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PCN Program Associated Field Survey and Laboratory Result Definitions

PCN Program Associated Field Survey and Laboratory Result Definitions

PALE CYST NEMATODE (PCN) PROGRAM
ASSOCIATED FIELD SURVEY AND LABORATORY RESULT DEFINITIONS

(Definitions updated: May 22, 2017)

BASELINE SURVEY
A full‐field survey at a sampling rate of 8,000 cc of soil per acre (equivalent to approximately 20 pounds of soil per acre) used to determine the presence/absence of PCN. The baseline survey is conducted as soon as practicable upon becoming regulated as an associated field when the field is not eligible to receive the first delimiting survey towards deregulation (eligibility requires at least one host crop grown and harvested from the field since the time of exposure to soil from an infested field).

DELIMITING (DELIMITATION) SURVEY
A full‐field survey at a sampling rate of 8,000 cc of soil per acre (equivalent to approximately 20 pounds of soil used to determine the presence/absence of PCN. A series of two negative delimiting surveys, each following harvest of the next two host crops grown on the field, is required to deregulate an associated field.

FOLLOW‐UP SURVEY
A full‐field survey used to determine the presence/absence of PCN in fields where laboratory results are inconclusive for PCN, suspect for PCN by morphological/morphometric analysis, or suspect for PCN by molecular (DNA) analysis. The deregulation requirement for fields deemed inconclusive for PCN or suspect for PCN by morphological/morphometric analysis is a series of two follow‐up surveys at the delimiting survey rate, one of which must follow the next host crop grown on the field. The deregulation requirement for fields deemed suspect for PCN by molecular (DNA) analysis is a negative follow‐up survey at the delimiting survey rate, following each of the next two host crops grown on the field.

NEGATIVE FOR PCN
No PCN cysts were found.

POSITIVE FOR PCN (INFESTED)
The minimum threshold for declaring a field positive for PCN (infested) is met by detecting a minimum of two cysts from two samples that were identified as Globodera sp. by morphological/morphometric analysis, and at least one of the cysts was viable and confirmed as Globodera pallida (PCN) by molecular (DNA) analysis.

SUSPECT FOR PCN BY DNA ANALYSIS
A single cyst was identified as Globodera pallida (PCN) by morphological/morphometric and molecular (DNA)analysis; however, the minimum threshold for declaring a field positive for PCN (infested) was not met.

SUSPECT FOR PCN BY MORPHOLOGICAL/MORPHOMETRIC ANALYSIS
Cyst(s) from one or more samples were identified as Globodera sp. by morphological/morphometric analysis. No viable, DNA‐containing material was found inside the cysts, so a definitive identification as Globodera pallida could not be made.

INCONCLUSIVE FOR PCN
Object(s) resembling Globodera sp. cysts were found in a soil sample(s); however, a definitive identification could not be made using either morphological/morphometric analysis or molecular (DNA) analysis. Some morphological characteristics of Globodera sp. were present such that PCN could not be ruled out.

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