Progress 10/01/06 to 09/30/11
Outputs
OUTPUTS: Objectives: 1) study the pathogen biology and epidemiology of, 2) investigate the genetics of disease resistance to: the major fungal pathogens of the small grains cereals in the Northern Great Plains, and 3) develop integrated management strategies for: the major fungal pathogens of the small grains cereals in the Northern Great Plains. Two activities were conducted to address objective #1. The first involved the study to investigate the relationship between inoculum load and i) final disease development and ii) mycotoxin accumulation in the grain. The study was conducted in both greenhouse and field environments and included both wheat and malting barley cultivars that varied in their level of resistance. In addition, samples collected in 2009 were evaluated for G. zeae biomass using real-time PCR in an effort to identify any relationship between fungal biomass, disease, and mycotoxin. The second activity involved the collection of isolates for the major rust diseases of wheat and oats from South Dakota. These isolates were then shared with scientists at the USDA-ARS Cereal Disease Lab for race determination. Isolates were also collected for tan spot and Septoria leaf blight. These will be used for germplasm evaluation efforts in the future. Two activities were conducted to address objective #2. First, each year we directly rated or assisted with the evaluation of several thousand lines of spring wheat, winter wheat, and oats (combined) for disease susceptibility to multiple pathogens. The second activity was to generate adapted germplasm with multiple, or novel, disease resistance. We worked collaboratively with the SDSU spring wheat breeder and a crop geneticist to introgress three novel sources of FHB resistance into regionally adapted germplasm. We advanced several of the crosses and generated multiple mapping populations. We also identified or procured seed of wheat and oat lines with slow-rusting resistance and initiated crosses. This material was shared with all programs for inclusion into their crossing blocks. In addition, we generated crosses between adapted spring wheat cultivars and lines from CIMMYT that are known to have novel genes for resistance to wheat stem rust. These were then advanced and evaluated in the field. We also generated a mapping population using a potentially novel source of resistance to common root rot of wheat. Additionally, several oat lines with durable rust resistance were obtained and provided to the SDSU oat-breeding project. Two activities were conducted to address objective #3. The first was to conduct foliar fungicide trials for stem rust of wheat and oats. We evaluated many of the currently registered fungicides using two different nozzle arrangements, i.e. standard flat-fan and twinjet types. The final activity was to evaluate seed treatment fungicides for efficacy against common root rot in spring wheat, winter wheat, and barley. Of particular interest is the efficacy of these fungicides in controlling seedling blight and limiting any subsequent winterkill in winter wheat since this combination continues to be an issue in the region. PARTICIPANTS: Major Project Contributors: Jeffrey Stein, Ex-Principle Investigator - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the projects related to the sources and genetics of disease resistance. Lawrence Osborne, Research Associate - Designed, rated, and analyzed several of the experiments in 2007. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Chris Nelson, Support Staff - Designed, rated, and analyzed several of the experiments in 2008-09. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Krishna Bondalapati, Support Staff - Designed, rated, and analyzed several of the experiments in 2010. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Graduate Students: Vivek Gupta and Prabin Tamang. Partner Organizations: The South Dakota Wheat Commission, Minnesota Wheat Research and Promotion Council, and the U.S. Wheat and Barley Scab Initiative (USDA-ARS) through support of related research activities. Collaborators: Karl Glover, SDSU Spring Wheat Breeder; Amir Ibrahim, Ex-SDSU Winter Wheat Breeder; Bill Berzonsky, SDSU Winter Wheat Breeder; Dennis Todey, SDSU Extension State Climatologist; Larry Osborne, Ex-SDSU Extension Plant Pathologist; Lon Hall, SDSU Oats Breeder; Bob Hall, SDSU Extension Agronomist ; Jose Gonzalez, SDSU Crop Geneticist; Yue Jin and Jim Kolmer, USDA-ARS, St. Paul, MN; Xiaming Chen, USDA-ARS, Pullman, WA. Training: The PI of this project provided disease-scouting training for the major foliar diseases of the small grain cereals to Crop Consultants, Certified Crop Inspectors, South Dakota Department of Agriculture Survey Specialists, and USDA-APHIS Crop Inspectors. Approximately 80 individuals attended these events. The PI also mentored four graduate students at SDSU who were conducting research related to this topic area. TARGET AUDIENCES: The primary target audiences for this research project are growers in South Dakota, and the region, that plant small grains cereals. Additionally, our efforts also impact Crop Consultants, Private Agronomists, and Extension Educators/Agents. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Objective #1: We have verified studies by others demonstrating that FHB severity tends to peak when about 50,000 spores/ml, with additional spores not significantly increasingly the number of blighted florets. In contrast, mycotoxin accumulation in the final grain samples was found to increase with the higher inoculum concentrations. This discovery may explain the phenomenon of inconsistent relationship between disease severity and mycotoxin concentrations. We developed mathematical functions that can be used to predict the incidence and severity of Fusarium head blight in wheat based on the number of G. zeae propagules present on the spikes during flowering. Similarly, we found that deoxynivalenol concentration increased in a linear manner in relationship to inoculum dosage. When the impact of varietal resistance was examined, the slopes of these functions were found to differ with the moderately resistant wheat genotype having a lower slope for all three factors. We confirmed that resistance in malting barley also reduces both disease development and deoxynivalenol accumulation in response to G. zeae inoculum dose. Mycotoxin accumulation was reduced by approximately 50% at the highest inoculum dosage. This reinforces the general recommendation that growers should plant resistant varieties of both wheat and malting barley as this practice may reduce both the level of disease that develops, and probably final mycotoxin concentration in the grain. The information generated from the sampling of rust isolates and race determination by the USDA-ARS-CDL, also part of objective #1, will be utilized to make informed recommendations to the SDSU wheat and oat breeders concerning the selection and introgression of effective rust resistance genes into elite germplasm and future varieties. We have also added the isolates collected to our bulk inoculum mixture for screening germplasm against these pathogens. Objective #2: The SDSU wheat breeders made selections out of the populations we generated which contained novel sources of wheat stem rust resistance. Additional sources for stem and leaf rust resistance have been obtained and will be introgressed into adapted germplasm in the future. Additionally, the crosses performed with novel sources of FHB resistance will eventually be pyramided with the Sumai3-based FHB resistance that is common in the regional breeding programs. Similalry, we now have a better nderstanding of the variability of common root rot, crown rot, and Pythium susceptibility in the spring wheat cultivars grown in the state. Objective #3: We found that the currently available fungicides are fairly effective at controlling the disease. However there was not always a strong relationship between disease control and yield and therefore further research is necessary in this area to better understand the management of this disease. In the seed treatment trial, we found that many of the commercially available fungicides are effective are limiting losses in spring wheat. This lower level of efficacy may be a related to spring infections after the fungicides have been metabolized by the plant.
Publications
- Tamang, P. 2011. Virulence pattern of Cochliobolus sativus in eastern South Dakota and assessing the genetic resistance to spot blotch. MS thesis. South Dakota State University, Brookings, SD.
- Bondalapati, K., Stain J.M., Neate, S., Halley, S.A., Osborne, L.E., Hollingsworth, C. 2011. Development of weather-based predictive models for Fusarium head blight and deoxynivalenol accumulation for spring malting barley. Plant Dis. DOI: 10.1094/PDIS-05-11-0389.
|
Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Major research emphases in 2010 were to: 1) study the pathogen biology and epidemiology of and 2) investigate the genetics of disease resistance to: the major fungal pathogens of the small grains cereals in the Northern Great Plains. Two primary activities were conducted to address objective #1 (pathogen biology & epidemiology). The first (item A) was a continuation of a study initiated in 2007 which attempted to determine the relationship between Gibberella zeae inoculum dosage and i) final disease development and ii) mycotoxin accumulation in the grain. The 2010 effort was conducted in the field at two locations and included both wheat and malting barley cultivars that varied in their level of resistance to G. zeae. The plants were inoculated with varying doses of the pathogen and evaluated for disease, mycotoxin accumulation in the grain, and yield. Mycotoxin analysis is underway. In addition, samples collected from a similar study in 2009 were evaluated for G. zeae biomass using real-time PCR in an effort to identify any relationship between fungal biomass, disease, and mycotoxin. The second (item B) was the collection of isolates for the major rust diseases of wheat and oats (leaf, stem, stripe, and/or crown) from producer's fields and research plots throughout South Dakota. Some of these isolates were shared with scientists at the USDA-ARS for race determination. Isolates were also collected for tan spot and Septoria leaf blight. These will be used for germplasm evaluation efforts in the future. Two primary activities were conducted to address objective #2 (genetics of disease resistance). The first (item C) was the evaluation of breeding material for susceptibility to the major fungal pathogens of the small grain cereals in South Dakota. In 2010, we directly rated or assisted with the evaluation of several thousand lines (combined) of spring wheat, winter wheat, and oats for disease susceptibility to multiple pathogens. This consisted of both field evaluations and greenhouse inoculations. The principle diseases evaluated were the rusts, Fusarium head blight, leaf blights, and common root and Fusarium crown rot. The second activity (item D) was to generate adapted wheat germplasm with multiple, or novel, disease resistance traits. In 2010, we continued to work collaboratively with the SDSU spring and winter wheat, and also oat, breeding programs on this effort. Specifically, we generated crosses between adapted spring wheat cultivars and several wheat lines from CIMMYT that are known to have novel genes for resistance to wheat stem rust. These were then advanced and evaluated in the field. In addition, several oat lines with durable rust resistance were obtained and provided to the SDSU oat breeding project. PARTICIPANTS: Major Project Contributors: Jeffrey Stein, Principle Investigator - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the projects related to the sources and genetics of disease resistance. Krishna Bondalapati, Support Staff - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Graduate Students: Vivek Gupta, Ph.D. Candidate Prabin Tamang, M.S. Candidate Partner Organizations: The South Dakota Wheat Commission, South Dakota Crop Improvement Association, Minnesota Wheat Research and Promotion, and U.S. Wheat and Barley Scab Initiative (USDA-ARS) through support of related research activities. Collaborators: Bill Berzonsky, SDSU Winter Wheat Breeder; Karl Glover, SDSU Spring Wheat Breeder; Lon Hall, SDSU Oats Breeder; Larry Osborne, SDSU Extension Plant Pathologist; Jose Gonzalez, SDSU Crop Geneticist; Yue Jin and Jim Kolmer, USDA-ARS CDL, St. Paul, MN; Training: During the period in question, the PI also mentored eight graduate students at SDSU who were conducting research related to this topic area. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
From the activities conducted in 2010 as part of objective #1, item A (inoculum dosage), we found an association between the concentration of spores applied to the crop at flowering and the level of disease which developed. The latter was significantly lower for the resistant cultivars, indicating that high amounts of inoculum are needed to reach the same level of disease. This confers with out previous greenhouse studies. The grain samples are still being analyzed for toxin concentration. Concerning the fungal biomass study, we unable to find any associations between disease severity and G. zeae DNA, as measured by fungal biomass, and mycotoxin concentration in the grain. That stated, there were no differences in the level of disease in the 2009 study and therefore a lack of difference in the fungal biomass is not surprising. The information generated from the sampling of rust isolates and race typing by members of the USDA-ARS (objective #1, item B) will be utilized to make informed recommendations to the SDSU wheat and oat breeders concerning the selection and introgression of effective rust resistance genes into elite germplasm and future varieties. We have also added the isolates collected in 2010 to our bulk inoculum mixture for the greenhouse screening of advanced germplasm against these pathogens. Previous efforts to evaluate the sources and genetics of resistance (objective #2) for these diseases has resulted in the generation of breeding materials that have been, and are still being, used in the development of disease resistant varieties. Efforts in 2010 continued this trend. For example, we now have a better understanding of the variability of common root rot, crown rot, and Pythium susceptibility in the spring wheat cultivars grown in the state. The next step is to being to examine advanced germplasm to identify potentially useful parents for crosses. In addition, the SDSU wheat breeders made selections out of the populations we generated which contained novel sources of wheat stem rust resistance. These were sent to a winter nursery for increase and will be incorporated. Additional sources for stem and leaf rust resistance have been obtained and will be introgressed into adapted germplasm in the future.
Publications
- Stein, J.M., 2010. Common (dryland) root and foot rot and associated leaf and seedling diseases: Bipolaris sorokiniana. Compendium of Wheat Diseases and Insects: Third Edition. W.W. Bockus, R. Bowden, R. Hunger, T. Murray, W. Morrill, and R. Smiley (Editors). American Phytopathological Society, St. Paul, MN.
- Malla, S., A.M.H. Ibrahim, Y. Yen, W. Berzonsky, K.D. Glover, J. Stein. 2010. Quantitative Trait Loci Analysis of Novel Fusarium Head Blight Resistance in Tokai 66. Am. J. of Ag. Bio. Sci. 5:62-69.
|
Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Major research emphases in 2009 were to: 1) study pathogen biology and epidemiology of and 2) investigate the genetics of disease resistance to: the major fungal pathogens of the small grains cereals in the Northern Great Plains. Two activities were conducted to address objective #1 (pathogen biology & epidemiology). The first (item A) was an expansion of a study initiated in 2007 under greenhouse conditions which evaluated the relationship between Gibberella zeae inoculum dosage and i) final disease development and ii) mycotoxin accumulation in the grain. The 2009 effort was conducted in both greenhouse and field environments and included both wheat and malting barley cultivars that varied in their level of resistance. We hope to be able to validate our previous greenhouse research under field conditions and in both crops. Mycotoxin analysis is underway. The second (item B) was the collection of isolates for the major rust diseases of wheat and oats (leaf, stem, stripe, and/or crown) from producer's fields and research plots throughout South Dakota. These isolates were then shared with scientists at the USDA-ARS for race determination. Two activities were conducted to address objective #2 (genetics of disease resistance). The first (item C) was the evaluation of breeding material for susceptibility to the major fungal pathogens of the small grain cereals in South Dakota. In 2009, we directly rated or assisted with the evaluation of several thousand lines (combined) of spring wheat, winter wheat, and oats for disease susceptibility to multiple pathogens. This consisted of both field evaluations and greenhouse inoculations. The principle diseases evaluated were the rusts, Fusarium head blight, leaf blights, and to a lesser extent common root rot. The second activity (item D) was to generate adapted wheat germplasm with multiple, or novel, disease resistance. In 2009, we continued to work collaboratively with the SDSU spring and winter wheat breeding programs on this effort. Specifically, we continued to advance several crossings made in 2007 for FHB-resistance and initiated crosses using the durable stem rust germplasm obtained in 2008. PARTICIPANTS: Major Project Contributors: Jeffrey Stein, Principle Investigator - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the projects related to the sources and genetics of disease resistance. Chris Nelson, Support Staff - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Partner Organizations: The South Dakota Wheat Commission, South Dakota Crop Improvement Association, Minnesota Wheat Research and Promotion, and U.S. Wheat and Barley Scab Initiative (USDA-ARS) through support of related research activities. Collaborators: Karl Glover, SDSU Spring Wheat Breeder; Bill Berzonsky, SDSU Winter Wheat Breeder; Larry Osborne, SDSU Extension Plant Pathologist; Lon Hall, SDSU Oats Breeder; Jose Gonzalez, SDSU Crop Geneticist; Yue Jin and Jim Kolmer, USDA-ARS CDL, St. Paul, MN; Bob Hall, SDSU Extension Agronomist. Training: During the period in question, the PI also mentored six graduate students at SDSU who were conducting research related to this topic area. TARGET AUDIENCES: Target Audiences: The primary target audiences for this research project are growers in South Dakota, and the region, that plant small grains cereals. Additionally, our efforts also impact Crop Consultants, Private Agronomists, and Extension Educators/Agents. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
From the research conducted in 2009 as part of objective #1, item A (inoculum dosage), we have confirmed under greenhouse conditions that resistance in malting barley also reduces both disease development and deoxynivalenol accumulation in response to G. zeae inoculum dose. These relationships have yet to be mathematically characterized, however mycotoxin accumulation was reduced by approximately 50% at the highest inoculum dosage. This reinforces the general recommendation that growers should plant resistant varieties of both wheat and malting barley as this practice may reduce both the level of disease that develops, and probably final mycotoxin concentration in the grain. The information generated from the sampling of rust isolates and race typing by members of the USDA-ARS (objective #1, item B) will be utilized to make informed recommendations to the SDSU wheat and oat breeders concerning the selection and introgression of effective rust resistance genes into elite germplasm and future varieties. We have also added the isolates collected in 2009 to our bulk inoculum mixture for the greenhouse screening of advanced germplasm against these pathogens. Previous efforts at SDSU studying the sources and genetics of resistance (objective #2) for these diseases has resulted in the generation of breeding materials that have been, and are still being, used in the development of disease resistant varieties. Current efforts continue this trend. For example, the populations advanced in 2009 with novel sources of wheat stem rust resistance will eventually be incorporated into breeding programs in an effort to prepare for Ug99, and related, races of stem rust. This pro-active approach reduces the chance that major losses will occur to stem rust since elite germplasm will be available for development into varieties.
Publications
- Rosyara, U.R., J.L. Gonzalez, K.D, Glover, K. Gedye, and J.M. Stein. 2009. Family-based mapping of quantitative trait loci in plant breeding populations with resistance to Fusarium head blight in wheat as an illustration. Theor. Appl. Genet. 118:617-1631. DOI: 10.1007/s00122-009-1010-9.
- Babiker, E., A.M.H. Ibrahim, Y. Yen, and J. Stein. 2009. Development of a Microsatellite Marker for tagging stem rust resistance gene Sr35 in wheat. Aust. J. Crop Sci. 3:195-200.
- Stein, J.M., L.E. Osborne, K.D. Bondalapati, K.D. Glover, and C.A. Nelson. 2009. Fusarium Head Blight Severity and Deoxynivalenol Concentration in Wheat in Response to Gibberella zeae Inoculum Concentration. Phytopathology. 99:759-764. DOI: 10.1094/PHYTO-99-6-0759
|
Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Major research emphases in 2008 were to: 1) study pathogen biology and the epidemiology of, 2) investigate the genetics of disease resistance to, and 3) develop integrated management strategies for: the major fungal pathogens of the small grains cereals in the Northern Great Plains. Two activities were conducted to address objective #1 (pathogen biology & epidemiology). The first (item A) was a continuation of a study initiated in 2007 which evaluated the relationship between Gibberella zeae inoculum dosage and i) final disease development and ii) mycotoxin accumulation in the grain. The 2008 effort was expanded to include the impact of varietal resistance on this phenomenon. The second (item B) was the collection of isolates for the major rust diseases of wheat and oats (leaf, stem, stripe, and/or crown) from producer's fields and research plots throughout South Dakota. These isolates were then shared with scientists at the USDA-ARS for race determination. Two activities were conducted to address objective #2 (genetics of disease resistance). The first (item C) was the evaluation of breeding material for susceptibility to the major fungal pathogens of the small grain cereals in South Dakota. In 2008, we directly rated or assisted with the evaluation of several thousand lines of spring wheat, winter wheat, and oats (combined) for disease susceptibility to multiple pathogens. This consisted of both field evaluations and greenhouse inoculations. The principle diseases evaluated were the rusts, Fusarium head blight, leaf blights, and to a lesser extent common root rot. The second activity (item D) was to generate adapted wheat germplasm with multiple, or novel, disease resistance. In 2008, we continued to work collaboratively with the SDSU spring and winter wheat breeding programs on this effort. Specifically, we advanced several of the crosses made in 2007 to initiate the generation of multiple mapping populations. We also identified or procured seed of wheat and oat lines with potentially interesting traits (e.g. slow-rusting resistance). This latter material was shared with all programs for inclusion into their crossing blocks. Two activities were conducted to address objective #3 (integrated disease management strategies). The first (item E) was to conduct foliar fungicide trials for stem rust of wheat and oats. With the development of highly virulent races of stem rust in Africa (e.g. Ug99 / TTKS), it is very important that we understand how to mitigate losses in the unfortunate event that this race were to enter the U.S. and threaten wheat and barley production. As such, we evaluated many of the currently registered fungicides using two different nozzle arrangements, i.e. standard flat-fan and twinjet types. The final activity (item F) was to evaluate seed treatment fungicides for efficacy against common root rot in spring wheat, winter wheat, and barley. Of particular interest is the efficacy of these fungicides in controlling seedling blight and limiting any subsequent winterkill in winter wheat since this combination continues to be an issue in the region. PARTICIPANTS: Major Project Contributors: Jeffrey Stein, Principle Investigator - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the projects related to the sources and genetics of disease resistance. Chris Nelson, Support Staff - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Partner Organizations: The South Dakota Wheat Commission through support of related research activities. The U.S. Wheat and Barley Scab Initiative (USDA-ARS) through support of related research activities. Collaborators: Karl Glover, SDSU Spring Wheat Breeder Bill Berzonsky, SDSU Winter Wheat Breeder Larry Osborne, SDSU Extension Plant Pathologist Lon Hall, SDSU Oats Breeder Jose Gonzalez, SDSU Crop Geneticist Yue Jin and Jim Kolmer, USDA-ARS CDL, St. Paul, MN Xiaming Chen, USDA-ARS WSU, Pullman, WA Bob Hall, SDSU Extension Agronomist Training: During the period in question, the PI also mentored four graduate students at SDSU who were conducting research related to this topic area. TARGET AUDIENCES: The primary target audiences for this research project are growers in South Dakota, and the region, that plant small grains cereals. Additionally, our efforts also impact Crop Consultants, Private Agronomists, and Extension Educators/Agents. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
From the research conducted in 2008 as part of objective #1, item A, we have developed mathematical functions that can be used to predict the incidence and severity of Fusarium head blight in wheat based on the number of G. zeae propagules present on the spikes during flowering. Both functions were found to be negative exponential in nature. Similarly, we found that deoxynivalenol concentration increased in a linear manner in relationship to inoculum dosage. When the impact of varietal resistance was examined, the slopes of these functions were found to differ with the moderately resistant wheat genotype having a lower slope for all three factors. Our hypothesis is currently being validated with additional field data and we have expanded the study to include barley. The ultimate goal of such studies is to have these models incorporated into risk-advisory systems that growers can use to make management decisions. The information generated from the sampling of rust isolates and race typing by members of the USDA-ARS (objective #1, item B) will be utilized to make informed recommendations to the SDSU wheat and oat breeders concerning the selection and introgression of effective rust resistance genes into elite germplasm and future varieties. We have also added the isolates collected in 2008 to our bulk inoculum mixture for the greenhouse screening of advanced germplasm against these pathogens. Previous efforts at SDSU studying the sources and genetics of resistance (objective #2) for these diseases has resulted in the generation of breeding materials that have been, and are still being, used in the development of disease resistant varieties. Current efforts will continue. For example, the populations advanced in 2008 with novel sources of FHB resistance will eventually be pyramided with the Sumai3-based FHB resistance that is common in the regional breeding programs. Varieties developed from multiple disease resistant parents should be much less susceptible to FHB. This will reduce the impact of this disease on crop production, providing a direct benefit to producers through the reduced need for fungicide applications. From our stem rust fungicide studies in 2008 (objective #3, item E) we found that the currently available fungicides are fairly effective at controlling the disease. However there was not always a strong relationship between disease control and yield and therefore further research is necessary in this area to better understand the management of this disease. In the seed treatment trial, we found that many of the commercially available fungicides are effective are limiting losses in spring wheat, however this impact is much lower in winter wheat. This lower level of efficacy may be a related to spring infections after the fungicides have been metabolized by the plant.
Publications
- Allen, T., H. Maples, F. Workneh, J. Stein, and C. Rush. 2008. Distribution and recovery of Tilletia indica teliospores from regulated wheat fields in Texas. Plant Disease 92:344-350.
|
Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Major research emphases in 2007 were to: 1) study pathogen biology and epidemiology or and 2) investigate the genetics of disease resistance to: the major fungal diseases of the small grains cereals in the Northern Great Plains. Two activities were conducted to address objective #1 (pathogen biology & epidemiology). The first involved the inoculation of wheat with varying concentrations of Gibberella zeae (causal agent of Fusarium head blight, aka FHB) spores in order to investigate the relationship between inoculum load and i) final disease development and ii) mycotoxin accumulation in the grain. The second involved the collection of isolates for the major rust diseases of wheat and oats (leaf, stem, and/or crown) from producer's fields and research plots throughout South Dakota. These isolates were then shared with scientists at the USDA-ARS Cereal Disease Lab for race determination. We also planted a nursery with lines containing known resistance genes to Puccinia
striiformis (stripe rust of wheat) and wheat stem rust trap plots (highly susceptible cultivar) at multiple locations in the state. Two activities were conducted to address objective #2 (genetics of disease resistance). The first was to evaluate breeding material for susceptibility to the major fungal pathogens of the small grain cereals in South Dakota. In 2007, we directly rated or assisted with the evaluation of several thousand lines of spring wheat, winter wheat, and oats (combined) for disease susceptibility to multiple pathogens. This consisted of both field evaluations and greenhouse inoculations. The principle diseases evaluated were the rusts, leaf blights, and to a lesser extent root rots. The second activity was to generate adapted germplasm with multiple, or novel, disease resistance. In 2007, we focused on FHB and worked collaboratively with the SDSU spring wheat breeder and a crop geneticist to introgress three novel sources of FHB resistance into regionally adapted
germplasm. We also began to generate a mapping population using a potentially novel source of resistance to common root rot of wheat.
PARTICIPANTS: Major Project Contributors: Jeffrey Stein, Principle Investigator - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the projects related to the sources and genetics of disease resistance. Lawrence Osborne, Research Associated - Designed, rated, and analyzed several of the experiments. This individual's effort was focused primarily on the experiments dealing with pathogen biology and epidemiology. Partner Organizations: The South Dakota Wheat Commission through support of related research activities. Collaborators: Karl Glover, SDSU Spring Wheat Breeder; Amir Ibrahim, Ex-SDSU Winter Wheat Breeder; Lon Hall, SDSU Oats Breeder; Jose Gonzalez, SDSU Crop Geneticist; Yue Jin and Jim Kolmer, USDA-ARS, St. Paul, MN; Xiaming Chen, USDA-ARS, Pullman, WA Training: The PI of this project provided disease-scouting training for the major foliar diseases of the small grain cereals to Crop Consultants, Certified Crop
Inspectors, South Dakota Department of Agriculture Survey Specialists, and USDA-APHIS Crop Inspectors. Approximately 80 individuals attended these events. The PI also mentored four graduate students at SDSU who were conducting research related to this topic area.
TARGET AUDIENCES: The primary target audiences for this research project are growers in South Dakota, and the region, that plant small grains cereals. Additionally, our efforts also impact Crop Consultants, Private Agronomists, and Extension Educators/Agents.
Impacts
From the research conducted as part of objective #1 in 2007, we have verified studies by others demonstrating that FHB severity tends to peak when about 50,000 spores/ml are applied to wheat heads (under controlled conditions), with additional spores not significantly increasingly the number of blighted florets. In contrast, mycotoxin accumulation in the final grain samples was found to increase with the higher inoculum concentrations. This discovery may explain the phenomenon often found in field experiments were plots have nearly identical disease severity, but vastly different levels of mycotoxin concentrations. We plan to pursue this topic through additional greenhouse studies and the 2008 field season. Should this future research support our hypothesis that inoculum load can directly impact mycotoxin concentration in the grain, our results could be combined with the spore availability model developed through a previous collaboration (see publication section below)
and implemented on the FHB forecasting site that is funded by the U.S. Wheat and Barley Initiative (http://www.wheatscab.psu.edu/). This would offer producers an additional source of information that could be used in the integrated management of Fusarium head blight of wheat and barley and potentially increase grower profitability, while limiting unnecessary fungicide applications. The information generated from the sampling of rust isolates (and race determination by the USDA-ARS-CDL), also part of objective #1, will be utilized to make informed recommendations to the SDSU wheat and oat breeders concerning the selection and introgression of effective rust resistance genes into elite germplasm and future varieties. We have also added the isolates collected in 2007 to our bulk inoculum mixture for screening germplasm against these pathogens. Previous efforts at SDSU studying the sources and genetics of resistance (objective #2) for these diseases has resulted in the generation of
breeding materials that have been, and are still being, used in the development of disease resistant varieties. Current efforts will continue this trend. For example, the crosses performed in 2007 with novel sources of FHB resistance will eventually be pyramided with the Sumai3-based FHB resistance that is common in the regional breeding programs. Varieties developed from multiple disease resistant parents should be much less susceptible to FHB. This will reduce the impact of this disease on crop production, providing a direct benefit to producers through the reduced need for fungicide applications.
Publications
- Osborne, L.E., and Stein, J.M. 2007. Epidemiology of Fusarium Head Blight on Small Grain Cereals. Intl. J. Food. Microbiol. 119:103-108.
- Paul, P., P. Lipps, G. Shaner, G. Buechley, T. Adhikari, S. Ali, J. Stein, L. Osborne, and L. Madden. 2007. A distributed-lag analysis of the relationship between Gibberella zeae inoculum density on wheat spikes and weather. Phytopath. 97:1608-1624.
|
|