Animal and Plant Health Inspection Service

Program Aid No. 1941

Potato Cyst 

Nematode National 

Survey Plan:

“Looking” To Keep Potato 

Markets Open

Agricultural Pest Survey, pale cyst nematode 

was only detected by testing residual soil that 

accompanied potatoes into the storage facility. 

Pest survey specialists follow established survey 

guidelines to collect soil samples for PCN testing. 

During these surveys, each field must be sampled 

at a rate of one 5-pound sample per surveyed acre. 

All samples are collected and sent to an approved 

laboratory for diagnostic testing. Each soil sample is 

then processed in its entirety to get accurate 

test results.

The Benefits of Participation

Participation in the survey is voluntary. As a grower, 

your support is key to a successful survey and 

brings benefits to the entire potato industry. The 

more growers who participate in the survey, the 

more information we will have to show that—other 

than the isolated PCN detections in Idaho and New 

York—these pests are not present in the United 

States. This information will help improve the U.S. 

potato crop’s marketability at home and abroad. 

Even if we find more isolated cases of PCN through 

the survey, APHIS and the States are ready to 

contain any potential problems and minimize the 

negative effects that may result. In this way, survey 

and early detection will better protect the U.S. potato 

industry from the serious costs of allowing PCN to 

spread unchecked or become established here.

For More Information

To learn more about PCN, the National Survey Plan, 

and related topics, visit the APHIS Web site at 

www.aphis.usda.gov/planthealth/pcn.

If you have specific questions or want to join the 

survey, please call your nearest APHIS office. 

Contact information is listed on our Web site at 

www.aphis.usda.gov/planthealth/sphd.

USDA prohibits discrimination in all its programs and activities 

on the basis of race, color, national origin, age, disability, and 

where applicable, sex, marital status, familial status, parental 

status, religion, sexual orientation, genetic information, political 

beliefs, reprisal, or because all or part of an individual’s income 

is derived from any public assistance program. (Not all prohibited 

bases apply to all programs.) Persons with disabilities who require 

alternative means for communication of program information 

(Braille, large print, audiotape, etc.) should contact USDA’s 

TARGET Center at (202) 720-2600 (voice and TDD). To file a 

complaint of discrimination, write to USDA, Director, Office of 

Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 

20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 

(TDD). USDA is an equal opportunity provider and employer.

Photo credits: All of the images in this leaflet (except for the 

microscopic shot of PCN) were taken by pale cyst nematode 

personnel in Idaho during 2006. The microscope photo comes 

from the Forestry Images Web site and is reproduced by 

permission.

Revised May 2015

Producers share 

information 

on best 

management 

practices for 

minimizing the 

spread of PCN.

Mechanical wheel soil samplers like this one were used 

during the PCN survey in 2006.

Cleaning and sanitizing farm equipment is important in 

preventing the spread of PCN contamination to 

new locations.
Introduction

In the last few decades, trade with foreign countries 

has increased dramatically, opening new markets for 

U.S. commodities and filling American grocery stores 

with tastes from other nations. Similarly, international 

travel has exposed Americans to new cultures and 

brought visitors from all over the world to the United 

States. With these opportunities, however, come 

increased risks that invasive plant pests and diseases 

will enter our country.

The U.S. Department of Agriculture’s (USDA) Animal 

and Plant Health Inspection Service (APHIS) uses 

agricultural safeguarding tools and techniques, such 

as early detection through surveillance, to keep 

foreign pests and diseases out of the United States 

and protect American agriculture. Infestations of exotic 

pests such as the pale cyst nematode (Globodera 

pallida) and the golden nematode (G. rostochiensis)

can permanently damage agriculture and natural 

resources. Collectively, these pests are known as 

potato cyst nematodes (PCN). If PCN became 

established in the United States, their presence could 

eventually shut down potato exports to other countries. 

Some plant pests, such as the Japanese beetle and 

Asian gypsy moth, leave almost immediate evidence 

of their presence. Others, like PCN, can go undetected 

for months or years—even decades—without vigilant 

surveillance. When plant pests are detected early, we 

have more opportunities to effectively control them; 

minimize pesticide use; enhance product quality 

and marketability; and ensure an abundant, readily 

available, and affordable supply of food, fiber, plants, 

and plant products for domestic and export markets. 

Background

PCN are major pests of potato crops in cool weather 

areas. Pale cyst nematode was detected for the first 

time in the United States in 2006 at a grader facility 

in eastern Idaho. After conducting rigorous surveys, 

agriculture officials isolated the pest to potato 

fields within a small 7.5-mile radius spanning two 

counties in southeastern Idaho. Golden nematode 

was first detected in 1941 in Long Island, NY 

(Nassau County). Since then, it has been confined 

to small areas within eight counties in that State. 

Both nematodes originated in South America and 

are now widely distributed in many potato-growing 

regions throughout the world. In North America, the 

pale cyst nematode and golden nematode are also 

present in Quebec, Alberta, and on the islands of 

Newfoundland and Vancouver Island in Canada.

The main host plant for PCN is potatoes. Other 

plants within the potato family, including tomatoes, 

eggplants, and some weeds, can also serve as 

hosts. PCN are soil-borne, microscopic nematodes 

that infest feeder roots, where the females attach, 

feed, and become sedentary. Nematodes reproduce 

sexually. Males are attracted to females by a 

pheromone (sex attractant) and may mate several 

times. Females form cysts containing 200 to 600 

eggs. Cysts can stay dormant for up to 30 years 

while the eggs inside remain viable. When there are 

large numbers of nematodes, they can cause wilting, 

stunted growth, poor root development, and early 

plant death. If left uncontrolled, PCN can reduce 

yields up to 80 percent in potato fields. 

Preventing the Spread 

To keep PCN from spreading, APHIS restricts 

the interstate movement of certain products from 

regulated areas in Idaho and New York. These 

products include the following: 

n potatoes and other PCN host crops

n root crops

n nursery stock

n soil, compost, humus, muck, peat, and 

 decomposed manure 

n grass sod

n hay, straw, fodder, and plant litter

n used farm and construction equipment

n garden and dry beans (Idaho)

	 n small grains and soybeans (New York)

	 n ear corn, except shucked (New York)

These products can be moved outside of a 

quarantined area only when accompanied by a 

certificate or limited permit signed by a State or 

Federal inspector.

National Survey Plan

Working closely with the potato industry, APHIS’ 

Plant Protection and Quarantine (PPQ) program 

developed a multiyear, science-based National 

Survey Plan to detect PCN in potato-producing 

States. The survey’s intent is to find any potential 

problems early and gather information to show 

trading partners that U.S. potatoes are PCN-free.

If a new detection of PCN occurs, APHIS and 

State officials will take regulatory actions, such 

as quarantines and eradication efforts, to protect 

other potato fields and minimize the impact on the 

potato industry as a whole. In such an event, APHIS 

is committed to working with potato growers and 

State counterparts to develop a reasonable and 

appropriate response.

Survey Methods

PCN infestations may show up as patches of poor 

growth. Affected potato plants may have yellowing, 

wilting, or dead leaves, but these symptoms are 

not always present. For example, in Idaho in 2006, 

as part of a survey through USDA’s Cooperative 

This is a 

microscope 

shot of the 

anterior part of 

a juvenile PCN.

A laboratory 

technician analyzes 

extracted soil 

samples, looking for 

evidence of PCN. 

Here, potatoes move on a conveyor belt into a storage 

cellar.

A survey specialist 

collects soil 

samples from a 

potato field during 

the PCN survey in 

2006.

The orange balls 

are PCN cysts on 

a potato root.