Mycotoxin fears prompt a major fusarium study

20 July 2001

Mycotoxin fears prompt a major fusarium study

By Charles Abel

FEARS that mycotoxins produced by fusarium fungi on cereal ears could cause a new food scare have prompted agchem company Aventis to launch a major drive to find an integrated solution.

"CSL disease monitoring shows a significant increase in fusarium," says cereals products manager Alison Daniels. Wet springs followed by cool, wet summers, the rise of lo-till establishment and changing ear spray practices have all favoured the disease over recent years, she notes.

Canada, the US and the Netherlands already have mycotoxin regulations to protect consumers and new EU limits for myco-toxin levels in grain are likely soon.

But the real concern is a consumer reaction rather than the arrival of limits, says Dr Daniels. "We want to be proactive in minimising risks, not reactive."

Trials to develop integrated control strategies in France and Germany have been running since 1994, the disease posing a greater risk there, with some fields literally turning pink with fusarium, says Dr Daniels.

Now work is underway in the UK with agchem distributor Agrovista.

"The aim is to identify the tools we need to deal with this if it does become an issue," says the firms Craig Morgan.

Widespread use of Amistar (azoxystrobin) in T3 ear sprays has given the disease a new toehold, the strob fungicide removing its main competitors, allowing mycotoxin-producing fusarium strains to move in.

Furthermore, mycotoxins can be a problem even when fusarium symptoms are not visible, says Dr Daniels. "Mycotoxins are formed ahead of the fusarium infection, to interfere with the host plants natural defence response. So they can diffuse into the grain ahead of fungal growth."

Work in Europe already suggests the T3 ear spray timing is not a total solution. Instead growers there are being urged to use fusarium-active products in the seed treatment, early stem-base treatment and a delayed, but robust T2 or early-T3 spray.

"No single fungicide can clean fusarium out of the ear, because the infection sits so deep within the glumes. So whole season management, including a pre-anthesis protectant spray, is likely to be the key," says Dr Daniels.

To identify the best approach for the UK, plots at the Agrovista trials site at Cockayne Hatley, near Sandy, Beds, have been inoculated by CSL with a worst-case scenario level of fusarium and misted every 20 minutes during flowering to simulate severe, but realistic, disease pressure.

Treatments have been chosen to reflect the possible components of an integrated fusarium strategy, and are geared to test the value of Aventiss prochloraz fungicide, which is widely used in Europe to combat the disease.

Inputs include Jockey (fluquinconazole + prochloraz) seed dressing compared with single-purpose seed dressing and a kresoxim-methyl based T1 spray compared with Foil (fluquinconazole + prochloraz).

At the pre-flowering (GS59) stage ear sprays of Amistar, Amistar/Foil, Amistar/Foil/adjuvant, high rate prochloraz and various triazole mixes are being compared.

CSL protocols are being used to check for fusarium on stem-bases and ears, and grain will be harvested and milled for mycotoxin checks.

"Our aim is to come up with an integrated strategy that will help growers minimise the threat from mycotoxins in their grain," says Dr Daniels. Results will be available later this year. &#42


&#8226 Food-scare concerns.

&#8226 T3 spray not sole solution.

&#8226 Integrated strategy needed.

&#8226 Plots misted at flowering.

&#8226 Results post-harvest.

&#8226 Mirrors work in Europe.

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