Juniper, one of Scotland’s most loved and treasured plants, is in serious 'critical' decline and being killed off by a deadly new disease, according to a new survey.

Observations reported by the conservation group, Plantlife Scotland, suggest that 79 per cent of juniper in 2014 was mature, old or dead. And as many as 63 per cent of bushes surveyed were found to have brown patches, a sign that they were suffering from ill health or disease.

A new air-borne fungal disease known as Phytophthora austrocedri is spreading across Scotland and having a severe impact on juniper, Plantlife says. The disease was first recorded in Argentina in 2007, and it is not known how it arrived in the UK.

Juniper is also being eaten by deer, cleared by foresters and burnt by land managers. A report published this weekend by Plantlife concludes that the species is now in a “critical state”.

Juniper is a native coniferous shrub famous for its dark purple berries, which are used to flavour gin and stews. Historically a defining characteristic of Scottish woodlands and mountainsides, it is gradually disappearing.

Plantlife asked volunteers to report sightings of juniper across the country in a “citizen science” survey. “We know juniper populations are struggling, but they now face an additional threat,” said the head of Plantlife Scotland, Dr Deborah Long.

It was vital to work with landowners to help juniper bushes resist the disease and the other risks they face, she argued. “We need to ensure juniper has a future. It needs active conservation effort and intervention now for it to survive.”

The Conservative MSP for Mid Scotland and Fife, Murdo Fraser, is a species champion for juniper. “Juniper is one of our most iconic species,” he said.

“Used not only by birds as cover and food, it is a key native plant for human use too. Today though, juniper is in trouble.”

Fraser described Plantlife’s report as “a call to action” to ensure the future generations “get to smell crushed juniper berries and delight in the assorted shape and sizes of juniper” in the countryside.

He added: “Land managers, visitors, conservationists and politicians can all do something for juniper." Plantlife has produced a guide on how to manage uplands to help juniper.