How do I time an FHB application in a “stagey” crop?

This is a difficult question and there really is no easy answer. However, there are a few things you should consider:

  1. The ideal timing is early flower. Generally, wheat begins to flower about 3 days after head emergence and flowering usually lasts between 3 and 5 days. Target to hit as many heads as possible at the early flower stage.
  2. The majority of yield is determined by the main heads, so make sure you’re targeting early flowering on the main heads (ie. not the tillers)
  3. Consider the forecast. If your crop is really stagey and there is really no one time to hit the majority of the heads, think about the ideal conditions for infection – in the last week, has there been free moisture (precipitation or high humidity) for a 12 hour period and have temperatures ranged from 16 to 30°C? If not, consider holding off on an application until conditions are more favourable for disease. Use FHB risk models, such as the one produced by MAFRD (http://www.gov.mb.ca/agriculture/crops/seasonal-reports/) as a guide.
  4. It’s better to be early than too late. Fungicides are designed to be used preventatively, not curatively.

Additional resources:

http://www.realagriculture.com/2013/06/wheat-school-ideal-staging-plus-nozzle-selection-for-fusarium-control/

Submitted by:  Holly Derksen, Field Crops Pathologist, MAFRD

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