Plant-parasitic nematodes (PPNs) are common in perennial cropping systems, particularly where traditional fertility and floor management practices biologically disturb soil ecosystems. Four vineyard floor management treatments were applied to mature ‘Norton’ vines—(1) grower control (mown tall fescue in the aisle with herbicide-treated bare driplines), (2) red fescue (creeping red fescue established throughout aisle and dripline), (3) successional cover crops (annual rotation of cereal rye, oats, and sorghum-sudangrass using no-till planting), and (4) compost (a mix of hardwood mulch and composted winery pomace applied across aisle and dripline)—in combination with two nitrogen fertility regimes: no nitrogen (0 lb N/ac) and N fertilization (20 lb N/ac applied at budbreak, bloom, and veraison (60 lb N/ac total)). The study was conducted on a Hosmer silty-clay loam in southern Illinois, arranged in a randomized complete block design with four replications. Soil samples were analyzed for populations of plant-parasitic nematode genera—including Pratylenchus, Helicotylenchus, Xiphinema, and Longidorus—alongside soil nutrient metrics such as water-extractable potassium (WEK), phosphorus (WEP), and organic carbon (WEOC), as well as percent organic matter (OM), carbon-to-nitrogen ratio (C:N), and soil respiration (CO₂). Results showed that red fescue may act as a host for Pratylenchus, particularly when supported by nitrogen fertilization (236/100cc) in the vineyard dripline, compared to 156/100cc under compost, 204/100cc under successional cover, and 164/100cc in the grower control during the same period. The increase may be attributed to red fescue’s weak, fibrous root system, which lacks the structural defenses of deeper-rooted species and may act as an attractant. Although Pratylenchus have higher damage thresholds, these population densities have the potential to affect grapevine health. In contrast, compost and successional cover treatments suppressed multiple PPN genera while significantly improving nutrient availability. Populations of Xiphinema and Longidorus were reduced by 57–92% under compost and successional treatments with no nitrogen, compared to the control. These treatments also increased WEK by up to 249%, raised WEP, and elevated OM to 2.6%, compared to 2.1% in the control. Soil respiration reached 68.4 kg/ha, and estimated nitrogen release was as high as 62.8 kg/ha, while maintaining stable C:N ratios (~12.5), indicating enhanced nutrient cycling and organic matter mineralization. These findings suggest that biologically diverse vineyard floor management can suppress plant-parasitic nematodes while simultaneously improving soil nutrient relationships. Integrating organic amendments and dynamic cover cropping into vineyard systems offers a strategy to reduce pest pressure, enhance nutrient cycling, and build soil health.
