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Animal and Plant Health Inspection Service
U.S. Department of Agriculture
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Potentially Actionable Suspect Sample Policy: Xanthomonas spp.* causative agent for Citrus Canker


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

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 Xanthomonas spp., the causative agent for Citrus canker (CC), 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 (leaves, twigs, or/and fruit).

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 Xanthomonas 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 or forwarded to the PPQ Domestic Identification Plant Pathology Lab for final determination.

PPQ Domestic Identification Plant Pathology Lab
USDA APHIS PPQ Kansas State University
4024 Throckmorton Plant Sciences Center
Manhattan, KS 66506
Phone: (785) 532-1349

Notify APHIS laboratories and the APHIS Domestic Diagnostics Coordinator prior to shipping samples. Email a notification of the suspect positive sample going forward for confirmation to the Domestic Diagnostics Coordinator:


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

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

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

4 Sample: A sample refers to a single bag of leaves or a twig with attached leaves. Each sample is to contain 5-12 symptomatic leaves, if possible. It is strongly encouraged that each sample is from a single plant. Fruit or twigs without leaves could be collected if leaves are not available. In addition to the plant sample an inactivated (boiled) bacterial streaming suspension prepared according to the WI-B-T-2-2 can be submitted.

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

*Xanthomonas spp. refers to 1) Xanthomonas axonopodis pv. citri (Xac A, A* and AW) with synonyms X. citri pv. citri, or X. citri subsp. citri or X. campestris pv. citri or X. smithii subsp.citri and 2) X. axonopodis pv. aurantifolii (Xac B & C) with a synonym X. fuscans subsp. aurantifolii.

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