Insuring crop seeds are free from weed seeds prevents adding to the seedbank unnecessarily. Weed seed is regularly spread around and between farms as a contaminant of sowing seed. It is important to check seed analysis before purchasing seed-lots to avoid importing weed seed.
Growers need to understand the certification standards and allowable weed seed contamination levels of commercial seed in their region. The Seed Analysis Certificate, which should be supplied with all seed purchases, provides details of the type and level of weed seed contamination.
Purchasing certified or commercial seed is not a guarantee of weed-free status. Always check the fine print and the Seed Analysis Certificate. When purchasing seed of a public variety from another grower, be alert to weed seed contamination and where possible, know the weed status of any farm from which you buy seed.
Plan seed purchases ahead of time and inspect the paddock where the seed is being grown
Obtain a sample of the seed and have it analysed for both weed seed contamination and weed seed germination.
When intending to retain seed on-farm for sowing, it is important to plan ahead to ensure a clean collection. When planning seed collection, demarcate ‘seed’ paddocks and ensure weed numbers in these paddocks are very low.
Hand-pull problem weeds and those in low numbers in the paddocks from which seed is being kept.
In the long-term, it will pay off to apply stringent management procedures to a seed block to avoid spreading weeds in seed. Seed cleaners cannot guarantee a weed-free sample and seed cleaning works best in conjunction with other preventive measures as outlined above. Ensure the seed cleaning contractor is prepared to take the time to do a thorough job and that the seed cleaning plant is itself thoroughly cleaned prior to coming onto the property
Some weed seeds are very similar in size and weight compared to the seed being cleaned and is unlikely to be removed during seed cleaning. This is particularly true of a mobile seed cleaning plant without a gravity table. Transporting seed to a larger seed cleaning plant with a gravity table may obtain better results, but the economics of doing so need be calculated first.
Keep good records of seed purchases. Keeping records of seed purchases enables a degree of traceability if there are problems such as weed contamination or low germination.
