Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2006
Publication Date: 3/1/2007
Citation: Handoo, Z.A., Skantar, A.M., Carta, L.K., Chitwood, D.J., Saad, H., Palanisamy, S. 2007. First report of the pale cyst nematode (globodera pallida) in the united states. Plant Disease. 91(3):325. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plant roots and cause an estimated ten billion dollars of crop loss each year in the United States and 100 billion dollars globally. Cyst nematodes are an important group damaging the roots of many kinds of plants worldwide. In order to determine if cyst nematodes are causing agricultural problems, crop specialists routinely conduct field surveys looking for the presence of the nematodes. This brief report describes how a team of ARS and University of Idaho scientists identified a type of a potato cyst nematode in some waste soil at a potato processing plant in Idaho. Subsequent investigations led to the identification of the same nematode from a field located in northern Bingham County in eastern Idaho. This discovery is significant because it is the first report of this nematode in the United States. Because the nematode causes economic damage to potatoes in Europe and is regulated as a quarantine pest by many countries, this report will interest or be used by researchers planning future surveys, evaluating quarantine strategies, and identifying nematode species.
Technical Abstract: In 2006, a cyst nematode was discovered in tare dirt at a potato processing facility in eastern Idaho. The nematode was found during a routine survey conducted jointly by the Idaho State Department of Agriculture and the USDA Animal and Plant Health Inspection Service through the Cooperative Agricultural Pest Survey program. Extensive additional sampling from two suspect fields led to the identification of the same nematode in a 45-acre field located in northern Bingham County. The morphology of cysts, second-stage juveniles and molecular analyses established the identity of the species as the pale cyst nematode Globodera pallida (Stone, 1973) Behrens, 1975. Morphological characters used for identification included cyst shape, characteristics of cyst terminal cone including nature of fenestration, cyst wall pattern, anal-vulval distance, number of cuticular ridges between anus and vulva, and Granek’s ratio. The second-stage juvenile morphologies critical for identification were the following: body and stylet length, shape of stylet knobs, shape and length of tail and hyaline tail terminus, and number of refractive bodies in the hyaline part of tail. Diagnosis as G. pallida was clearly confirmed by two molecular tests. First, PCR-RFLP profiles of a ribosomal DNA fragment using restriction enzymes RsaI, TaqI, and AluI were consistent with a G. pallida control and not G. rostochiensis. Second, the ribosomal DNA region that extends from the 3’ end of the 18S ribosomal subunit and includes all of ITS1, 5.8S, and ITS2, to the 5’ end of the 28S ribosomal subunit was used to generate sequence for the most accurate species determination. Sequences obtained from three individual juveniles were compared to those from several Globodera species, revealing unequivocal similarity to G. pallida. This detection represents a new country record for G. pallida in the United States. Collection of additional information regarding distribution of this nematode within the region is underway.