2018
Determination of phytophthora sojae populations and assessment of management strategies
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Lead Principal Investigator:
Martin Chilvers, Michigan State University
Co-Principal Investigators:
Project Code:
18-05
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Phytophthora sojae and P. sansomeana have the potential to rob yield from Michigan soybean producers. It has been twenty years (1993-1997) since a detailed survey has been conducted for the Phytophthora sojae pathotypes (races) present in Michigan. I often receive questions from growers and seed dealers regarding which Rps resistance genes and trait packages should be used for Phytophthora stem and root rot management. This survey of pathotypes and examination of management practices (seed treatments and resistance packages) will enable us to provide up-to-date information to Michigan soybean farmers. Phytophthora sansomeana is a newly described species that can cause disease on soybean,...

Unique Keywords:
#soybean diseases
Information And Results
Project Deliverables

Update on Phytophthora sojae pathotype (race) composition in Michigan
Information on current fungicide sensitivity of P. sojae in Michigan

Final Project Results

Updated September 8, 2020:
The study provides an updated look at real management strategies that farmers can use to control Phytophthora root and stem rot (resistance packages, seed treatments, planting density, crop rotation). Determining effective resistance genes to P. sojae allows for informed management recommendations to farmers as well as informing soybean breeders on a shift in the populations pathotype for coordinated breeding of new lines. 1K and 1C genes are the most readily available for Phytophthora resistance and also two of the most susceptible (no longer useful) genes identified in our study. Likewise, two genes, 3B and 4, were identified as potentially useful, but are not currently available in any commercial soybean lines.
Phytophthora sansomeana appears to have a wide host range, showing an ability to cause disease on a variety of commonly planted field crops in Michigan. This could become problematic if the pathogen spreads as all hosts tested appear to be able to act as hosts (symptomatic or not) and soybean appears to be the most susceptible and important host. Fortunately, P. sansomeana was only identified in two fields in Michigan in this survey, but is likely present in more that were not sampled.
Field trial data suggests that in high oomycete pressured fields, a seed treatment containing a fungicide active against oomycetes would significantly increase stand. However, yield data suggests that there is little significant increase in yield when using a seed treatment. This could mean that farmers planting oomycide treated seed in lower density, saving on seed costs, would still attain the same yield. Economic benefits of seed treatments have not yet been evaluated for this study.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.