How far can you cut fungicide inputs on ‘resistant’ wheat?

Traditionally good disease resistance in wheat came with a big yield penalty which most growers weren’t willing to accept, meaning large acreages of barn fillers like Oakley, Conquerer and Santiago were the norm, with high inputs and high output. But with increasing input costs, creeping resistance and loss of actives due to legislation, the sustainability of this approach has been increasingly questioned.

In the last few years the plant breeders have been producing varieties with good resistance and little or no yield penalty. This opens the possibility of reducing fungicide inputs, but the question is how far can you cut without losing yield to disease and do these varieties respond strongly to fungicides due to greening or other physiological effects?

These questions are being addressed at the AHDB arable Strategic Farm at Stowmarket in Suffolk. Brain Barker the farm manager and owner has been experimenting with tailoring PGR and fungicide inputs to crop potentials based on plant, tiller and ear counts, but the results are not very easy to interpret and Brian is not sure if it’s the right approach. So over the next few years another approach is being looked at, tailoring inputs to varietal resistance.

The tramline trial will compare the performance of KWS Silverstone, KWS Santiago, KWS Siskin, Graham and Shabras under three different fungicide programmes. Silverstone and Santiago are your more traditional barn fillers, but Graham, Shabras and Siskin are up there with them in terms of RL yields and offer better septoria resistance. It will be interesting to see if their yields hold up with reduced fungicide inputs under real world conditions where spray timings and conditions can be compromised or whether they are still worth extra fungicide spend.

If the weather stays good, Brian will be sowing the trial next week in the first wheat slot after linseed. As well as yields, local trials specialists Envirofield will be monitoring the crop for disease as well as measuring crop development. Once the trial is complete a full economic analysis will also be done, to see how the numbers stack up.

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Paul Gosling

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