Distribution, Levels, and HG Types of SCN Populations in Missouri
- Soybean cyst nematode (SCN) continues to spread throughout soybean-producing regions of the United States.
- Heavy reliance on soybean varieties with SCN resistance from the plant introduction (PI) 88788 is driving changes in the approach to SCN management in Missouri.
- Further exacerbating this problem is the increasing prevalence of virulent SCN populations that are able to reproduce on soybean varieties with PI 88788 resistance, thereby reducing its effectiveness.
- A survey was conducted of grower-submitted soil samples from across Missouri to evaluate the distribution, levels, and HG types of SCN.
- Objectives of this study were to:
- Increase awareness among farmers of the presence and level of SCN within their fields.
- Confirm the existence of virulent SCN populations in grower fields and the need for alternative SCN management strategies.
- Soil samples were solicited from Missouri growers.
- 293 soil samples were received from different Missouri fields in 2016.
- Cysts were extracted from each sample and a SCN egg count was determined for each sample.
- HG type tests were conducted for 28 SCN populations representing different regions of Missouri.
Figure 1. Percentage of soil samples that tested positive for SCN.
- This study determined that 87% of soil samples tested were positive for SCN (Figure 1).
- Samples from 293 fields evaluated showed that 74% of samples had egg counts > 500 eggs/250cc (Figure 2).
- All of the SCN populations evaluated for HG type showed reproduction on PI 88788 (HG type 2). Some populations (43%) showed reproduction on both Peking and PI 88788 (HG type 1.2) (Figure 3).
- 68% of SCN populations had a female index (FI) > 50% on PI 88788 (Table 1).
Figure 2. Number of soil samples at the various SCN egg count threshold values (250cc).
Figure 3. HG types of SCN populations (n=28).
Table 1. HG types of SCN populations.
See a larger image. (JPG 154 KB)
Authors: Dr. Melissa G. Mitchum and Amanda Howland, University of Missouri
Research conducted by Dr. Melissa G. Mitchum and Amanda Howland, University of Missouri, as a part of the Pioneer Crop Management Research Awards (CMRA) Program. This program provides funds for agronomic and precision farming studies by university and USDA cooperators throughout North America. The awards address crop management information needs of Pioneer agronomists. The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation.