Course: Seed treatment and health | Last Updates: 7th October 2015
The ban on using these seed treatments on oilseeds, maize, peas and some vegetable crops arose from concerns about their impact on the environment, especially on bee health. This whole issue has put the spotlight on seed treatments and highlights the need to make sure that everyone involved in the use of treated seed, such as treatment contractors, growers and farm staff, follow best practice. In order to avoid any further restrictions, it is important that the industry shows that it uses treated seed carefully.
All seed treated with a pesticide is potentially under scrutiny and we all have to play our part to safeguard their use. Despite these concerns, it must be remembered that all approved products have been through a rigorous registration process that allows safe use when applied and drilled as directed.
Why should we worry?
Treated seed is something that farmers pretty much take for granted. Early seed treatment began with mercury treatments in the 1920s, which were widely adopted over 50 years ago. These have since been replaced with an armoury of contact and systemic materials that control a range of diseases and insect pests.
Treating seed is an effective way of applying fungicides and insecticides. The approach should be used as part of an integrated pest management strategy and is the only way some damaging seed-borne diseases like bunt (wheat), loose smut (wheat/barley) and leaf stripe (barley) can be controlled. Seed dressings can also provide early protection against a range of damaging foliar diseases, such as yellow rust.
They also offer a precisely targeted mechanism for dealing with pests. For example, a seed dressing to control grain and bird-cherry aphids can replace a broad spectrum pyrethroid insecticide applied through a crop sprayer.
Seed treatments are applied to the seed where they are needed to protect the young plant through the establishment period. By using a seed treatment the amount of active ingredient applied per hectare of crop can be reduced by up to 75% compared with a spray programme. With continual pressure to reduce pesticides use on farm seed treatments is a way of achieving such a goal. For instance, using a seed treatment is the only reliable and effective control of Myzus persicae (peach potato aphid) in sugar beet and the all-important virus yellows it carries, as well as soil pests. Just over 60g of ai/ha can replace a couple of foliar sprays and a soil-applied granular insecticide.
Used correctly, seed treatments are a cost-effective and safe way of applying pesticides, but we have to remember they are pesticides and that legislators treat them as such. Registering new products is just as costly and difficult as other agrochemicals and the need to preserve existing products is equally important.
Stewardship in the use of seed treatments is becoming a factor in the approval of new products. Thus companies have responded by providing extensive stewardship advice to support their products. Information is available from company websites and seed suppliers.
Working with the manufacturers, the seed industry has developed the European Seed Treatment Assurance Scheme (ESTA), which is designed to ensure seed treatments are applied safely and to a high standard so that farmer customers can be sure the treated seed they buy is reliable and safe to use. This is a pan-European scheme designed to ensure that where growers see the ESTA logo they can be assured the seed has been treated correctly, no matter where in the EU it is sourced.
Although in the past few years the spotlight has focused on neonicotinoids, it is important to note that stewardship guidelines apply to all seed dressings, not just these materials.
These messages are not new – they have been on seed bag labels for years. What is important is growers need to be seen to be acting on these messages. Just like other pesticides, seed bags have a label stuck or attached and must be read before use. The label provides essential information on safe use and if further information is required, advice can be sought from the supplier, seed treatment manufacturer or a BASIS registered agronomist.
Key risk areas
The main concerns driving seed stewardship are environmental, and the key factors and how to address them are what we will concentrate on in this academy.
However, it goes without saying that human health is paramount, so drill and seed treatment plant operators should always wear the appropriate protective clothing as outlined on the label, and wash hands after working with treated seed.
Storage of treated seed
Treated seed, as with any seed, should be stored securely in dry conditions away from livestock and the risk of damage to bags by passing tractors and machinery that can cause spills. To prevent the risk of contamination to water, seed should be stored away from drains and watercourses.
Accidental seed spills
Spills potentially carry the biggest risk to the environment, as there is such a concentration of material in one spot. This can attract wildlife such as birds and small mammals, and if wet the seed treatment can dissolve in the water and spread.
To avoid spills, take care when loading the drill. And don’t fill the drill where seed spillage is difficult to clear up, such as grass verges. Handle bags with care and ensure no seed is released in transit, either from the drill or from an empty trailer – be sure to remove any spilt seed.
Always clear up spilt seed immediately. Small spills can be buried in the field; larger spills should be cleared up into a seed bag for later safe disposal. A spill kit consisting of spade, spare seed bag and label, plus canvas sheet for use when calibrating, should be carried.
It was dust arising from poorly treated maize seed at drilling that gave some seed treatments their initial bad press. In 2008, many bees were killed in Germany as dust containing neonicotinoid settled on flowering crops.
To keep dust to a minimum, make sure a quality dressing is applied to ESTA standards. Handle bags with care, and don’t drop seed into the hopper from too great a height.
Drills – especially precision vacuum drills – must vent into the soil or on to the ground not into the air. Some manufacturers offer retro-fitted kits for older vacuum drills that need adapting. Take extra care if it is windy as fine dust can be prone to drift.
Ensure seed is buried
All treated seed must be suitably covered by soil so it does not attract birds and mammals. The most important message here is that broadcasting seed treated with pesticides is forbidden – and that includes Autocasting. Before considering broadcasting treated seed you should check with your supplier.
It is also worth remembering that some seed treatments such as tefluthrin, which controls wheat bulb fly, must be buried adequately to work effectively.
A properly maintained drill operated at the right speed in a good seed-bed will help ensure seed is covered. Do not force the drill round sharp corners or coulters may ride out, and ensure coulters are in the soil and the drill is moving forward before seed is released.
Cloddy seed-beds can be a problem; patience may be needed to achieve a finer tilth. If a lot of seed remains on the surface, a post-drilling harrowing or rolling might be needed as soon as the seed-bed is fit to travel, though it could be argued that seed wasn’t buried at the time of drilling.
Once drilling is completed, check difficult areas like corners and headlands where seed may be left on surface, and take action to cover it.
Do not reuse seed bags, except to store treated seed, and dispose of them as contaminated waste.
Finally, make and keep a record of the drilling operation.
Safe use of treated seed is important for both our health and for the environment. Each bag of treated seed has a label giving the essential safety phrases to note when handling and sowing treated seed. They are common sense, but it is important they are acted upon. Failure to do so could restrict the future supply of the products needed for successfully growing profitable crops.
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