Prevalence of root-knot nematode in tomato polyhouses: A soil sampling study from Delhi and nearby areas

The study, carried out across 14 polyhouses located in Delhi, Kurukshetra, Palwal, Panipat, and Sonipat, 0revealed prevalence of nematode infestations in soils of 78.6 per cent (11/14) of polyhouses. While two polyhouses surpassed the pathogenic threshold (2 J2/cc soil) at the preplanting stage, eight exceeded its threshold level during midplanting (up to 19.9 J2/cc), with all nine facilities assessed at the maturity stage surpassing it (up to 30.5 J2/cc). The highest nematode multiplication rates were observed in the Marinika cultivar (midplanting: 17.9; maturity: 37.8), particularly in soils lacking management interventions. Conversely, polyhouses implementing biocontrol agents (e.g., Trichoderma spp., Pseudomonas spp.) demonstrated reduced nematode proliferation, with the lowest rates recorded in Alawalpur I (6.3 and 10.6 at midplanting and maturity, respectively). Chemical treatments, such as Velum Prime, exhibited only transient suppressive effects. These findings emphasize the necessity of revising preplanting threshold criteria and implementing integrated nematode management (INM) approaches to ensure sustainable tomato production under protected cultivation systems