Practical experience of using a prediction system to control strawberry powdery mildew

Strawberry powdery mildew, caused by Podospheara aphanis, is a major threat to strawberry production in the UK. Infection by P. aphanis causes a progression of symptoms on strawberry plants thus leading to great yield loss. There is also a growing pressure on growers to reduce the amount of fungicides used to control P. aphanis. A rule based prediction system to predict High Risk Days for strawberry powdery mildew development has been developed to alert the grower when fungicide spraying is necessary. The prediction system monitors temperature and humidity, and records the accumulated number of hours of disease conducive conditions needed for the fungus to develop from conidiospore development through colony formation to conidiospore production. Work reported from the 2012 season showed that the Area Under the Disease Progress Curve (AUDPC) was halved when the prediction system was compared with an unsprayed control. The work reported here from 2013 was part of a farm wide trial of the prediction system, which also proves that the use of prediction system can give good disease control on strawberry powdery mildew.