Potato Cyst Nematode Detected In Idaho

Published online: Apr 21, 2006 NPC Insider Report
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On Wednesday, the U.S. Department of Agriculture (USDA) in coordination with the Idaho State Department of Agriculture (ISDA) announced a confirmed finding of potato cyst nematode in a soil sample collected from a potato processing facility in Idaho.  The nematode does not pose any threat to human health, but can reduce the yield of potatoes and other crops. There is no sign that the quality of tubers grown in Idaho has been affected. ISDA's early discovery of the potato cyst nematode is credited to the department's participation in the Cooperative Agricultural Pest Survey (CAPS), a surveillance program managed jointly by USDA's Animal and Plant Health Inspection Service (APHIS) and state departments of agriculture. Idaho and all other potato-producing states conduct routine surveillance and inspections for nematodes and other pests of concern.


As a result of these survey efforts, two cysts - the size of pinheads - were found in a soil sample sent for testing at the University of Idaho. The university identified the cysts as that of the potato cyst nematode. USDA's Agricultural Research Service confirmed the finding.


This is the first time the potato cyst nematode has been found in the United States. The university has conducted more than 9,000 soil sample tests since 2003. To date, no other cysts have been found in any other Idaho samples.


APHIS and ISDA scientists have isolated the origin of the cysts to two fields, totaling approximately 500 acres, on a farm in Idaho. APHIS is in the process of placing the two fields under quarantine and will conduct extensive sampling of the soil in cooperation with ISDA to determine whether additional potato cyst nematodes are present. APHIS and ISDA are also working to trace the origin of the seed that was planted in these fields.


APHIS has informed our trading partners, including the North American Plant Protection Organization, about the detection in accordance with international guidelines. These guidelines and the findings of the epidemiological investigation will provide a basis to quickly address any questions or concerns raised by our trading partners.


Earlier this week, APHIS issued an Emergency Action Notice restricting the movement of soil and potatoes from isolated Idaho facilities, including the processing facility where the sample was collected. This step was taken as a precaution until the facilities can be thoroughly evaluated and we can confirm that they pose no risk of spreading potato cyst nematode.


Processed potatoes are not considered a source for infection because nematodes cannot survive the cooking process, which includes steaming and drying.


The potato cyst nematode, Globodera pallida, is a major pest of potato crops in cool-temperate areas. It primarily affects plants within the potato family including tomatoes, eggplants, and some weeds. If left uncontrolled, nematodes can cause up to 80 percent yield loss.


Scientists believe the potato cyst nematode originated in Peru and is widely distributed in potato-growing regions throughout the world. In North America, the nematode is also known to be present on the island of Newfoundland, Canada. Potato cyst nematode infestations may be associated with patches of poor growth. Affected potato plants may exhibit yellowing, wilting or death of foliage - none of which has been observed in Idaho potato fields.


Early detection of pests minimizes agricultural production costs and enhances product quality and marketability. Crop rotation and the use of resistant potato cultivars and nematicides (fumigants or granular systemic compounds) is an effective and practical means of control. The common recommendation is seven years without potatoes. The integration of these methods can be used to keep the nematode population levels below economic thresholds.


Nationwide, CAPS personnel track more than 400 pests that pose a concern to U.S. agriculture and plant resources.


At this point, Canada and Mexico have implemented a temporary prohibition on the import of all potatoes and soil from Idaho due to the detection.  Japan has closed their borders to fresh potatoes.  The NPC is working very closely with USDA and Idaho Department of Agriculture to reopen these markets.  While this is a very serious pest, it is already under quarantine and control and we do not believe that it should impact shipments from any other areas outside of the quarantine. 


For further information, contact the NPC at (202) 682-9456.