What is impatiens downy mildew?
Impatiens downy mildew is a disease caused by the fungus-like organism Plasmopara obducens. It was found for the first time in the UK in 2003 and is likely to have arrived on imported commercial propagation material (seed or cuttings). For a short time statutory action was taken by Defra against confirmed outbreaks of the disease, but this approach was soon dropped. The wet summer of 2008 triggered the most widespread outbreak of the disease so far, with many gardens, nurseries and local authority displays affected. Attacks are most likely in summer, or spring in greenhouses. Outbreaks of downy mildew have been confined to Impatiens walleriana, the common bedding busy Lizzie. No cases have been found on New Guinea Impatiens, Impatiens x hawkeri, or on the few species of Impatiens found growing in the wild in the UK.
