Basil: Improving knowledge and Control of Downy Mildew in protected and outdoor crops


Summary: Downy mildew in basil is a devastating disease caused by the plant pathogen Peronospora belbahrii. Work on the disease has already determined the conditions required for sporulation, however little work has been done to address the sources of infection, conditions required for infection and spore survival, or the most effective ways to control the disease. 

Additional information:

See related AHDB-funded research on basil downy mildew (PE 024a)

Project code:
PE 024
01 September 2015 - 31 August 2017
AHDB Horticulture
AHDB sector cost:
Project leader:


PE 024_GS_Final_2017 PE 024_GS_Annual_2016 PE 024_Final_2017_Report PE 024_Annual_2016_Report

About this project

Aims and Objective: 


The project aims to generate best practice guidelines to improve the control of basil downy mildew on crops grown under protection and outdoors.


1. Epidemiology

1.1 Determine whether Peronospora belbahrii is present in UK seed lots and whether infected seed acts as a primary source of infection

1.2  Determine whether P. belbahrii can be detected in soil from outdoor production sites

1.3 Determine the conditions required for infection of basil by P. belbahrii

1.4 Determine survival of the different spore types under various environmental conditions

1.5 Determine the level of oospore production under protected and outdoor conditions

2. Determine the existence and importance of alternate hosts for P. belbahrii

3. Control

3.1.   Evaluate fungicide programmes in large-scale 'commercial' trials (protected and outdoor production) for efficacy against P. belbahrii.

3.2.   Evaluate the safety of fungicides & programmes for use on basil seedlings.

3.3.     Evaluate periods of illumination during the dark period to determine those which provide best suppression of infection and/or sporulation by P. belbahrii.

4. Dissemination of outputs from project through best practice guidelines, an article in HDC News  and presentation at appropriate grower meetings

The production of best practice guidelines (objective 4) is dependent on results from the other objectives, however if necessary these could be produced based on the knowledge of epidemiology and control gained from other downy mildew diseases caused by Peronospora species. The remaining objectives are relatively independent of each other. In the absence of seed borne infection, determination of the existence of different strains or races of P. belbahrii (objective 1.3) would be dependent on the receipt of infected plant material from the industry.