BlightSpy is an upgrade on our longstanding Blight Watch website, allowing potato growers and agronomists to monitor weather forecasts for the predicted occurrence of Hutton Criteria.

What does BlightSpy do?

  • Provides a blight risk forecast for next 48 hours, with up to 8 days ahead available

  • Provides data on both temperature and humidity

  • Gives national and regional overviews, allowing each site to be seen in context

  • Enables a backwards look at previous conditions for each site to see the conditions crops have experienced

  • Provides comparison of forecast with actual weather, to assess the accuracy of the tool

  • Includes a view of Fight Against Blight results, to better inform risk assessment

How to use:

The front page shows a map of Britain. The weather data point dots are in three colours, red for a full Hutton period, amber for a near miss and green for no Hutton criteria.

Click on the list of regions to the left of this map, to focus on the area of interest. The distribution of coloured dots will give an immediate impression of whether there is risk and where it lies.

Click on the point nearest to your fields. The table to the right of the screen shows the forecast information on temperature and relative humidity for the area selected. Input data is added each morning by 11am. Users are advised to check each day, since predictions often change.

The default is the Look forward view. Click on the box called ‘Look backward view’ to see the results for a site throughout this season or last.

Under Look backward view a further box is marked ‘+ Obs data’ Click on this to see a comparison of the forecast Hutton criteria with that from actual recorded weather. Such comparisons are available for only a limited number of points, as shown on the map.

What is a Hutton Criteria

A Hutton Criteria occurs when two consecutive days have a minimum temperature of 10°C, and at least six hours of relative humidity at or above 90%. Prediction of a Hutton criteria is shown by a red dot on the map. An amber dot shows a near miss. This is calculated by looking at 4 pieces of data, the relative humidity at or greater than 90% and the minimum temperature, on each of two days. If RH > 90% occurs on 5 hours on either day or minimum temperature is 9oC on either day, while the other criteria meet those required for Hutton, then a near miss is illustrated on the map.