UW Soybean Plant Health
There are often one or more race-specific Phytophthora resistance genes in commercial soybean varieties (Table 1). The genes present in specific soybean varieties are listed each year in the University of Wisconsin Soybean Variety Test Results 1997-2006 (UW-Extension publication A3654). Your seed dealer will also have this information.
About Phytophthora sojae |
Detecting Phytophthora in your fields |
Managing Phytophthora sojae |
Monitor the performance of the varieties you choose. When optimum disease conditions develop later in the growing season, scout those areas of the fields to look for stem rot development. If a large number of plants with Phytophthora stem rot are found, choose varieties with a different Rps gene and higher levels of partial resistance for next year. This pathogen does adapt to the Rps genes, but it is a slow process. Careful monitoring of plant performance is all that is needed.
Table 1. Race-specific Phytophthora resistance genes and their effectiveness in Wisconsin.
Soybean genes |
Phytophthora races controlled |
Effectiveness in Wisconsin |
Rps 1-a |
1, 2, 10, 11, 13-18, 24 |
limited effectiveness |
Rps1-b |
1, 3-9, 13-15, 17, 18, 21, 22 | |
Rps 1-c |
1-3, 6-11, 13, 15, 17, 21, 23, 24 |
effective in 75% of fields |
Rps 1-k |
1-11, 13-15, 17, 18, 22, 24 |
effective in 99% of fields |
Rps 3 |
1-5, 8, 9, 11, 13, 14, 16, 18, 23, 25 |
|
Rps 4 |
1-4, 10, 12, 16, 18-21, 25 |
|
Rps 6 |
1-4, 10, 12, 14-16, 18-21, 25 |
|
Rps 1k, 6 |
1-11, 12-22, 24, 25 |
Soybean varieties with the same resistance genes may perform differently because of different levels of field resistance (tolerance to Phytophthora root rot). We are working to gather information on the level of tolerance for each variety.
Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: University of Wisconsin-Madison, Departments of Agronomy, Entomology, and Plant Pathology at www.plantpath.wisc.edu/soyhealth.
Last update 3/5/07