Overview
Inspect entire consignment, and remove commodity units that show evidence of being infested.
- Examples include grading and removal of fruit, vegetables, wood, bulbs or plants for planting that show evidence of being infested.
- Evaluating the efficacy of this measure requires evidence that the grading process is sufficiently sensitive to exclude infested commodity units, either through detecting the pest or symptoms associated with that pest.
- Commercial grading practices may be considered as part of the production system when conducting a pest risk assessment. Symptom grading may be used as a phytosanitary measure where the grading process is sufficiently accurate.
- For assurance, compliance with any symptom grading requirements can be assessed at a pre-border inspection by authorised personnel, with oversight by the NPPO or relevant authority of the exporting jurisdiction.
Evidence to support efficacy
Demonstrating the efficacy of this measure requires evidence that the symptom grading technique is sufficiently sensitive when it comes to detecting and removing infested units. This can initially be determined experimentally, and then tested and confirmed under operational conditions. The latter may be supported by historical data showing detection rates in existing grading systems. Factors that influence detection efficacy include the pest stage or symptoms that need to be detected, the commodity and the detection method (e.g. visual, destructive or optical sensors). The operational capability of the producer and the need to limit waste by minimising “false positives” should be considered when designing a feasible symptom grading measure. Technological advances, such as optical grading and artificial intelligence, may enhance the accuracy and efficiency of grading practices.
Applying the measure
How it is used
Symptom grading can be an important phytosanitary measure for pests where detection efficacy is high, such as pathogens that cause obvious disease symptoms, insects that either feed externally on fruit, or leave visible external damage if they feed internally, or pests that hitchhike on a commodity.
Symptom grading is commonly applied to plants for planting, fruits and vegetables, wood, and bulbs, tubers and seed potatoes. Often removal or treatment of infested or diseased units is a standard commercial practice. In this case it can be recognised during pest risk assessment. Where this is not sufficient it can be included as a phytosanitary measure.
Symptom grading can be applied during production (for example, the removal of diseased plants being grown for export), at harvest (e.g. when picking fruit) and post-harvest (e.g. when grading and packing fruit). Optical scanning technologies offer the potential for automated detection and removal of commodity units that are infested or have pest symptoms.
Symptom grading can also be applied to hitchhiker pests on carriers such as sea containers or traded vehicles. In this case, each individual unit is inspected and units on or in which evidence of the pest is found (e.g. webbing, or the pest itself) are treated.
Use with other measures
Symptom and quality grading based on quality specifications (to minimise vulnerability of the commodity) are often conducted at the same time. Symptom grading is commonly undertaken prior to applying a measure to reduce pests in consignments (such as treatment or surface cleaning).
Similar measures
Removing symptomatic commodity units can be similar in process to an inspection with remedial action measure. However, detection of an infested unit results in its removal, with no consequences for the broader consignment.
Although quality and symptom grading are often done simultaneously, they reduce risk in different ways. Symptom grading specifically targets infested units for removal based on visual evidence of infestation, whereas quality grading removes units that belong to quality categories that have a higher risk of being infested, irrespective of whether they show signs of infestation.
Assurance of correct implementation
For assurance, there may be requirements for training and standard operating procedures to ensure that the commodity is symptom graded consistently across the industry. Ongoing calibration and verification of grading equipment with appropriate record keeping will also be required. Compliance against any grading specifications may be assessed as part of a pre-border consignment inspection by authorised personnel, with oversight by the NPPO or relevant authority of the exporting jurisdiction.