Fang. Reactions of tallgrass prairie grasses to tan spot and take-all pathogens from wheat and the potential for apparent competition. In Review Cox, C.M., K. A. Garrett, T. S. Cox, W. W. 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LTER Ecological Research , All Scientist Meeting. September 18-21, 2003, Seattle, WA. Poster presented. Gage, S.H., M. Colunga-Garcia, G.R. Safir. 2003. Application of climate and crop data into a framework for regional crop modeling. American Society of Agronomy-Crop Science Society of American-Soil Science Society of America meeting. November 2-6, 2003, Denver, CO. Garrett, K.A., S. P. Dendy, A. G. Power, G. K. Blaisdell, H. A. Alexander, and J. K. McCarron. 2004. Barley yellow dwarf disease in natural populations of dominant tallgrass prairie species in Kansas [Disease Note]. Plant Disease 88:574. Garrett, K.A., M. Kabbage, and W. W. Bockus. 2004. Managing for fine-scale differences in inoculum load: Seeding patterns to minimize loss to wheat take-all. Precision Agriculture 5:291-301. Garrett, K.A., L. V. Madden, G. Hughes, and W. Pfender. 2004. New applications of statistical tools in plant pathology. Phytopathology 94:999-1003. Garrett, K.A., M. Kabbage, and W. W. Bockus. 2003. Managing for fine-scale differences in inoculum load: seeding patterns to minimize loss to Gaeumannomyces graminis var. tritici. Precision Agriculture in press Grace, P.R., M. Colunga-Garcia, S. H. Gage, G.R. Safir, and G. P. Robertson. 2004. The potential impact of climate change on soil organic and agricultural management on carbon resources in the North Central Region of the United States. Ecosystems. (In Press) Gutierrez, L.J. and B.B. McSpadden Gardener. 2004. Identification and fungicide sensitivity of fungal pathogens causing tomato fruit rot in Ohio. Phytopathology 94:S37. Gutierrez, Laura J. 2004. Fungicide sensitivity and biological control potential of tomato fruit rot pathogens in Ohio. Master's Thesis. The Ohio State University, Department of Plant Pathology. Huber, D.M. 2003. Nutrient-Disease interactions in the take-all disease of cereals. Proc. Symposium on Take-all, April 2003, Temuco, Chili. Huber, D.M. 2003. The role of plant nutrition in disease. Proc. Symposium March 2003, Relacao entre Nutricao de Plantas e Incidencia de Doencas, Piracicaba, SP, Brazil. Jiang, W., K. A. Garrett, T. Harvey, and R. L. Bowden. The Window of risk for emigration of wheat streak mosaic virus varies with host eradication method. In Review. Kaitany, R., H. Melakberhan, G.Bird, and G. Safir. 2000. Association of Phytophthora sojae with Heterodera glycines nutrient stressed soybeans. Nematropica. 30:193-199. Kaitany, R.C., L.P. Hart, and G.R. Safir. 2001. Virulence composition of Phytophthora soja in Michigan. 2001. Plant Disease 85:1103-1106. Kilic-Ekici, O. and Yuen, G.Y. 2003. Induced resistance as a mechanism of biological control by Lysobacter enzymogenes strain C3. Phytopathology 93:1103-1110. Kilic-Ekici, O. and Yuen, G.Y. 2004. Comparison of strains of Lysobacter enzymogenes and PGPR for induction of resistance against Bipolaris sorokiniana in tall fescue. Biological Control 30:446-455. Kobayashi, D.Y., Reedy, R.M., Palumbo, J.D., and Yuen, G.Y. 2005. A clp gene homologue belonging to the Crp gene family globally regulates lytic enzyme production, antimicrobial activity, and biological control activity by Lysobacter enzymogenes strain C3. Appl. Environ. Microbiol. 71:261-269. Mathew, F.M. and L.E. del Rio. 2003. Development of a less complex medium for production of Sporidesmium sclerotivorum. On-line publication no. P-2004-0030-NCA. www.apsnet.org/meetings/div/nc03abs.asp Morgan, G. W., K. A. Garrett, T. C. Todd, and N. A. Tisserat. Effects of fungicides, burning and topographic position on dominant tallgrass prairie grasses and their pathogens. In Review American Midland Naturalist. McSpadden Gardener, B. 2003. Ecology of Bacillus species in agricultural soils. Phytopathology 93:S117. Abstract. McSpadden Gardener, B. 2003. Microbial biodiversity in agricultural systems: General and specific barriers to inoculation. Phytopathology 93:S100. Abstract. 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