Plant Pathology Commons^™

Population Dynamics Of Sugar Beets, Rhizoctonia Solani, And Laetisaria Arvalis: Responses Of A Host, Plant Pathogen, And Hyperparasite To Perturbation In The Field, Michael F. Allen, Michael G. Boosalis, Eric D. Kerr, Anne E. Muldoon, Harold J. Larsen

Department of Plant Pathology: Faculty Publications

Rhizoctonia solani causes crown rot of sugar beets, a severe disease that has destroyed up to 60% of the plants in a test field in western Nebraska. Laetisaria arvalis, a natural hyperparasite of Rhizoctonia spp., was isolated from fields in western Nebraska. To test for the potential for biological control of R. solani, in November 1980 (following harvest) we applied various combinations of a nematicide (Telone II; Dow Chemical Co.), a nutrition source (sugar beet pulp), and an inoculum of L. arvalis in a randomized block design. Populations of R. solani, L. arvalis, and sugar beets were …

Synthesis And Localization Of A Development-Specific Protein In Sclerotia Of Sclerotinia Sclerotiorum, Geraldine Russo, James L. Van Etten

Department of Plant Pathology: Faculty Publications

A development-specific protein (SSP) makes up about 35 to 40% of the total protein in sclerotia of the fungus Sclerotinia sclerotiorum. The protein consists of three charge isomers, with one isomer making up 80 to 90% of the total. In vitro translation of poly(A)⁺ RNA isolated from cells in early stages of sclerotia formation revealed that 44% of the amino acids incorporated was into SSP. In vivo- and in vitro-synthesized forms of SSP migrated at identical rates on both isoelectric focusing and denaturing polyacrylamide gels, indicating that SSP was not synthesized as a larger precursor. This was significant …

A Survey For Viruses From Fresh Water That Infect A Eucaryotic Chlorella-Like Green Alga, James L. Van Etten, Cecil H. Van Etten, Jeffrey Johnson, Dwight Burbank

Department of Plant Pathology: Faculty Publications

Viruses which formed plaques on lawns of a eucaryotic, chlorella-like green alga were detected in 37% of the 35 freshwater samples surveyed. Virus populations, monitored in seven locations, fluctuated both qualitatively and quantitatively over an 8-month period.

Partial Purification And Characterization Of A Polysaccharide Depolymerase Associated With Phage-Infected Erwinia Amylovora, Peter A. Vandenbergh, Ann M. Wright, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

Erwinia amylovora infected with bacteriophage ERA103 produced an enzyme which degraded the extracellular polysaccharide of noninfected cells. The depolymerase enzyme was purified 15-fold by a procedure which included ammonium sulfate precipitation, ultracentrifugation, CM-Sephadex batchwise separation, Sephadex G-50 column chromatography, and Sephacryl S-200 column chromatography. The enzyme had a molecular weight of approximately 21,000 and a pH optimum of 6.0. Activity was enhanced by supplements of 2-mercaptoethanol or dithiothreitol.

Sequence Relationships Among Soil-Borne Wheat Mosaic Virus Rna Species And Terminal Structures Of Rna Ii, Y. H. Hsu, M. K. Brakke

Department of Plant Pathology: Faculty Publications

Gel-separated RNAs of the wild-type (WT), Lab 1 and Lab 2 isolates of soil-borne wheat mosaic virus (SBWMV) were transferred to nitrocellulose filters and hybridized with specific cDNA. RNA I, but not RNA II, from all three SBWMV isolates hybridized to cDNA copied from SBWMV WT RNA I. RNA II from all three SBWMV isolates hybridized to cDNA copied from SBWMV WT RNA II, confirming the hypothesis that the Lab 1 and Lab 2 isolates arose by deletion of part of RNA II of WT virions. RNA I1 from SBWMV WT (0∙5L RNA) or from SBWMV Lab 1 (0.35L RNA) …

Conjugative Plasmid In Corynebacterium Flaccumfaciens Subsp. Oortii That Confers Resistance To Arsenite, Arsenate, And Antimony(Iii), Carol A. Hendrick, William P. Haskins, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

Gene transfer systems for phytopathogenic corynebacteria have not been reported previously. In this paper we describe a conjugative 46-megadalton plasmid (pDG101) found in Corynebacterium flaccumfaciens subsp. oortii COIOI that mediates resistance to arsenite, arsenate, and antimony(III). Transfer of the plasmid from CO101 to four other strains from the C. flaccumfaciens group occurred between cells immobilized on nitrocellulose filters or on agar surfaces. Transconjugant strains expressed the same levels of metal resistance as the donor strain and were able to act as donor strains in subsequent matings. The physical presence of the plasmid was detected by agarose gel electrophoresis. Arsenite-sensitive derivatives …

Clavibacter: A New Genus Containing Some Phytopathogenic Coryneform Bacteria, Including Clavibacter Xyli Subsp. Xyli Sp. Nov., Subsp. Nov. And Clavibacter Xyli Subsp. Cynodontis Subsp. Nov., Pathogens That Cause Ratoon Stunting Disease Of Sugarcane And Bermudagrass Stunting Disease, Michael J. Davis, A. Graves Gillaspie Jr, Anne K. Vidaver, Russell W. Harris

Department of Plant Pathology: Faculty Publications

A total of 23 strains of coryneform bacteria that cause ratoon stunting disease of sugarcane and Bermudagrass stunting disease were examined. These included 17 sugarcane strains from Florida, Louisiana, South Africa, Brazil, and Japan and six Bermudagrass strains from Florida and Taiwan. The sugarcane and Bermudagrass strains contained 2,4-diaminobutyric acid, rhamnose, and fucose in their cell walls, suggesting a relationship to some other phytopathogenic coryneform bacteria and related organisms with similar cell wall compositions. The cellular protein patterns of the sugarcane and Bermudagrass strains after polyacrylamide gel electrophoresis resembled the patterns of Corynebacterium michiganense subspecies more than the patterns of …

Proceedings Of The 11th Annual Meeting, Southern Soybean Disease Workers (March 27-29, 1984, Ft. Walton Beach, Florida): Economics Of Soybean Disease, H. Jack Walters, Richard E. Stuckey, Edwin F. Koldenhoven, Murray E. Nance, James D. Arnett

Southern Soybean Disease Workers: Conference Proceedings

Contents

1984 Southern Soybean Disease Workers Officers

1984 Southern Soybean Disease Workers Program Committee

1984 Southern Soybean Disease Workers Committee Chairmen

Workshop

Diagnosing early season soybean disorders. D Stuckey and A Wrather

General session

Presidential address. HJ Walters

Southern United States Soybean Disease Loss Estimate for 1983. Southern Soybean Disease Workers, Soybean Disease Loss Estimate Committee. RP Mulrooney

Soybean nematodes. R Dunn presiding

A New Publication on the Soybean Cyst Nematode. WF Moore

Soybean Cultivars and Development of Populations of Meloidogyne incognita in Soil: A Concept of Tolerance. R Rodríguez-Kábana and DB Weaver

A Comparison of Soybean Cultivars for …

Results Of The Thirteenth International Winter Wheat Performance Nursery Grown In 1981, S. L. Kuhr, C. J. Peterson, V. A. Johnson, P. J. Mattern, J. W. Schmidt

Nebraska Agricultural Experiment Station: Historical Research Bulletins

This is the thirteenth report of results from an International Winter Wheat Performance Nursery (IWWPN) organized in 1968 by the Nebraska Agricultural Experiment Station in cooperation with the Agricultural Research Service (ARS), U. S. Department of Agriculture, under contract number AID/ta-C-1093 with the U. S. International Development Corporation, Agency for International Development. The Nursery was designed to (1) test the adaptation and stability of winter wheat cultivars in a range of latitudes, daylengths, fertility conditions, water management regimes, and disease complexes; (2) identify superior winter cultivars to serve as recipient genotypes for high protein and high lysine genes; (3) test …

Book Review: Plant Infectious Agents, Myron K. Brakke

Department of Plant Pathology: Faculty Publications

This is not the book to go to for exhaustive coverage or detailed experimental protocol, but it is excellent for a concise version of recent developments in the molecular biology of plant viruses.

Two Purified Rnas Of Soil-Borne Wheat Mosaic Virus Are Needed For Infection, Yukio Shirako, Myron K. Brakke

Department of Plant Pathology: Faculty Publications

RNAs of soil-borne wheat mosaic virus (SBWMV) from virions 281 nm, 138 nm and 92 nm long (designated here by relative lengths as 1∙0L, 0∙SL and 0∙35L, respectively), were isolated and purified by three cycles of sucrose density gradient centrifugation. Infectivity assays with these RNAs proved the bipartite nature of SBWMV, the combination of 1∙0L and either 0∙5L or 0∙35L RNAs being required for infection and for multiplication of progeny viruses. The 0∙5L RNA underwent deletion mutation, producing smaller variants with various sizes, of which 0∙4L and 0∙35L RNAs were confirmed to be functional in combination with 1∙0L RNA. The …

Mutations, The Abberant Ratio Phenomenon, And Virus Infection Of Maize, Myron K. Brakke

Department of Plant Pathology: Faculty Publications

Viruses interact genetically in various ways with bacterial and animal hosts, e.g. by lysogeny in bacteriophage and by incorporating a DNA copy of retrovirus RNA into the host genome. These phenomena lead to mutations, to the transfer of host genes by viruses, and to latent viruses being transmitted from generation to generation essentially as host genes. In contrast, there are no known examples of the incorporation of viral genomes into plant DNA.

Spontaneous Deletion Mutation Of Soil-Borne Wheat Mosaic Virus Rna Ii, Yukio Shirako, Myron K. Brakke

Department of Plant Pathology: Faculty Publications

The wild-type (WT) isolate of soil-borne wheat mosaic virus has two species of rodshaped virions 281 nm and 138 nm in length, which are designated as virions 1∙0L and 0∙5L, respectively. We reported previously that virions shorter than 0∙5L arose in assay plants inoculated with separated and recombined 1∙0L RNA and 0∙5L RNA and suggested that these short virions were caused by deletion mutation of 0∙5L RNA. We now report that these short virions arose after a period of several months in wheat plants that had been inoculated manually with unpurified WT isolate, and also when plants infected naturally in …

Biosynthesis And Degradation Of Storage Protein In Spores Of The Fungus Botryodiplodia Theobromae, Gary Petersen, Kurt Dahlberg, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Muiridin, a spore-specific protein of the fungus Botryodiplodia theobromae, comprises about 25% of the mature pycnidiospore protein. It has an apparent molecular weight of 16,000 to 17,000 and is rich in glutamine, asparagine, and arginink. Muiridin is synthesized in developing spores via a precursor with an apparent molecular welght of 24,000. Two other polypeptides present in young developing spores with apparent molecular weights of 18,000 and 15,000 are immunologically related to muiridin. We propose a pathway for muiridin synthesis. Muiridin is actively degraded during the germination of spores from 30-day old cultures. This degradation is independent of exogenous amino …

Results Of The Twelfth International Winter Wheat Performance Nursery Grown In 1980, S. L. Kuhr, C. J. Peterson, V. A. Johnson, P. J. Mattern, J. W. Schmidt

Nebraska Agricultural Experiment Station: Historical Research Bulletins

This is the twelfth report of results from an International Winter Wheat Performance Nursery (IWWPN) organized in 1968 by the Nebraska Agricultural Experiment Station in cooperation with the Agricultural Research Service (ARS), U.S. Department of Agriculture, under contract number AID/ta-C-1093 with the U.S. International Development Corporation, Agency for International Development. The Nursery was designed to (1) test the adaptation and stability of winter wheat cultivars in a range of latitudes, daylengths, fertility conditions, water management regimes, and disease complexes; (2) identify superior winter cultivars to serve as recipient genotypes for high protein and high lysine genes; (3) test the degree …

Proceedings Of The 10th Annual Meeting, Southern Soybean Disease Workers (March 15-17, 1983, Houston, Texas): Significance Of Soybean Diseases, Wayne Winner, H. Jack Walters, Dick Stuckey, Jerry Berggren, J. Dan Smith

Southern Soybean Disease Workers: Conference Proceedings

Contents

1983 Southern Soybean Disease Workers Officers

1983 Southern Soybean Disease Workers Program Committee

Committee Chairmen

General session

Presidentiial address. W Winner

Soybean Research Needs and the American Soybean Association. KJ Smith

American Soybean Association Pesticide Assessment in the Administrative Hearing: An Educational Guide for the Agricultural Scientist. MT Olexa and AH Daniels

Soybean Disease Loss Estimate. E Koldenhoven

The influence of cultural practices on disease incidence. JG Kantzes presiding

The Relationship Between Chloride Uptake and Leaf Scorch of Soybeans. MB Parker, TP Gaines, and GJ Gascho

Effect of No-tillage on Fusarium Blight of Soybean on Delmarva. B Carroll

Effect …

Results Of The Eleventh International Winter Wheat Performance Nursery Grown In 1979, S. L. Kuhr, V. A. Johnson, P. J. Mattern, J. W. Schmidt

Nebraska Agricultural Experiment Station: Historical Research Bulletins

This is the eleventh report of results from an International Winter Wheat Performance Nursery (IWWPN) organized in 1968 by the Nebraska Agricultural Experiment Station in cooperation with the Agricultural Research Service (ARS), U.S. Department of Agriculture, under contract number AID/ta-C-1093 with the U.S. International Development Corporation, Agency for International Development. The Nursery was designed to (1) test the adaptation and stability of winter wheat cultivars in a range of latitudes, daylengths, fertility conditions, water management regimes, and disease complexes; (2) identify superior winter cultivars to serve as recipient genotypes for high protein and high lysine genes; (3) test the degree …

Effects Of Two Species Of Va Mycorrhizal Fungi On Drought Tolerance Of Winter Wheat, Michael F. Allen, Michael G. Boosalis

Department of Plant Pathology: Faculty Publications

Roots and soils from western Nebraska fields of native and planted grasslands, and winter wheat of varied fallow-wheat cultivation duration, were evaluated for vesicular-arbuscular (VA) mycorrhizal root infection and spore numbers and types. Increased cultivation decreased percentage mycorrhizal infection in wheat and reduced spore numbers of Glomus fasciculatus, the dominant VA mycorrhizal fungus in these soils. Spore numbers of other VA mycorrhizal fungi did not change significantly with cultivation although mean numbers of G. mosseae increased with continued wheat production. Water relations and growth were determined for greenhouse-grown non-mycorrhizal, G. fasciculatus-infected, and G. mosseae-infected wheat in wet …

Taxonomic Limits Of The Genus Nagelus (Thorne And Malek, ]968) Siddiqi, 1979 With A Description Of Nagelus Borealis N.Sp. From Alaska, Thomas O. Powers, James G. Baldwin, A. H. Bell

Department of Plant Pathology: Faculty Publications

Tire genus Nagelus (Thorne and Malek, 1968) Siddiqi, 1979 is modified and a new species from Alaska is described. The combination of scanning electron microscopy and light microscopy permits the characterization of Nagelus spp. as having a broadly oval face pattern, no longitudinal striations on the lip region, deirids surrounded by six incisures, and an irregularly tapering tail with a large hyaline region. Nagelus leptus (Allen, 1955) Siddiqi, 1979, N. alpensis Doucet and Luc, 1981, N. camelliae (Kheiri, 1972) Siddiqi, 1979, N. jamelensis (Nesterov, 1973) Siddiqi, 1979, and N. obscurus (Allen, 1955) n. comb. are retained on this basis. Nagelus …

Proceedings Of The 9th Annual Meeting, Southern Soybean Disease Workers (April 14-15, 1982, Ft. Walton Beach, Florida): Better Yield, Higher Quality = Greater Profit, Walter J. Walla, Wayne Winner, H. Jack Walters, Jerry Berggren, J. Dan Smith

Southern Soybean Disease Workers: Conference Proceedings

Contents

1982 Southern Soybean Disease Workers Officers

1982 Southern Soybean Disease Workers Program Committee

Committee Chairmen

General session

Presidential address. Walter Walla

Role of American Soybean Association in Soybean Production. KL. Bader

Agricultural Chemistry World Wide. D Wolf

Soybean disease management. W Winner presiding

Soybean Disease Loss Estimate. E Koldenhoven

Disease Management Panel Discussion: The Consultant and Soybean Disease Control. R Carver

Disease Management: Chemical Industries' Point of View. HL McMenemy

Management Tactics for Soybean Diseases. DP Schmitt

Farmer and Soybean Disease Control. J Andries

Soybean nematodes. J Arnett presiding

Standardized Nematicide Research Report. A Wrather

Nematode Parasites …

Viruses Of Symbiotic Chlorella-Like Algae Isolated From Paramecium Bursaria And Hydra Viridis, James L. Van Etten, Russel H. Meints, Daniel Kuczmarski, Dwight E. Burbank, Kit Lee

Department of Plant Pathology: Faculty Publications

We previously reported that isolation of symbiotic Chloreila-like algae from the Florida strain of Hydra viridis induced replication of a virus (designated HVCV-1) in the algae. We now report that isolation ofsymbiotic Chlorella-like algae from four other sources of green hydra and one source ofthe protozoan Paramecium bursaria also induced virus synthesis. Algae from one of these hydra contained a virus identical to HVCV-1 (based on its rate of sedimentation, buoyant density, reaction to HVCV-1 antiserum, and DNA restriction fragments) whereas algae from the other three hydra contained. another similar, but distinct, virus (designated HVCV-2). The virus from the paramecium …

Influence Of Vesicular-Arbuscular Mycorrhizae On Water Movement Through Bouteloua Gracilis (H.B.K.) Lag Ex Steud, Michael F. Allen

Department of Plant Pathology: Faculty Publications

Root growth characteristics and water transport were compared between non-mycorrhizal Bouteloua gracilis and vesicular-arbuscular mycorrhizal Bouteloua gracilis infected with Glomus fasciculatus. Mycorrhizal plants did not have significantly different leaf area or root length from non-mycorrhizal plants, hut did have significantly fewer and shorter root hairs. Mycorrhizal plants had 50% lower leaf resistance with no change in leaf or root water potentials; thus transpiration was increased 100% with a 50% reduction in whole-plant, soil-to-root and root-to-leaf resistance. Assuming that the difference in water uptake was due to transport via the mycorrhizal hyphae, estimated fungus-to-root transport was 2◦8 x 10^{-5 …}

The Plant Pathogenic Corynebacteria, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

The plant pathogenic corynebacteria are a fascinating group of bacteria that produce effects as diverse as any in the microbial world, ranging from wilts to abnormal growths. Several new pathogens have been discovered since this group was reviewed by Jensen (75), Starr (157), and Lelliott (96). Most subsequent reviews have dealt with taxonomy. The areas covered in this review necessarily reflect my biases and limitations. However, this review attempts to be comprehensive in some areas, and it calls attention to other areas that would benefit from more detailed investigation.

Results Of The Tenth International Winter Wheat Performance Nursery Grown In 1978, S. L. Kuhr, V. A. Johnson, P. J. Mattern, K. D. Wilhelmi, J. W. Schmidt

Nebraska Agricultural Experiment Station: Historical Research Bulletins

This is the tenth report of results from an International Winter Wheat Performance Nursery (IWWPN) organized in 1968 by the Nebraska Agricultural Experiment Station in cooperation with the Science and Education Administration (SEA), U.S. Department of Agriculture, under contract number AID/ta-C-1093 with the U.S. International Development Corporation, Agency for International Development. The Nursery was designed to (1) test the adaptation and stability of winter wheat cultivars in a range of latitudes, daylengths, fertility conditions, water management regimes, and disease complexes; (2) identify superior winter cultivars to serve as recipient genotypes for high protein and high lysine genes: (3) test the …

Influence Of Phosphate Source On Vesicular-Arbuscular Mycorrhizae Of Bouteloua Gracilis, Michael F. Allen, James C. Sexton, Thomas S. Moore Jr., Martha Christensen

Department of Plant Pathology: Faculty Publications

Non-mycorrhizal and vesicular-arbuscular mycorrhizal Bouteloua gracilis infected with Glomus fasciculatus were grown in defined media containing different phosphate sources and compared with respect to phosphate content and form, biomass, chlorophyll concentration, and root phosphatase activity. The phosphate sources were sodium monobasic phosphate, a mixture of sodium monobasic phosphate and calcium phytate, and calcium phytate. Inositol and inositol plus calcium were added to the sodium phosphate medium as additional treatments. Mycorrhizal infection was highest in roots of plants grown in the presence of phytate (75%). Lower root infection levels were noted in plants from the sodium phosphate (19%) and mixed phosphate …

Recessive Alleles Found At R And C Loci In Maze Stalks Showing Aberrant Ratio At The A Locus, Myron K. Brakke, R. G. Samson, W. A. Compton

Department of Plant Pathology: Faculty Publications

Corn stocks showing virus-induced aberrant ratio (AR) at the “A” locus were found to have recessive alleles at the R and/or C loci. Since by the known pedigree these loci should be homozygous dominant, the results suggest an inactivation of maize genes by a mechanism as yet unknown. The presence of recessive alleles at these additional loci can explain the segregation ratios obtained in these particular stocks.

Effects Of Reduced Tillage And Multiple Cropping On Plant Diseases, Donald R. Sumner, Ben Doupnik Jr., M. G. Boosalis

Department of Plant Pathology: Faculty Publications

In the past, tillage research on plant diseases was concerned primarily with practices that buried plant residues in single-crop production systems. The burial of plant debris to destroy pathogens is an ancient agricultural prac­ tice (34). Each crop was tested as a single entity, and most crop rotations were based on one crop per year. Interest in notill and conservation tillage systems and mUltiple cropping has increased in the past two decades be­ cause of the scarcity and increased cost of fossil fuels, periodic world food shortages, and the concern over soil erosion (73,110). These concerns are of such paramount …

Proceedings Of The 8th Annual Meeting, Southern Soybean Disease Workers (March 11-12, 1981, Memphis, Tennessee): Soybeans, The Crop Of The Future

Southern Soybean Disease Workers: Conference Proceedings

General Session

Presidential Address - Glen Whitney

The Influence of Plant Diseases on American Agriculture - Wiley Garrett

Integrated Pest Management: A National Prospective - B. Blair

Development in Brazil, the Future World Supplier of Food: Industry Overview - Ray Smith

Soybean Disease Loss Estimate - R. V. Sturgeon

Soybeans, Seed, Seedling, and Soil-Borne Disease, James Kantzes presiding

Standardized Seed Treatment Research Report - M. C. McDaniel

Soybean Seedling Disease Control and Plant Populations - Norman Horn

Metalaxyl: A New Seed Dressing and Soil Treatment Fungicide - H. V. Morton and D. Houseworth

Soybean Seed Treatment: U. S. Status …

Comparative Water Relations And Photosynthesis Of Mycorrhizal And Non-Mycorrhizal Bouteloua Gracilis H.B.K. Lag Ex Steud., Michael F. Allen, William K. Smith, Thomas S. Moore Jr., Martha Christensen

Department of Plant Pathology: Faculty Publications

The rangeland grass, Bouteloua gracilis was inoculated with its mycorrhizal symbiont, Glomus fasciculatus, to determine the influence of vesicular-arhuscular mycorrhizae on water status, stomatal behaviour and photosynthesis as well as gross plant morphology, biomass and phosphorus content. Mycorrhizal infection increased transpiration rates by over 100% with 50 to 70% lower leaf resistances to water vapour diffusion. Leaf xylem pressure was not different between mycorrhizal and non-mycorrhizal plants indicating that whole-plant resistance to water transport was reduced by more than 50%. Photosynthetic rates under saturating light conditions increased 68% with infection as a consequence of a 33% reduction in stomatal …

In Vitro Translation Of The Three Bacteriophage Φ6 Rnas, Diane A. Cuppels, James L. Van Etten, Dwight E. Burbank, Leslie C. Lane, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

In vitro translation of the three single-stranded RNAs transcribed in vitro by bacteriophage φ6 RNA polymerase revealed that the large RNA codes for phage proteins P1, P2, P4, and P7, the medium RNA codes for P3, P6, and P10, and the small RNA codes for P5, P8, and P9.