Globodera rostochiensis

Scientific Name	Globodera rostochiensis (Wollenweber)
Synonyms	Heterodera rostochiensis
Common Names	English: Potato cyst nematode, golden nematode; German: Kartoffelzystenälchen; French: Nématode à kystes de la pomme de terre; Spanish: Nematodo de la patata; Italian: Nematode dorato della patata
Description	Tiny (max. 1mm; 0.039 inch) in length, whitish, threadlike worms; the females as cysts are golden- to dark brown and have a diameter of up to 0.8 mm (0.03 inch).

Damage

The larvae hatch in the spring, as soon as soil temperatures reach 12-15°C (53.6 - 59°F). In their second development stage (second stage juveniles J2), they bore into roots, preferably near the growing tips. The host plant cells react to this invasion by merging and forming giant cells (called syncytia). This tends to hinder the transport of plant sap, as vascular tissues are often involved, affecting large parts of the roots, which will ramify and become shrubby, turn brown, and eventually die off. Attacked plants suffer from an inadequate nutrient and water supply, so they become weakened, appear stunted or chlorotic, wilt, and frequently die off.
If nematode densities are extremely high, tubers can become infected, too.

Lifecycle

Having fed for some time on a syncytium, the male will move around in order to find a mate: the female stays sessile inside the plant tissue. The several hundred eggs produced by the female remain in its body after copulation, which makes it swell up considerably. It breaks through the root surface, becomes spherical, and darkens as the result of secreting phenolic compounds. The female eventually dies, and its cuticle transforms into a cyst, which detaches from the root. Eggs protected in this way can remain viable for up to 15 years (up to 30 years according to some authors). They hatch irregularly over a period of several years, a process which is triggered by root exudates from host plants.
Although it is hardly mobile, G. rostochiensis is widespread in most potato-growing countries of the world. Once introduced, it is nearly impossible to eradicate, due to the longevity of its cysts in the soil. It has one generation per year.

Additional Crop Information

Solanaceae, especially potato, tomato, egg plant.

Agricultural Importance

Crop losses can reach 70%. Further economic damage can result from the trade restrictions and quarantine measures necessitated by the occurrence of the pest.

Useful non-chemical contribution to Integrated Weed Management

The main routes of dispersal are contaminated soil and plant material. Hygiene and strict adherence to quarantine regulations are of paramount importance. When infestation has already occurred, long crop rotations, including the use of resistant varieties and non-solanaceous crops, help to prevent population build-up.