Overview
Production and post-production of the commodity limited to seasonal periods when the target pest is rare or inactive.
- An example is “winter window” production, where the commodity is grown and exported only during winter when the target pest is inactive.
- Evaluating the efficacy of this measure requires knowledge of the seasonal phenology and abundance of the pest relative to the commodity, carrier, or conveyance.
- Limit seasonal overlap is generally considered when estimating conducting a pest risk assessment and can influence the seasonal application of other measures. It can also be used as a measure to manage risk by restricting production and post-production to seasons when the pest is rare or inactive.
- Assurance can be achieved through labelling requirements that allow trace back, and by audit of monitoring records of variables that contribute to limit seasonal overlap.
Evidence to support efficacy
Evidence is required to demonstrate that there is a time of year when the pest is rare or not physiologically able to infest the commodity when it is vulnerable to infestation. This may include knowledge of the seasonal abundance of the pest in relation to the time when the commodity is vulnerable to infestation. Any differences in the seasonal dynamics of the pest or host commodity across the production region or between years should also be considered.
Applying the measure
How it is used
Production (e.g. harvest times) or post-production activities (e.g. when a commodity can be stored outside) are restricted to low-risk times of the year. Times can be fixed, or calibrated to environmental cues where seasonal overlap varies between years and locations.
Limited seasonal overlap can be considered during pest risk assessment when it is a feature of the production or trading system. For example, if the commodity is only grown when a pest is not active. Limited seasonal overlap is commonly used as a phytosanitary measure to limit production to times of the year when the target pest is known to be inactive. A limited seasonal overlap measure can also be applied to international shipping to manage the risks associated with hitchhiker pests. For example, if shipping, without the application of additional measures, is limited to times of the year when hitchhiker pests are inactive.
Use with other measures
Limited seasonal overlap is often combined with poor pest habitat.
There may be less requirement for other measures such as pest monitoring with corrective action or pest management in areas and times where limited seasonal overlap can be demonstrated. Alternatively, importing countries may seasonally modify the intensity of their assurance inspections (inspection with remedial action).
Similar measures
This measure reduces biosecurity risks in a similar way to limit exposure time to pest, by restricting the temporal overlap between the pest and commodity. However, limit exposure time to pest is focused on a smaller time scale when the pest is assumed to be active, for example, from harvest to packing.
Assurance of correct implementation
Assurance can be achieved by only approving commodity imports that are produced during a defined seasonal interval. Similar to the restricted to poor pest habitat measure, assurance may also require identifying the key environmental variables that limit seasonal overlap (e.g. temperature or other environmental cues) and establishing methodologies and records for monitoring these. Additionally, triggers for corrective actions or suspensions (e.g., maximum temperature thresholds) may also need to be defined. There may be requirements for record-keeping to facilitate trace back, and to provide further confirmation that the commodity was produced only during the approved interval.