A Survey of Plant-parasitic and Entomopathogenic Nematodes on Small Vegetable Farms in Indiana

Small vegetable farms typically grow a wide diversity of crops, frequently use season extension techniques such as high tunnels, and are more likely to adopt organic practices for pest and nutrient management. These production characteristics can have significant impacts on soil nematode communities, including both plant-parasitic nematodes (PPNs) and entomopathogenic nematodes (EPNs). We conducted a targeted survey of PPNs and EPNs on 18 small vegetable farms in Indiana. Of the 24 samples collected, we found that PPNs were widespread (95.8% of samples), while EPNs were also common (66.7%). Nine PPN genera were detected, with spiral (Helicotylenchus spp.), lesion (Pratylenchus spp.), dagger (Xiphinema spp.), and root-knot (Meloidogyne spp.) being the most prevalent. Spiral nematodes population densities were especially high, exceeding 5000 individuals per 500 cm³ of soil in three samples. High populations of lesion nematodes were also observed. Root-knot nematodes were detected in 50% of samples, with 16.7% of all samples exceeding the action threshold. PPN abundance was significantly higher in organically managed high tunnel soils compared with organic open-field soils. Co-occurrence analysis revealed no significant relationships between PPNs and EPNs. This survey provides the first baseline data on the prevalence and abundance of PPNs and EPNs on small vegetable farms in Indiana. These results will support the development of management strategies for PPNs and improve understanding of the potential role of EPNs in insect pest management on small vegetable farms.