Seed mixes
Seed mixes “that do not contain restricted seeds” require a Seed Analysis Certificate to accompany the consignment (see approved seed laboratories).
Seed mixes “containing restricted seeds” are also to be accompanied by a valid Plant Heath Certificate, for restricted seeds (see summary of restricted seed types).
All seed mixes are not subject to International Seed Testing Association requirements for bulk search weights. Instead Quarantine WA (QWA) utilises world best practise by following the Association of Official Seed Analysts (AOSA), method as outlined below:
- The seed supplier must advise the sampler of the components of the mixture and the relative percentage of each type of seed in the mix.
- This information must be supplied to the seed testing laboratory together with the sample, which must be drawn by an accredited sampler.
- It is recommended that the sample provided to the laboratory is at least 1 kg to ensure a sufficient sample is drawn.
- The Bulk Search Weight (BSW) of the mixture is to be calculated by allocating a corresponding proportion of the scheduled BSW for each seed type to the total BSW for the sample (see example below).
- The seed testing laboratory shall annotate the component percentages as advised by the client on the Seed Analysis Certificate so QWA can verify the BSW was sufficient, together with a listing of non-component seeds found (if any).
See example below:
Example - Calculating the Bulk Search Weight (BSW) of a seed mixed consignment
| Components | % component | ISTA BSW | Total BSW |
| Phalaris canariensis | 24% | 200g | 48g |
| Panicum miliaceum | 26% | 150g | 39g |
| Carthamus tinctorius | 25% | 900g | 225g |
| Helianthus annuus | 25% | 1000g | 250g |
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| Total BSW | 562g |
Maximum lot size of mixed seed consignments
The maximum lot size for a mixed seed consignment shall be determined by the ISTA maximum lot size of each component apportioned to correspond with the percentage of the mixture represented by that component. See example below:
Example - Calculating the maximum lot size for a mixed seed consignment
| Components | % component | ISTA max lot size (kgs) | Total BSW |
| Phalaris canariensis | 24% | 10 000 | 2 400kg |
| Panicum miliaceum | 26% | 10 000 | 2 600kg |
| Carthamus tinctorius | 25% | 25 000 | 6 250kg |
| Helianthus annuus | 25% | 25 000 | 6 250kg |
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| Maximum lot size | 17 500kg |
Additional requirements for seed with altered lot codes or other descriptions, such as coated or blended seeds
A statutory declaration is to be made on the exporting company’s letterhead by a responsible officer of that company containing the following information:
- Detail of original lot code and seed name/type.
- Detail of new lot code and seed name/type.
- For blends: details of each component in the seed mix/blend including individual lot codes and names and percentages.
- For coated seed: details of the increase in lot weight (if any).
- Name of person making the declaration, their position and signature plus date of issue.