Impatiens growers are being warned of a potentially serious outbreak of Downy Mildew, the first since 2003.

An urgent alert is being sent to Impatiens growers for them to check their plants for the Downy Mildew found on cutting raised material in the United Kingdom early last week.

This disease alert has followed some new findings of Impatiens Downy Mildew, discovered by John Buxton of ADAS in a glasshouse on a nursery. Since then other reports of the disease have been found in different localities.

The seriousness of the outbreak is well illustrated by the co-ordinated approach being taken by Judith Turner of the Central Science Laboratory (CSL), Martin McPherson of Stockbridge Technology Centre and the HDC with PC 230 project co-ordinators Martin Squire and Mike Smith.

Downy Mildew (Plasmopara abducens) was first reported as a new disease in the UK in 2003 and caused considerable damage to plants as a result of leaf yellowing and ultimately loss of foliage.

Dr McPherson of STC said that all Impatiens growers should immediately look for signs of yellowing on the lower leaves and turn them over for the characteristic white downy fungal growth on the under-surface. To date white flowered varieties had been most affected.

In an alert notice sent to growers, they were being asked that a sample of any suspect material be sent to either Dr Turner at CSL or Dr McPherson at STC, both of whom have the diagnostic facilities to identify the disease.

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