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Talking Agronomy with Sarah Symes: silly season stage one starts again

Some winter barley may require a TO application as net blotch and rhynchosporium have both been seen out in the field
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As another March draws closer and silly season stage one starts again, we are thinking about possible options for fungicide usage this spring.


There are many wheat crops carrying infections of yellow rust, brown rust or mildew and if the weather becomes conducive to an epidemic, an early fungicide could be needed. A pre-T0 timing may be required so slow these diseases before we get to a normal T0 timing at the end of March/beginning of April when final leaf 4 emerges.


We have a very high proportion of very susceptible varieties to rusts and/or mildew, including Gallant, Solstice, Claire, KWS Santiago, and many crops have become lush following the mild autumn and winter. Options for rust control include triazoles or strobilurin based products to give good protectant activity and knock down action. Chlorothalonil could be included to improve septoria protection. SDHI fungicides are best saved for the more important T1 and/or T2 timing as these can only be used twice in one season.


Some winter barley crops may require a T0 application as net blotch and rhynchosporium have both been seen out in the field, Proline (prothioconazole) is extremely broad spectrum and a good option to consider, while other triazoles such as epoxiconazole will also give good protection of a range of diseases.


Some oilseed rape crops are looking very forward coming out of winter, so some growth regulation may be needed in thick and vigorous crops. These can be defined as 60 plants or more established per square metre, and above ankle height. Nitrogen + sulphur applications on these crops need to be delayed for a couple of weeks. On ‘normal’ crops the first application needs to be applied at late rosette or roughly from the end of February, providing conditions are warm and there is active growth, and you can travel.


Application rates will be dependent on canopy size and yield potential. We will be using iPhone apps to analyse canopy size and how much nitrogen is in the crop, and, following the wettest January on record, I think we can safely assume the amount of nitrogen left in the soil will be small. Using all this information we will calculate the final nitrogen requirement.


Some early nitrogen or nitrogen + sulphur applications could be applied now on cereals, around 25%-30% of the total dose, the rest should be applied in one or two applications between GS31 and GS32. The crops getting early treatments are second wheats, winter barley and first wheat after oats or spring barley (a result of messed up rotations after the autumn of 2012). We are seeing worsening sulphur deficiencies, a result of less being deposited in rainfall. Trial results are showing increasing yield responses over a wide range of soil types where nitrogen + sulphur has been applied in contrast to just nitrogen.


Out in the field, growth regulation is a hot topic. Applications will be based around chlormequat, which is a low cost, safe option. Where the likelihood of lodging is greater, a split will be made which will give a better straw shortening effect than just the one application. For thicker forward crops, Moddus (trinexapac-ethyl) can be added to a half rate of chlormequat.


Some spring drilling can start on lighter soils, but for others, it will be best to hold on until soil conditions are good. Look to be planting about 350-375 seeds/sq.m for spring cereals. Spring rape and spring linseed drilling should be delayed until April/May, and when soil conditions have warmed up so crop establishment is rapid. That is the best way to reduce flea beetle damage following the recent ban on neonicotinoid seed dressings.


  • Sarah Symes is an independent agronomist working with the Hampshire Arable Systems partnership. Based in Hampshire, she advises clients growing cereals, oilseed rape and pulses
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