Potato Cyst Nematode Update

Published online: May 01, 2006 PGI News Flash
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With the recent discovery of the nematode, Globodera Pallida, in a tare dirt sample, more and more questions, not answers, are being raised. Unfortunately, the first-time discovery of this exotic nematode in the United States is likely to lead to a number of changes in the Idaho potato industry.

The primary questions are: 1) In what fields are the nematodes located? and 2) Where did they come from?

The Idaho State Department of Agriculture and the USDA's Animal and Plant Inspection Service are working hard to answer these questions. In fact, they are gearing up to have some 50 people in Idaho Falls involved with the investigation.

In legal matters, one is considered innocent until proven guilty; however, in this case, one will basically be considered guilty until proven innocent. As a result, the suspected fields are being sampled in a set pattern, with one sample being taken every four paces.

This heavy sampling has a 95 percent confidence rate. New equipment is being built and lab space expanded to handle this survey and other possible subsequent surveys.

Even with this survey, it is still very possible that the nematodes will not be found in those fields. It is even possible that the tare dirt containing the nematodes came from a different farm altogether. Should this be the case, a wider geographic survey will be required.

The seed farms supplying seed to the suspected fields for the 2005 crop will also be surveyed shortly. However, it is important to recognize that even if the nematodes are found in the suspected fields, it does not mean they arrived there with the 2005 seed. They could have been introduced in previous years' crops or by other movement of soil.

The Potato Cyst Nematode is not likely to burrow into potatoes, as do root knot nematodes. These nematodes are transported with soil, on seed, equipment or by some other means.

These nematodes also had to come from somewhere. The only place currently allowed to export seed to the United States is Canada, and the only place in Canada with this nematode is Newfoundland, which has a tight quarantine.

Canada does allow some seed importation from Europe. Growers with knowledge of ANY seed imported from Europe or other areas of the world including South America are encouraged to please report this activity to the Idaho Department of Agriculture at (208) 332-8500 or the PGI office at (208) 785-1110.

Please report on any other possibilities or ideas of how this nematode might have arrived in Idaho. Remember, we are all guilty until we find the nematodes, trace where they came from, and establish quarantine measures to contain it.

The following are some "Best Management Practices" to control the spread of this nematode from the University of Idaho. Keep in mind that no one in the United States has ever had to deal with Globodera Pallida before. It is similar to the Golden Nematode found in parts of New York, but is different enough that management will also need to be different.

 - Increase levels of sanitation between fields and farms to prevent movement of soil.
 - Plant only certified seed - including a plant health certificate and shipping point inspection.
 - Longer rotations are advised, since 40 percent of this nematode's population is reduced each year potatoes are not planted. Tomatoes and egg plants are the only other known crop hosts.
 - As with other pests it appears that this nematode can also grow on nightshade weeds, so nightshade control is also important.