In addition, recent research has highlighted how different oomycete species that attack soybean and corn seedlings are adapted to different temperatures. Although cool temperatures that impose stress on the plant contribute to seedling disease, the recent work has highlighted that some oomycete species prefer cool temperatures while others favor warm temperatures. These recent findings also demonstrate that the disease temperature optima for the various Pythium species corresponded to higher fungicide EC50 values. These findings have implications in efforts to tailor seed treatment blends and the screening of soybean varieties for seedling and root rot resistance (Matthiesen et al. 2016, Rojas et al. 2017c).
In future studies we would like to understand how the use of seed treatments could contribute to oomycete fungicide resistance development. We would also like to better understand seed treatment and oomycete interactions with other fungal seedling pathogens like Rhizoctonia and Fusarium.
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This research summary was based on the following manuscripts
Matthiesen, R., L., Ahmad, A. A., and Robertson, A. E. 2016. Temperature affects aggressiveness and fungicide sensitivity of four Pythium spp. that cause soybean and corn damping off in Iowa. Plant Disease, 100(3):583-591. Article / Google Scholar
Noel, Z. A., Rojas, A. J., Jacobs, J. L., & Chilvers, M. I. 2019a. A High-Throughput Microtiter-Based Fungicide Sensitivity Assay for Oomycetes Using Z ′-Factor Statistic. Phytopathology, 109(9):1628-1637. Article / Google Scholar
Noel, Z. A., Sang, H., Roth, M. G., & Chilvers, M. I. 2019b. Convergent evolution of C239S mutation in Pythium spp. β-tubulin coincides with inherent insensitivity to ethaboxam and implications for other Peronosporalean oomycetes. Phytopathology, 109(12):2087-2095. Article / Google Scholar
Rojas, J. A., Jacobs, J. L., Napieralski, S., Karaj, B., Bradley, C. A., Chase, T., Esker, P. D., Giesler, L. J., Jardine, D. J., Malvick, D. K., Markell, S. G., Nelson, B. D., Robertson, A. E., Rupe, J. C., Smith, D. L., Sweets, L. E., Tenuta, A. U., Wise, K. A., and Chilvers, M. I. 2017a. Oomycete Species Associated with Soybean Seedlings in North America—Part I: Identification and Pathogenicity Characterization. Phytopathology, 107(3):280-292. Article / Google Scholar
Rojas, J. A., Jacobs, J. L., Napieralski, S., Karaj, B., Bradley, C. A., Chase, T., Esker, P. D., Giesler, L. J., Jardine, D. J., Malvick, D. K., Markell, S. G., Nelson, B. D., Robertson, A. E., Rupe, J. C., Smith, D. L., Sweets, L. E., Tenuta, A. U., Wise, K. A., and Chilvers, M. I. 2017b. Oomycete Species Associated with Soybean Seedlings in North America—Part II: Diversity and Ecology in Relation to Environmental and Edaphic Factors. Phytopathology, 107(3):293-304. Article / Google Scholar
Rojas, J. A., Miles, T. D., Coffey, M. D., Martin, F. N., and Chilvers, M. I. 2017c. Development and Application of qPCR and RPA Genus- and Species-Specific Detection of Phytophthora sojae and P. sansomeana Root Rot Pathogens of Soybean. Plant Disease, 101:1171-1181. Article / Google Scholar
Martin Chilvers, Michigan State University; Austin McCoy, Michigan State University; Zachary Noel, Auburn University; Alejandro Rojas, University of Arkansas; Alison Robertson, Iowa State University; Travis Faske, University of Arkansas; Daren Mueller, Iowa State University; Damon Smith, University of Wisconsin-Madison; Albert Tenuta, Ontario Ministry of Agriculture, Food and Rural Affairs; Kiersten Wise, University of Kentucky.
All photos were provided by and are the property of the authors and reviewers.
The authors wish to acknowledge the Michigan Soybean Promotion Committee, North Central Soybean Research Program, the United Soybean Board, and the United States Department of Agriculture - National Institute of Food and Agriculture (USDA-NIFA) for generous support of this research.
This publication was developed by the Crop Protection Network, a multi-state and international collaboration of university/provincial extension specialists and public/ private professionals that provides unbiased, research-based information to farmers and agricultural personnel.
This information in this publication is only a guide, and the authors assume no liability for practices implemented based on this information. Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.