Soybean Varieties With Non-88788 SCN Resistance Adapted To Minnesota

1.Department of Agronomy and Plant Genetics, 2.Department of Plant Pathology, 3.University of Minnesota Extension

The most common source of SCN resistance in commercial soybean varieties adapted to Minnesota is PI 88788. Over 90% of the varieties entered into the 2022 UMN Variety trials carried this single source of SCN resistance. The PI 88788 resistance source provides good resistance to some races of SCN. Over time, however, the overuse of this resistance source has led to shifts in SCN populations to those able to overcome PI88788 resistance. There has been increased interest in alternative sources of SCN resistance such as Peking and PI 89772. The commercial availability of these varieties adapted to Minnesota has gradually increased in recent years. However, little independent information is available on their actual resistance to SCN races known to overcome the PI 88788 source. Study methods Starting in the spring of 2021, we have annually solicited seed of commercial varieties advertised to carry a non-88788 source of resistance and tested submissions for resistance to Race 1 (HG Type 2.5.7) using a greenhouse bioassay with five replicates. Each container (one plant) was inoculated with 4000 SCN eggs. After 30 days a Female Index (FI) was calculated for each entry using Williams 82 as the susceptible check. The FI was calculated with the following formula:

FI = (# of cysts on entry/# of cysts on Williams 82) x100

If the FI was <10%, an entry was considered resistant (R). If the FI was 10 – 30%, it was considered moderately resistant (MR). If the FI was 30-60%, it was considered moderately susceptible (MS), and greater than 60% susceptible (S).

Source: umn.edu