Life Sciences 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 …

The Isolation, Property Analysis And Determination Of In Planta Growth Ability Of Extracellular Polysaccharide Mutants Of Corynebacterium Michiganense Pv Insidiosum, Mary C. Paschke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Corynebacterium michiganense pv insidiosum, the organism responsible for bacterial wilt of alfalfa, produces an extracellular polysaccharide (EPS) that has been linked to its virulence. The EPS is composed of three different-sized molecules (components I, II and III). It has been demonstrated that this EPS accumulates in the vascular system of infected plants and causes disruption of the flow of water.

The importance of EPS to the survival and pathogenicity of C.m. pv insidiosumis not known. In order to begin assessing the value of EPS, mutant strains that are EPS-deficient were isolated after UV mutagenisis. Analysis by gel filtration …

Leaf Rust Of Wheat, Donald E. Hershman

Agriculture and Natural Resources Publications

Leaf rust of wheat, caused by the fungus Puccini recondita f. sp. tritici, can cause heavy yield losses in wheat. Growers frequently underestimate the losses caused by leaf rust because the disease never destroys an entire crop in Kentucky and seldom causes severe shriveling of the grain. Yet the disease reduces the number of Kernels per head, as well as grain test weight. Grain from severely rusted plants is also lower in protein content.

Some leaf rust occurs in the state every year, but variations in the weather and the amount of rust overwintering in the southern states produce …

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) …

Keeping Ahead Of Powdery Mildew In Barley, T N. Khan, K. Young, P. A. Portmann

Journal of the Department of Agriculture, Western Australia, Series 4

Powdery mildew is one of the world's most significant barley diseases. In Australia, and more particularly Western Australia, its importance has been under-rated, and only recently has interest in this disease emerged.

Powdery mildew was widespread throughout Western Australia's southern cereal growing areas in 1983. Only a prolonged dry period in August and early September of that year prevented possible large-scale crop losses. Similar outbreaks occurred in 1984.

While some barley varieties are resistant to infection, the use of fungicides, particularly seed dressings, can minimise further infection.

Corn Stalk Rots, Paul Vincelli, Donald E. Hershman

Agriculture and Natural Resources Publications

Stalk rots are the most common diseases of dent corn in Kentucky. It is estimated that these diseases reduce annual yields by a minimum of 3 percent. In certain years, yield losses may reach 10 to 20 percent. Losses are due to (1) premature plant death which results in poor filling of ears or light test weights for the grain, and (2) harvest losses associated with stalk breakage or lodging. Furthermore, problems with ear rot are usually greater where lodging occurs, particularly when the harvest season is wet.

Germination And Host Range Of Branched Broomrape (Orobanche Ramosa) From Texas, Robert D. Coffin

Biological Sciences Theses & Dissertations

The effect of temperature on the germination of Orobanche ramosa L., branched broomrape, was investigated by dividing the physiological stages leading to germination into discrete events: pretreatment, a period when the seed becomes receptive to stimulant, and posttreatment, when stimulant application (GR-24) induces germination. Seed was pretreated and posttreated at 16 different temperature combinations. Optimal pretreatment was at 15°C and 18°C, maximum posttreatment at 18°C. Highest germination was obtained by pretreating and posttreating seed at 18°C, lowest at 24°C. The effect of different pretreatment regimes was tested. Seeds were pretreated over moist filter paper and in soil for Oto …

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 …

Source Of Inoculum, Yield And Quality Of Tomato As Affected By Leveillula Taurica, Wayne B. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Tomato transplant stock from southern Nevada served as a source of inoculum and developed disease symptoms of tomato powdery mildew approximately three weeks before Utah-grown transplants. Plants from Nevada and Utah were equally infected seven weeks after planting and no differences in severity or yield were detected at the end of the season due to rapid spread of the fungus. Tomato yields were reduced ca 40% in check plots when compared to plots treated with triadimefon, propiconazol or sulfur. The amount of sunburned fruit in check plots was three to four times greater than in plots where the disease was …

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 …

Root Knot Nematode In Gardens And Commercial Vegetables, John R. Hartman, William C. Nesmith

Agriculture and Natural Resources Publications

The root knot nematode (Meloidogyne spp.) causes damage by its feeding and reproduction on plant roots. There are several pathogenic species of this nematode but the two most commonly found in Kentucky are the southern root knot nematode, M. incognita and the northern root knot, M. hapla. These nematodes can attack numerous plants including vegetables, fruits, field crops, ornamentals and common weeds. Frequently, Meloidogyne interacts with other plant pathogens to form a disease complex in which the resulting disease is much more severe than that caused by either component alone. These nematodes are particularly serious when high populations …

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.

The Stripe Rust Threat, B R. Whan, T. N. Khan

Journal of the Department of Agriculture, Western Australia, Series 4

The wheat disease stripe rust caused crop losses estimated at $20 million in New South Wales during an epidemis in 983. Economic crop losses were reported in neighbouring States and as far westas Ceduna in South Australia. In some States large areas were sprayed with fungacide at considerable cost to control disease spread.

Wheat stripe rust has not been found in Western Australia yet, but all current evidence indicates that it will eventually reach this State.When it does, it has the potential to cause considerable crop losses every year, unlike the spasmodic losses from stem rust, and it will greatly …

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 …

A 'Natural Herbicide' Against Calotrope?, A H. Cheam

Journal of the Department of Agriculture, Western Australia, Series 4

Buffel grass produces a chemical compound which is toxic to the growth of calotrope seedlings, a declared weed in Western Austrsalia north of the 26th parallel. This new discovery id highly significant in view of the increasing emphasis now placed on weed management as opposed to weed control and the desire to use fewer pesticides.

Virus, Viroid, Mycoplasma And Rickettsial Diseases Of Plants In Western Australia, L K. Price, George Mclean

Technical Bulletins

Provides details of the virus, viroid, mycoplasma and rickettsial diseases recorded on plants in Western Australia. To establish these records, a range of tests have been used including sap transmission; leaf dip electron microscopy; aphid transmission and serology. The authenticity for each record is noted in the list of pathogens.

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 …

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 …

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 …

A Biosystematic Study Of The Polemonium Reptans L. Complex In The Eastern United States Including P. Reptans L. Var. Reptans, P. Reptans L. Var. Villosum Braun And Related Taxa (Polemoniaceae), Bill Lucas

Theses, Dissertations and Capstones

The taxonanic relationship of Polemoniun reptans L. var. reptans and P. reptans L. var. villosum Braun (Polemoniaceae) is examined in this studly. The former taxon occurs throughout most of the eastern deciduous forest while the latter is rare and limited to southern Ohio and northcentral Kentucky. The natural coherence of the species has provided a bimodal frequency distribution which displays clustering of the two varieties at opposite ends of a continuum. Significant differences were obtained using the BMDP7M multivariate analysis (0.05 level of significance) based on morphometric information gathered from herbarium specimens throughout the midwest and eastern states, between var. …

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 …