Progress 07/30/01 to 03/10/04
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Grass seed is an important commodity utilized in lawns, golf courses, pastures, parks, and for soil stabilization in the U.S. and around the world. Grass seed production is centralized in the Pacific Northwest states, but seed yields can be significantly reduced by several fungal diseases that attack the plants and their seeds. Grass diseases such as stem rust can cause losses as great as 95% in ryegrass and 40% in tall fescue, and seed production is currently dependent on fungicide applications. A disease of orchardgrass, choke, can reduce seed yields in excess of 30% by the third year of production and no methods are yet available to control this disease. Other organisms that specifically infect the seeds in the inflorescence not only cause yield reductions but can restrict seed exports due to their
presence as seed contaminants. By understanding how pathogens infect grass seed plants and how the pathogens spread, effective alternative options can be developed to replace dependency on chemical fungicides as the sole means of control. Our research concerns disease control, based on cultural practices and genetic resistance and development of science-based decision aids to minimize fungicide applications. Goals of the project include: 1) characterize the physical interactions that impact resistance of selected Kentucky bluegrass cultivars to Claviceps purpurea, 2) develop a biological and epidemiological understanding of the infection process, epidemiology, and host range of Epichloe and evaluate cultural disease controls, 3) develop a seed separation protocol to remove galls of Anguina or Rathayibacter from orchardgrass seed, 4) create and implement a stem rust model to optimize timing of fungicidal sprays for effective rust control with minimal applications, and 5) determine the
genetic variability of Puccinia graminis subsp. graminicola on grasses grown for seed. The research is coded 60% NP303 Plant Disease and 40% NP 205 Rangeland and addresses the following research needs as defined in the National Program Action Plan: 1) to study the genetic variability of isolates of the rust fungus from perennial ryegrass and tall fescue in order to guide further research with host resistance, 2) to better understand the host- parasite relations of ergot with Kentucky bluegrass, 3) to improve precision agriculture decisions and optimize pesticide use and timing for control of stem rust in perennial ryegrass and tall fescue through epidemiological studies of stem rust, 4) to conduct biological and epidemiological research on choke disease of orchardgrass and develop biologically-based management decisions. The research benefits growers through improved means of cost-effective disease control, benefits consumers through healthy grass seed, and benefits society through
reduction in pesticide usage and improvements in disease control through emphasis on cultural management. 2. List the milestones (indicators of progress) from your Project Plan. This project was terminated 3/10/2004 (Normal Progression) and replaced by CRIS project 5358-22000-031-00D approved through the OSQR process. Milestones are listed for continuity. Year 1 (FY 2003 beginning August 2002) Survey commercial fields for choke Establish field plots for ergot and choke studies Determine the effect of temperature on expression of choke in orchardgrass Determine efficiency of removal of galls of Anguina during harvest Determine efficiency of removal of galls of Anguina during seed cleaning Determine efficiency of removal of galls of Anguina during harvest Determine efficiency of removal of galls of Anguina during seed cleaning Determine the duration of susceptibility of Kentucky bluegrass to ergot. Determine the effect of pollination on susceptibility of Kentucky bluegrass to ergot.
Evaluate management practices for choke control Derive algorithms relating weather parameters to stem rust epidemic Incorporate management measures into stem rust epidemic model inputs Quantify spatial development of infection foci of stem rust in perennial ryegrass Develop a yield loss function for stem rust on perennial ryegrass seed crops Test and validate the rust epidemic model under commercial grower contributions Year 2 (FY 2004) Complete survey of commercial fields for choke Complete determination of efficiency of removal of galls of Anguina during harvest Complete determination of efficiency of removal of galls of Anguina during seed cleaning Continue to determine the duration of susceptibility of Kentucky bluegrass to ergot. Continue to determine the effect of pollination on susceptibility of Kentucky bluegrass to ergot. Determine whether infection of orchardgrass by Epichloe typhina occurs through injured or cut leaves or stems. Continue to evaluate management practices for
choke control Continue to derive algorithms relating weather parameters to stem rust epidemic Continue to incorporate management measures into stem rust epidemic model inputs Continue to quantify spatial development of infection foci of stem rust in perennial ryegrass Continue to develop a yield loss function for stem rust on perennial ryegrass seed crops Continue to test and validate the rust epidemic model under commercial grower contributions Year 3 (FY 2005) Continue to determine the duration of susceptibility of Kentucky bluegrass to ergot. Continue to determine the effect of pollination on susceptibility of Kentucky bluegrass to ergot. Continue to determine whether infection of orchardgrass by Epichloe typhina occurs through injured or cut leaves or stems. Continue to evaluate management practices for choke control Continue to derive algorithms relating weather parameters to stem rust epidemic Continue to incorporate management measures into stem rust epidemic model inputs
Continue to quantify spatial development of infection foci of stem rust in perennial ryegrass Complete a yield loss function for stem rust on perennial ryegrass seed crops Continue to test and validate the rust epidemic model under commercial grower contributions Isolate and purify cultures of Puccinia graminis subsp. graminicola from perennial ryegrass Evaluate and choose perennial ryegrass clones resistant to rust Identify a differential series of host clones resistant to rust Year 4 (FY 2006) Continue determination of the duration of susceptibility of Kentucky bluegrass to ergot. Continue determination of the effect of pollination on susceptibility of Kentucky bluegrass to ergot. Continue to determine whether infection of orchardgrass by Epichloe typhina occurs through injured or cut leaves or stems. Complete Evaluation of management practices for choke control Complete derivation of algorithms relating weather parameters to stem rust epidemic Continue to incorporate management
measures into stem rust epidemic model inputs Continue to quantify spatial development of infection foci of stem rust in perennial ryegrass Continue to test and validate the rust epidemic model under commercial grower contributions Continue to isolate and purify cultures of Puccinia graminis subsp. graminicola from perennial ryegrass Continue to evaluate and choose perennial ryegrass clones resistant to rust Continue to identify a differential series of host clones resistant to rust Year 5 (FY 2007) Complete determination of the duration of susceptibility of Kentucky bluegrass to ergot. Complete determination of the effect of pollination on susceptibility of Kentucky bluegrass to ergot. Complete determination of the effect of temperature on expression of choke in orchardgrass Complete incorporation of management measures into stem rust epidemic model inputs Complete quantification of spatial development of infection foci of stem rust in perennial ryegrass Complete testing and
validation of the rust epidemic model under commercial grower contributions Complete Isolation and purification of cultures of Puccinia graminis subsp. graminicola from perennial ryegrass Complete evaluation and choosing of perennial ryegrass clones resistant to rust Complete identification of a differential series of host clones resistant to rust 3. Milestones: A. The milestones scheduled to be addressed in FY 2004 include: Complete survey of commercial fields for choke Complete determination of efficiency of removal of galls of Anguina during harvest Complete determination of efficiency of removal of galls of Anguina during seed cleaning Continue to determine the duration of susceptibility of Kentucky bluegrass to ergot. Continue to determine the effect of pollination on susceptibility of Kentucky bluegrass to ergot. Determine whether infection of orchardgrass by Epichloe typhina occurs through injured or cut leaves or stems. Continue to evaluate management practices for choke
control Continue to derive algorithms relating weather parameters to stem rust epidemic Continue to incorporate management measures into stem rust epidemic model inputs Continue to quantify spatial development of infection foci of stem rust in perennial ryegrass Continue to develop a yield loss function for stem rust on perennial ryegrass seed crops Continue to test and validate the rust epidemic model under commercial grower contributions Data collection was completed for the choke survey. Choke in orchardgrass was first reported in seed production fields in 1998. The survey verifies that the disease has spread quickly among commercial seed production fields and is increasing within fields. Management of choke depends on an understanding of the dynamics of disease spread and increase. Results from this study provide important information on the ability of choke to develop among seed production fields. Collection of field samples was completed for studies to determine the efficiency
of removal of galls of Anguina during harvest and seed cleaning. Since sample collection occurred though July, 2004, we have not yet had time for data compilation and analysis. Studies of Kentucky bluegrass were offset by one year due to sulfur burn from inadvertent use of the wrong sulfur product in the greenhouse that resulted in loss of all plant material. New plants were established. Studies concerning the infection of orchardgrass by Epichloe were initiated. The studies are ongoing and will continue into 2005. A second year of field studies to evaluate management practices for choke control was completed. Since sample collection occurred through July, 2004, we have not yet had time for data compilation and analysis. Studies concerning rust (modeling effects of weather parameters and management measures, development of yield loss function, and model validation under commercial conditions) are on schedule, except for infection foci studies which have been delayed due to poor stand
establishment in field plots. B. Milestones to be addressed over the next 3 years (FY 2005, 2006, and 2007) are detailed in the annual report for the replacement project 5358- 22000-031-00D. 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2004: This project was terminated 3/10/2004 (Normal Progression) and replaced by CRIS project 5358-22000-031-00D. The most significant accomplishments for FY2004 are detailed in the annual report for the replacement project. B. Other significant accomplishments: This project was terminated 3/10/2004 (Normal Progression) and replaced by CRIS project 5358-22000-031-00D. Other significant accomplishments for FY2004 are detailed in the annual report for the replacement project. C. Significant activities that support special target populations: None D. Progress Report: None 5. Describe the major accomplishments over the life of the project, including their predicted or actual
impact. Surveys of choke in orchardgrass were completed. Choke was first reported in orchardgrass seed production fields in 1997. Surveys indicated that choke is present in nearly all orchardgrass fields and that the disease continues to increase annually in infested fields. This information is important to growers in evaluating the number of consecutive years that a field can be maintained. A method was developed to extract and quantitatively estimate the level of infection of Anguina and Rathayibacter in orchardgrass seed lots. Export of grass seed to some countries can be prevented by the presence of Anguina in the seed. The method provided for the first time, a means to quantitatively estimate the percentage of galls in orchardgrass seed and provided the first quantitative estimates of number of galls present in commercial field samples. The method is especially important for population studies and assessment of management practices for nematode control. Algorithms were derived to
relate weather parameters to stem rust epidemic. Initiation of rust is weather dependent and understanding the effect of weather parameters is essential to predicting rust onset. Algorithms were derived that relate overnight and early morning temperature and moisture to stem rust infection levels. This information was incorporated into a stem rust prediction model currently used by growers. Additional management measures were incorporated into a stem rust epidemic model. Stem rust is a devastating disease of grasses and depends on fungicides for disease control, although cultural management approaches may also aide in disease control. We determined that the major proportion of final disease severity derives from a previously unknown process of within-plant spread of the disease. The effect of fungicides on this process was measured, and incorporated into a management model for stem rust control. Adjustment of planting date was determined to be an important cultural management measure
for stem rust in perennial ryegrass. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? The current version of a model for stem rust development, including fungicide effects, is now available on an interactive website. End-users (growers, farm advisers, extension agents) now have access to this model, which incorporates research done under this CRIS, to aid in disease management decision-making. In the future, revised versions of the model will be produced to incorporate additional research results and refinements from validation studies. The website has been presented to end-users by means of individual meetings with extension agents, experiment farm Field Day, and an interview with a local agricultural newspaper. The log for the website for April -
June 2004 shows that there were 77 unique visitors to the site, and the predictive model was run over 400 times (these numbers do not include use by USDA or OSU personnel) . 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. Alderman, S.C., Ocamb, C.M. Yield loss estimates associated with panicle diseases of orchardgrass. 2004. In 2003 Seed Production Research at Oregon State University, USDA-ARS Cooperating. Department of Crop and Soil Science Ext/CrS. 123. p. 49. Pfender, W. Fall planting date affects spring stem rust level in first- year perennial ryegrass. 2004. In 2003 Seed Production Research at Oregon State University, USDA-ARS Cooperating. Department of Crop and Soil Science Ext/CrS. 123. p. 41-43. Pfender, W. Rapid rust increase after flowering is due to spread within a plant, not change in susceptibility. 2004. In 2003 Seed Production Research at Oregon State University, USDA-ARS
Cooperating. Department of Crop and Soil Science Ext/CrS. 123. p. 44-45. Pfender, W. Importance of plant growth stage in effectiveness of fungicides for rust control. Presentation given at the Oregon Seed Growers League Annual Meeting, Portland, Oregon, December 8, 2003.
Impacts
(N/A)
Publications
- Alderman, S.C., Halse, R.R., White, J.F. 2004. A reevaluation of the host range and geographical distribution of claviceps species in the united states. Plant Disease.88:63-81.
- Pfender, W.F. Role of phenology in host susceptibility and within-plant spread of stem rust during reproductive development of perennial ryegrass. Phytopathology.2004.94:308-316.
- Alderman, S.C., Barker, R.E. 2003. Evaluation of resistance to claviceps purpurea in kentucky bluegrass based on incidence and severity estimates. Plant Disease.87:1043-1047.
- Ocamb, C.M., Alderman, S.C. 2004. Fusarium species associated with tall fescue seed production in oregon. Plant Health Progress. doi:10.1094/PHP- 2004-0319-01-RS.
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Progress 10/01/02 to 09/30/03
Outputs
1. What major problem or issue is being resolved and how are you resolving it? Grass seed is an important commodity utilized in lawns, golf courses, pastures, parks, and used for soil stabilization in the U.S. and around the world. Production of grass seed is centralized in the Pacific Northwest states and can be significantly limited by several fungal diseases that attack the plants and their seeds. By understanding how pathogens infect grass seed plants and spread, effective alternative options can be developed to replace dependency on chemical fungicides as the sole means of control. Our research concerns disease control, based on cultural practices and genetic resistance and through development of science-based decision aids to minimize fungicide applications. 2. How serious is the problem? Why does it matter? Grass seed production would not be possible without fungicide applications to control stem rust. Stem rust causes losses as great as 95% in ryegrass and
40% in tall fescue. A disease of orchardgrass, choke, can reduce seed yields in excess of 30% by the third year of production and no methods are yet available to control this disease. Other organisms that specifically infect the seeds not only cause yield reductions but restrict seed exports due to their presence as seed contaminants. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? This research contributes to the National Program 303, Plant Diseases (60%) and NP205 Rangeland, Pasture and Forages (40%). The research addresses cultural control, pathogen characterization, and host plant resistance 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY2003 year. Stem rust is the most important disease constraint to production of cool- season grass seed, and information is needed about conditions regulating disease development so that fungicide is applied only
when necessary. In research at the USDA/ARS National Forage Seed PProduction Research Center, laboratory and field studies quantied the development and spread of the pathogen within and among individual host plants. We determined that, at a critical point early during the epidemic development, spread of the pathogen within plants is more significant than aerial dispersal of spores among plants. This discovery provided critical new information in our effort to develop a disease-advisory and fungicide decision tool to enable grass seed producers to control this disease in the most economic manner. B. Other significant accomplishments. Currently there is no information on the population dynamics of Anguina, a nematode that infects orchardgrass plants by reproducing in the developing seeds and replacing seeds with galls containing large numbers of the nematodes. We conducted extensive field surveys and quantified the population of galls in commercial orchardgrass fields. This research
showed that 50 to 70% of the nematode galls were returned to the field during commercial harvest of the grass seed. This study provided new knowledge on the population dynamics of Anguina and suggested that improvements to harvest operations will help remove galls from infected fields. Very little is known about choke, a serious new disease in orchardgrass, an important forage grass used for livestock production. Scientists at the USDA/ARS NFSPRC conducted field surveys and to learn more about how the disease is spread in seed producing fields in the Willamette Valley of Oregon. This research showed that the disease has spread from commercial fields into naturalized populations of orchardgrass in the foothills surrounding the Willamette Valley. This study provides important information on how this new pathogen is emerging within a geographical area and how this spread contributes to new sources of infection. C. None D. None 5. Describe the major accomplishments over the life of the
project, including their predicted or actual impact. Stem rust was identified as a serious pathogen on several cool season grasses grown for seed. We have shown the effect of low winter temperature and key spring weather variables on disease development and these findings will be used to develop a disease warning system to help growers reduce the number of fungicide applications. We also found that delaying autumn planting date may reduce the severity of spring stem rust epidemics in perennial ryegrass. An infection model was developed that successfully correlates amounts of infection with the overnight and early morning temperature and moisture measured by automated weather stations in grass seed fields. A new leaf spot disease of hard fescue, which first appeared in 1998, was investigated and fungicides were identified for effective leaf spot control. The discovery of choke disease on orchardgrass for the first time in Oregon, and the subsequent quantification of its distribution
and severity, is very important for growers and users of orchardgrass seed nationwide. We determined that systemic fungicides are not effective for control of choke, suggesting that a non-pesticide approach will be required to manage this disease. A method was developed to extract and quantitatively estimate the level of infection of Anguina and Rathayibacter in orchardgrass seed lots, providing for the first time, a means to quantitatively estimate the percentage of galls in orchardgrass seed. The method provides the means to obtain nematodes for studies on the biology, ecology, and control of Anguina. 6. What do you expect to accomplish, year by year, over the next 3 years? In 2004, the mode of entry of Epichloe into orchardgrass will be determined. The potential growth of Epichloe on leaf sheaths will be determined. The stem rust model will be tested at several locations in western Oregon and its use as a management tool will be assessed. Regional maps comparing actual rust
observations with model epidemic development will be constructed. Field experiments to assess the importance of overwinter survival for rust epidemic onset will be done. Yield loss in orchardgrass, due to infection from Anguina, will be determined. The duration of susceptibility of cultivars of Kentucky bluegrass to ergot will be determined. In 2005, a mathematical model for rust spore dispersal will be constructed, and combined with other submodels to produce a provisional stem rust epidemic model. The effect of post harvest residue management treatments for control of choke will be determined. The establishment and spread of newly emergent pathogen of orchardgrass choke disease will be quantified and mapped. The effect of pollination on susceptibility of Kentucky bluegrass to ergot will be determined. In 2006, host physical attributes that could impact resistance of Kentucky bluegrass to ergot will be investigated to determine if these attributes affect genotypic differences in
susceptibility. The spatial increase of stem rust foci will be described and modeled mathematically. Genetic variability in the rust population will be assessed with the use of genetically pure rust isolates and host genotypes. 7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? We used presentations at meetings and farm visits to instruct growers and industry field scouts how to recognize diseases of grass seed crops. Research presentations on weather-based modeling of rust epidemics were made at Oregon State University Experiment Station Field Day and at 3 other grower/industry meetings in the area. We cooperated with industry groups and Oregon State University Extension, calculating rust hazard indices with data from their automated weather stations.
8. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: This does not replace your peer-reviewed publications listed below). Alderman, S.C., Pfender, W.F. Grass Diseases. In Grass Seed Crops Insect Disease Notebook, Mellbye, M., Gingrich, G., Young, W.C., III, ed., OSU Extension Service, December, 2002. Ocamb, C., Alderman, S.C. Presented a verbal and written summary of orchardgrass stem rot disease at the Oregon State University Hyslop Field Day, May 28, 2003. Pfender, W.F., Alderman, S.C. Presented a summary of Research Progress and current outlook for diseases of orchardgrass at the Oregon Seed Growers League annual meeting, December 10, 2002. Schmitz, J. Model helps grass seed growers decide when to treat for rust, Salem Capital Press, October 25, 2002.
Impacts
(N/A)
Publications
- ALDERMAN, S.C., BILSLAND, D.M., GRIESBACH, J.A., MILBRATH, G.M., SCHAAD, N. W., POSTNIKOVA, E. USE OF A SEED SCARIFIER FOR DETECTION AND ENUMERATION OF GALLS OF ANGUINA AND RATHAYIBACTER SPECIES IN ORCHARD GRASS SEED. PLANT DISEASE. 2003. v.87. p. 375-379.
- PFENDER, W.F. PREDICTION OF STEM RUST INFECTION SEVERITY IN PERENNIAL RYEGRASS, BASED ON OVERNIGHT AND POST-SUNRISE DEGREE-HOURS OF MOISTURE DURATION. PHYTOPATHOLOGY. 2003. v. 93. p. 467-477.
- PFENDER, W.F., ALDERMAN, S.C. EVALUATION OF POST-HARVEST BURNING OR FUNGICIDES TO REDUCE POLYETIC EPIDEMIC RATE IN ORCHARDGRASS CHOKE DISEASE. PLANT DISEASE. 2002. v.87. p. 375-379.
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Progress 10/01/01 to 09/30/02
Outputs
1. What major problem or issue is being resolved and how are you resolving it? Grass seed production is centralized in the Pacific Northwest states but can be significantly limited by several fungal diseases that attack the plants and their seeds. Grass seed is an important commodity utilized in lawns, golf courses, pastures, parks, and used for soil stabilization in the U.S. and around the world. By understanding how pathogens infect grass seed plants and spread, effective alternative options can be developed to replace dependency on chemical fungicides as the sole means of control. Our research concerns disease control, based on cultural practices and genetic resistance and through development science-based decision aids to minimize fungicide applications. 2. How serious is the problem? Why does it matter? Grass seed production would not be possible without fungicide applications to control stem rust. Stem rust causes losses as great as 95% in ryegrass and 40% in
tall fescue. A disease of orchardgrass, choke, can reduce seed yields in excess of 30% by the third year of production and no methods are yet available to control this disease. Other organisms that specifically infect the seeds in the inflorescence not only cause yield reductions but can restrict seed exports due to their presence as seed contaminants. 3. How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? This research contributes to the National Program 303, Plant Diseases (60%) and NP205 Rangeland, Pasture and Forages (40%). The research addresses cultural control, pathogen characterization, and host plant resistance. 4. What was your most significant accomplishment this past year? Stem rust is the most important disease constraint to production of cool- season grass seed, and information is needed about conditions regulating infection so that fungicide applications can be made only when necessary. In research at NFSPRC,
field studies were conducted to identify and measure weather variables that determine infection probability for stem rust of perennial ryegrass seed crops. An infection model was developed that successfully correlates amount of infection with the overnight and early morning temperature and moisture measured by automated weather stations in grass seed fields. This infection model will be the central component of a disease-advisory and fungicide decision tool for managing stem rust in grass seed fields. Other significant accomplishments: A method developed last year to remove galls of Anguina and Rathayibacter was applied to collect galls for identification and characterization of the nematode and bacterial species, and to estimate within-field populations. The number of galls per gram of seed from orchardgrass seed production fields was determined. Galls collected during the study will provide the basis for description of a new species of Anguina. The ability of quantify galls
provides a means of assessing and comparing the effectiveness of cultural or chemical approaches for control of Anguina or Rathayibacter. Choke disease, caused by Epichloe typhina, is detrimental to orchardgrass seed production, and management methods are needed to prolong the useful life of seed fields. Scientists at NFSPRC tested several possible cultural management methods in a three-year field study. Propane-assisted burning of post-harvest stubble and vegetation reduced the year-to-year spread of choke disease in orchardgrass by about 70%. This research provides one option for cultural management of this disease, and suggests the importance of post-harvest residue treatments in disease management. To evaluate resistance of Kentucky bluegrass to the fungal disease ergot, efficient and reliable assessment methods must be identified. Methods of ergot assessment were compared for within and between year variability. A ranking of 104 cultivars of Kentucky bluegrass for resistance to
ergot, based on four years of field observations, was completed and susceptibility of Kentucky bluegrass to ergot was found to range from highly susceptible to highly resistant. Identification of susceptible and resistant cultivars will support further development of resistant cultivars and facilitate studies of the mechanism of resistance of Kentucky bluegrass to ergot. Significant accomplishments/activities that support special target populations: None 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact? Stem rust was identified as a major pathogen on several cool season grasses grown for seed. We have shown the effect of low winter temperature and key spring weather variables on disease development and these findings will be used to develop a disease warning system that can be used by growers to reduce the number of fungicide applications. We also found that delaying autumn planting date may reduce the severity of spring
stem rust epidemics in perennial ryegrass. A new leaf spot disease of hard fescue, which first appeared in 1998, was investigated and fungicides were identified for effective leaf spot control. The discovery of choke disease on orchardgrass for the first time in Oregon, and the subsequent quantification of its distribution and severity, is very important for growers and users of orchardgrass seed nationwide. We determined that systemic fungicides are not effective for control of choke, suggesting that a non-pesticide approach will be required to manage this disease. A method was developed to extract and quantitatively estimate the level of infection of Anguina and Rathayibacter in orchardgrass seed lots, providing for the first time, a means to quantitatively estimate the percentage of galls in orchardgrass seed. The method provides the means to obtain nematodes for studies on the biology, ecology, and control of Anguina. 6. What do you expect to accomplish, year by year, over the
next 3 years? In 2003, GFP modified strains of Epichloe will be produced to facilitate studies of the infection of orchardgrass by the pathogen. Longevity of the spores of Epichloe under various environmental conditions will be determined. In stem rust research, the effect of fall planting date on spring epidemic development will be verified and quantified. The relationship of rust severity to seed yield loss will be determined. Temporal effects of pre- and post-infection fungicide application will be quantified for inclusion in the rust model. Species of Claviceps occurring in the U.S. will be determined and their geographical and host range distribution in the U.S defined. In 2004, the mode of entry of Epichloe into orchardgrass will be determined. A mathematical model for rust spore dispersal will be constructed, and combined with other submodels to produce a provisional stem rust epidemic model. The stem rust model will be tested at several locations in western Oregon and its use
as a management tool will be assessed. Regional maps comparing actual rust observations with model epidemic development will be constructed. Field experiments to assess the importance of overwinter survival for rust epidemic onset will be done. . In 2005, genetic variability in the rust population will be assessed with the use of genetically pure rust isolates and host genotypes. The spatial increase of stem rust foci will be described and modeled mathematically. The effect of post harvest residue management treatments for control of choke will be determined. The efficiency of insects as vectors of Claviceps purpurea will be determined. Host physical attributes that could impact resistance of Kentucky bluegrass to ergot will be investigated to determine if these attributes affect genotypic differences in susceptibility. 7. What technologies have been transferred and to whom? When is the technology likely to become available to the end user (industry, farmer other scientist)? What
are the constraints, if known, to the adoption durability of the technology? We used presentations at meetings and farm visits to instruct growers and industry field scouts how to recognize choke disease. Research presentations on weather-based modeling of rust epidemics were made at Oregon State University Experiment Station Field Day and at 2 other grower/industry meetings in the area. We cooperated with two different industry groups, calculating rust hazard indices with data from their automated weather stations. A Memorandum of Understanding for work on stem rust management was implemented with a company that produces automated weather stations and disease-management software. 8. List your most important publications and presentations, and articles written about your work (NOTE: this does not replace your review publications which are listed below) Alderman, S.C. Blind seed disease. USDA-ARS Miscellaneous Publication Number 1567. 2001. 32p. Alderman, S.C. and D.M. Bilsland.
Separation of Anguina from orchardgrass seed. W.C. Young III, ed. Dept. Crop & Soil Science Ext/Crs. 2002. 121:81. (technical report). Pfender, W.F., Alderman, S.C. Tests of propane burning or fungicides to reduce orchardgrass choke disease. W.C. Young III, ed. Dept. Crop & Soil Science Ext/Crs. 2002. 121:74-77. (technical report). Mellbye, M. Stem rot of orchardgrass. Update. Linn Co. Extension Newsletter. 2002.
Impacts
(N/A)
Publications
- Butler, M.D., Alderman, S.C., Hammond, P.C., Berry, R.E.. Association of insects and ergot (Claviceps purpurea) in Kentucky bluegrass seed production fields. Journal of Economic Entomology. 2002. v.94. p.1471-1476.
- Duncan, R.A., Sullivan, R., Alderman, S.C., Spatafora, J.W., White, J.F. Jr. Claviceps purpurea var. spartinae var. nov.: an ergot adapted to the aquatic environment. Mycotaxon. 2002. v.81. p.11-25.
- Martin, S.B., Stowell, L.J., Gelernter, W.D., Alderman, S.C. Rapid blight: a new disease of cool season turfgrasses. Phytopathology. 2002. v.92. Abstract S53.
- Pfender, W.F., Whittaker, G. Local focus expansion rates in grass stem rust estimated with nonparametric spatial analysis. Phytopathology. 2002. v.92. Abstract S65.
- Pfender, W. Host range differences between populations of Puccinia graminis subsp. graminicola obtained from perennial ryegrass and tall fescue. Plant Disease. 2001. v.85. p.993-998.
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