Phytophthora Warning

Juniper under threat

The Heather Trust has been concerned about Phytophthora (pronounced fy-TOFF-thora) for some time, although initially because of concerns that the disease could have an effect on heather itself. While P. ramorum has a devastating impact on blaeberry (V. myrtilis), it so far seems as though heather is relatively safe from large scale damage.

However, equally worrying is the sudden appearance of a different kind of Phytophthora which targets juniper, a vital component of the moorland environment, and one which has suffered terrible declines over the past century. Phytophthora austrocedrae has been found to have killed large numbers of juniper trees in the North Pennines, and the extent of the damage could be far worse.

Juniper trees have considerable value as cover for a range of birds and mammals, including black grouse, but the species may be better known to moorland managers in Scotland in its low-growing variant, often mixed in with heather or on rough ground on the moorland margin. These low-growing junipers are a feature of moorland in the North East of Scotland, and while they are perhaps less well known than the classic upright "tree" form, they are equally vulnerable to P. austrocedrae.

Austrocedrae was first identified in Argentina in 2007, where it was responsible for damaging a native species of cedar. The pathogen attacks the roots and stem bases of juniper, causing symptoms of die-back which vary from a few brown or orange shoots to an entire reddening of the plant, leading ultimately to death. It is unknown how this type of Phytophthora came to Britain, but the family of pathogens to which it belongs is renowned for being highly mobile, infectious and persistent.

Plantlife has recently started a survey on Phythophthora austrocedrae, and they are urging people to get in touch with them if they encounter juniper which appears to have been infected by the disease. This coincides with the Scottish Plant Health Strategy which was unveiled by the Scottish Executive last week in a push to raise awareness about plant diseases.


For information on Phytophthora which is relevant to moorland managers, have a look at our Members' Briefing.