Root Knot Nematode

Meloidogyne species




A disease caused by nematodes that are about 0.5 mm long, thin and transparent. They can only be seen under a microscope. Long slender males are found in the soil and pear shaped females are found in roots. Larvae entering roots cause lumps on the roots which may interfere with the transport of nutrient and water leading to plant symptoms such as slow, stunted growth, wilting in hot weather and pale leaves. On Potatoes lumps occur all over the tuber. The roots may have many lumps and may appear knotted due to branching where nematodes attack.

Species Affected:


Cabbage, Cauliflower, Onion and Sweet corn are tolerant of Root Knot Nematode.



Favoured by warm climates and light soils.

Each female can lay 2000 eggs.

Spread by running water, soil and infested plants. Soli adhering to shoes and implements also transfers them to new areas.

Life Cycle:

Eggs are laid in a gelatinous mass in the soil or enter the soil as root tissue breaks down. Larvae hatch from the eggs and enter the root, usually near the tip. Their saliva causes plants to produce some large cells and many small cells to form a lump on the root. The root may branch or continue growing and other larvae enter the tip forming more lumps.

Origin and History:



They are a serious pest of glasshouse horticulture.

Management and Control:

Avoid water stress to compensate for the damaged roots.

Remove and destroy diseased plants. Do not compost them.

Fumigate infested areas before planting.

Use nematicides.

Fallow the soil to reduce numbers.


Wash soil from roots and dip in water at 460C for 16 minutes.

Related and Similar Species:




Collated by HerbiGuide. Phone 08 98444064 for more information.