Growers preparing to spray for phoma infection in oilseed rape have a new interactive tool at their disposal to help them treat crops at the optimum moment this season.

The online map from Rothamsted Research uses a “traffic light” style mapping system to tell growers when 10% phoma leaf spotting, which is generally regarded as the threshold to consider a fungicide application, is likely to be reached in their area.

The forecast uses temperature and rainfall data to simulate the development of the phoma fungus on crop debris and subsequent infection of young plants.

See also: Phoma disease alert for oilseed rape after recent rains

Earlier this week disease forecaster Neal Evans, who works with Rothamsted Research on forecasts, told Farmers Weekly:  “The phoma risk is likely to be higher and earlier than in recent years.”

Use the map below to find the 10% phoma infection date for oilseed rape in your area.

Phoma prediction date map key

• Red marker – site has already passed the predicted date for 10% plants affected
• Yellow marker – predicted date for 10% plants affected within seven days
• Blue marker – at least seven days before the prediction date for 10% plants affected

Find out more about Rothamsted Research’s phoma forecasting work.