Globodera pallida |
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Rev 10/05/2006 |
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| White cyst nematode, Potato cyst nematode |
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Classification |
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Hosts |
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Morphology and Anatomy |
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Life Cycle |
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Economic Importance |
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Damage |
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Distribution |
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Management |
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Feeding |
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References |
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Classification:
- Tylenchida
Tylenchina
Tylenchoidea
Heteroderidae
Heteroderinae
- Globodera pallida
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Morphology and Anatomy:
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Females: Cyst stage present.
Body globose, spheroidal, with a short neck and no terminal cone. Cuticle thick, with superficial, lace-like pattern; D-layer present. Vulva terminal, of medium length. Vulval area circumfenestrate; superficial tubercles near vulva. No anal fenestration, but anus and vulva lying both in a "vulval basin." Underbridge and bullae rarely present. All eggs retained in body (no egg-mass).
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| Note: Globodera rostochiensis passes through a yellow stage before rupturing root cortex. Globodera pallida remains creamy white until dying and becoming a brown cyst. |
| Males: Vermiform; body twisted into a C or S shape.
Lateral field with four lines. Spicules greater than 30 µm in length, distally pointed. No cloacal tubus. Tail short, hemispherical. |
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Second-stage juveniles: Stylet less than 30 µm long. Lateral field with four lines. Esophageal glands filling body cavity. Tail conical, pointed, with terminal half hyaline. Phasmids punctiform. |
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| There are some morphological differences between G. pallida and G. rostochiensis; e.g., in juvenile lip region, etc. | |
Several pathotypes of G. rostochiensis exist: British A, Dutch A,B,C.
For G. pallida: British B and E, Dutch D.
Pathotype classifications are based on ability of nematode to reproduce on resistant cultivars.
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Distribution:
Wide distribution in potato-growing regions of Europe. Discovered in Idaho in the US in April, 2006; extent of infestation under investigation..
Genus probably originated in Peru with Solanum tuberosum and other Solanum spp.
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Center, EPPO, Globodera pallida meeting in Boise Idaho (May, 2006), and literature review, the presence of Potato Cyst Nematode (PCN), Globodera
pallida, has been reported in the following countries:
Europe: Austria, Belgium, Croatia, Czechia, Faroe Islands, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland, United Kingdom. As of 2006, it is reported as eradicated in Denmark. Asia: Cyprus, India, Pakistan, Turkey. Africa: Algeria, Tunisia. North America: Canada. Central America: Panama. South America: Argentina, Bolivia, Chile, Colombia, Ecuador, Falkland Islands, Peru, Venezuela. Reports of occurrence in several other countriies are considered invalid or unreliable as of May, 2006. Other than the discovery in Idaho, G. pallida is not reported from USA. In 14 of the countries, the races of the nematode have been identified. In 63% of the countries infested with PCN there are no data about races. The International Potato Center in Lima, Peru maintains a worldwide collection of races and offers a free service for species and race identification. (Matos and Canto-Saenz, 1990; EPPO, 2006) |
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Economic Importance:
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Feeding:
Feeding site establishment and development typical of genus.
Nurse cell system is a multinucleate syncytium.
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Hosts:
Very narrow range: potato, tomato, and some weeds.
There are several pathotypes of G. pallida: British B and E, Dutch D.
Pathotype classifications are based on ability of nematode to reproduce on resistant cultivars.
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Life Cycle:
Egg hatch is stimulated by host root diffusate (60-80%) - only about 5% hatch in water. Some eggs do not hatch until subsequent years.
J2 moves into root, establishes feeding site, and undergoes 3 more molts.
Adult males do not feed. Sex is determined by food supply - males develop in adverse conditions and heavy infestations.
Nematodes reproduce sexually; males are attracted to females by a pheromone sex attractant. Nematodes may mate several times.
Annual population decline in the absence of a host varies from 18% in cold soils (Scotland) to 50% in warm soils, with an average decline rate about 30% - so population decline follows this pattern: 100-70-50-35-23-etc.
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Damage:
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In Scotland, 1 ton/acre is lost for every 20 eggs/g soil. Supply of water and nutrients to upper plant is diminished.
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Management:
Crop Sequence:
Continuous cropping of cultivars resistant to G. rostochiensis selects for pathotypes of G. pallida.
Widely used.
Resistance:
Seeds of three varieties segregating for resistance to two pathotypes of Globodera rostochiensis (Ro1 and Ro2) and two pathotypes of G. pallida (Pa2 and Pa3) have been released by Cornell University and USDA/ARS. The resistance is suitable for North American production. It was developed in anticipation that pathotypes of G. pallida, which are prevalent in many other potato production areas of the world, are ever introduced into North America.
The combined resistance in this germplasm is from S. tuberosum ssp andigena and S. vernei. Brodie et al (2000).
Reducing Spread:
As of September 2006, the U.S. Department of Agriculture has issued a potato advisory for a specific area of Southeast Idaho. People are asked to take precautions when gleaning potatoes missed by the harvester. Agriculture departments have been testing fields in the regulated area. While people aren't discouraged from picking potatoes, they should wash off their shoes in between fields to prevent the spread. For more information regarding the regulated area, contact the Potato Cyst Nematode Project Office at 208-351-9857.
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References:
Luc, Maggenti & Fortuner, Rev. Nematol. 11(2):159-176 (1988)
H. Ferris
Brodie, B. B.; Scurrah, Maria; Plaisted, R. L.. 2000. Release of germplasm resistant to multiple races of potato cyst nematodes. American Journal of Potato Research 77: 207-209.
Matos, A. and M. Canto-Saenz. 1990?? Worldwide distribution of the
potato cyst nematode Globodera spp. International Potato Center.
P.O. Box 5969. Lima - Peru. (Published in Nematropica)