A survey of plant parasitic nematodes of soybeans in Delaware and Maryland 2019-2021

Abstract

Soybean cyst nematode is the most yield-limiting pathogen of soybean across Delaware (DE) and eastern shore Maryland (MD). To update nematode distribution and population data, a three-year soil survey was conducted from 2019 to 2021. Soybean fields across DE and nine MD counties were sampled from August through October. Three hundred and eleven soil samples were collected, including two hundred and 22 predictive samples and 89 diagnostic samples. Across all samples, nine nematode taxa were identified. Soybean cyst nematode (Heterodera glycines, 53.38%), root-knot nematode (Meloidogyne incognita, 18.33%), lesion nematode (Pratylenchus spp., 57.23%), and spiral nematode (Helicotylenchus spp., 54.34%) were most abundant in the region. Among these taxa, 66% of SCN samples had populations above the economic threshold; 39% of RKN; and 14% of lesion. Results from this survey highlight the continued challenge of SCN in the region and that other nematode taxa like RKN and lesion should be monitored. Many fields have multiple nematode genera present, and interactions are poorly understood.