Browsing by Author "Wilkinson, Carol A."
Now showing 1 - 20 of 64
Results Per Page
Sort Options
- 1998 Dark-fired Tobacco Production GuideReed, T. David; Jones, J. L.; Johnson, Charles S.; Semtner, Paul J.; Wilkinson, Carol A. (Virginia Cooperative Extension, 1997)
- 2014 Flue-Cured Tobacco Production GuideReed, T. David; Johnson, Charles S.; Semtner, Paul J.; Wilkinson, Carol A. (Virginia Cooperative Extension, 2014)An annually-produced guide to the production of flue-cured tobacco, issued in cooperation with the Virginia Bright Flue-Cured Tobacco Board.
- 2015 Flue-Cured Tobacco Production GuideReed, T. David; Johnson, Charles S.; Semtner, Paul J.; Wilkinson, Carol A. (Virginia Cooperative Extension, 2015)An annually-produced guide to the production of flue-cured tobacco, issued in cooperation with the Virginia Bright Flue-Cured Tobacco Board.
- 2017 Flue-Cured Tobacco Production GuideReed, T. David; Johnson, Charles S.; Semtner, Paul J.; Wilkinson, Carol A. (Virginia Cooperative Extension, 2017)An annually-produced guide to the production of flue-cured tobacco, issued in cooperation with the Virginia Bright Flue-Cured Tobacco Board.
- 2019 Flue-Cured Tobacco Production GuideReed, T. David; Johnson, Charles S.; Wilkinson, Carol A.; Barts, Stephen (Virginia Cooperative Extension, 2019)An annually-produced guide to the production of flue-cured tobacco, issued in cooperation with the Virginia Tobacco Board.
- Burley Tobacco Production Guide, 2008Peek, Danny R.; Reed, T. David; Johnson, Charles S.; Semtner, Paul J.; Wilkinson, Carol A. (Virginia Cooperative Extension, 2008)This manual provides information on selecting varieties, greenhouse transplants, and management practices, fertilization, crop rotations, cover crops, sucker control, disease control, weed control, insect pests, curing, and other topics.
- Burley Tobacco Production Guide, 2011Peek, Danny R.; Reed, T. David; Johnson, Charles S.; Semtner, Paul J.; Wilkinson, Carol A. (Virginia Cooperative Extension, 2011)This report provides data on burley tobacco test plots, including agronomic practices, greenhouse management, fertilizer use, crop rotation, cover crops, sucker control, and control of diseases, weeds and insect pests. Also discusses curing practices.
- Burley tobacco variety information for 1995Wilkinson, Carol A.; Reed, T. David; Johnson, Charles S. (Virginia Cooperative Extension, 1995)
- Burley tobacco variety information for 1996Wilkinson, Carol A.; Reed, T. David; Johnson, Charles S. (Virginia Cooperative Extension, 1996)
- Burley tobacco variety information for 1999Wilkinson, Carol A.; Reed, T. David; Johnson, Charles S. (Virginia Cooperative Extension, 1998)
- Burley tobacco variety information for 2000Wilkinson, Carol A.; Peek, Danny R.; Reed, T. David; Johnson, Charles S. (Virginia Cooperative Extension, 2000)
- Burley tobacco variety information for 2001Peek, Danny R.; Wilkinson, Carol A.; Reed, T. David; Johnson, Charles S. (Virginia Cooperative Extension, 2001)
- Burley variety information for 1994Wilkinson, Carol A.; Reed, T. David; Johnson, Charles S. (Virginia Cooperative Extension, 1994)
- Characterization of delayed flowering in soybean in VirginiaAbeysiriwardena, D. S. de Z. (Virginia Tech, 1990-12-13)Delayed flowering has the potential to overcome the problem of restricted vegetative growth, prior to flowering, that is often associated with double-cropped soybeans [Grycine max (L.) Merr.]. Objectives were to study delayed flowering in soybeans as influenced by date of planting, to estimate the lengths of the component vegetative periods in soybeans under short-day conditions, and to study the mode of inheritance of delayed flowering in soybeans. Date of planting experiments conducted in the field at two Virginia locations using 27 cultivars and breeding lines showed that genotypic differences exist for delayed flowering, especially between delayed and normal flowering isolines. Lengths of the juvenile and inductive periods were estimated for some selected early and late flowering genotypes. F85-84l7 had a longer juvenile period, and F85-1226 had both longer juvenile and inductive periods than their respective early flowering isolines and cultivar Essex. cultivar. The method of moving plants from inductive short-days to long-days, which has been used to estimate the length of inductive period, was adapted to estimate the length of the juvenile period as well. Delayed flowering in soybeans appeared to be controlled by two loci, each with two alleles, and delayed flowering appeared to be recessive. Anyone of the genes in the homozygous recessive state delayed flowering. F85-1226 may be segregating for both genes while F85-84l7 appeared to contain only one.
- Characterization of Hulled and Hulless Winter Barley, Hordeum vulgare L., Through Traditional Breeding and Molecular TechniquesBerger, Gregory Lawrence (Virginia Tech, 2012-11-28)Phenotypic and genotypic characterization of hulled and hulless winter barley (Hordeum vulgare L.) is necessary for improvement using traditional and molecular breeding techniques. Identification of genomic regions conferring resistance to Fusarium head blight (caused by Fusarium graminearum), leaf rust (caused by Puccinia hordei G. Otth), powdery mildew [caused by Blumeria graminis (DC.) E.O. Speer f. sp. hordei Em. Marchal], net blotch (caused by Pyrenophora teres) and spot blotch [caused by Cochliobolus sativus (Ito & Kuribayashi) Drechsler ex Dastur] will greatly aid in breeding for improved resistance. Determining factors that contribute to yield differences between hulled and hulless genotypes, and identification of markers associated with yield and yield related traits will greatly aid in improvement of hulled and hulless genotypes. The hulled cultivar Nomini, hulless cultivar Eve, and hulless line VA06H-48 were consistently resistant to Fusarium head blight (FHB) and had low deoxynivalenol (DON) accumulation. Screening with molecular markers on chromosomes 2H and 6H for FHB and DON identified quantitative trait loci (QTL) which may confer resistance in Virginia Tech germplasm. Evaluation of hulled and hulless full-sibs from four populations indicated that grain volume weight and protein concentration were significantly (P d 0.05) higher for hulless genotypes, while seedling emergence and grain ash concentration were significantly (P d 0.05) higher for hulled genotypes. In linear regression analysis, none of the assessed traits explained yield variation in all populations and environments. Identification of hulless genotypes having yield potentials similar to those of their hulled sibs should be possible after adjusting for hull weight. A genome wide association study was used to identify chromosome regions governing traits of importance in six-rowed winter barley germplasm and to identify single nucleotide polymorphisms (SNPs) markers for use in a marker-assisted breeding program. Significant SNPs associated with previously described QTL or genes were identified for heading date, test weight, yield, grain protein, polyphenol oxidase activity, and resistance to leaf rust, powdery mildew, net blotch, and spot blotch. Novel QTL also were identified for agronomic, quality, and disease resistance traits. These SNP-trait associations provide the opportunity to directly select for QTL contributing to multiple traits in breeding programs.
- Characterization of the soybean genome in regions surrounding two loci for resistance to soybean mosaic virusHayes, Alec J. (Virginia Tech, 2003-08-01)Soybean mosaic virus (SMV), has been the cause of numerous and often devastating disease epidemics, causing reduction in both the quality and quantity of soybeans worldwide. Two important genes for resistance to SMV are Rsv1 and Rsv4. Alleles at the Rsv1 locus have been shown to control resistance to all but the most virulent strain of SMV. This locus has been mapped previously to the soybean F linkage group. Rsv4 is an SMV resistance locus independent of Rsv1 and confers resistance to all strains of SMV. This locus has not been mapped previously. The purpose of this study is to investigate the two genomic regions that contain these vitally important resistance genes. A population of 281 F2 individuals that had previously been genotyped for reaction to SMV was evaluated in a mapping study which combined bulk segregant analysis with Amplified Fragment Length Polymorphism (AFLP). A Rsv4-linked marker, R4-1, was identified that mapped to soybean linkage group D1b using a reference mapping population. More than 40 markers were mapped in the Rsv4 segregating population including eleven markers surrounding Rsv4. This will provide the necessary framework for the fine mapping of this important genetic locus. Previous work has located Rsv1 to a genomic region containing several important resistance genes including Rps3, Rpg1, and Rpv. An RFLP probe, NBS5, whose sequence closely resembles that of several cloned plant disease resistance genes has been mapped to this chromosomal region. The efficacy of using this sequence to identify potential disease resistance genes was assessed by screening a cDNA library to uncover a candidate disease resistance gene which corresponds to this NBS5 sequence. Two related sequence classes were identified that correspond to NBS5. Interestingly, one class corresponds to a full length gene closely resembling other previously cloned disease resistance genes offering evidence that this NBS5-derived clone is a candidate disease resistance gene. A new marker technique was developed by combining the speed and efficiency of AFLP with DNA sequence information from cloned disease resistance genes. Using this strategy, three new markers tightly linked to Rsv1 were identified. One of these markers, which maps 0.6 cM away from Rsv1, has motifs consistent with other cloned disease resistance genes, providing evidence that this approach is an efficient method for targeting genomic regions where disease resistance genes are located.
- Characterizing resistance in flue-cured tobacco to Globodera tabacum solanacearumWang, Jie (Virginia Tech, 1996)Resistance to Globodera tabacum solanacearum in flue-cured tobacco was characterized in vitro, in the greenhouse, and field. The objectives of this study included evaluation of hatching of G. t. solanacearum as stimulated by root exudate, penetration and development of G. t. solanacearum on roots, and the effects of G. t. solanacearum on growth, yield, and quality of flue-cured tobacco. Root exudate from resistant (NC 567) and susceptible (K 326) flue cured tobacco cultivars had similar effects on hatching of G. t. solanacearum. Dilution of root exudate reduced hatching and hatching appeared to increase with increased temperature. More swollen and flask shaped nematodes developed in roots of K 326 than those of NC 567. Resistance reduced development of vermiform juveniles to swollen nematodes in NC 567. However, development of swollen nematodes to flask shaped nematodes was similar for both cultivars. Resistance to G. t. solanacearum was effective at 17, 22, 27, and 31°C. Infection by G. t. solanacearum suppressed number of leaves, plant height, fresh weight of leaves, and feeder roots. Reduction in fresh leaf weight at 11 weeks after transplanting was greater for the susceptible cultivar, K 326, than for the resistant cultivar, NC 567. However reduction in fresh feeder root weight and increases in the ratio of leaf weight to feeder root weight at 11 weeks after transplanting between both cultivars. Yield and grade index of cured leaves were negatively correlated with area under curves of total nematode population densities per gram of feeder root. The rate parameters of regression models suggested that the two cultivars responded similarly to infection by G. t. solanacearum in yield and quality reduction. However, K 326 had a higher yield potential in the absence of nematodes.
- Controlling Tobacco Mosaic Virus in Tobacco through ResistanceBagley, Christopher A. (Virginia Tech, 2001-12-07)Tobacco mosaic virus (TMV) infects all classes of tobacco (Nicotiana tabacum L.) and causes losses worldwide. The N gene is the most effective means of controlling TMV; however, this gene is associated with reduced yield and quality in flue-cured tobacco. The mode of inheritance of TMV resistance was determined in two tobacco introductions (TI) from N. tabacum germplasm, both of which produced a hypersensitive response when inoculated with TMV. Inheritance studies with TI 1504 and TI 1473 indicate that a single dominant gene controls resistance. The gene governing resistance in TI 1504 is allelic to the N gene in NC 567. The gene providing resistance in TI 1473 is not allelic to the N gene, providing a potentially new source of resistance. Currently, plant breeders must rely on the N gene. The N gene is used in the heterozygous state to help overcome poor agronomic effects associated with homozygous resistance; however, systemic movement of TMV is occasionally seen in resistant plants. A TMV susceptible inbred (K 326), a resistant inbred (NC 567), and three resistant hybrids (NC 297, RGH4, and Speight H2O) were inoculated with TMV at transplanting, layby, and topping using different inoculation methods. Plant parts were tested for viral presence and biological activity. Viral movement into all plant parts was observed in K 326. No systemic movement was evident in the plant parts of NC 567, while virus did move into the corollas, pistils, late season sucker growth, and roots of the resistant hybrids showing systemic necrosis.
- Development of a Greenhouse Tobacco Seedling Performance IndexClarke, Jodie Johnson (Virginia Tech, 2001-05-02)Tobacco seed performance is traditionally measured as percentage germination at 14 d under controlled laboratory conditions. However, under greenhouse conditions, seed lots with equal 14-d germination may exhibit substantial differences in uniformity of early seedling growth and spiral root incidence that impact the number of usable transplants. A seedling performance index (SPI) was developed to quantitatively describe greenhouse tobacco seedling performance. The 14-d emergence, relative leaf area uniformity, and seedling leaf area determined by computer image analysis were used to calculate the index. Greenhouse tobacco seed trials demonstrated that seed with the Rickard pellet had higher emergence, but the higher spiral root incidence associated with the Rickard pellet lowered the SPI compared to the Cross Creek pellet. Primed seed lots of flue-cured cultivars (NC 72 and NC 71) had a significantly higher SPI than the nonprimed seed lots at one location but not at a second location. Seed lots sown in Premier Pro-Mix TA commercial medium had a higher spiral root incidence, which resulted in a lower SPI compared to Carolina Choice, Carolina Gold, and Sunshine LP5 commercial media. The index quantitatively determined differences in seedling performance under greenhouse conditions not reflected by standard germination tests. Significant differences in the SPI were observed among seed lots with certified 90% germination. The SPI is a simple method to describe seedling performance because the data used to calculate the SPI is obtained from one seed tray image. In contrast, frequent counting and seedling evaluations are involved with standard germination and vigor tests.
- The Effect of Nematode Isolate and Soil Environment on the Tobacco cyst Nematode (Globodera tabacum solanacearum), a Pathogen of Flue-cured Tobacco and Other Solanaceous CropsRideout, Steven L. (Virginia Tech, 1998-12-02)Tobacco cyst nematodes (TCN), Globodera tabacum solanacearum, are one of the most serious pests for Virginia flue-cured tobacco (Nicotiana tabacum L.) farmers. These nematodes continue to spread to new farms every year and are now reported in 11 Virginia counties, seven North Carolina counties, and one farm in Maryland. The objectives of this study were to determine the ability of different populations of TCN to reproduce upon both a susceptible (K326) and resistant (NC567) cultivar, to compare TCN reproduction in non-infested soils with currently TCN-infested soils, and to examine reproduction and pathogenicity of TCN on other solanaceous crops. Tobacco cyst nematode reproduction on the TCN-resistant cultivar NC567 was significantly reduced when compared to the TCN-susceptible cultivar K326. Although significant differences among the populations were detected on both cultivars, the differences were not consistent across experiments. Results indicate similar pathogenicity among TCN populations on resistant and susceptible flue-cured tobacco cultivars. Plant breeders may use one population of the tobacco cyst nematode to screen tobacco germplasms for TCN resistance. Significant differences were noted in TCN reproduction among the various soils used in this study. However, the differences were inconsistent, making correlations between TCN reproduction and soil edaphic characteristics unreliable. Sterilizing the soils did not increase TCN reproduction. Reproduction in non-infested soils indicates that TCN will continue to spread throughout tobacco producing regions. Although traditionally an exclusive pest of tobacco, TCN's spread may threaten production of other solanaceous crops. Eggplant (Solanum melongena L.), pepper (Capsicum spp. L.), and tomato (Lycopersicon spp. L.) were confirmed to be hosts of TCN under field conditions. Eggplant was highly susceptible to TCN reproduction and yield suppression, exhibiting a 64% yield reduction in plots not treated with a nematicide compared to fumigated plots. Tomato allowed high rates of TCN reproduction but did not suffer yield loss. Tobacco cyst nematode reproduction was suppressed on pepper compared to the other two crops. No crop loss was noted in nontreated pepper plots compared to plots treated with a nematicide. Results would indicate that tobacco rotations including tomato or eggplant would be unacceptable due to high TCN reproduction rates. The tobacco cyst nematode does not seem to jeopardize the production of tomato and pepper in the southeastern United States, but does threaten profitability of eggplant production in this area.