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Seed treatments in spring barley for 2016

24 February 2016

After the introduction of the Sustainable Use Directive there has been much discussion about integrated pest management (IPM) in Scottish crops over the winter meetings. At its best, IPM should be about the ‘win:wins’ – things that we can do to really target treatment, reduce our reliance on pesticides and get maximum benefit to the crop whilst having minimal downsides to the environment. Seed treatments are a good example – here we can start by testing seed to identify the key risks and then use these very targeted treatments to address the disease risks in that particular seed lot. This gets crops off to the best start possible. Choosing to grow a spring crop at all also has IPM benefits – it is at lower risk of foliar diseases compared to its winter crop equivalent so is inherently less reliant on chemical sprays and other inputs. A guiding principal for IPM should be ‘prevention is better than cure’ and in the context of healthy seed this should start well before drilling  and in fact would ideally start the season before with careful care of the mother crop. If you plan to home-save seed then knowing what disease was in the parent crop guides you to the risk in the following crop for things like net blotch and any of the classic seed borne seed treatments such as fusarium, leaf stripe and loose smut. But other diseases such as ramularia and rhynchosporium are also seed borne but sit outside any certification schemes. Certification schemes are also a plus point in reducing or preventing disease risk – seed that you buy will come with that built in assurance that the parent crop was of good quality.

Seed treatments keep a very effective lid on leaf stripe and loose smut and will also give good management of seedling blights caused by fusariums. But seed testing for germination and the diseases present in a seed lots where seed is home-saved should be a precursor to deciding what seed treatments should be selected. Loose stripe is one disease that is carried very deep in the seed and which is only partially controlled by some seed treatments so, where this is identified as a risk, particular care in selecting appropriate treatment is needed as not all are fully effective.

A high fusarium or microdochium level on spring barley seed can increase the risk of poor emergence and early seedling blights. Usually spring barley will emerge rapidly in warming soils and so is at less risk but this year, with so many wet soils, it is possible the risk might be slightly higher. You can reduce this risk by waiting to drill until soils are warming so that you get speedy emergence – which is another nice example of a non-chemical strategy to prevent or avoid an anticipated risk. Spring barley is a crop where some growers choose to drop a seed treatment altogether – to do this you really need to be confident about the health of your seed lot, so testing for good germination and the presence of diseases like loose smut and leaf stripe are very important.  Seed borne diseases can build extremely rapidly in just one or two seasons. If you decide, on the basis of good emergence and health test results, not to use a seed treatment then make sure that soil conditions are good and emergence likely to be rapid. You are very unlikely to need any of the higher dose seed treatments which provide protection against foliar diseases in a spring crop because of that inherently lower risk of rhychosporium and other foliar diseases compared to the winter crop. The same is true of seed treatments which provide take-all control – the risk of this disease is much reduced in the spring crop by the simple strategy of vastly delaying the drilling date compared to an autumn sown crop where the disease has much more time to wreak damage.

Because of their tailored nature seed treatments can be used to get crops off to the best possible start and, if used strategically, will be a definite ‘win’ all round.

Fiona Burnett, Crop & Soil Systems, SRUC

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