Golden cyst nematode
Golden cyst nematode
Alternative common names:
The golden cyst nematode is native to South America. Itaffects potato and tomato plantsas well as a variety of other root crops. This nematode was first reported in South Africa in 1971 by a farmer near Pretoria and then from small farms around Johannesburg and Bon Accord. In April 1999, it was reported from the Ceres area in the Western Cape.
Where does this species come from?
What is its invasive status in South Africa?
NEMBA Category 1b.
Where in South Africa is it a problem?
Gauteng and Western Cape.
How does it spread?
Through imported potatoes.
Why is it a problem?
It affects root growth in susceptible species, especially in potatoes and tomatoes, by forming cysts on the roots. The cysts, which are composed of dead nematodes, are formed to protect the female’s eggs and are typically yellow-brown in colour.
What does it look like?
Description: Adult nematodes are sedentary and sausage-shaped. Females eventually become sac-like. Their posteriors protrude from the host’s root and are visible as tiny white, yellow or brown embedded objects. Once a female dies, its body hardens to form cyst. In spring, when the roots of the host crop exude chemicals, eggs are stimulated to hatch.
Habitat: Survives best in climates with relatively moist summers and mild winters. The three commercial crops that are hosts of potato cyst nematodes are: potatoes, tomatoes and eggplants.
Breeding: The cyst, the protected resting stage of this group of nematodes, contains eggs, which are stimulated to hatch when they are in proximity to the roots of a host plant. Once hatched, the larvae undergo four larval stages: the first occurs within the egg, the second stage – the infective stage – occurs within the soil, while the third and fourth stages (maturing stages) occur within the plant root. When the males are fully developed, they migrate back into the soil. The free roaming males fertilise the embedded females. After copulation the males die. Fertilised females begin to swell as the eggs develop within their bodies. When the females die their body walls gradually harden and darken to form a protective layer around the eggs – the females progress from white to a golden yellow before darkening into the cyst. A new cyst may contain as many as 500 eggs and persist in the soil for more than 20 years. There is a reduction in the number of viable eggs within a cyst over time. Mortality appears to be greatest under cultivation due to the higher temperatures in arable land.