Ash dieback was the big environmental story of 2012 – and the deadly fungus Chalara fraxinea threatening to blight our ash and so change the face of our countryside is not about to drift away in 2013.

In December, Government figures revealed that the number of infected sites had more than doubled to 291 compared with the previous month.

More than half are mature woodland areas which were most likely infected by spores blown from continental Europe or Norway in the wind, rather than by diseased young trees imported from abroad, experts said. But how can you tell if the ash in your own garden is infected?

How is it carried?

Local spread, up to ten miles, may be via wind. Over longer distances, the risk of disease spread is most likely to be through the movement of diseased ash plants.

What are the symptoms?

Dead or dying tops of trees, most easily seen throughout summer; wilting leaves, most visible in spring and early summer; lesions and cankers on stems/branches/shoots, visible throughout the year; dieback of leaves with brown/black leaf stalks, seen throughout summer; fruiting bodies on fallen blacked leaf stalks, visible June to October; staining of wood under bark lesions, visible throughout the year. Check your trees as they emerge into leaf, watching for symptoms.

Is there a cure?

No. Once infected, trees can’t be cured. However, not all trees die of the infection. Some have genetic resistance.

What about newly-planted ash trees?

The Forestry Commission advises people to check on any young trees planted in the last five years and is urging gardeners to buy disease-free stock from reputable suppliers.

How can I protect ash trees in my garden?

To reduce spread of the disease, remove all ash leaf litter from around the trees in the autumn and winter to reduce spores the following summer. Safely dispose of leaves by burning, burying or composting, although in some areas and circumstances disposal might need to be undertaken by a local authority.

Urban and veteran ash trees should be examined to establish any infection present, and the disease status of the tree should ideally be assessed by a professional.

What can I do if I think my tree has ash dieback?

Fill out the Forestry Commission’s ‘Tree Alert’ form on its website forestry.gov.uk, or call the Chalara helpline on 08459 335577.