Sclerotinia infection warnings give 48 hour heads-up

We’ve just launched our sclerotinia forecasting service for 2018:

The one day of spring we had earlier in the week, however, was not enough to see most OSR crops reach the yellow bud/flowering stage. Unsurprisingly, sclerotinia infection risk in the UK is still very low.

This year, the forecast is based on weather conditions only. When there are at least 23 hours when temperature is more than  7°C and relative humidity is greater than 80%, there is a greater risk of sclerotinia spores infecting a crop. A sclerotinia spray will need to be applied before these conditions are reached, hence the need to forecast these spells.

Unlike previous years, air borne spore levels are not taken into account, so you will need to keep an eye on the BASF monitoring of apothecial germination to see that side of things.

Of course, if your crop is not in flower then no amount of spores or conducive weather conditions will cause infection in your crop. However, an infection event at early flower is more damaging to yield than one at late flower, so make sure you keep a close eye on your crop growth stage.

If you’re not near one of the 15 sites shown in the forecast, you could look at your local weather forecast: if temperatures dip below 7°C or 80% relative humidity in a 23 hour period, risk is likely to be low.

Even if you don’t use this forecast to decide on the necessity or timing of your first sclerotinia spray, I hope it will help you when deciding on a second spray.

Follow me on Twitter @CatherineGar4

Catherine Garman

Catherine Garman

Catherine is Crop Health & Protection Scientist (Diseases) at AHDB

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