1) What fusarium species are being found in / on grain, and in what proportion?
The latest DEFRA wheat disease survey results published on Crop Monitor suggest that virtually all (97%) samples are showing symptoms of ear blight. Around two-thirds of the samples have been tested further to isolate which pathogens are responsible. There are regional differences, but nationally Microdochium nivale is present in at least 93% of the samples, and is the dominant cause of head blight symptoms.
Fusarium graminearum is present in 40% of samples, meaning mycotoxin risk is high this year in some regions, while Fusarium poae has been found in 30% of samples.
For the full picture visit the Crop Monitor web site.
2) What effect will each species have on planted seed next season?
Microdochium nivale is recognised as being by far the most important pathogen to have the potential to impact on crop establishment with Fusarium culmorum having a much lesser effect
3) What level of Microdochium nivale would constitute a risk for next season's crops?
Unprotected wheat seed starts to be at risk from Microdochium nivale present from 10% infection and the risk gets greater the later the crop is sown when the seedlings are growing much slower and so are vulnerable to the pathogen for longer.
4) What control can you expect from seed treatments?
No seed treatment can guarantee complete control of a severe infection of Microdochium nivale. What the seed treatment does is increase the potential for increased crop establishment but the degree of improvement will be dependent on the severity of infection and the conditions under which the crop is being grown. However, trials with effective seed treatments have shown substantial improvements in crop establishment when sown with severely infected seed in the late winter.
5) Is there greater risk from using home-saved treated seed rather than bought seed this year?
So long as the seed is viable and treated with a good seed treatment by competent operators, home saved seed should not be at any greater risk than bought-in seed.
6) Should growers be considering trying to buy over-yeared seed this season rather than this year's crop?
There is probably going to be a shortage of over-yeared seed available this season. So long as this year’s harvested seed is inherently viable and treated competently with a good fungicide seed treatment, the crop should establish well. Growers are advised to avoid sowing late under cool and wet conditions.