Safe storage and handling of sunflower seed
For safe storage and optimum quality, sunflowers should be stored ‘cool and dry’.
Cool temperatures minimise the conditions that encourage storage pests, including rust red flour beetle and a range of grain storage moths. Dry storage minimises the risks of mould development and hot spots.
The ideal storage for sunflower is an above ground, cone-based, aerated and sealable silo. Above ground storages are easier to clean out once they are empty, reducing carry over of storage pests. Aeration can reduce grain temperatures in the silo, which slows the pest breeding lifecycle and reduces population build up. Keep silos aerated, however when insects are detected, seal up the silo to achieve an effective pest fumigation.
Effective and safe storage of sunflower seed requires close attention to storage hygiene, aeration and monitoring for pests and moulds.
Clean out empty silos, grain handling equipment, such as field bins and augers, and headers to reduce the carry over of storage pests from one season to the next, and minimise early infestation pressure. Winter is a good time to undertake storage hygiene as pests are not moving or flying out. As with other oilseeds, there are few insecticides registered to be used as a hygiene treatment of stored sunflower seed. If possible, use diatomaceous earth products, e.g. Dryacide®, to provide suitable control, rather than any of the other insecticides for structural surface treatment prior to filling storages with sunflower seed. As with any product, before applying treatments, check with your buyer or bulk handler (depot) for acceptability of treatments, and read labels carefully.
Aeration, preferably using an automatic controller, promotes uniform, cool storage conditions and is a key best practice strategy for maintaining oil and seed quality.
During autumn, aim for stored sunflower temperatures in the range of 18–23°C. For the winter months 10–18°C is achievable. Using aeration it should be possible to reduce grain harvest temperature (typically around 30°C) to below 20°C, making it difficult for storage pests to breed. The insects do not die under these cooler conditions, but their breeding stops or slows, avoiding pest outbreaks.
Aeration provides uniformity of moisture content through the bulk of the silo. The safe delivery standard is 9% moisture content (mc) for a typical sunflower seed sample with an oil content of 40%. If samples have an oil content of greater than 45% or an extended storage period is planned, aim for 8% moisture content.
The seed sample from the header has an important impact on safe storage of sunflower seeds. Large pieces of stalk or damp pieces of head coming in with the sample can encourage the development of mould in grain around the storage edges. A high percentage of ‘fines’ coming from the header can cause a core to form from the point of fill in the storage, which can restrict the aeration air flow.
Check stored sunflower and other oilseed at least once a fortnight, as opposed to monthly inspection of cereal grains. To monitor for insects, collect and sieve a sample of seed taken from the bottom and top of storages (if safe). Look at the top surface of the sunflower seed for pest movement, such as moths, and check for any bad odours that may indicate the presence of moulds or moisture.