Biostimulants can benefit wheat yields if the correct product is applied at the optimum time, according to work by agronomy firm Hutchinsons.
Trials over several years show phosphite-based biostimulants – such as Phorce and Advance 66 – can be particularly beneficial for improving tiller retention in winter wheat, providing they are applied early enough in the season.
Hutchinsons technical manager Dick Neale says this is because phosphites effectively “trick” root tips into thinking they are short of phosphate, which in turn stimulates an increase in lateral root development.
For this to have a beneficial effect on yield, phosphites must be applied in time to build root mass before plants start to shed tillers, so autumn and GS 30 are the best timings, explains Mr Neale.
“Wheat plants generally want to throw off 40% of their tillers between growth stage 30 and 31 as they sort out what can be supported through to harvest.
“Signals from the roots indicating the availability of nutrients play a key role in this process, so if we can increase root mass and the plant’s ability to extract soil nutrients, then they will retain more tillers. More tillers clearly leads to more grain at harvest.”
In Hutchinsons trials, two applications of Phorce – in autumn and at GS 30 – gave a yield benefit of 0.5t/ha over the untreated. Once wheat is beyond GS 31, a phosphite-based biostimulant has little or no effect because plants have dropped tillers by this point.
Growers should therefore always use growth stage to determine application timing for biostimulants, rather than going by fungicide timings, says Mr Neale.
If the T1 fungicide timing is used as the cut-off, for example, this will be too late for biostimulants to work effectively. This is because many T1s are applied at GS 32, by which time tillers will have been lost.
“You’ve got to understand how biostimulants are impacting on the plant. All too often, the reason they don’t work is because people have applied the wrong product at the wrong time.”
Plants with strong root systems and a better ability to take up nutrients are likely to be healthier and more resilient to stress, foliar diseases, and lodging, Mr Neale says.