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Animal and Plant Health Inspection Service
U.S. Department of Agriculture
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Potentially Actionable Suspect Sample Policy: Phyllosticta citricarpa causative agent for Citrus Black Spot (CBS)


A Potentially Actionable Suspect Sample (PASS) is a regulatory sample3 from the environment or an APHIS approved exclusionary facility5 where preliminary diagnostics indicate Phyllosticta citricarpa, a USDA regulated pathogen, is present and requires confirmation by the USDA-APHIS-PPQ-S&T, Plant Pathogen Confirmatory Diagnostics Laboratory (PPDCL).

Samples Collected from a Non-Regulated Area

Any regulatory sample collected from a non-regulated area1 or APHIS approved exclusionary facility that tests positive using APHIS approved tests for the presence of Phyllosticta citricarpa, the causative agent for Citrus black spot (CBS), is considered a PASS and must be forwarded to the USDA APHIS PPQ S&T PPCDL for final determination. Sample4 should consist of symptomatic plant material (fruit or leaves).

Sample Diagnostics
USDA APHIS PPQ Science & Technology
Plant Pathogen Confirmatory Diagnostics Laboratory (PPCDL)
9901 Powder Mill Rd. Bldg. 580
Laurel, MD 20708
Phone: (301) 313-9208 or -9271

When forwarding materials notify the lab at: You must include number of samples, screening diagnostic results and tracking information in this communication. Do not ship samples on Fridays or the day before a federal holiday.

Additional information for preparation and submission of samples can be found at Request Official Confirmation of Preliminary Pest Identifications of Domestic Samples

Samples Collected from a Regulated Area

A regulatory sample collected in a regulated area2 where preliminary diagnostics indicate Phyllosticta citricarpa is considered a PASS and requires confirmation by the USDA APHIS PPQ S&T PPCDL laboratory ONLY under the following conditions:

  • The sample is an unusual detection (novel symptoms or new host) and/or
  • The sample will result in the expansion of a previously established regulated area

If none of these conditions apply, the sample should be evaluated by the State designated laboratory for final determination.


1 Non-Regulated Area: Any area where CBS is not known to occur in the United States.

2 Regulated Area: Any APHIS recognized area where CBS has been federally confirmed.

3 Regulatory Sample: This is a sample of regulatory concern to APHIS for CBS collected by regulatory officials.

4 Sample: A sample refers to a fruit or single bag of leaves (5-12 symptomatic leaves). It is strongly encouraged that each sample (fruit or leaf) is from a single plant.

5 APHIS approved exclusionary facility: a greenhouse structure designed to exclude quarantine pests that is approved by APHIS to produce citrus nursery stock for interstate movement.

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