Phoma Leaf Spot Forecast

Use the phoma leaf spot forecast to guide crop monitoring and help time fungicide sprays in the autumn. Based on temperature and rainfall information, the model predicts treatment threshold starting-week dates at hundreds of locations.

About the forecast

Temperature and rainfall information* is used to simulate the development of Leptosphaeria maculans – a key pathogen responsible for phoma leaf spot and phoma stem canker.

The forecast page (<1 of 2>) predicts the date of the starting week when 10% of oilseed rape plants could potentially show symptoms of phoma leaf spot.

This level of infection relates to a treatment threshold for varieties with lower disease ratings for stem canker (7 and below).

The tool also shows how the current year compares to recent years – allowing ‘earliness’ or ‘lateness’ to be assessed.

The predicted infection status page (<2 of 2>) shows the proportion of the crop currently (today) forecast to have ‘no symptoms’, ‘infections taking place’ and ‘10% incidence'.