KIRK Engineering & Natural Resources, Inc. Engineers, Scientists, and Natural Resource Planners

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Soil Sampling Potato Cyst Nematode Services

Introduction

Over the last two 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 U.S. With these opportunities, however, come increased risks associated

with the potential movement of plant pests and diseases into 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 prevent the establishment of foreign agricultural pests and diseases in the U.S.

and protect American agriculture. KirK is contracted with the USDA APHIS program in North

Dakota to provide services for surface soil sampling for Potato Cyst Nematode (PCN). PCN is a

microscopic roundworm which causes growth retardation or at very high densities damage to the

roots and early senescence of potato crops. Infestations of exotic pests such as the pale cyst

nematode (Globodera pallida) and the golden nematode (G. rostochiensis) can permanently

damage agricultural resources. Collectively, these pests are known as PCN. If PCN were to

become established in the U.S., their presence could eventually shut down potato exports to other

countries.

PCN can go undetected for months or years—even decades—in the absence of vigilant

surveillance. Early detection of pests provides optimal control opportunities, minimizes the use

of pesticides, enhances product quality and marketability, and results in an abundant, readily

available, and affordable supply of food, fiber, plants, and plant products for domestic and export

markets.

PCN originated in South America and are now widely distributed in many potato-growing

regions throughout the world. In North America, the G.pallida and G. rostochiensis species of

nematodes are known to be present in Quebec, Alberta, and on the islands of Newfoundland and

Vancouver in Canada.

A major pest of potato crops in cool areas outside of the U.S., pale cyst nematode was detected

domestically for the first time in 2006 at a grader facility in eastern Idaho. After launching a

rigorous survey, agriculture officials isolated the pest to just nine potato fields in southeastern

Idaho. Golden nematode was first detected in 1941 in Long Island, New York (Nassau County).

Since then, it has been confined to small areas within nine counties in New York. Together, PCN

primarily affect plants within the potato family, including tomatoes, eggplants, and some weeds.

If left uncontrolled, PCN can reduce yields up to 80 percent in potato fields.

APHIS continues to provide soil screening to verify that U.S. potatoes are PCN-free and aid in

early detection of PCN. KirK uses USDA approved soil sampling methods and equipment for

seed potato and commercial production fields.

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APHIS National Survey Plan

Working closely with the potato industry, APHIS’ Plant Protection and Quarantine (PPQ)

program developed a multi-year, science-based National Survey Plan for the detection of PCN in

all potato-producing states. The intent of the survey is to detect any potential problems early and

gather information to demonstrate to trading partners that U.S. potatoes are PCN-free.

Seed potatoes pose the greatest risk (pathway) for PCN introduction and contamination from one

field to another. Therefore, the survey in each state will first target seed potatoes and then

commercial production fields. While the selection of production fields is designed to be random,

the surveys also give particular attention to fields with a higher likelihood of infestation and

detection. If a new detection of PCN occurs, APHIS and state officials will take regulatory

actions 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 reasonable and appropriate regulatory actions.

Survey Methods

PCN infestations may be associated with patches of poor growth. Affected potato plants may

exhibit yellowing, wilting, or death of foliage, but these symptoms are not always present. For

example, in Idaho in 2006, pale cyst nematode was only detected by testing tare soil in a potato-

storage facility as part of a survey through USDA’s Cooperative Agricultural Pest Survey. Pest

survey specialists, including KirK specialists, use full field surveys to collect soil samples for

PCN testing. During a full field survey, each field must be sampled at a rate of one 5-pound

sample per surveyed acre. All samples must be collected and sent to an approved laboratory for

diagnostic testing. Each soil sample must be processed in its entirety in order to obtain accurate

test results.

The Benefits of Participation

Participation in the survey is voluntary and is funded by USDA–APHIS on a first come first

serve basis. The benefits of the survey to the entire potato industry are directly related to the

level of participation. In other words, more participation in the survey will generate more

information to demonstrate this pest is not present in the U.S., other than the isolated PCN

detections in Idaho and New York. This information will help to improve the domestic and

international marketability of the U.S. potato crop. Even if additional isolated cases of PCN are

detected through the survey, APHIS and state partners are prepared to localize and contain any

potential problems and minimize the effects to local potato producers. In this way, survey and

early detection will better protect the U.S. potato industry from the serious consequences of

allowing PCN to spread unchallenged or become established in the U.S.

Background on PCN, the National Survey Plan, and other related materials are available online

at www.aphis.usda.gov/plant_health/plant_pest_info/index.shtml.

Credits: A portion of the text above is adapted from USDA APHIS program brochure 1941.

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Having Your Potato Fields Sampled and Tested for PCN

All PCN soil sampling is directed by and overseen through state agricultural departments and/or

APHIS. Soil samples can be analyzed by APHIS or state laboratories as directed by the PCN

program in your state. If you want to have your potato fields tested on an ongoing or periodic

basis, first contact your state agricultural depart or the nearest APHIS program and sign up for

the voluntary program. Potato seed farms which export to international markets are required to

sample for PCN. Sampling requirements differ from state to state as well as the methodology and

participation in the program. Contact your local, state, or federal agricultural representatives

responsible for PCN sampling for assistance with signing up for the program.

Typically the state or federal PCN program will coordinate collection of soil samples on your

fields, as described in the National Survey Plan. However, if the voluntary program cannot

accommodate additional producers in a given year KirK can assist you in collecting soil samples.

KirK is required to work through your state agricultural department or APHIS program to ensure

proper oversight and sample handling. If you need assistance in making agency contacts, KirK

can provide this service for you and help you plan your soil sampling work at no charge.

Scheduling Seed Exports and PCN Results

Soil sampling can be scheduled to occur post potato harvest and completed in a relatively short

time period ranging from less than a day to several days. Weather can hamper soil sampling and

wet conditions can significantly delay both hand and mechanical soil sampling. As a rule of

thumb, if you can make a ball of soil from your potato field, conditions are too wet to sample.

Soil samples should be dried prior to shipping them off for PCN testing. The time it takes to

obtain results from PCN testing is dependant on the backlog at the laboratory where the samples

are sent. Depending on where and how many samples are waiting to be tested, results will be

ready in matter of weeks to months. Be sure to consider your export and other schedules when

seeking certification that your potatoes are free of PCN.

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Photographic Summary of PCN Sampling in North Dakota

PCN soil sampling requires specialized

equipment. This trailer holds the soil sampler,

4-wheeler, and pressure washer needed for

sampling and equipment decontamination.

KirK uses soil samplers built by AMS

of American Falls, ID which are

considered to be the fastest sampling

system for PCN.

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Soil samples can be collected if

potato veins are still present in the

field or samples can be collected

after finishing the field.

Soil samples are collected from

potato fields following harvest.

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Soil sampling equipment is hauled to the field in a clean,

decontaminated condition. The equipment is inspected

and unloaded when ready to use.

Typical soil conditions

for PCN sampling post-

harvest.

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KirK field crew and team

leaders meet daily to plan

soil sampling to ensure it

is completed on time,

appropriately, and with

excellent communication

between the producer and

APHIS personnel.

Each field crew member is

outfitted to be independent with

tools, sample bags, and field

equipment required.

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Flagging is used as a visual aid to

mark 24-ft wide swaths used to

collect samples on potato fields.

Once unloaded, sampler arms are

extended 12-ft wide and the unit

is lowered to begin soil sampling.

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Dry soils are ideal for

sampling, but soil can

be sampled in moist

conditions, such as

after a moderate rain

and one to two days of

wind and sun. Wet soil

conditions must be

avoided.

This sampler is ready to begin

sampling a 1,815 ft long pathway

that is 24-ft wide totaling one acre.

One 5-lb (2000 cc) sample is

collected on each one acre pathway.

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Soil samples from the

three wheels are

combined into one 5-

lb (2000 cc) soil

sample at the end of

the 1,815 ft. pathway.

The samples are stored

in high density paper

bags, labeled, and

stapled for rack drying,

shipping, and testing at a

PCN laboratory. A

chain-of-custody form is

completed to track the

individual sampling,

field number, and

sample number from

collection through

analysis.

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Each sampler uses a

field book to record

the field number, land

owner, date, GPS

waypoint for each

sample, and sample

numbers. If any

positive PCN results

are detected, the

waypoints can be used

to track samples down

to a single acre for

confirmation testing.

Each farmer / landowner

is assigned a field

number, location,

acreage, potato variety,

target number of

samples, and aerial

photograph showing

access and sampling

field.

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GPS of the sampling

pathway (tracks) and

waypoints (sample

collection at the end of a

one-acre pathway) are

downloaded to computer.

Field data is imported into a geographic

information system (GIS) for mapping,

shown here on a 2009 aerial photograph.

Wet areas not sampled

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Quality control is our top priority and KirK team leaders, along with

APHIS supervisors, inspect and oversee all sampling activities to ensure

representative and reproducible soil samples are collected using approved

sampling techniques and data handling.