The guava root-knot nematode (Meloidogyne enterolobii) is a highly aggressive species of root-knot nematode that is not manageable with currently existing nematode management methods. This study was conducted to evaluate the suppressive ability of winter cover crops against M. enterolobii. Eleven winter cover crops (rye, wheat, barley, triticale, oat, Austrian winter pea, crimson clover, balansa clover, hairy vetch, purple top turnip, and daikon radish) were evaluated against M. enterolobii in a growth room environment. Root-knot nematode-susceptible tomato (Solanum lycopersicum cv. Rutgers) was used as a control. Nematode reproduction on cover crops ranged from 1 to 501,373 eggs/g root, with oat supporting the least nematode reproduction and crimson clover supporting the greatest nematode reproduction. The crops significantly suppressing egg production on roots and second-stage juveniles in the soil relative to the control were oat, winter pea, wheat, barley, rye, and triticale. Hairy vetch, purple turnip, daikon radish, and crimson clover were good hosts, while balansa clover, wheat, winter pea, barley, rye, triticale and oat were poor or non-hosts, with the latter four crops producing substantial biomasses. Employment of these cover crops that suppress or do not support M. enterolobii reproduction while adding substantial biomass to the soil may lead to sustainable nematode management.

Root-knot nematodes (Meloidogyne spp.) are major pests of vegetable crops, causing significant yield losses in numerous species worldwide. Their widespread distribution and polyphagous nature make them particularly challenging to manage effectively. The use of biological agents and botanical extracts has emerged as a sustainable alternative to chemical nematicides. The present study evaluated the effectiveness of aqueous extracts from Moringa oleifera and a novel strain of plant growth-promoting rhizobacteria, Bacillus australimaris strain LWD73, native to Florida, in reducing Meloidogyne incognita infection and enhancing plant growth. The combined application of M. oleifera extracts and B. australimaris LWD73 significantly reduced the number of galls, eggs per root system, second-stage juveniles (J2) per 60 cc of soil, and the nematode reproduction factor. Moreover, it improved key growth parameters in tomato cultivar HM1824. Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS) analyses of M. oleifera extracts identified antimicrobial and nematicidal phytochemicals. Similarly, solid-phase microextraction GC-MS (SPME-GC/MS) analysis of B. australimaris LWD73 revealed the presence of volatile organic compounds (VOCs), including 2-nonanone and 2-undecanone, which are known for their potent nematicidal properties. The synergistic application of M. oleifera and B. australimaris LWD73 demonstrated enhanced nematode suppression and improved plant growth, offering a promising, eco-friendly approach to managing root-knot nematodes in vegetable crops.