Pale Cyst Nematode

When PCN is detected, it stops commerce in potatoes and nursery stock. It can seriously harm our agricultural production, environment, and economy. Here's what to look for:

• Cysts
  • Dead females (cysts) can be found on the roots and potato tubers. They can stay dormant for up to 30 years, while the eggs inside remain viable.
• Field damage
  • Stunted plants with yellowing leaves, wilting, and eventually plant death.

PCN Photo Gallery

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PCN spreads when soil from an infested field is moved to a new location on farming equipment, seed potatoes, or waste from potato grading operations. All farming equipment used on infested land must be pressure washed to remove soil. Equipment with difficult to reach areas, such as harvesters, may need to be steam treated or fumigated to ensure it is nematode-free. Pressure washing and steam treatments are coordinated through APHIS.

To prevent the spread of PCN:

• Make sure all farm machinery, trucks, construction, and other equipment are clean when going from field to field. Do not allow any equipment in your fields unless it has been thoroughly cleaned. This is especially important when renting land, as you may not have records of previous crop history.
• Check the condition of trucks and other vehicles entering your operation. Find out where they have been and what sanitation treatments they have had. Seed potato shipments are a particular concern for PCN spread because trucks may make more than one stop.
• Do not spread waste from potato grading, processing, or storage operations on farmland or place it in an area where it can be spread to farmlands.
• Leave hedgerows, sod barriers, or sod strips between fields and along highways.
• Buy only certified seed that comes from fields tested and found to be PCN-free.
• Plant a PCN-resistant variety (if available) in your noninfested fields at least once every 4 years.
• Plant cover crops as soon as possible when land is not in use because wind and water erosion can spread PCN cysts.
• Tell people in your operation about the seriousness of PCN and potato diseases. Make sure they follow all precautions. Provide equipment needed to conduct proper cleaning and disinfection procedures.
• Segregate potatoes in storage by field.
• Do not reuse previously used bags or containers for potato transport. Be sure all commercial transport vehicles are free of soil.
• Do not allow temporary help, custom applicators, or utility companies to bring their vehicles onto your farmland without proper cleaning. Do not allow them to bring any bags or containers with them to the field.
• Do not use common headlands, farm roads, and public roads as turning areas.
• Prohibit nonauthorized entry onto farmlands using “No Trespassing” signs.
• Do not assume that nonregulated fields are free of PCN.

PCN-infested fields are treated with a chemical fumigant in late summer or early fall and sometimes in early spring, depending on soil temperature. These treatments continue until PCN is eradicated. APHIS monitors eradication progress.