Identification of factors which influence infection and control of the newly emerged Peronospora causing downy mildew on aquilegia

Aquilegia downy mildew is caused by a species of Peronospora which is currently unnamed. The first occurrence of the disease appears to be on a nursery in 2011, with more widespread reports in gardens during 2013. Since this report the disease has become more widespread causing plant loss both on nursery and in gardens. Some of these losses have led to extensive coverage in the national press.

Preventative foliar application of Fubol Gold, Fenomenal, Signum and Revus all gave 100% control of downy mildew infections. The range of active ingredients showing effective protectant control of aquilegia downy mildew suggests that effective spray programmes could be identified which do not rely on a single mode of action of active ingredient. This should reduce the risk of a fungicide resistant population developing. A risk grid was also developed, which indicated that where the humidity was greater than 90%, the risk of infection was highest.

Project aim(s):

The project aims to generate data which will enable growers to combat the threat from the newly emerging downy mildew on aquilegia (ADM). The outputs from the project will generate best practice guidelines for aquilegia crops grown under protection or outdoors.

Project objective(s):

1. Determine the conditions required for infection and sporulation of the Peronospora sp. responsible for ADM.
2. Determine the survival of conidia under differing environmental conditions.
3. Establish best practice methods (cultural and chemical) to prevent and control infections of ADM.
4. Dissemination of outputs from project through best practice guidelines and presentation at grower meetings.

Benefits to Industry: 
The number of growers who have been adversely affected by ADM is unclear. However, the high level of press coverage warning of the dangers from the disease has led to concern amongst growers that a loss of sales could be similar to that seen for downy mildew on impatiens. Determining an understanding of the pathogen responsible for aquilegia downy mildew will ensure effective management strategies can be developed which would minimise future losses from the disease.