Defending Onion Crops Against Stem, Bulb & Root-Knot Nematodes: Stopping Rot & Maximizing Bulb Tonnage
ಹಂಚಿ
Onion (Allium cepa) is an economically important vegetable crop cultivated for domestic consumption, processing, and export. Plant-parasitic nematodes reduce onion productivity by damaging roots and bulbs, weakening plants, and increasing vulnerability to fungal and bacterial diseases. Depending on infestation levels, onion yield losses may range from 20–60%, particularly in light-textured soils with continuous onion cultivation.
The major nematodes affecting onion include Stem and Bulb Nematode (Ditylenchus dipsaci), Root-knot nematodes (Meloidogyne spp.), and Lesion nematodes (Pratylenchus spp.). Stem and bulb nematodes invade onion tissues, causing bulb distortion, splitting, and poor storage quality.
Biological management provides long-term suppression of nematodes while improving soil fertility and root development.
Paecilomyces lilacinus suppresses root-knot nematodes by parasitizing eggs and females.
Pochonia chlamydosporia helps reduce nematode egg survival in the rhizosphere.
Trichoderma spp. improve root growth, nutrient uptake, and suppress soil-borne fungal pathogens associated with onion root diseases.
Pseudomonas spp. improve root vigor and induce natural plant resistance while enhancing nutrient availability.
Bacillus spp. promote healthy root systems, improve nutrient cycling, and support biological suppression of nematodes.
Together, these microorganisms improve bulb quality, increase plant vigor, and reduce dependence on chemical nematicides.
Common Onion Nematodes
- Stem and bulb nematode (Ditylenchus dipsaci)
- Root-knot nematode (Meloidogyne incognita)
- Lesion nematode (Pratylenchus spp.)
Biological Benefits
- Suppresses nematode populations
- Improves root development
- Enhances bulb formation
- Reduces disease incidence
- Improves nutrient uptake
- Promotes beneficial soil biology
- Supports sustainable onion cultivation