Progress 11/01/12 to 09/30/17
Outputs
Target Audience:Soybean growers, crop consultants, agricultural professionals, soybean breeders, research scientists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Professional Development as Research Associate - Lorien Radmer Special topics and directed studies research of undergraduates - Marissa Scherven, Victor Brenk Workshop, seminar, and professional meeting registration and travel supported by project funds for Grace Anderson, Lorien Radmer How have the results been disseminated to communities of interest?Presentations at professional meetings, at commodity group meetings, in commodity group in-house publications, and in broadcast media interviews What do you plan to do during the next reporting period to accomplish the goals?Conduct phenotyping of 280 early maturity group soybean lines for resistance to Pythium irregulare and Pythium ultimum. Establish field experiments to characterize the benefit of fungicidal seed treatment on emergence, stand establishment, and final yield.
Impacts
What was accomplished under these goals?
Seedling and soil samples from 49 soybean production fields in Minnesota yielded 30 Pythium species and four Phytopythium species. The species were identified using ITS and COX1 sequences as compared to reference sequences in the NCBI database. Pathogenicity was evaluated in an in-vitro assay at three temperatures, 15, 20, and 25o C. Pathogenicity was expressed as reduction in root growth of germinating seeds and as lesion severity or as a reduction in root length of seedlings. Seven of the 21 Pythium spp. were pathogenic on both soybean and corn, reducing root growth by 20% or more, while two Pythium and one Phytopythium spp. were pathogenic only on soybeans. This is the first report of P. recalcitrans as a pathogen of soybean and of Phytopythium spp. as a pathogen on either corn or soybean in Minnesota. P. ultimum and P. irregulare were the most pathogenic Pythium species on either soybeans or corn. P. conidiophorum, P. irregulare, P. intermedium, P. ultimum, and P. sylvaticum were pathogenic on soybean at the three temperatures. P. acrogynum, P. inflatum, P. sylvaticum, P. ultimum increased in pathogenicity with increasing temperature. On corn P.antheridium, P. conidiophorum, P. intermedium, P. irregulare, P. heterothallicum, P. minus, P. recalcitrans, P. sylvaticum, and P. ultimum were pathogenic at 15 and 20o C. At 25o C pathogenicity of P. heterothallicum, P. minus, P recalcitrans, P. schmitthenneri,P. torulosum increased further. Sensitivity to azoxystrobin, ethaboxam, mefenoxam, pyraclostrobin, and trifloxystrobin of isolates of ten pathogenic Pythium species was tested in an in-vitro assay. Isolates of Pythium and Phytopythium species varied in sensitivity to the fungicides but most were highly sensitive to mefenoxam and ethaboxam, with EC50 values less than 10-2 of that observed for the strobilurin fungicides. Only P. acrogynum did not display any sensitivity to ethaboxam at rates of 0.0, 0.5 or 5 µg/ml. Treatment with 100 µg/ml decreased growth by only 24%. However, only one isolate of P. acrogynum was available for testing and it is unknown if these results are representative of the species or are unique to the one isolate collected in this study. The results indicate that Pythium spp. in Minnesota soybean fields are diverse, vary in sensitivity to fungicides, and may be significant causes of seedling disease on soybean and corn.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2015
Citation:
Radmer, L., Anderson, G., Malvick,DM., Rendahl, A., Mallik, A, and Kurle, J.E. 2015. Pythium species isolated from Minnesota soybean fields, their relative pathogenicity to soybeans and corn, and their sensitivity to seed treatment fungicides. Submitted to Plant Disease.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2015
Citation:
Radmer, L., Anderson, G., Malvick, D.M., and Kurle, J.E. Pythium species from Minnesota soybean fields, their relative pathogenicity to soybeans and corn, and their sensitivity to seed treatment fungicides. Phytopathology. (105 Suppl. 4):S4.115.
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Soybean growers, crop consultants, agricultural professionals, soybean breedeers, research scientists Changes/Problems:Extreme variability in results of seed and seedling pathogenicity phenotyping experiments has delayed completion of resistance evaluation for early maturity group soybean lines. What opportunities for training and professional development has the project provided?Seed and seedling pathogenicity trials provided opportunities for directed studies projects by undergraduate researchers. How have the results been disseminated to communities of interest?The results were disseminated to communities of interest by presentations at professional meetings, commodity group meetings, in in-house publications of commodity groups, and in broadcast media interviews. What do you plan to do during the next reporting period to accomplish the goals?Plan to further investigate the role of Phytopythium spp. as components of the soybean seed, seedling, and root rot complex. Once protocol development is completed plan to conduct phenotyping of 280 early maturity group soybean lines for resistance to Pythium irregulare and P. ultimum.
Impacts
What was accomplished under these goals?
Fungicide sensitivity assays were completed for five fungicides commonly used as seed treatments on 10 selected Pythium species collected in Minnesota. Based on results obtained in these experiments, EC50 values were determined . Sensitivity to azoxystrobin, ethaboxam, mefenoxam, pyraclostrobin, and trifloxystrobin of isolates of ten pathogenic Pythium species was tested in an in-vitro assay. Isolates of Pythium and Phytopythium species varied in sensitivity to the fungicides but most were highly sensitive to mefenoxam and ethaboxam, with EC50 values less than 10-2 of that observed for the strobilurin fungicides. Only P. acrogynum did not display any sensitivity to ethaboxam at rates of 0.0, 0.5 or 5 µg/ml. Treatment with 100 µg/ml decreased growth by only 24%. However, only one isolate of P. acrogynum was available for testing and it is unknown if these results are representative of the species or are unique to the one isolate collected in this study. The results indicate that Pythium spp. in Minnesota soybean fields vary in sensitivity to fungicides. Sensitivity to azoxystrobin, ethaboxam, mefenoxam, pyraclostrobin, and trifloxystrobin of isolates of ten pathogenic Pythium species was tested in an in-vitro assay. Isolates of Pythium and Phytopythium species varied in sensitivity to the fungicides but most were highly sensitive to mefenoxam and ethaboxam, with EC50 values less than 10-2 of that observed for the strobilurin fungicides. Only P. acrogynum did not display any sensitivity to ethaboxam at rates of 0.0, 0.5 or 5 µg/ml. Treatment with 100 µg/ml decreased growth by only 24%. However, only one isolate of P. acrogynum was available for testing and it is unknown if these results are representative of the species or are unique to the one isolate collected in this study. The results indicate that Pythium spp. in Minnesota soybean fields vary in sensitivity to fungicides. Aggressiveness of Pythium and Phytopythium species on susceptible soybean varieties was evaluated in seedling assays conducted in inoculated growth media. Pythium minus and P. pleroticum were less aggressive than the soybean pathogens, P. ultimum and P. irregulare. P. minus caused both reduced root and shoot growth. P. pleroticum infection resulted in increased root dry weight. The four Phytopythium spp.,Phytopythium litorale, Ph. boreale, Ph.megacarpum, and an unidentified Phytopythium spp, were as aggressive as P. ultimum and P. irregulare and caused seed & seedling rot and lesions on developing plant roots. The results indicate that Phytopythium spp. should be considered pathogens of soybean. Experiments were conducted to develop protocols for identifying varietal resistance to seed and seedling pathogenicity. Resistance to seed rot caused by Pythium irregulare and P. ultimum was characterized for thirteen soybean varieties in assays of radical elongation conducted in-vitro on inoculated PCNB. There were significant differences in resistance to infection by both Pythium species. Seedling pathogenicity assays of resistance to seed rot or post emergence damping-off were conducted in inoculated growth media. Severe mortality made analysis and interpretation of the results difficulty. The experiments are being repeated at much lower inoculum concentrations.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Radmer, L., Anderson, G., Malvick, D., Rendahl, A. Mallik, A., and Kurle, J. 2016. Pythium, Phytophthora, and Phytopythium spp. associated with soybean in Minnesota, their relative aggressiveness on soybean and corn and their sensitivity to seed treatment fungicides. Plant Dis. dx.doi.org/10.1094/PDIS-02-16-0196-RE
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Brenk, V., Anderson, G.A., and Kurle, J.E. 2016. Pythium and Phytopythium spp. isolated from soybean in Minnesota exhibit symtiotic behaviors ranging from parasitism to mutualism. 106 (Suppl. 4):S4.185.
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Progress 10/01/14 to 09/30/15
Outputs
Target Audience:Soybean growers, crop consultants, agricultural professionals, soybean breeders, research scientists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Professional Development as Research Associate - Lorien Radmer Special topics and directed studies research of undergraduates - Marissa Scherven, Victor Brenk Workshop, seminar, and professional meeting registration and travel supported by project funds for Grace Anderson, Lorien Radmer How have the results been disseminated to communities of interest?Presentations at professional meetings, at commodity group meetings, in commodity group in-house publications, and in broadcast media interviews What do you plan to do during the next reporting period to accomplish the goals?Conduct phenotyping of 280 early maturity group soybean lines for resistance to Pythium irregulare and Pythium ultimum. Establish field experiments to characterize the benefit of fungicidal seed treatment on emergence, stand establishment, and final yield.
Impacts
What was accomplished under these goals?
Seedling and soil samples from 49 soybean production fields in Minnesota yielded 30 Pythium species and four Phytopythium species. The species were identified using ITS and COX1 sequences as compared to reference sequences in the NCBI database. Pathogenicity was evaluated in an in-vitro assay at three temperatures, 15, 20, and 25o C. Pathogenicity was expressed as reduction in root growth of germinating seeds and as lesion severity or as a reduction in root length of seedlings. Seven of the 21 Pythium spp. were pathogenic on both soybean and corn, reducing root growth by 20% or more, while two Pythium and one Phytopythium spp. were pathogenic only on soybeans. This is the first report of P. recalcitrans as a pathogen of soybean and of Phytopythium spp. as a pathogen on either corn or soybean in Minnesota. P. ultimum and P. irregulare were the most pathogenic Pythium species on either soybeans or corn. P. conidiophorum, P. irregulare, P. intermedium, P. ultimum, and P. sylvaticum were pathogenic on soybean at the three temperatures. P. acrogynum, P. inflatum, P. sylvaticum, P. ultimum increased in pathogenicity with increasing temperature. On corn P.antheridium, P. conidiophorum, P. intermedium, P. irregulare, P. heterothallicum, P. minus, P. recalcitrans, P. sylvaticum, and P. ultimum were pathogenic at 15 and 20o C. At 25o C pathogenicity of P. heterothallicum, P. minus, P recalcitrans, P. schmitthenneri,P. torulosum increased further. Sensitivity to azoxystrobin, ethaboxam, mefenoxam, pyraclostrobin, and trifloxystrobin of isolates of ten pathogenic Pythium species was tested in an in-vitro assay. Isolates of Pythium and Phytopythium species varied in sensitivity to the fungicides but most were highly sensitive to mefenoxam and ethaboxam, with EC50 values less than 10-2 of that observed for the strobilurin fungicides. Only P. acrogynum did not display any sensitivity to ethaboxam at rates of 0.0, 0.5 or 5 µg/ml. Treatment with 100 µg/ml decreased growth by only 24%. However, only one isolate of P. acrogynum was available for testing and it is unknown if these results are representative of the species or are unique to the one isolate collected in this study. The results indicate that Pythium spp. in Minnesota soybean fields are diverse, vary in sensitivity to fungicides, and may be significant causes of seedling disease on soybean and corn.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2015
Citation:
Radmer, L., Anderson, G., Malvick,DM., Rendahl, A., Mallik, A, and Kurle, J.E. 2015. Pythium species isolated from
Minnesota soybean fields, their relative pathogenicity to soybeans and corn, and their sensitivity to seed treatment fungicides. Submitted to Plant Disease.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Radmer, L., Anderson, G., Malvick, D.M., and Kurle, J.E. Pythium species from Minnesota soybean fields, their relative pathogenicity to soybeans and corn, and their sensitivity to seed treatment fungicides. Phytopathology. (105 Suppl.4):S4.115.
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Soybean growers, crop consultants, agricultural professionals, soybean breeders, research scientists Changes/Problems: Will investigate and address source of variability in experiemental results caused (apparently) by environmental conditions in both greenhouse and growth chamber. What opportunities for training and professional development has the project provided? Professional development Graduate students coadvisees - Juan Maytas,Justin Briggs Graduate student committees - Yong Bao, Kyle Haralson, Jordan Briggs, Michelle Grabowski Undergraduate research opportunity program awards for Adam Barbeau Special topics and directed studies research of Adam Barbeau, and Milan Milanovich (Student through World Learning Global Student Exchange Program). Undergraduate internship for Adam Barbeau Professional Development as Post-doctoral researcher - Florence Sessoms Workshop, seminar, and professional meeting registration and travel supported by project funds for Grace Anderson, Lorien Radmer, Florence Sessoms. How have the results been disseminated to communities of interest? Presentations at professional meetings, commodity group conventions, field days, workshops, webinars What do you plan to do during the next reporting period to accomplish the goals? Complete investigation of etiology of infection by Fusarium solani. Continue survey of Pythium species. Determine pathogenicity of predominant species on both corn and soybean. Determine level of sensitivity of most commonly occurring Pythium species to metalaxyl, trifloxystrobin, and azoxystrobin.
Impacts
What was accomplished under these goals?
In field studies the effectiveness of the biocontrol agent Trichoderma harzianum was investigated for control of white mold caused by Sclerotinia sclerotiorum and Sudden Death Syndrome caused by Fusarium virguliforme. The treatment was applied as either foliar treatment for control of White Mold or seed application for control of Sudden Death Syndrome. Severity of both diseases was not reduced by the application. In growth chamber studies the etiology of root rot caused by Fusarium solani was investigated in a system using standard soil mixes containing peat or manufactured media and a system using gel media. The gel media enabled visualization of infection by microscopic examination without laborious root washing and staining. Utilizing the gel media research into the effects of uninfested inoculum substrates and substrates infested with F. solani or F. virguliforme on disease symptom expression and plant growth demonstrated that spurious symptoms, particularly lesion-like root discoloration and poor root development, occurs with uninfested inoculum substrates such as seed of sorghum, rye, barley, or oats used to inoculate soil during screening experiments. Inoculation with uninfested seed resulted in poor root development and decreased plant growth when compared to either plants root-inoculated with infested substrates or to an uninoculated control. The effect is dependent on species of plant seed used as a substrate (the most severe effects were caused by red sorghum) and is also determined by the soybean cultivar planted. Soybean cultivars differ in their response to a substrate. Apparent lesion development caused by the substrate differs from that caused by infection by Fusarium solani. Detailed examination of root development and infection by F.solani demonstrated that root infection occurs at the point where lateral roots emerge from the root through the epidermis and that lesions spread laterally from the point of infection. The lesion caused by the infection can be distinguished from lesion-like symptoms caused by inoculum substrates. A survey of Pythium species associated with stand establishment problems and seedling damping off in soybean was completed by baiting either symptomatic seedlings or soil samples collected in Minnesota. Thirty-one species were identified and identity confirmed using both morphological and molecular techniques, sequencing the ITS region and the cox1 gene. The predominant species isolated were Pythium ultimum, P. heterothallicum, P. sylvaticum, and P. oopapillum. Pathogenicity, measured in vitro as reduction in root length, of the 21 most common species was evaluated at three temperatures, 15, 20, and 25o C on both corn and soybean. P. conidiophorum, P. irregulare, P. intermedium, P. ultimum, and P. sylvaticum were pathogenic on soybean at the three temperatures. P. acrogynum, P. inflatum, P. sylvaticum, P. ultimum increased in pathogenicity with increasing temperature. P.antheridium, P. conidiophorum, P. intermedium, P. irregulare, P. recalcitrans, P. sylvaticum, and P. ultimum were pathogenic on corn at 15 and 20oC. Results at 25o C were incomplete.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Radmer, L., Anderson, G., Malvick, D., and Kurle, J. 2014. Pathogenicity of Pythium species isolated from Minnesota soybean fields on soybeans and corn. Phytopathology. 104 (Suppl. 3):S3.94.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Sessoms, F.J., Otto-Hanson, L.K., Lencowski, Malvick, D.K., and Kurle, J.E. 2014. Etiology of soybean root rot caused by Fusarium solani and its effect on root and above ground plant development. Phytopathology. 104 (Suppl. 3):S3.106.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Sessoms, F., Otto-Hanson, L., Barbeau, A., Malvick, D., Kurle, J. 2014. Inoculum substrate influences root development and causes discoloration similar to Fusarium solani infection of soybean. Phytopathology. 104 (Suppl. 3):S3.175.
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Progress 11/01/12 to 09/30/13
Outputs
Target Audience: Soybean growers, crop consultants, agricultural professionals, Changes/Problems: No major changes at this time. What opportunities for training and professional development has the project provided? Professional development for graduate students coadvisees - Juan Maytas, Joanne Kirsch Graduate student committees - Yong Bao, Kyle Haralson, Jordan Briggs, Bruce Potter, Michelle Grabowski Regents scholarship tuition support for technical staff - Grace Anderson Undergraduate research opportunity program awards for Lu Yin, and Adam Barbeau Special topics and directed studies research of Lu Yin, Adam Barbeau, and Milan Milanovich (Student through World Learning Global Student Exchange Program. Undergraduate internship for Adam Barbeau Workshop, seminar, and professional meeting registration and travel supported by project funds for Joanne Kirsch and Grace Anderson. How have the results been disseminated to communities of interest? Presentations at professional meetings, commodity group conventions, field days, workshops, webinars What do you plan to do during the next reporting period to accomplish the goals? Complete investigation of etiology of infection by Fusarium solani. Continue survey of Pythium species. Initiate survey of Rhizoctonia solani occurrence.
Impacts
What was accomplished under these goals?
A survey of Pythium species associate with stand establishment problems was completed by baiting soil samples collected from 32 locations in Minnesota. Five species were identified and identity confirmed using both morphological and molecular techniques. Pythium irregulare and Pythium ultimum were the predominant species.The etiology of root rot caused by Fusarium solani is being investigated. The effects of F. solani on plant germination and growth is influenced by fungal isolate, soybean cultivar, stage of plant development, soil temperature, and soil moisture. In general, soil inoculation with F. solani caused poor germination and reduced plant populations. However, plants that did germinate and flowered appeared to benefit from infection with greater root and above ground growth and greater seed yield. Research was conducted into the effects of inoculum methods and inoculum substrates infested with F. solani or F. virguliforme on disease symptom expression and plant growth. Management of this root rot fungus should emphasize control of its effects during seed germination. When investigating the etiology of F. solani spurious symptoms, particularly lesion-like root discoloration and poor root development, were observed when many infested inoculum substrates such as seed of sorghum, rye, barley, or oats are used to inoculate soil during screening experiments. Inoculation with uninfested seed resulted in poor root development and decreased plant growth when compared to either plants root-inoculated with infested substrates or to an uninoculated control. The effect is dependent on species of plant seed used (most severe effects were seen when red sorghum was used as a substrate) but is also determined by the soybean cultivar planted. These effects are particularly relevant for evaluation of soybean cultivars and evaluation of pathogenicity of fungal isolates and can cause misleading symptoms unrelated to the effect of the pathogen.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Kurle, J.E., Barbeau, A., Otto-Hansen, L.K. , Anderson , G. Spurious symptoms caused by inoculum carriers used in plant disease resistance evaluation. Phytopathology. 103(Suppl. 3):S3.5.
Anderson, G.M., Martin, M.J., Kaufman, J.L., Chai, Y., Kurle, J.E., and Steffenson, B.J. Efficacy of disinfestants in killing urediniospores of wheat stem and soybean rusts. Phytopathology. 103(Suppl. 3):S3.2
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