Characterizing Soybean Cyst Nematode Populations in Missouri
Applied Research
Anthony Ohmes
Field Specialist in Agronomy
University of Missouri Extension
Jackson
Abstract
Soybean Cyst Nematode (SCN; Heterodera glycines) was first confirmed in Missouri in 1956. SCN is a serious soybean pathogen, costing Missouri producers an estimated average annual yield loss exceeding 3% and estimated revenue loss exceeding $90 million dollars. The two primary Integrated Pest Management (IPM) strategies are host resistance and crop rotation. A third being nematicides. The challenges include: SCN eggs protected in a hardened cyst prolongs survival, three to six generations in a single season, up to 30% yield loss without visual symptoms, and plant introduction (PI) 88788 as the primary source of SCN-resistance for over three decades. Continued monitoring is critical for maintaining updated crop loss potential and devising strategic management plans with current resistant cultivars. University of Missouri (MU) has five decades of SCN surveying. As a MU Extension Field Specialist in Agronomy, I was directly involved in collecting samples across Southeast Missouri for the 2005, 2015, and 2024/25 surveys. Surveys differed in sampling locations and methods over the decades. Samples were collected from soybean fields and submitted to MU’s SCN Diagnostics Lab to determine SCN prevalence/density by SCN egg counts and virulence phenotypes by HG Type testing. Jeff Barizon, Senior Research Specialist in Nematology and PhD candidate, under Dr. Mandy Bish, MU State Extension Specialist in Field Crop Pathology, headed the 2024/25 survey and summarized all data. Results from the 2024/25 survey indicate SCN is statewide with 80% of samples testing positive for SCN and 91% of Southeast Missouri samples. SCN populations have continued to increase with 92% of samples containing moderate to high densities with a statewide median egg count of 2,100 and 2,800 for Southeast Missouri. The median Female Index (FI) (reproduction rate on PI 88788 relative to susceptible soybean) was 68%. Virulence to Peking-based SCN-resistance was lower with a median FI of 11%. In summary, higher egg counts are likely due to increased SCN virulence on PI 88788 soybean, costing yield. It will be important to steward Peking soybeans in rotation with PI 88788 soybeans to ensure both types of SCN-resistance have utility until new genetics are available.
Poster has NOT been presented at any previous NACAA AM/PIC
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Authors: Anthony Ohmes, Jeff Barizon, Mandy Bish
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Ohmes, A. Field Specialist in Agronomy, University of Missouri, Missouri, 63755
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Barizon, J. Senior Research Specialist in Nematology , University of Missouri, Missouri, 65211
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Bish, M. Assistant Research Professor & State Extension Specialist in Field Crop Pathology, University of Missouri, Missouri, 65211