Root-knot nematode symptoms and their cultural management in Onion

Causal Agent: Meloidogyne hapla

Symptoms:

• Small, swollen galls 1-2 mm (0.06 in.) in diameter can be found on the roots when infected plants are carefully lifted from the ground and freed from soil particles without damaging the roots.
• Depending on the species causing infection, the shape of the galls can be round or spindly, and with or without short root branches that rise from the upper part of galls.
• It is often possible to see white to dark brown egg masses on the surface of the roots.
• Above ground symptoms may include stunting and yellowing that resembles water and nutrient deficiency and poor or irregular plant stands.

Chemical control:

• Soil fumigation
• Crop rotation to a non-host or a long fallow period helps to reduce populations of root-knot nematodes.