Commodity risk assessment of Prunus spinosa plants from United Kingdom

Abstract

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by potted plants and bundles of bare-root plants or cell grown young plants or graftwood/budwood of Prunus spinosa imported from the United Kingdom, taking into account the available scientific information, including the technical information provided by the UK. All pests associated with the commodities were evaluated against specific criteria for their relevance for this opinion. One quarantine pest, Scirtothrips dorsalis, one protected zone quarantine pest Bemisia tabaci (European population) and one non-regulated pest, the scale Eulecanium excrescens, that fulfilled all relevant criteria were selected for further evaluation. The risk mitigation measures proposed in the technical Dossier from the UK were evaluated, taking into account the possible limiting factors. For these pests, expert judgement is given on the likelihood of pest freedom, taking into consideration the risk mitigation measures acting on the pest, including uncertainties associated with the assessment. The degree of pest freedom varies among the pests evaluated, with E. excrescens being the pest most frequently expected on the imported potted plants. The Expert Knowledge Elicitation indicated with 95% certainty that between 9981 and 10,000 plants per 10,000 would be free from the above-mentioned scale.

Keywords: European Union; blackthorn; pathway risk assessment; plant health; plant pest; quarantine; sloe.

FIGURE 1

Conceptual framework to assess likelihood that plants are exported free from relevant pests. Source: EFSA PLH Panel (2019).

FIGURE 2

Prunus spinosa cell‐grown plants (photo provided by DEFRA).

FIGURE 3

Prunus spinosa bare‐root plants in bundles washed, ready for dispatch (photo provided by DEFRA).

FIGURE 4

Field grown Prunus spinosa plants (photo provided by DEFRA).

FIGURE 5

Elicited certainty (y‐axis) of the number of pest‐free Prunus spinosa commodities (x‐axis; log‐scaled) out of 10,000 designated for export to the EU from the UK for all evaluated pests visualised as descending distribution function. Horizontal lines indicate the percentiles (starting from the bottom 5%, 25%, 50%, 75%, 95%). The Panel is 95% confident that 9981, − (Eulecanium excrescens – potted and bare‐root plants), 9986 (Bemisia tabaci – potted plants), 9989 (Bemisia tabaci – graftwood/budwood/cell grown plants), 9990 (Eulecanium excrescens – graftwood/budwood/cell grown plants), 9993 (Bemisia tabaci – bare‐root plants), 9999 (Scirtothrips dorsalis – all commodities), will be pest free.

FIGURE 6

Explanation of the descending distribution function describing the likelihood of pest freedom after the evaluation of the proposed risk mitigation measures for potted plants designated for export to the EU based on the example of Eulecanium excrescens.

FIGURE A.1

(A) Elicited uncertainty of pest infestation per 10,000 potted plants (histogram in blue–vertical blue line indicates the elicited percentile in the following order: 1%, 25%, 50%, 75%, 99%) and distributional fit (red line); (B) uncertainty of the proportion of pest‐free plants per 10,000 (i.e. = 1 – pest infestation proportion expressed as percentage); (C) descending uncertainty distribution function of pest infestation per 10,000 plants.

FIGURE A.2

(A) Elicited uncertainty of pest infestation per 10,000 bare‐root plants (histogram in blue–vertical blue line indicates the elicited percentile in the following order: 1%, 25%, 50%, 75%, 99%) and distributional fit (red line); (B) uncertainty of the proportion of pest‐free plants per 10,000 (i.e. = 1 – pest infestation proportion expressed as percentage); (C) descending uncertainty distribution function of pest infestation per 10,000 plants.

FIGURE A.3

(A) Elicited uncertainty of pest infestation per 10,000 bundles of graftwood/budwood or cell‐ grown plants (histogram in blue–vertical blue line indicates the elicited percentile in the following order: 1%, 25%, 50%, 75%, 99%) and distributional fit (red line); (B) uncertainty of the proportion of pest‐free plants per 10,000 (i.e. = 1 – pest infestation proportion expressed as percentage); (C) descending uncertainty distribution function of pest infestation per 10,000 plants.

FIGURE A.4

(A) Elicited uncertainty of pest infestation per 10,000 potted or bare‐root plants (histogram in blue–vertical blue line indicates the elicited percentile in the following order: 1%, 25%, 50%, 75%, 99%) and distributional fit (red line); (B) uncertainty of the proportion of pest free plants per 10,000 (i.e. = 1 – pest infestation proportion expressed as percentage); (C) descending uncertainty distribution function of pest infestation per 10,000 plants.

FIGURE A.5

(A) Elicited uncertainty of pest infestation per 10,000 bundles of graftwood/budwood or cell‐grown plants (histogram in blue– vertical blue line indicates the elicited percentile in the following order: 1%, 25%, 50%, 75%, 99%) and distributional fit (red line); (B) uncertainty of the proportion of pest‐free bundles per 10,000 (i.e. = 1 – pest infestation proportion expressed as percentage); (C) descending uncertainty distribution function of pest infestation per 10,000 bundles.

FIGURE A.6 (A) Elicited uncertainty of pest infestation per 10,000 plants (histogram in blue–vertical blue line indicates the elicited percentile in the following order: 1%, 25%, 50%, 75%, 99%) and distributional fit (red line); (B) uncertainty of the proportion of pest‐free plants per 10,000 (i.e. = 1 – pest infestation proportion expressed as percentage); (C) descending uncertainty distribution function of pest infestation per 10,000 plants.