Samples must be analyzed using a methodology approved by APHIS at a laboratory approved by APHIS. The following methodology is approved by APHIS.

Optional ELISA Prescreening. An APHIS-approved ELISA may be used to prescreen plant samples to determine the presence of Phytophthora spp.

Negative prescreening results. If all samples from a single nursery are found to be negative through APHIS-approved ELISA prescreening, no further testing is required. The nursery may be considered free of evidence of Phytophthora ramorum, and plants in the nursery are eligible for interstate movement under certificate in accordance with § 301.92-5.

Positive prescreening results. If ELISA prescreening reveals the presence of Phytophthora spp. in any plants, each sample that returns positive ELISA results must be tested as provided in paragraph (b) of this section.

Mandatory testing procedures. If ELISA prescreening is not performed, or if results of ELISA prescreening are positive for Phytophthora spp. in any sample, the sample must be analyzed using an APHIS-approved test. Samples will be considered positive for Phytophthora ramorum based on positive results of any approved test. Positive PCR or other molecular tests do not require confirmatory culture tests, nor do positive culture tests require confirmatory PCR or other molecular tests; however, if culture tests return other than positive results, an APHIS-approved PCR or other molecular test must be conducted, as provided in paragraph (b)(1) of this section.

PCR or other molecular tests—(i) Negative results. If the results of PCR or other molecular tests are negative for all samples in a nursery, no further testing is required. The nursery may be considered free of evidence of Phytophthora ramorum and plants in the nursery are eligible for interstate movement under certificate in accordance with § 301.92-5.

Positive results. If any samples tested using PCR or other molecular tests return positive results for Phytophthora ramorum, the nursery from which they originate is prohibited from moving plants interstate. The nursery will be eligible to ship certain plants interstate when an inspector determines that those plants are free of evidence of Phytophthora ramorum.

Culture Test—(i) Negative results. If the results of culture tests are other than positive for any samples taken from a single nursery, plants in the nursery must continue to be withheld from shipment in accordance with § 301.92-11 and each plant sample must be tested again using a PCR or other molecular test, as described in this section.

Positive results. If any culture tests return positive results for Phytophthora ramorum, the nursery from which they originate is prohibited from moving plants interstate as directed by an inspector. The nursery will be eligible to ship certain plants interstate when an inspector determines that those plants are free of evidence of Phytophthora ramorum.

Other test methods. Other test methods may be acceptable if approved by APHIS.