Globodera rostochiensis

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Globodera rostochiensis cysts (click on image to enlarge it)
Author(s): Gordon Berg, DPI Victoria
Source: PaDIL

Globodera rostochiensis (Wollenweber, 1923) - (golden potato cyst nematode)

The species is a destructive cyst nematode found in many potato growing regions. Although potato is the main host, it can also infect some related crops like tomatoes or eggplants. It is native to South America and has invaded a number of different countries. For example it was discovered in Germany in 1913, in Canada in the 1960s and in the 1970s in Mexico and South Africa. Apart from crop losses, it often results in considerable quarantine efforts to limit the spread of the nematode.

Yield losses can exceed 50% if potato is grown repeatedly in an infested field. It has been estimated that for 20 eggs and juveniles per gram of soil the potato yield is reduced by 2 t per hectare.

The cysts and eggs are very durable and can persist in the soil for many years. They usually spread through contaminated soil which is attached to farm equipment or through infested plants and tubers.

Infested fields show localized patches of stunted, wilting and yellowing plants, with small tubers. Management primarily involves strict quarantine procedures to prevent the nematode from reaching uninfested fields. This includes restrictions of moving soil and plants from quarantined areas, import regulations for seed potatoes, as well as regular inspections and the analysis of soil samples. Many countries are implementing inspection and certification schemes for fields growing seed potatoes.

Eradication from an infested field, e.g. through soil fumigation, is often not possible. Partially resistant cultivars are available or are under development. However, there are also a number of pathotypes of the nematode which react differently to a given cultivar. Crop rotation and soil solarization (placing a clear plastic over the moist soil in the summer) also helps to reduce the number of viable cysts in infested soil.

Vernacular names
• Deutsch: gelber Kartoffelnematode
Kartoffelzystenälchen
• English: potato root nematode
golden nematode
yellow potato cyst nematode
golden potato cyst nematode
golden cyst nematode
• Español: nematodo de la patata
nematodo dorado de la papa
• Français: nématode doré de la pomme de terre

Hatching of the eggs is stimulated by root exudates from the host plant. The first juvenile stage develops inside the egg and the 2nd stage (J2) hatches from the eggs and is attracted to the potato roots by specific compounds released by the roots. The J2 penetrates the tip of a fine root, migrates inside the root and after passing through the 3rd and 4th juvenile stage develops into an adult. Females swell when they develop eggs with part of their body protruding from the root. Mature males leave the root, locate and fertilize females still attached to the root. The mature female is almost spherical and golden-yellow. The female finally dies and becomes a brown, durable cyst filled with around 500 eggs.

The J2 nematodes are about 500 µm long with a conical and pointed tail. Morphological characteristics of the J2 stage, used for identification, include shape of the stylet kmob and length of the stylet and stylet shaft. However, these characters are variable and identification by PCR and DNA sequence comparison is recommended. The cysts have a diameter of about ½ mm, mature males are slightly longer than 1 mm.

See also the closely related pale potato cyst nematode.

For an identification guide see the EPPO (2917) Standard PM 7/40 (4).

Synonyms:
Heterodera rostochiensis