Skip to main content

Nacobbus aberrans

EPPO code


Common names

English name: False root-knot nematode
Nordic names:

Major host plants

Potatoes are the most significant host, but several other plants are also attacked: Brassica oleracea, Capsicum, carrots, cucumbers, lettuces, sugarbeet, and tomatoes. The nematode species may be divided in different races on specific crops. Several weeds are susceptible and can function as a permanent source of inoculum in fields.


The galls are apparently similar to those caused by Meloidogyne spp. but tend to be more discrete and rounded, giving a beaded appearance, whereas Meloidogyne galls frequently connect to form elongated swellings along the root. Roots of potato plants are deformed and few tubers are produced.

Courtesy of EPPO - CIP (PE)

See more pictures on EPPO's website


The nematode originates in South-America, and has spread into North-America. It has been introduced and eradicated in a few European countries.

A map can be downloaded from EPPO's website. See instructions here.


Larvae hatch from eggs in the soil and invade host roots. Within the roots, females and worm-like males are developed. When the nematodes feed on root tissue it causes histological changes which lead to gall formation. Eggs are laid in a gelatinous matrix which protrudes from the root surface into the soil. Two or more generations per year are completed according to the growing period of the host. The nematodes’ optimum temperature for development is reported to be around 25oC.

Major pathway(s)

N. aberrans can be carried in potato tubers and soil as well as roots of other host plants.

Detection and inspection

N. aberrans can be detected at harvest time in potato tubers. Nematodes are found only in the outer 2 mm of the tubers. Identification of the species needs to be done in a laboratory.

Pest status and importance

N. aberrans is one of the three main nematode pests of potato in the Andean region.

Source of information

See further information here:

Author: Jorma Rautapää
Editor: Dorthe Vestergaard