United States 

Department of 

Agriculture

Animal and 

Plant Health 

Inspection 

Service

Plant Protection 

and Quarantine

New Pest Response 

Guidelines

Synchytrium endobioticum (Schilb.) Percival

Potato Wart Disease
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an equal opportunity provider and employer.

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Department of Agriculture over others not mentioned. USDA neither guarantees nor warrants the standard of 

any product mentioned. Product names are mentioned solely to report factually on available data and to provide 

specific information.

This publication reports research involving pesticides. All uses of pesticides must be registered by appropriate 

state and/or federal agencies before they can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other 

wildlife—if they are not handled or applied properly. Use all pesticides selectively and carefully. Follow 

recommended practices for the disposal of surplus pesticides and pesticide containers.
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Contents

Figures and Tables ............................................................................................... 4

1. Introduction ................................................................................................... 5

2. Pest Overview ................................................................................................ 6

3. Pest Identification ........................................................................................ 10

4. Survey .......................................................................................................... 18

5. Eradication and Control Options .............................................................. 23

6. Environmental Compliance ........................................................................ 25

Literature Cited ................................................................................................. 28

Appendix A: Survey Preparation, Sanitization, and Clean-Up ..................... 32

Authors and Reviewers ...................................................................................... 34

S. 

endobioticum
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Figures and Tables

Figures

Figure 3-1 Resting spores of S. endobioticum magnified 100× ..................... 11

Figure 3-2 Single resting spore of S. endobioticum........................................ 12

Figure 3-3 A) Resting spore; B) germinating resting spore of 

S. endobioticum............................................................................. 12

Figure 3-4 External sporangia releasing S. endobioticum zoospores............. 13

Figure 3-5 Galls on stem................................................................................. 14

Figure 3-6 Healthy sprout (left) and infected sprout (right)........................... 15

Figure 3-7 Fresh tuber gall ............................................................................. 15

Figure 3-8 Potato tuber with fresh galls ......................................................... 16

Figure 3-9 Potato tuber covered in galls......................................................... 16

Figure 3-10 Powdery scab (Spongospora subterranea) lesions on potato....... 17

Figure 3-11 Potato smut (Thecaphora solani) Barrus on Solanum tuberosum

L. (potato) ..................................................................................... 17

Figure 4-1 1.5-acre field (256 ft x 256 ft) overlaid with a square grid pattern 

and grid sampling frequency of 8 x 8 pace ................................... 20

Tables

Table 2-1 List of reported experimental plant hosts of S. endobioticum in 

Solanaceae ......................................................................................... 8

Table 4-1 Sampling frequency using a square grid pattern for potato wart 

disease survey activities .................................................................. 19

S. 

endobioticum
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1. Introduction

Plant Protection and Quarantine (PPQ) develops New Pest Response Guidelines 

(NPRGs) in preparation for potential future pest introductions. This document is 

based on the best information available at the time of development and may not 

reflect the latest state of knowledge at the time the pest is detected. In addition, 

the PPQ response must be tailored to the specific circumstances of each pest 

introduction event, which cannot be predicted. Therefore, this document provides

general guidelines that can be used as a basis for developing a situation-specific 

response plan at the time a new pest is detected.

Chapter

1
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2. Pest Overview

Key Information

♦ Synchytrium endobioticum is listed as a Select Agent by the USDA Select 

Agent Program. Only the USDA APHIS PPQ Science and Technology 

Beltsville Laboratory should attempt molecular diagnostics for identifying 

S. endobioticum. For more information, please visit 

https://www.selectagents.gov/.

♦ Synchytrium endobioticum produces sporangia that can remain dormant 

and viable in soil for 30–50 years.

♦ Human-assisted movement of infected potato tubers and infested soil 

spreads S. endobioticum to new locations.

♦ Currently, quarantine regulations are in place to prevent the introduction 

of this fungal pathogen into potato production systems in the United 

States. There are no chemical or non-chemical treatments available for use 

against S. endobioticum.

♦ Synchytrium endobioticum has different pathotypes that continue to 

change, complicating possible control and eradication options.

Taxonomy

Scientific Name

♦ Synchytrium endobioticum (Schilb.) Percival

Synonym(s)

♦ Chrysophlyctis endobiotica Schilb.

♦ Synchytrium solani Massee

Common Name(s)

♦ potato wart disease

♦ black wart of potato

Chapter

2
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♦ wart disease

♦ black scab

Biology and Ecology

Life Cycle

Synchytrium endobioticum has two reproductive cycles (Franc, 2007). The 

asexual reproduction cycle occurs during spring and summer when favorable 

conditions (adequate water supply for gemination of sporangia) occur. The sexual 

reproduction cycle occurs during autumn and winter when conditions are 

unsuitable (inadequate water supply) for sporangia germination. Both cycles 

produce sporangia that germinate into infectious mobile spores. However, the 

sexual cycle produces resting sporangia that can survive up to 50 years at depths 

up to 50 cm (20 inches) in the soil (Franc, 2007). The sporangia produced during 

the asexual cycle are short-lived and responsible for the secondary disease cycle.

Each reproductive cycle takes about 10-12 days to complete (Weiss, 1925).

Synchytrium endobioticum depends on live hosts to complete its life cycle. In the 

spring, resting sporangia germinate in decaying warts and soil, releasing their 

mobile spores (Franc, 2007; Hampson, 1993). These mobile spores can travel up 

to 2 inches in wet soil and infect new growth of susceptible hosts (Franc, 2007). 

After the mobile spores infect the host, characteristic warty galls are produced

(Fig. 3-4). As long as conditions are suitable, including adequate water, the 

disease cycle will continue with the production of more sporangia. When adverse 

conditions (including water shortages) occur, galls decay and release resting 

sporangia into the soil. 

Potato wart disease can occur when summers are cool with an average 

temperature of 18°C (64°F), winters are long (160 days) with an average 

temperature of 5°C (41°F), and precipitation levels are moderate (28 inches).

During ideal conditions, potato wart disease can develop from an inoculum 

density of less than one resting sporangium per gram of soil (Hampson, 1992). 

Hosts

Potato, Solanum tuberosum L., is the only known cultivated host of S. 

endobioticum (Obidiegwu et al., 2014). Solanum lycopersicum L. (tomato), may 

be a host of S. endobioticum but the data to support this is unclear. We found no 

evidence that S. endobioticum damages tomato plants. Researchers think that 
Last update 16DEC2020 Synchytrium endobioticum 8

tomato may just be a reservoir host (a host that does not develop severe symptoms 

but provides inoculum for spreading S. endobioticum to new areas) (Baker et al., 

2007; Lyman et al., 1920). Some uncultivated solanaceous plants are considered 

experimental hosts (Table 2-1). 

Table 2-1 List of reported experimental plant hosts of S. endobioticum in Solanaceae

Scientific name Common name References

Datura spp. jimsonweed Hampson, 1979

Nicandra physalodes (L.) 

Gaertn.

apple-of-Peru Martin, 1929

Phadtare and Sharma, 1971

Nicotiana rustica L. Aztec tobacco Phadtare and Sharma, 1971

Nicotiana spp. tobacco Phadtare and Sharma, 1971

Physalis alkekengi L. var. 

franchetii (Mast.) Makino 

(=Physalis franchetii Mast.)

hozuki Hampson, 1979

Schizanthus spp. schizanthus Hampson, 1979

Solanum americanum Mill. 

(=Solanum nodiflorum

Jacq.)

American nightshade Martin, 1929

Phadtare and Sharma, 1971

Solanum chacoense Bitter wild potato Weiss, 1925

Solanum commersonii

Poir.

Commerson’s nightshade Weiss, 1925

Solanum dulcamara L. bitter nightshade Cotton, 1916

Solanum dulcamara L. var. 

villosissimum Desv.

climbing nightshade Martin, 1929

Solanum jamesii Torr. wild potato Weiss, 1925

Solanum lycopersicum L. tomato Lyman et al., 1920

Solanum nigrum L. black nightshade Cotton, 1916

Solanum pimpinellifolium L. 

(=Lycopersicon 

pimpinellifolium (L.) Mill.)

currant tomato Phadtare and Sharma, 1971

Sarbhoy et al., 1975

Solanum pseudocapsicum

L.

Jerusalem-cherry Phadtare and Sharma, 1971

Sarbhoy et al., 1975

Solanum sisymbriifolium

Lam.

sticky nightshade Sarbhoy et al., 1975

Solanum spp. nightshade Alvarez, 1976

Solanum villosum Mill. red nightshade Martin, 1929

Dispersal

Human-Assisted Spread

Humans can disperse S. endobioticum through movement and trade of infected 

potato tubers or tubers contaminated with infested soil (Obidiegwu et al., 2014). 
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The pathogen can also spread by moving infested soil on farm machinery, 

equipment and tools, and footwear (Hampson and Coombes, 1996; Hampson and 

Coombes, 1989; Obidiegwu et al., 2014).

Natural Dispersal

In wet soil, Synchytrium endobioticum mobile spores can swim a distance of up to 

2 inches (Franc, 2007; Weiss, 1925). These mobile spores remain viable in the 

soil for a maximum of 2 hours after forming, depending on temperature (Curtis, 

1921; Franc, 2007; Percival, 1910). Earthworms may disseminate S. endobioticum

over a small area (4 to 10 inches) (Hampson and Coombes, 1989).

Synchytrium endobioticum can be spread over longer distances in 1) manure from 

animals that have ingested infected tubers, 2) infested soil on animals’ hooves, 3) 

runoff of contaminated irrigation water, and 4) windblown dust from infested 

fields (Hampson, 1981, 1996; Hampson and Coombes, 1989; Joestring, 1990; 

Obidiegwu et al., 2014). 
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3. Pest Identification 

Species ID/Diagnostic

Synchytrium endobioticum lacks hyphae and instead produces mobile zoospores 

within sporangia. Synchytrium endobioticum is most readily detected by 

surveying field soil (Chapter 4 of this document). The sporangia must be 

extracted from soil prior to identification. 

Extracting the Pathogen from Soil

The sporangia are usually found in small aggregates or clumps of soil that 

measure 0.1 to 2.0 mm in diameter (depending on soil type). These soil 

aggregates must be broken up to extract, and then examine and count the 

sporangia (Pratt, 1976). The soil must be dried completely before extracting the 

sporangia. Various extraction methods have been developed that vary by the 

volume of soil that can be processed (20 to 100 grams), the sieving system 

(electro-magnetic or manual), and the reagents (chloroform, calcium chloride, and 

zinc sulphate) used (van Leeuwen et al., 2005; Pratt, 1976). Each technique has its 

limitations, and the extraction method should be chosen based on the equipment 

and supplies already available. Below are the extraction methods routinely 

recommended: 

♦ The European and Mediterranean Plant Protection 

Organization Modified Standard PM 3/59 method consists of 

wet sieving a 100 grams soil sample with two stacked sieves, 

(upper sieve, 75μm and lower sieve, 25μm), drying the 

sediment on filter paper, centrifuging with chloroform or 

CaCl2, collecting on filter paper, and resuspending in 

lactoglycerol (van Leeuwen et al., 2005). 

♦ The Dutch Plant Protection Service (PPS) method is capable of 

processing smaller sample sizes (20 to 80 grams), wet-sieving 

with stacked sieves, 75 μm (upper) and 25μm (lower), 

centrifuging with CaCl2, and then counting the sporangia in 

CaCl2 (van Leeuwen et al., 2005). 

Chapter

3
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Morphological Identification

Summer sporangia

Synchytrium endobioticum may produce a sorus, a cluster of one to nine

sporangia that measures 0.025–0.038 × 0.062–0.087 mm. The sporangia are 

polyhedral, ovoid to almost round, light golden brown, aseptate, transparent, 

smooth, and thin-walled. Each sporangium measures 0.041–0.064 × 0.047–

0.075 mm (Obidiegwu et al., 2014; SPHDS, 2016; Walker, 1998). 

Resting sporangia

Resting sporangia are thick-walled structures, usually spherical to ovoid in 

shape, golden brown, and 0.024–0.075 mm in diameter. The wall is 

ornamented with irregularly shaped wing-like protrusions (EPPO, 2004; Pratt, 

1976) (Figs. 3-1 to 3-3).

 

Figure 3-1 Resting sporangia of S. endobioticum magnified 100× (image credit 

Alexandra Schlenzig, Science and Advice for Scottish Agriculture (SASA))
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Figure 3-2 Single resting sporangia of S. endobioticum (image credit A) Science and 

Advice for Scottish Agriculture (SASA)

Figure 3-3 A) Resting sporangia; B) germinating resting sporangia of S. endobioticum

(image credit Donna Smith, Canadian Food Inspection Agency)

Mobile spores (zoospores)

Mobile spores are pear-shaped and measure 0.0015 to 0.0022 mm in diameter. 

They have a posterior flagellum approximately 0.0025 mm in length (Lange and 

Olson, 1978; Walker, 1998) that allows them to swim in water through soil (Fig. 

3-4).

A

B
Last update 16DEC2020 Synchytrium endobioticum 13

 

Figure 3-4 External sporangia releasing S. endobioticum zoospores (image credit 

Donna Smith, Canadian Food Inspection Agency)

Molecular Identification

♦ Polymerase Chain Reaction (PCR) can accurately detect and quantify S. 

endobioticum from soil extracts and infected plants (van den Boogert et 

al., 2005). 

♦ Microarray-based hybridization can detect S. endobioticum along with 

other pathogens in infected plants (Abdullahi et al., 2005).

♦ Real-time PCR can accurately quantify potato wart from soil extracts, 

warts, and different parts of infected plants (Smith et al., 2014; van GentPelzer et al., 2010). 

Signs and Symptoms

The main diagnostic symptoms of potato wart disease are galls that form on plant 

parts below ground (i.e., stolon bud, stem base, and tuber eyes) (Figs. 3-5 and 3-

6). Young developing tubers infected with S. endobioticum can be spongy and 

distorted. As the tubers mature, the eyes can develop galls (Obidiegwu et al., 

2014). Tubers may be mangled or entirely replaced by galls (Stevenson et al., 

2001). Sprouts can also be so severely infected that the potato plant fails to 

develop from planted tubers (Hampson, 1993). Galls rarely form on above-ground 

plant parts such as leaves, flowers, and upper stems and do not form on roots 

(Hampson and Coombes, 1985; Stevenson et al., 2001). Galls are initially white to 

brown, but they turn black at maturity and eventually decay (Putnam and 

Sindermann, 1994; Stevenson et al., 2001) (Figs. 3-7 to 3-9). They are mostly 

round and measure on average between 0.40 to 3.20 inches in diameter 
Last update 16DEC2020 Synchytrium endobioticum 14

(Stevenson et al., 2001). Galls in decaying tissues contain microscopic sporangia

(Figs. 3-1 to 3-3).

Potato wart symptoms can be confused with other potato diseases. Powdery scab 

(causal agent: Spongospora subterranea) is soil borne, affects stems and stolons, 

and causes wart-like galls on tubers (Fig. 3-10) (Merz, 2008). Potato smut (causal 

agent: Thecaphora solani), is characterized by warty swellings on the surface of 

potato tubers (Fig. 3-11) (Chalkley, 2016). False wart or pseudo-wart, like potato 

wart, can have outgrowths in the eyes of tubers. However, false wart may be 

caused by a chemical contaminant rather than a pathogen (EPPO, 2004; USDAAPHIS, 1990). 

 

Figure 3-5 Galls on stem (image credit Alexandra Schlenzig, Science and Advice for 

Scottish Agriculture (SASA)) 
Last update 16DEC2020 Synchytrium endobioticum 15

 

Figure 3-6 Healthy sprout (left) and infected sprout (right) (image credit Donna 

Smith, Canadian Food Inspection Agency)

 

 

Figure 3-7 Fresh tuber gall (image credit Donna Smith, Canadian Food Inspection 

Agency)
Last update 16DEC2020 Synchytrium endobioticum 16

 

Figure 3-8 Potato tuber with fresh galls (image credit Science and Advice for Scottish 

Agriculture (SASA)

 

 

Figure 3-9 “Potato tuber covered in galls” [image credit 2012, Her Majesty the Queen 

in Right of Canada (Canadian Food Inspection Agency)] 
Last update 16DEC2020 Synchytrium endobioticum 17

 

Figure 3-10 Powdery scab (Spongospora subterranea) lesions on potato courtesy of 

Ministry of Agriculture, Food and Rural Affairs, Ontario CropIPM.

 

 

Figure 3-11 Potato smut (Thecaphora solani) Barrus on Solanum tuberosum L. (potato) 

William M. Brown Jr., photographer, Bugwood.org licensed under a Creative Commons 

Attribution 3.0 License. 
Last update 16DEC2020 Synchytrium endobioticum 18

4. Survey

Survey Types

Plant regulatory officials will conduct detection and, where appropriate,

delimitation surveys for S. endobioticum. The purpose of a detection survey is to 

determine the presence or absence of S. endobioticum in an area or in fields where

it is not known to occur. Fields that shared farm equipment with an infested field

or received seed from the same seed source or farm as an infested field should be 

targeted for detection surveys (CFIA, 2002).

After a new detection is confirmed in a field, state and federal inspectors may use 

a delimitation survey to define the spatial extent of the infestation in a field.

Timing of Surveys

In fields currently planted in potatoes, surveys are ideally conducted near or at 

tuber harvest. In fields that are fallow or planted with another crop, there is no 

preferred time for the survey. 

Detection Survey

Synchytrium endobioticum produces symptoms mainly on below-ground plant 

parts. Therefore, a visual survey of the above-ground parts is not reliable for 

detecting the pathogen. Instead, we recommend sampling the field soil. Most 

potatoes grown in North America are harvested with mechanical harvesters, but 

they can also be harvested using other tools like a spading fork or plough (Bohl 

and Johnson, 2010). Consider the safety of surveyors when collecting samples. 

The distribution of S. endobioticum in fields is patchy and unpredictable, most 

likely from random planting of diseased seed tubers. For the detection survey, 

surveyors will systematically collect soil samples throughout the field to obtain a 

representative sample of the field. For instructions on pre-survey preparation, 

sanitation, and clean-up, refer to Appendix A. 

Chapter

4
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Collecting Soil Samples

1. Determine the size of the field. 

2. Look at Table 4-1 to decide how many soil samples to collect. For example, if 

your field is larger than 1 acre, then collect one subsample (soil core) every 8 

paces, which is roughly 20 feet. Figure 4-1 demonstrates how to survey a 1.5 

acre-field.

Table 4-1 Sampling frequency using a square grid pattern for potato wart disease 

survey activities (CFIA, 2002).

Size of Field Grid sampling frequency

< 0.5 acres 2 x 2 pace *

0.5 - 1.0 acres 4 x 4 pace

> 1.0 acres 8 x 8 pace

* One pace is approximately 2.5 feet. Therefore, if the field size is less than 0.5 acres, a soil core would be collected at every 5 

feet in a square grid pattern covering the entire field.

3. Begin sampling by walking the specified number of paces from Table 4-1 or 

use a mechanical sampler calibrated with the specified number of paces 

(distance). Take soil cores using a 1.9 cm soil probe (Oakfield model L or 

equivalent) along a square grid pattern (Fig. 4-1). 

4. Combine 60 soil cores into a clean bucket and mix well. Transfer the 60 soil 

cores to a double-walled paper bag (or two single paper bags placed inside 

one another). This bag represents one composite sample.

5. Securely close the bag and record collector’s name, grower’s name, field 

location, and date on the outside of the bag.

6. Continue to move the specified number of paces down the field and collect 

soil cores along the grid in the direction of the arrow (Fig. 4-1) until the 

survey is complete. 

7. Make sure all bags containing the composite samples are in a secure container 

for transportation to a designated laboratory.
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Figure 4-1 1.5-acre field (256 ft x 256 ft) overlaid with a square grid pattern and grid 

sampling frequency of 8 x 8 pace. The blue dot represents where you should take 1 soil 

core.

Symptomatic tubers

1. At harvest, if symptomatic tubers are present, place 1 to 3 symptomatic tubers

in a paper bag and seal. The number of tubers per bag will depending on the 

number of symptomatic tubers and their size. 

a. Do not add any extra moisture into the bag.

b. Label the paper bag with the grower’s name, location (field and/or 

storage bin), host cultivar, collector’s name, and date.

c. Make sure the bag is in a secure container for transportation to a 

designated laboratory.
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Delimitation Survey

After S. endobioticum has been detected and confirmed by USDA-APHIS, a 

delimitation survey can help determine to what extent the pathogen has spread 

across the field (Laidlaw, 1985). Random planting of infected seed potatoes and 

the movement of farm equipment across the field may randomize spread in the 

field. 

Collecting Soil Samples

1. Follow the same instructions for the detection survey to collect soil cores (Fig. 

4-1 and Table 4-1), but do not combine soil cores into a composite sample.

2. Place each soil core into a double-walled paper bag.

3. Securely close the bag and record collector’s name, grower’s name, field 

location, within-field location, and date on the outside of the bag.

4. Place the samples in a secure container appropriate for transport to the 

laboratory. 

Sample Submission and Identification Confirmation

1. Soil samples should be sent to a laboratory capable of extracting sporangia 

from the soil and making a tentative identification of suspect sporangia. PPQ 

may designate a laboratory for processing these samples. 

2. After using a procedure for extracting sporangia from soil in Chapter 3 of this 

document, laboratory staff will view the sample under the microscope. 

3. If a S. endobioticum suspect is found using morphological criteria, stop 

processing the sample. Depending on the extraction method used, transfer the 

sample to a labelled centrifuge tube or a petri dish and wrap it with bubble 

wrap. Laboratories should not attempt molecular diagnostics for identifying S. 

endobioticum because of the special authorizations and strict requirements for 

handling select agents.

4. Place the centrifuge tubes upright in a cooler with freezer bags/cold packs and 

close the lid. DO NOT freeze the samples. 

5. Tape and package the box for shipment.

6. Fill out a PPQ Form 391 

https://www.aphis.usda.gov/library/forms/pdf/PPQ_Form_391.pdf.

7. Send the suspect sample along with the printed copy of the PPQ Form 391 to 

the address below. Time the shipment so that it does not arrive on a Friday, 

Saturday, or Sunday. 

Sample Diagnostics

USDA APHIS PPQ

S&T Beltsville Laboratory

Bldg. 580
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9901 Powder Mill Rd.

Laurel, MD 20708

Phone 301-313-9208 or 301-313-9271 

 

8. After mailing the specimens, send an email with the tracking number of the 

package to APHIS-PPQCPHSTBeltsvilleSampleDiagnostics@usda.gov.
Last update 16DEC2020 Synchytrium endobioticum 23

5. Eradication and Control 

Options

Overview

This information can be used by PPQ decision-makers after a detection to assess 

the suitability of potential actions to eradicate, contain, or suppress S.

endobioticum. The efficacy and feasibility of each control option will depend on 

the pest situation at the time of detection. Factors including detection location 

(e.g., natural or urban environment, agricultural crops, greenhouses, orchards), 

area of spread, the climatic region, the time of year, the phenology of the host,

and current practices already in place contribute to determining whether a 

particular control option is appropriate.

Eradication Options

Quarantine and Regulatory Procedures

Eradication of S. endobioticum in the United States will be difficult due to its 

ability to persist in the soil for years and the lack of adequate available resistant 

potato cultivars. The first eradication of this pathogen in the United States took 70 

years (Putnam and Hampson, 1989; Hartman, 1955; Laidlaw, 1985; McDonnell 

and Kavanagh, 1980). The quarantine area for this pathogen includes all positive 

fields and any fields that have come in contact with infected crop residue, seed, or 

infested soil. Movement of potentially infected host materials and potentially 

infested soil on equipment should be limited within and not allowed out of the 

quarantine area.

Host Removal

All potato crops growing in the quarantine area must be destroyed using 

glyphosate or a similar herbicide at the labeled rate (Baker et al., 2007; USDAAPHIS, 1990). This includes all remaining potatoes and plant parts. All dead 

plant material must be burned in place, removed, double bagged, and sent to an 

approved landfill (EPPO, 2007; USDA-APHIS-PPQ, 2008; USDA-APHIS, 

1990). Check local ordinances for guidelines and documentation for burning 

material.

Chapter

5
Last update 16DEC2020 Synchytrium endobioticum 24

Chemical Control

Methyl bromide has been used in limited areas for eradication (Rasmussen and 

Mygind, 1977). However, we do not recommend using this chemical in a field 

setting because of potential serious environmental effects. If a storage building 

needs to be decontaminated with methyl bromide, use the following application 

rate (Rasmussen and Mygind, 1977; USDA-APHIS, 1990):

♦ Apply methyl bromide at a rate of 240 g/m3 for 24 hours at 15.5 °C (60 

°F) or above.

♦ Seal or tarp building to ensure effective treatment.

Alternative Control Techniques

Non-Chemical Treatments

There are no non-chemical treatments available for use against S. endobioticum

(Baker et al., 2007).

Host Resistance

The main control method for S. endobioticum is the use of resistant potato 

varieties. Researchers have conducted host resistance experiments in the 

European Union, but not in the United States (Baker et al., 2007); therefore, little 

is known about the resistance to or susceptibility of preferred U.S. potato varieties 

to S. endobioticum (Baker et al., 2007). 
Last update 16DEC2020 Synchytrium endobioticum 25

6. Environmental Compliance

Overview

Program managers of Federal emergency response or domestic pest control 

programs must ensure that their programs comply with all Federal Acts and 

Executive Orders pertaining to the environment, as applicable. Two primary 

Federal Acts, the National Environmental Policy Act (NEPA) and the Endangered 

Species Act (ESA), often require the development of significant documentation 

before program actions may commence. Environmental and Risk Analysis 

Services (ERAS), a unit of APHIS’ Policy and Program Development Staff 

(PPD), is available to provide guidance and advice to program managers and 

prepare drafts of applicable environmental documentation. In preparing draft 

NEPA documentation ERAS may also perform and incorporate assessments that 

pertain to other Acts and Executive Orders, described below, as part of the NEPA

process. The Environmental Compliance Team (ECT), a part of PPQ’s 

Emergency Domestic Programs (EDP), assists ERAS in development of 

documents and implements any environmental monitoring. Program leadership is 

strongly advised to consult with ERAS and/or ECT early in the development of a 

program in order to conduct a preliminary review of applicable environmental 

statutes and to ensure timely compliance. 

Environmental monitoring of APHIS pest control activities may be required as 

part of compliance with environmental statutes, as requested by program 

managers, or as suggested to address concerns with controversial activities.

Monitoring may be conducted with regards to worker exposure, pesticide quality 

assurance and control, off-site chemical deposition, or program efficacy. Different 

tools and techniques are used depending on the monitoring goals and control 

techniques used in the program. Staff from ECT will work with the program 

manager to develop an environmental monitoring plan, conduct training to 

implement the plan, provide day-to-day guidance on monitoring, and provide an 

interpretive report of monitoring activities.

The following is list of pertinent laws and Executive Orders:

National Environmental Policy Act (NEPA) – NEPA requires all Federal 

agencies to examine whether their actions may significantly affect the quality of 

Chapter 

6
Last update 16DEC2020 Synchytrium endobioticum 26

the human environment. The purpose of NEPA is to inform the decision-maker 

prior to taking action and to inform the public of the decision. Actions that are 

excluded from this examination, actions that normally require an Environmental 

Assessment, and actions that normally require Environmental Impact Statements 

are codified in APHIS’ NEPA Implementing Procedures located in 7 CFR 372.5.

The three types of NEPA documentation are:

1. Categorical Exclusion

Categorical exclusions are classes of actions that do not have a significant 

effect on the quality of the human environment and for which neither an 

environmental assessment (EA) nor an environmental impact statement 

(EIS) is required. Generally, the means through which adverse 

environmental impacts may be avoided or minimized have actually been 

built into the actions themselves (see 7 CFR 372.5(c)).

2. Environmental Assessment (EA)

An EA is a public document that succinctly presents information and 

analysis for the decision-maker of the proposed action. An EA can lead to 

the preparation of an environmental impact statement (EIS), a finding of 

no significant impact (FONSI), or the abandonment of a proposed action. 

3. Environmental Impact Statement (EIS)

In the event that a major Federal action may significantly affect the quality 

of the human environment (adverse or beneficial), or, the proposed action 

may result in public controversy, an EIS is prepared. 

Endangered Species Act (ESA) – This statute requires that programs consider 

their potential effects on federally protected species. The ESA requires programs 

to identify protected species and their habitat in or near program areas and 

documentation of how adverse effects to these species will be avoided. The 

documentation may require review and approval by the U.S. Fish and Wildlife 

Service and the National Marine Fisheries Service before program activities can 

begin. Knowingly violating this law can lead to criminal charges against 

individual staff members and program managers.

Migratory Bird Treaty Act – This statute requires that programs avoid harm to 

over 800 endemic bird species, eggs, and their nests. In some cases, permits may 

be available to capture birds, which require coordination with the U.S. Fish and 

Wildlife Service.

Clean Water Act – This statute requires various permits for work in wetlands 
Last update 16DEC2020 Synchytrium endobioticum 27

and for potential discharges of program chemicals into water. This may require 

coordination with the Environmental Protection Agency, individual states, and the 

Army Corps of Engineers. Such permits would be required even if the pesticide 

label allows for direct application to water.

Tribal Consultation – This Executive Order requires formal government to 

government communication and interaction if a program might have substantial

direct effects on any federally-recognized Indian Nation. This process is often 

incorrectly included as part of the NEPA process, but must be completed prior to 

general public involvement under NEPA. Staff should be cognizant of the conflict 

that could arise when proposed federal actions intersect with tribal sovereignty. 

Tribal consultation is designed to identify and avoid such potential conflict.

National Historic Preservation Act – This statute requires programs to consider 

potential impacts on historic properties (such as buildings and archaeological 

sites) and requires coordination with local State Historic Preservation Offices.

Documentation under this act involves inventorying the project area for historic 

properties and determining what effects, if any, the project may have on historic 

properties. This process may require public involvement and comment prior to the 

start of program activities.

Coastal Zone Management Act – This statute requires coordination with states 

where programs may impact Coastal Zone Management Plans. Federal activities 

that may affect coastal resources are evaluated through a process called “federal 

consistency”. This process allows the public, local governments, Tribes, and state 

agencies an opportunity to review the federal action. The federal consistency 

process is administered individually by states with Coastal Zone Management 

Plans.

Environmental Justice – This Executive Order requires consideration of 

program impacts on minority and economically disadvantaged populations. 

Compliance is usually achieved within the NEPA documentation for a project. 

Programs are required to given consider if the actions might disproportionally 

impact minority or economically disadvantaged populations, and if so, how such 

impact will be avoided.

Protection of Children –This Executive Order requires federal agencies to 

identify, assess, and address environmental health risks and safety risks that may 

disproportionately affect children. If such a risk is identified, then measures must 

be described and implemented to minimize such risks.
Last update 16DEC2020 Synchytrium endobioticum 28

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Survey Preparation, 

Sanitization, and Clean-Up

Introduction

Use Appendix A for instructions on how to prepare for and conduct a survey, as 

well as instructions for proper cleaning and sanitizing of supplies and equipment 

after the survey.

1. Prior to beginning a survey, determine whether there have been recent 

pesticide applications that would render it unsafe to inspect the plants and 

soil. Look for posted signs indicating recent pesticide application. Ask the 

property owner or manager if there is a re-entry period in effect due to 

pesticide application. If there have been recent pesticide applications, then 

wait the appropriate re-entry period. 

2. Determine whether quarantines for other pests or crops are in effect for the 

survey area. Comply with all quarantine requirements.

3. When visiting the area to conduct surveys or take samples, take strict 

measures to prevent contamination by S. endobioticum or other pests 

between properties during inspections. These strict measures include 

wearing protective clothing, gloves, and footwear and changing them before 

entering and exiting each site. Other strict measures include sanitizing 

vehicles, equipment, and tools. 

4. Clean and sanitize equipment and tools after each use:

a. Disinfect tools and equipment with any contaminating soil by spraying 

or immersing them in 0.15 percent a.i. solution of quaternary ammonium 

(quat) or 10 percent hypochlorite solution (bleach). Allow the tools to air 

dry.

b. Use quat carefully in non-planted areas because it can kill vegetation on 

contact.

c. Do not remove soil from survey equipment (small or hand-held) before 

treatment if there is a possibility the soil will contaminate the site. 

Saturate the contaminating soil with quat or bleach prior to its removal; 

once the soil is saturated, it is no longer considered contaminated.

d. Disinfect footwear at a designated area, such as the entrance of a 

property, when entering and leaving a site. 

Appendix

A
Last update 16DEC2020 Synchytrium endobioticum 33

e. To disinfect storage areas, drench the area thoroughly with quat or 

bleach. Do not rinse. 

5. Designate a flat area or an area with a buffer around it to capture runoff 

when disinfecting large pieces of equipment. Disinfect the equipment with a 

high-pressure delivery system, such as a steam pressure wash system to 

penetrate the soil and debris that may still adhere to it. After the equipment 

is clean, saturate it with quat.

6. Disinfect vehicles including tires, wheel wells, and under the chassis using 

the following instructions:

a. Make sure equipment is dry at the time of treatment to facilitate efficacy 

of the solution.

b. Wash thoroughly with quat.

c. Do not rinse for at least 1 hour; after 1 hour, rinse equipment only if 

specifically required by owner or operators. 
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Authors and Reviewers

Authors

Tonia Quintero, USDA-APHIS-PPQ-PERAL

Jose Rodriguez, USDA-APHIS-PPQ-PERAL

Editor

Rosemary Hallberg, NCSU-CIPM

Reviewers

Michelle Gray, USDA-APHIS-PPQ_PERAL

Walter Gutierrez, USDA–APHIS–PPQ-PERAL

Lisa Ferguson, USDA-APHIS-PPQ-PERAL

Wendy Marchant, USDA-APHIS-PPQ-PERAL

Nancy Osterbauer, USDA–APHIS–PPQ-PERAL

Cover Image

Potato tubers with galls from Prince Edward Island, Canada (image credit 2012

and 2014 Her Majesty the Queen in Right of Canada (Canadian Food Inspection 

Agency))

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