Plant Pathology Commons^™

An Antibiotic Complex From Lysobacter Enzymogenes Strain C3: Antimicrobial Activity And Role In Plant Disease Control, S. Li, C. C. Jochum, F. Yu, K. Zaleta-Rivera, L. Du, Steven D. Harris, Gary Y. Yuen

Department of Plant Pathology: Faculty Publications

Lysobacter enzymogenes C3 is a bacterial biological control agent that exhibits antagonism against multiple fungal pathogens. Its antifungal activity was attributed in part to lytic enzymes. In this study, a heat-stable antifungal factor (HSAF), an antibiotic complex consisting of dihydromaltophilin and structurally related macrocyclic lactams, was found to be responsible for antagonism by C3 against fungi and oomycetes in culture. HSAF in purified form exhibited inhibitory activity against a wide range of fungal and oomycetes species in vitro, inhibiting spore germination, and disrupting hyphal polarity in sensitive fungi. When applied to tall fescue leaves as a partially-purified extract, HSAF at …

Uses Of The Pseudomonas Syringae Effector Protein Hopu1 Related To Itsability To Adp-Rbosylate Eukaryotc Rna Binding Protens, James R. Alfano, Zheng Qing Fu, Thomas E. Elthon

Department of Plant Pathology: Faculty Publications

The bacterial plant pathogen Pseudomonas Syringae injects effector proteins into host cells via a type III protein secre tion system to cause disease. The invention relates to the discovery that the type III effector HopU1 is a mono-ADP ribosyltransferase (ADP-RT) and suppresses plant innate immunity. The HopU1 substrates in Arabidopsis thaliana extracts were RNA-binding proteins that possess RNA recognition motifs (RRMs). A. thaliana knock-out lines defective in the glycine-rich RNA-binding protein AtGRP7, a HopU1 substrate, were more susceptible than wild type plants to P syringae. The ADP-ribosylation of AtGRP7 by HopU1 required two arginines within the RRM. The inven tion …

Comparison Of Plant Growth-Promotion With Pseudomonas Aeruginosa And Bacillus Subtilis In Three Vegetables, A. O. Adesemoye, M. Obini, E. O. Ugoji

Department of Plant Pathology: Faculty Publications

Our objective was to compare some plant growth-promoting rhizobacteria (PGPR) properties of Bacillus subtilis and Pseudomonas aeruginosa as representatives of their two genera. Solanum lycopersicum L. (tomato), Abelmoschus esculentus (okra), and Amaranthus sp. (African spinach) were inoculated with the bacterial cultures. At 60 days after planting, dry biomass for plants treated with B. subtilis and P. aeruginosa increased 31% for tomato, 36% and 29% for okra, and 83% and 40% for African spinach respectively over the non-bacterized control. Considering all the parameters tested, there were similarities but no significant difference at P < 0.05 between the overall performances of the two organisms.

In Planta Distribution Of ‘Candidatus Liberibacter Asiaticus’ As Revealed By Polymerase Chain Reaction (Pcr) And Real-Time Pcr, Satyanarayana Tatineni, Uma Shankar Sagaram, Siddarame Gowda, Cecile J. Robertson, William O. Dawson, Toru Iwanami, Nian Wang

Department of Plant Pathology: Faculty Publications

Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide, and is caused by a phloem-limited fastidious prokaryotic α- proteobacterium that is yet to be cultured. In this study, a combination of traditional polymerase chain reaction (PCR) and real-time PCR targeting the putative DNA polymerase and 16S rDNA sequence of ‘Candidatus Liberibacter asiaticus,’ respectively, were used to examine the distribution and movement of the HLB pathogen in the infected citrus tree. We found that ‘Ca. Liberibacter asiaticus’ was distributed in bark tissue, leaf midrib, roots, and different floral and fruit parts, but not in endosperm and …

Three Genes Of Citrus Tristeza Virus Are Dispensable For Infection And Movement Throughout Some Varieties Of Citrus Trees, Satyanarayana Tatineni, Cecile J. Robertson, Stephen M. Garnsey, Moshe Bar-Joseph, Siddarame Gowda, William O. Dawson

Department of Plant Pathology: Faculty Publications

Citrus tristeza virus (CTV), a member of the Closteroviridae, possesses a 19.3-kb positive-stranded RNA genome that is organized into twelve open reading frames (ORFs). The CTV genome contains two sets of conserved genes, which are characteristic of this virus group, the replication gene block (ORF 1a and 1b) and the quintuple gene block (p6, HSP70 h, p61, CPm, and CP). With the exception of the p6 gene, they are required for replication and virion assembly. CTV contains five additional genes, p33, p18, p13, p20 and p23, in the 3′ half of the genome, some of which (p33, p18 and …

Regulation Of Apical Dominance In Aspergillus Nidulans Hyphae By Reactive Oxygen Species, Camile P. Semighini, Steven D. Harris

Department of Plant Pathology: Faculty Publications

In fungal hyphae, apical dominance refers to the suppression of secondary polarity axes in the general vicinity of a growing hyphal tip. The mechanisms underlying apical dominance remain largely undefined, although calcium signaling may play a role. Here, we describe the localized accumulation of reactive oxygen species (ROS) in the apical region of Aspergillus nidulans hyphae. Our analysis of atmA (ATM) and prpA (PARP) mutants reveals a correlation between localized production of ROS and enforcement of apical dominance. We also provide evidence that NADPH oxidase (Nox) or related flavoproteins are responsible for the generation of ROS at hyphal tips and …

An Immunofluorescence Assay To Detect Urediniospores Of Phakopsora Pachyrhizi, Fulya Baysal-Gurel, Melanie L. Lewis Ivey, Anne E. Dorrance, Douglas Luster, Reid Frederick, Jill Czarnecki, Michael J. Boehm, Sally A. Miller

Department of Plant Pathology: Faculty Publications

An indirect immunofluorescence spore assay (IFSA) was developed to detect urediniospores of Phakopsora pachyrhizi, utilizing rabbit polyclonal antisera produced in response to intact nongerminated (SBR1A) or germinated (SBR2) urediniospores of P. pachyrhizi. Both antisera were specific to Phakopsora spp. and did not react with other common soybean pathogens or healthy soybean leaf tissue in enzyme-linked immunosorbent assay (ELISA). SBR1A and SBR2 bound to P. pachyrhizi and P. meibomiae urediniospores were detected with goat anti-rabbit Alexa Fluor 488-tagged antiserum using a Leica DM IRB epifluorescent microscope with an I3 blue filter (excitation 450 to 490 nm, emission 515 nm). The …

Virulence Diversity Of The Common Bean Rust Pathogen Within And Among Individual Bean Fields And Development Of Sampling Strategies, C. Jochua, M. I. V. Amane, J. R. Steadman, X. Xue, K. M. Eskidge

Department of Plant Pathology: Faculty Publications

There is a dearth of information on pathogen variation within an individual field. In this study, virulence diversity of Uromyces appendiculatus, cause of bean rust, within individual fields was investigated. From six bean fields in the United States, Honduras, Dominican Republic, and South Africa, 380 U. appendiculatus isolates were differentiated into 65 virulence phenotypes on bean lines containing Andean- and Middle American-derived rust resistance genes. Race variation among bean rust isolates from different geographic regions was found, and virulence phenotypes found in fields from tropical and subtropical regions were more virulent and diverse than those found in fields from …

Branching Of Fungal Hyphae: Regulation, Mechanisms And Comparison With Other Branching Systems, Steven D. Harris

Department of Plant Pathology: Faculty Publications

The ability of rapidly growing hyphae to generate new polarity axes that result in the formation of a branch represents one of the most important yet least understood aspects of fungal cell biology. Branching is central to the development of mycelial colonies and also appears to play a key role in fungal interactions with other organisms. This review presents a description of the two major patterns of hyphal branching, apical and lateral, and highlights the roles of internal and external factors in the induction of branch formation. In addition, potential mechanisms underlying branch site selection are outlined, and the possible …

First Report Of Annual Bluegrass Weevil, Listronotus Maculicollis, Damage In Ohio, John L. Koenig, David J. Shetlar, Joseph W. Rimelspach, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Annual bluegrass weevil [Listronotus maculicollis (Kirby) (1)] larvae, pupae, and adults were recovered and identified in a sample received by the C. Wayne Ellett Plant and Pest Diagnostic Clinic (CWEPPDC) at Ohio State University on 19 June 2007. Damage to the approaches and collars of four golf course putting greens was detected by the superintendent of Stonewater Golf Club, Highland Heights, OH (a suburb of Cleveland) during the week of 11 June 2007. The superintendent suspected damage from the larvae of the black turfgrass ataenius, Ataenius spretulus (1). Insecticide applications applied to suppress black turfgrass ataenius did not provide …

Rapid Development Of Fungicide Resistance By Sclerotinia Homoeocarpa On Turfgrass, Young-Ki Jo, Seog Won Chang, Michael J. Boehm, Geunhwa Jung

Department of Plant Pathology: Faculty Publications

Dollar spot, caused by Sclerotinia homoeocarpa, is the most prevalent and economically important turfgrass disease in North America. Increasing levels of fungicide resistance, coupled with tightening environmental scrutiny of existing fungicides, has left fewer options for managing dollar spot. More knowledge about S. homoeocarpa populations is needed to improve dollar spot management strategies, especially with respect to minimizing the development of fungicide resistance. Population diversity of S. homoeocarpa was examined using inter-simple sequence repeat markers and vegetative compatibility assays. Two subgroups were found in S. homoeocarpa field populations on both fairway and putting green turfgrass at a research field …

Inoculation Strategies To Assess Biological Interactions Between Fusarium And Alternaria Species Infecting Sorghum, Deanna L. Funnell-Harris, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

New cultivars of sorghum are being developed for increased food use, as livestock feed, and for the bioenergy industry by manipulation of secondary metabolic pathways through breeding. Previous work has suggested that such modifications may have an impact on cultivar response to fungal pathogens. We investigated four inoculation strategies that may be used in studies involving pathogens of sorghum. Plants of elite sorghum genotypes ‘Wheatland’ and RTx430, commonly used in breeding programs, were inoculated with isolates of Alternaria alternata, Fusarium equiseti, Fusarium proliferatum, Fusarium solani, Fusarium thapsinum, and Fusarium verticillioides recovered from field-grown sorghum. Wound inoculation of the peduncles …

Wheat Streak Mosaic Virus Lacking Helper Component-Proteinase Is Competent To Produce Disease Synergism In Double Infections With Maize Chlorotic Mottle Virus, Drake C. Stenger, Brock A. Young, Feng Qu, Thomas Jack Morris, Roy French

Department of Plant Pathology: Faculty Publications

The tritimovirus Wheat streak mosaic virus (WSMV) and the machlomovirus Maize chlorotic mottle virus (MCMV) each cause systemic chlorosis in infected maize plants. Infection of maize with both viruses produces corn lethal necrosis disease (CLND). Here, we report that complete deletion of the WSMV helper component-proteinase (HC-Pro) coding region had no effect on induction of CLND symptoms following coinoculation of maize with WSMV and MCMV. We further demonstrated that elevation of virus titers in double infections, relative to single infections, also was independent of WSMV HC-Pro. Thus, unlike potyvirus HC-Pro, WSMV HC-Pro was dispensable for disease synergism. Because disease synergism …

Pseudomonas Avr And Hop Proteins, Their Encoding Nucleic Acids, And Use Thereof, James R. Alfano, Alan Collmer, Samuel W. Cartinhour, David J. Schneider

Department of Plant Pathology: Faculty Publications

One aspect of the present invention relates to isolated nucleic acid molecules encoding avirulence proteins or polypeptides of Pseudomonas syringae pv. syringae DC 3000, or nucleic acid moleculues which are complementary thereto. Expression vectors, host cells, and transgenic plants which include the DNA molecules of the present invention are also disclosed. Another aspect relates to the isolated proteins or polypeptides and compositions containing the same. The various nucleic acid molecules and proteins of the present invention can be used to impart disease resistance to a plant, make a plant hypersusceptible to colonization by nonpathogenic bacteria, modify a metabolic pathway in …

Association Of Ergot Alkaloids With Conidiation In Aspergillus Fumigatus, Christine M. Coyle, Shawn C. Kenaley, William R. Rittenour, Daniel G. Panaccione

Department of Plant Pathology: Faculty Publications

Ergot alkaloids are mycotoxins that affect the nervous and reproductive systems of exposed individuals through interactions with monoamine receptors. They have been studied more widely in ergot fungi and grass endophytes but also are found in Aspergillus fumigatus, an opportunistic human pathogen that reproduces and disseminates exclusively through conidia. The ergot alkaloids festuclavine and fumigaclavines A, B and C are present in or on conidia of A. fumigatus. Cultures of the fungus that are free of conidia are difficult to obtain, obscuring comparisons of conidia versus vegetative hyphae as sources of the ergot alkaloids. To create conidiation-deficient strains of A. …

Regulation Of Hyphal Morphogenesis By Cdc42 And Rac1 Homologues In Aspergillus Nidulans, Aleksandra Virag, Maurice P. Lee, Haoyu Si, Steven D. Harris

Department of Plant Pathology: Faculty Publications

The ability of filamentous fungi to form hyphae requires the establishment and maintenance of a stable polarity axis. Based on studies in yeasts and animals, the GTPases Cdc42 and Rac1 are presumed to play a central role in organizing the morphogenetic machinery to enable axis formation and stabilization. Here, we report that Cdc42 (ModA) and Rac1 (RacA) share an overlapping function required for polarity establishment in Aspergillus nidulans. Nevertheless, Cdc42 appears to have a more important role in hyphal morphogenesis in that it alone is required for the timely formation of lateral branches. In addition, we provide genetic evidence …

Response Of Soybean Cultivars To Bean Pod Mottle Virus Infection, Amy D. Ziems, Loren J. Giesler, George L. Graef, Margaret G. Redinbaugh, Jean L. Vacha, Sueann Berry, Laurence V. Madden, Anne E. Dorrance

Department of Plant Pathology: Faculty Publications

Bean pod mottle virus (BPMV) has become increasingly common in soybean throughout the north-central region of the United States. Yield loss assessments on southern soybean germplasm have reported reductions ranging from 3 to 52%. Currently, no soybean cultivars have been identified with resistance to BPMV. The objective of this study was to determine the impact of BPMV infection on soybean cultivars representing a broad range of northern soybean germplasm by comparing inoculated and noninoculated soybean plants in paired row studies. In all, 30 and 24 cultivars were evaluated in Nebraska (NE) in which soybean plants were inoculated at the V3 …

Basa Regulates Cell Wall Organization And Asexual/Sexual Sporulation Ratio In Aspergillus Nidulans, Shaojie Li, Dapeng Bao, Gary Yuen, Steven D. Harris, Ana M. Calvo

Department of Plant Pathology: Faculty Publications

Sphingolipid C4 hydroxylase catalyzes the conversion of dihydrosphingosine to phytosphingosine. In Saccharomyces cerevisiae, Sur2 is essential for sphingolipid C4 hydroxylation activity but not essential for normal growth. Here we demonstrate that the Aspergillus nidulans Sur2 homolog BasA is also required for phytosphingosine biosynthesis but is also essential for viability. We previously reported that a point missense mutation in basA resulted in aberrant cell wall thickening. Here our data suggest that accumulation of dihydrosphingosine is responsible for this phenotype. In addition, two different mutations in basA consistently accelerated the transition from asexual development to sexual development compared to the wild-type …

Free-Living Dorylaimid Nematodes From Nature Reserves In Costa Rica. The Genus Pachydorylaimus Siddiqi, 1983, A. Esquivel, P. Guerrero, R. Peña-Santiago, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

A taxonomic study of three species, two known and one new, belonging to the genus Pachydorylaimus Siddiqi, 1983 from natural areas in Costa Rica is presented. Pachydorylaimus holovachovi sp. n. is described and can be distinguished by its body 0.90-1.00 mm long, lip region 14-17 μm wide, odontostyle 13-15 μm long, odontophore morphology with differentiated hyaline spindle-shaped area surrounding its junction to pharyngeal lining but lacking distinct basal flanges, total stylet length 35- 44 μm, pars refringens vaginae absent, V = 43-47, female tail straight and tapering to an acute tip (57- 78 μm, c = 12.5-15.8, c’ = 2.0-3.0), …

Genetic Diversity In Populations Of Xanthomonas Campestris Pv. Campestris In Cruciferous Weeds In Central Coastal California, A. Ignatov, A. Sechler, E. L. Schuenzel, I. Agarkova, B. Oliver, A. K. Vidaver, N. W. Schaad

Department of Plant Pathology: Faculty Publications

Xanthomonas campestris pv. campestris (X. campestris) infects a large number of cruciferous plants, including weeds. California has one of the largest and most diverse populations of wild cruciferous plants in the world. Although considerable information is available on the genetic diversity of X. campestris in commercial crop plants, nothing is known about the diversity in strains infecting weeds. To assess the genetic diversity among strains of X. campestris in weeds in noncultivated and cultivated areas, strains of the pathogen were isolated from populations of cruciferous weeds growing in coastal valley crop-production sites and from remote nonproduction sites along the …

Expression Analysis Of Rice Defense-Related Genes In Turfgrass In Response To Magnaporthe Grisea, Young-Ki Jo, Guo-Liang Wang, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Magnaporthe grisea (anamorph = Pyricularia grisea) causes blast on rice (Oryza sativa) and gray leaf spot on turfgrass. Gray leaf spot is a serious disease on St. Augustinegrass (Stenotaphrum secundatum), perennial ryegrass (Lolium perenne), and tall fescue (Festuca arundinacea). Virulence assays performed in this study revealed that M. grisea collected from rice could also cause disease on St. Augustinegrass and tall fescue. One rice isolate, Che86061, caused similar disease reactions on susceptible cultivars of rice and St. Augustinegrass and an incompatible interaction on resistant cultivars of both species. To explore whether …

Whole-Genome Expression Profiling Defines The Hrpl Regulon Of Pseudomonas Syringae Pv. Tomato Dc3000, Allows De Novo Reconstruction Of The Hrp Cis Element, And Identifies Novel Coregulated Genes, Adriana O. Ferreira, Christopher R. Myers, Jeffrey S. Gordon, Gregory B. Martin, Monica Vencato, Alan Collmer, Misty D. Wehling, James R. Alfano, Gabriel Moreno-Hagelsieb, Warren F. Lamboy, Geneviene Declerck, David J. Schneider, Samuel W. Cartinhour

Department of Plant Pathology: Faculty Publications

Pseudomonas syringae pv. tomato DC3000 is a model pathogen of tomato and Arabidopsis that uses a hypersensitive response and pathogenicity (Hrp) type III secretion system (T3SS) to deliver virulence effector proteins into host cells. Expression of the Hrp system and many effector genes is activated by the HrpL alternative sigma factor. Here, an open reading frame-specific whole-genome microarray was constructed for DC3000 and used to comprehensively identify genes that are differentially expressed in wild-type and ΔhrpL strains. Among the genes whose differential regulation was statistically significant, 119 were upregulated and 76 were downregulated in the wild-type compared with the ΔhrpL …

Microbial Content Of Abattoir Wastewater And Its Contaminated Soil In Lagos, Nigeria, A. O. Adesemoye, B. O. Opere, S. C. O. Makinde

Department of Plant Pathology: Faculty Publications

Microbial content of wastewater in two abattoirs and the impact on microbial population of receiving soil was studied in Agege and Ojo Local Government Areas in Lagos State, Nigeria. Wastewater samples were collected from each of the abattoirs over three months period and examined for microbial content. Soil samples contaminated with the wastewaters were also collected and analyzed for microbial content as compared to soil without wastewater contamination in the neighborhood (control). Some physico-chemical parameters of the samples such as total dissolved solid, chemical oxygen demand, etc., were examined. The wastewater samples from both abattoirs were highly contaminated; Agege abattoir …

Inducible Yeast System For Viral Rna Recombination Reveals Requirement For An Rna Replication Signal On Both Parental Rnas, Hernan Garcia-Ruiz, Paul Ahlquist

Department of Plant Pathology: Faculty Publications

To facilitate RNA recombination studies, we tested whether Saccharomyces cerevisiae, which supports brome mosaic virus (BMV) replication, also supports BMV RNA recombination. Yeast strains expressing BMV RNA replication proteins 1a and 2a^pol were engineered to transiently coexpress two independently inducible, overlapping, nonreplicating derivatives of BMV genomic RNA3. B33' lacked the coat protein gene and negative-strand RNA promoter. B35' lacked the positive-strand RNA promoter and had the coat gene replaced by the selectable URA3 gene. After 12 to 72 h of induction, B33' and B35' transcription was repressed and Ura⁺ yeast cells were selected. All Ura⁺ cells …

Bacillus Species Nrrl B-30212 For Reducing Fusarium Head Blight In Cereals, David A. Schisler, Naseem L. Khan, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Four yeasts (NRRL Y-30213, NRRL Y-30214, NRRL Y-30215, and NRRL Y-30216) and 1 bacterium (NRRL B-30212) have been identified as being superior antagonists capable of suppressing Fusarium head blight (head scab) in cereals, particularly in wheat and barley. Fusarium head blight is primarily caused by the fungus Gibberella zeae (anamorph=Fusarium graminearum).

Crop Updates 2006 - Lupins And Pulses, Peter White, Mark Seymour, Amelia Mclarty, Wayne Parker, Ian Pritchard, Bob French, Rodger Beermier, Bevan Buirchell, Mark Sweetingham, Jon Clements, Geoff Thomas, Roger Jones, Sofia Sipsas, John Quealy, Leigh Smith, Gordon Francis, Huaan Yang, Jeffrey Boersma, Margaret Pallotta, Chengdao Li, Krishnapillai Sivasithamparam, M. Nelson, H. Phan, S. Ellwood, P, Moolhuijzen, M. Bellgard, J. Hane, A. Williams, J. Fos-Nyarko, B. Wolko, M. Książkiewicz, M. Cakir, M. Jones, M. Scobie, C. O'Lone, S. J. Barker, R. Oliver, W. Cowling, Laurie Maiolo, Martin Harries, Jo Walker, Murray Blyth, Stephen Cosh, Dirranie Kirby, Kedar Adhikari, Patrizia Guantini, Katie Bell, Ken Adcock, Ciara Beard, Anne Smith, Tim Maling, Art Diggle, Debbie Thackray, Kadambot Siddique, Ping Si, Huaan Yang, Vijay Jayasena, Florence Kartawinata, Ranil Coorey, Ken Dods, Kerry Regan, Tanveer Khan, Jenny Garlinge, Rod Hunter, Pam Burges, Eric Armstrong, Glen Riethmuller, Greg Shea, Moin Salam, Jean Galloway, Pip Payne, Bill Macleod, Brenda Coutts, Pooran Gaur, Heather Clarke, Stuart Morgan, Alan Harris, Ted Knights, Kristy Hobson, Chris Matthews, Colin Hanbury, Tim Pope, Mike Baker, Leanne Young, Syed Muhammad Nasar-Abbas, Julie Plummer, D. Harris, Phill Chambers, Michael Materne, Dennis Van Gool, Huyen Phan, Simon Ellwood, J. Hane, Angela Williams, R. Ford, S. Thomas, R. Oliver, Rory Coffey, Chris Poole, Theo Pfaff, Judith Lichtenzveig, Lars Kamphuis, Nola D'Souza, Emma Groves, Karam Singh

Crop Updates

This session covers sixty six papers from different authors:

2005 LUPIN AND PULSE INDUSTRY HIGHLIGHTS

1. Lupin Peter White, Department of Agriculture

2. Pulses Mark Seymour, Department of Agriculture

3. Monthly rainfall at experimental sites in 2005

4. Acknowledgements Amelia McLarty EDITOR

5. Contributors

6. Background Peter White, Department of Agriculture

2005 REGIONAL ROUNDUP

7. Northern agricultural region Wayne Parker, Department of Agriculture

8. Central agricultural region Ian Pritchard and Bob French, Department of Agriculture

9. Great southern and lakes Rodger Beermier, Department of Agriculture

10. South east region Mark Seymour, Department of …

Carbon-To-Nitrogen Ratio And Carbon Loading Of Production Media Influence Freeze-Drying Survival And Biocontrol Efficacy Of Cryptococcus Nodaensis Oh 182.9, Shouan Zhang, David A. Schisler, Michael J. Boehm, Patricia J. Slininger

Department of Plant Pathology: Faculty Publications

Fusarium head blight (FHB), caused by Gibberella zeae, is a devastating disease of wheat worldwide. Cryptococcus nodaensis OH 182.9 is an effective biocontrol agent for this disease. Development of a dried product of OH 182.9 would have potential advantages of ease of handling, favorable economics, and acceptance by end users. Isolate OH 182.9 was grown for 48 and 72 h in semi-defined complete liquid (SDCL) medium with carbon-to-nitrogen (C/N) ratios of 6.5:1, 9:1, 11:1, 15:1, and 30:1, and in SDCL C/N 30:1 media with varied carbon loadings of 7, 14, 21, and 28 g/liter. Total biomass production and cell …

First Report Of Sudden Death Syndrome Of Soybean Caused By Fusarium Solani F. Sp. Glycines In Nebraska, A. D. Ziems, L. J. Giesler, G. Y. Yuen

Department of Plant Pathology: Faculty Publications

During August of 2004, soybean (Glycine max (L.) Merr.) plants exhibiting symptoms typical of sudden death syndrome (SDS) caused by Fusarium solani (Mart.) Sacc. f. sp. glycines (= Fusarium virguliforme Akoi, O'Donnell, Homma, & Lattanzi) (1) were observed in Nemaha and Pierce counties in eastern Nebraska. Leaf symptoms ranged from small chlorotic spots to prominent interveinal necrosis on plants at R5-R6 growth stages. Taproots of symptomatic plants were plated on potato dextrose agar (PDA) amended with hymexazol, ampicillin, and rifampicin (HAR). Resulting fungal isolates grew slowly and developed masses of blue macroconidia, characteristic of F. solani f. sp. glycines …

Avenacin Production In Creeping Bentgrass (Agrostis Stolonifera) And Its Influence On The Host Range Of Gaeumannomyces Graminis, S. L. Thomas, P. Bonello, P. E. Lipps, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Avenacinase activity has been shown to be a key factor determining the host range of Gaeumannomyces graminis on oats (Avena sativa). G. graminis var. avenae produces avenacinase, which detoxifies the oat root saponin avenacin, enabling it to infect oats. G. graminis var. tritici does not produce avenacinase and is unable to infect oats. G. graminis var. avenae is also reported to incite take-all patch on creeping bentgrass (Agrostis stolonifera). It is unknown whether creeping bentgrass produces avenacin and if the avenacin-avenacinase interaction influences G. graminis pathogenicity on creeping bentgrass. The root extracts of six creeping bentgrass …

Fungicide Sensitivity Of Sclerotinia Homoeocarpa From Golf Courses In Ohio, Young-Ki Jo, Amy L. Niver, Joseph W. Rimelspach, Michael J. Boehm

Department of Plant Pathology: Faculty Publications

Managing dollar spot, the most common and chronic disease on intensively cultivated turfgrass, relies on the judicious use of fungicides. The heavy use of fungicides has led to the development of isolates of Sclerotinia homoeocarpa insensitive to several classes of fungicides, including benzimidazoles, demethylation-inhibitors, and dicarboximides. In vitro fungicide sensitivity assays using single discriminatory concentrations of thiophanate-methyl, propiconazole, and iprodione were developed in this study for evaluating field efficacy of these fungicides and the prevalence of fungicide insensitivity within S. homoeocarpa isolated from golf courses throughout Ohio. Discriminatory concentrations for these fungicides were determined to be: thiophanate-methyl = 1,000 μg …