27 July 1998
Fusarium rampant in a record year

Question

I HAVE used Amistar as an ear wash at 0.33/ha. I have still got a lot of Fusarium – not full-blown orange, but most ears on Abbot have one or two diseased grain sites. Was I too late ? Should it have gone on well before anthesis instead of at or just after?

Responses

Dr Judith Turner, senior plant pathologist, crop disease research team, Central Science Laboratory, York

Dr David Jones, plant pathologist, ADAS Rosemaund, Herefordshire.

Answer 1

Dr Judith Turner, senior plant pathologist, crop disease research team, Central Science Laboratory, York

FUSARIUM ear blight is being recorded at unprecedented levels in wheat crop samples from England and Wales. Interim results from the 1998 CSL/ADAS survey of winter wheat diseases carried out at GS 73-75 indicate that the wet weather leaf diseases are at very high levels.

But potentially of greatest concern is the incidence and severity of fusarium ear blight caused by Fusarium culmorum, Microdochium nivale and possibly other Fusarium species. This leads to poor grain fill, shrivelled and mouldy grain and worst of all the threat of mycotoxin development in affected crops.

At present the magnitude of this threat to yield and quality and mycotoxin content cannot be predicted accurately.

Survey data indicate that the disease is currently affecting an average of 1% of the total ear area. Field trials carried out at CSL over the past three years have indicated that under favourable conditions disease severity could increase at least tenfold between now and harvest and that species such as F. culmorum are capable of producing significant levels of mycotoxins under UK conditions.

Unfortunately, there is nothing cereal growers can do about ear blight this year as sprays to control the disease should have already been applied. However, there are potential risks to next years crops from high levels of infected seed and increased inoculum in the soil.

Answer 2

Dr David Jones, plant pathologist, ADAS Rosemaund, Herefordshire.

THE only way to get respectable control of fusarium is to get the timing right.

Growers would have to have gone in with a full rate of Folicur (tebuconazole) shortly after ear emergence to catch the infection occurring at early flowering. An ear wash spray would have been standard practice this season for other diseases, but the reduced rates commonly used by growers would not have the desired effect on fusarium infection. Amistar doesnt control fusarium ear blight.

The crucial factor this year was the wet weather around anthesis during the first two weeks of June. There were very good conditions for infection. There will be more inoculum carried over from this year but if we have a dry June next year the risk will go.

However, this years infection will increase the importance of having seed tested – particularly if growers are planning to home-save.