Monitoring sooty blotch and fly speck based on visual symptoms is probably ineffective as a management tool because of the long interval between infection and symptom appearance.
- Where the diseases were a problem the previous year, probably specific control measures need to be applied in the current year to protect fruit.
- In the USA a simple model has been developed to predict the first symptoms of sooty blotch and fly speck.
- This is based on the hours of leaf wetness of four hours duration or greater accumulated from the first rain that occurred 10 days after petal fall.
- Fungicides are applied at a threshold value of 200-250 hours of leaf wetting.
- The threshold value of leaf wetting was shown to vary with region in the USA, which was probably associated with the fungus complex responsible for sooty blotch.
- In the Midwest of USA, cumulative hours of relative humidity greater than 97% was more accurate in forecasting SBFS than cumulative hours of leaf wetness.
- Whether this model ca be applied to the UK is not known.
- A model for sooty blotch is also included in the RIMpro system and has been tested in several locations in Europe but not in the UK.