Nathan Kleczewski, Extension Specialist – Plant Pathology; nkleczew@udel.edu
I previously mentioned that egg assays are more sensitive than larval extractions for assessing populations of soybean cyst nematodes. Below is an example of two actual samples that were processed by the University of Delaware Nematode assay service. A quick look at the Soybean cyst nematode vs SCN egg results illustrates the difference in sensitivity between egg counts and nematode counts when SCN populations are low. Although soybean cyst nematodes were detected in field 1, which contained a high population of SCN, none were observed up in field 2. This result may lead the individual to assume that SCN is not present in a field when in actuality it is present, just at lower levels.
Figure 1. An example of a nematode assay report showing the difference in detection limits for soybean cyst nematode counts vs egg counts.