While the 1250 parts per billion maximum for unprocessed cereals, which becomes a legal requirement from 1 July, should not generally be too difficult to achieve, the lower 500ppb for bread and breakfast cereals and 200ppb for baby food could prove harder, says Frontier’s Bob Mills.
“The ability to dilute during processing is just not there.
It means breakfast cereal manufacturers have to have grain below 500 parts per billion.”
The annual HGCA survey of mycotoxin levels illustrates his assertion that the lower targets could be a cause for concern. Average deoxynivalenol (DON) mycotoxin levels in 2003 were 218ppb and 583ppb in 2004.
Agronomically avoiding grain maize, which is a big source of infection, in the rotation and burying crop debris by ploughing will minimise growers’ risk, he says.
But the new legislation will probably also mean an increased focus on using fungicides to keep mycotoxin levels in check.
“T3 sprays need to become an integral part of the strategy rather than just using up what is left in the chemical store.
“That might only kick in when the legislation hits.
It might take us having a problem for a T3 to become a must do.”
To tackle fusarium effectively growers must get their timing right, he warns.
“Timing is as important at T3 as it is at flag leaf – it has a major influence.
“In the past growers have seen ear sprays as an extension of foliar disease control, and, quite rightly, expected to get four weeks of protection from their flag leaf sprays.
The problem is fusarium infection occurs before the T3 goes on.
Ideally, growers need to apply fungicides pre-infection, he says.
“Target ear sprays at early flowering.”
That might mean growers having to spray only two weeks after applying a flag leaf spray, he notes.
But, providing earlier sprays have given effective foliar disease control, fusarium should be targeted first.
“Choose the product which will give you greatest longevity against fusarium,” he advises.
Prothioconazole fits the bill, says Bayer CropScience’s Alison Daniels.
“It is setting new standards against true fusaria and Microdochium nivale.”
That claim is backed by CSL evaluation of different fungicides applied as protectants in a fusarium-inoculated trial – Proline (0.5 litres/ha) gave over 70% control compared with 60% from Folicur (tebuconazole) and about 54% control from Swing Gold (dimoxystrobin + epoxiconazole).
Importantly, Proline also gave a 70% reduction in mycotoxins compared with 57% with Folicur and 32% with Swing Gold.
A similar CSL trial evaluating performance against microdochium showed full rate Proline as being the strongest fungicide, giving 80% control compared with Swing Gold (0.75 litres/ha) and 1.25 litres/ha of Amistar Opti (azoxystrobin + chlorothalonil), which gave about 60% control.
“At lower doses Proline matched what the strobs can do,” Dr Daniels says.
Proline combines long-term protection with curative activity against fusarium.
In practice that gives some timing flexibility, she says.
Bayer trials have shown good DON suppression right through flowering.
The product is a good option where growers are looking to top-up septoria control, as well as control ear diseases and suppress mycotoxins, says Bayer’s Chris Cooksley.
But it does need back-up in curative brown rust situations, he admits.
“You can either top up with Folicur or use Fandango.”
Fandango (fluoxastrobin + prothioconazole) is seen by Bayer as their premium option.
“It is better on fusarium, microdochium and septoria than Swing Gold.
In TAG trials at Morley it gave 0.1t/ha yield advantage over standard treatments.”
For growers looking to pay less, Folicur remains a good option, he adds.