TAKE appropriate steps to protect output from this year's higher value wheat crops as they enter the grain-filling phase and head towards harvest, farmers are being urged.
National Agronomy Centre trials data from independent research and advisory organisation TAG (The Arable Group) over 22 years shows an average yield increase over and above a T1/T2 programme of 0.44 t/ha from applying an ear or T3 fungicide – either triazole or more recently triazole + strobilurin based – against yield and quality damaging diseases.
In addition, Syngenta data across 34 trials between 2004 and 2007 shows the potential loss from inadequate T3 protection increases from £50/ha to over £100/ha as grain price increases from £80/t to £160/t – while further Syngenta data across 68 trials between 2000 and 2007 has shown that a mixture of the strobilurin Amistar with triazole boosted yield by an average 0.3 t/ha, compared with a T3 triazole alone.
According to Stuart Knight, research development director for TAG, key foliar diseases to consider at T3 include late season Septoria and brown rust, together with Microdochium nivale, Fusarium species, glume blotch and sooty moulds on ears.
In line with these, he highlights three fungicide options for T3 sprays – of a straight triazole if a simple top-up for foliar disease control is required; a strobilurin + triazole mixture if broad-spectrum foliar and ear disease control is required to maximise yield and grain quality; or, if looking to reduce mycotoxins through control of Fusarium species, a Fusarium-active triazole at a higher dose. For the latter, timing is quite critical, he notes.
"At grain prices of £120-£160/t it is easier to justify the cost of adding a strobilurin," says Mr Knight. "In recent seasons we're getting more robust control from these mixes.
"Inevitably, there is a high probability that people will want to go down the strobilurin route on quality wheat. But it's not just for quality wheats. There are other reasons to use on feed wheats, depending on disease pressure," he adds.
Past data from TAG has shown that using a strobilurin + triazole mixture at T3, compared with a higher dose of straight triazole, not only produced a greater reduction in ear disease but gave a more consistent reduction across three different timings.
"At T3, the best response is likely to be to use a mix of triazole and strobilurin, rather than triazole alone." However, Mr Knight stresses not to forget that a maximum of two strobilurin applications can be made per crop. Use a higher triazole dose only if specifically targeting Fusarium, he suggests.
David Ranner, technical manager for Syngenta, agrees there are reasons for using effective T3 protection on both feed and quality wheat.
Each additional day that crops are kept green can result in a 0.15 t/ha yield gain and a 0.2 kg/hl specific weight increase, he says. But it's important to ensure the fungicides used are relevant to disease risks, which, in turn, can be highly related to weather, he notes.
"By using a tank mix of strobilurin with triazole you can cover a broad range of disease bases," explains Mr Ranner. "Also the strobilurin helps extend the period of protection.
"Crop potential looks very good this season, so should be worthwhile protecting, especially with good grain prices. The interval between flag leaf fungicides being applied and the time when crops start to mature is likely to be eight or nine weeks this season. If you don't use a T3 fungicide you're asking a lot for a flag leaf fungicide at T2 to give you eight or nine weeks protection.
"As well as improving yield, adding Amistar to a triazole at T3 has also given a 1.23 kg/hl increase in specific weight," Mr Ranner adds.
