Potato wart - Synchytrium endobioticum
Effective: April 2, 2013
Taxonomic Position: Synchytriales : Synchytriaceae
Pest Type: Fungi
Pest Code (NAPIS): FEANSHM
This pest is a member of the following surveys: Solanaceous Hosts
These Approved Methods are appropriate for: 2024, 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016, 2015
||NAPIS Survey Method
||Conduct a visual survey for wart symptoms at harvest.
||3031 - General Visual Observation
Climate Suitability Map
A Climate suitability map
is now available. This survey should only be considered in the states with appropriate climate conditions and suitable hosts for this pathogen.
The map was produced by the SAFARIS Team. SAFARIS is a modeling framework that enables PPQ to quickly respond to emergencies, efficiently survey for pests, and assess potential pest impacts by collecting critical geospatial data and developing predictive models. SAFARIS is developed and maintained by the NC State University, Center for Integrated Pest Management (CIPM) with support from PPQ PERAL.
The SAFARIS team used a climate suitability model for potato wart occurrence in the continental United States, that was developed by PPQ PERAL and NCSU CIPM, to support CAPS survey planning. The model predicts the suitability of an area for potato wart occurrence based on the likelihood of favorable climate conditions for the disease occurring using tools and data within SAFARIS. The detailed method used in this assessment is described here
The following are recommendations for executing the survey using the approved methods for pest surveillance. The recommendations are developed through literature review and consultation with subject matter experts.
No specific signs are present.
This fungus affects the stolons (underground stems) and tubers targeting the meristematic tissue by developing galls/warty growths. Young potato warts are white, soft, and pulpy in texture; the surface is rough and corrugated. Sometimes developing warts can become exposed at or above the soil line.
This disease does not usually present symptoms aboveground; however stems, leaves, and flowers can sometimes develop galls. Attacked plants may show reduced vigor. Small greenish warts may form in the place of aerial buds at stem bases.
Key Diagnostic or Identification
Morphological (screening) and Molecular (confirmation). All symptomatic potato tubers collected at harvest should be forwarded to CPHST Beltsville for screening and confirmation.
In Progress / Literature-based Diagnostics:
This pathogen cannot be grown on artificial culture media.
PCR: PCR methods for detecting S. endobioticum have been developed using the ITS region of the multi copy rDNA gene (Niepold and Stacheqicz, 2004; Byrne, 2008). An improved real-time PCR assay has recently been developed to detect S. endobioticum winter spores in soil and plant extracts (van Gent-Pelzer et al., 2010). PCR allows for detection and quantification of the pathogen in both soil and host tissues.
A soil assay using PCR primers and DNA probes is available and currently being used in Canada and the Netherlands for detection of S. endobioticum. This method detects S. endobioticum sporangia in soil extracts (van den Boogert et al., 2005).
Microarray: Work has been carried out to develop microarrays to detect this pathogen along with other important viral pathogens of potatoes using the 18S region of rDNA (Abdullahi et al., 2005).
Symptoms may be confused with powdery scab (Spongospora subterranean f. sp. subterrenea), bud proliferation, and potato smut (Thecaphora solani). Powdery scab spore balls can be differentiated from winter sporangia of Synchytrium endobioticum through microscopic examination as spore balls are made up of many small cysts.
Potato wart may also be confused with "false wart", which is caused by environmental conditions. Outgrowths caused by "false wart" are the same color as the tuber, unlike potato wart. Some other wild plant species found in potato fields may be infected with Synchytrium species other than S. endobioticum .