Onion downy mildew risk predictor

Downy mildew is an economically damaging disease of alliums around the world.

To manage onion downy mildew and to reduce how many times you need to spray your crop, you need to know if the conditions are right for to the disease to develop. 

We have developed MILLIONCAST to predict the rate of development of downy mildew spores based on temperature and relative humidity.

The tool is available on cropmonitor.co.uk.

To access the onion module on CropMonitor™, you need to register your email address on our database. Please contact Cathryn.lambourne@ahdb.org.uk who will pass your details on to CropMonitor. You can then register your onion fields.

How to use the tool

To help you get the most from the Onion downy mildew risk predictor, we have created these two videos:

MILLIONCAST is an acronym for MILdew on onION foreCAST. The accuracy of the tool was tested by comparing predictions with observations on infected plants on outdoor pots.

In 2019 the CropMonitor™ information service was extended to include the MILIONCAST risk prediction model for onion downy mildew and this was funded by AHDB.