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.