Most varieties will need treating with a similar level of fungicide this season, Dick Neale, technical manager of Hutchinsons says, although product focus might switch according to disease susceptibility. Economically it also doesn’t make sense to skimp on fungicides.
At current prices the difference in response between varieties is virtually immeasurable, he explains. Different varieties might allow some flexibility in prioritising treatments. For example, Alchemy, which is relatively clean against septoria, might allow Solstice to be treated on farm first. “But the level of fungicide will be similar, although the focus on product might change.”
But growers shouldn’t err on the side of caution when choosing rates. “Caution is not affording any disease in, because every bit of yield is important. There is no sensible argument to the constraint of fungicide this season. To any cynics: Do the sums.
“If most growers do nothing more than spending an extra £10/ha at each end of the programme, they probably won’t be too far off.”
T0 a must
The T0 spray is a must. “Our own data show the benefit of T0s in disease control.”
He recognises a lot of growers plan T0s but, when the crunch comes, they don’t always get done. “But they are rarely regretted,” he points out.
Timing needs to be planned back from the flag leaf spray. “Work back from GS37, which is usually around 15 May, and never allow a gap of more than four weeks, which means T0s should go on around the last 10 days of March.”
A fast-acting triazole fungicide, such as cyproconazole, in combination with chlorothalonil, is a good choice. “I find it more active at lower temperatures than other azoles it is good against rusts, has a good effect on mildew and with chlorothalonil does a good enough job on septoria inoculum.”
The obvious disease driver at T1 is septoria, but Mr Neale warns not to forget about stem-based diseases, especially eyespot, as well as the rusts, if conditions are right.
“Robigus, for example, is poor against eyespot. You need to ask: Is my crop infected does it have brown stems and penetrating lesions?”
If it does, or the farm has a history of eyespot, it is worth selecting a product containing boscalid, prothioconazole or prochloraz, he says. “In Hutchinsons trials under extreme pressure boscalid had the edge.”
But watch out for the rate of triazole in boscalid products, such as Tracker and Splice, he warns. “At 1 litre/ha it only supplies 0.5 litres/ha of epoxiconazole, so you need to add some more triazole.”
Mr Neale is an advocate of mixing triazoles, so would add an alternative triazole to epoxiconazole. “You get more activity on the genetic mix of septoria,” he explains. “We’re seeing more and more trials where the Opus element is giving the most disappointing control. We’ve also seen it with prothioconazole. The explanation can only be genetic.”
In non-eyespot situations he would always mix two carefully chosen triazoles, from the following: prothioconazole, tebuconazole, epoxiconazole, fluquinconazole and prochloraz.
But one, perhaps obvious, combination shouldn’t be used: Prothioconazole + epoxiconazole. “It helps prothioconazole on brown rust, but not necessarily on septoria.”
Prothioconazole plus prochloraz is another one to avoid in brown rust situations, he notes.
Flag and ear sprays
Strobilurin fungicides should definitely be included in the flag leaf spray this season, Mr Neale advises. “No one can deny they deliver 0.3t/ha extra yield consistently, which is an economic response. Personally I believe they deliver more than that in the field, and if it is a brown rust year, then they are among the best fungicides we have.”
A mix of triazoles plus chlorothalonil should be also be included to cover septoria, was well as rust.
Along with the usual reasons to apply an ear spray – protecting quality and topping up foliar disease control, growers have two other reasons to treat this season, Mr Neale says. “One is helping fully use nutrients inputs, the other is safeguarding against hiccoughs in marketing.”
Trials illustrated the former last year, he says, where there was a tonne/ha response to a T3 fungicide in higher N plots, compared with no response where the fungicide wasn’t used.
- Variety input levels similar
- Worth protecting yields
- T0s and ear sprays more likely
- Strobs a must at flag