Hate them or love them, there must be thousands of Leylandii hedges up and down the country. The pride and joy of some gardens, and the light-sucking scourge of their neighbours.

Leylandii are a man-made plant, a sterile hybrid resulting from a cross between two vigorous conifers: Chamaecyparis nootkatensis from north America and Cupressus macrocarpa from California.

This extremely fast growing conifer has been the subject of many a dispute between neighbours (often resulting in costly court cases). To the delight of some and the dismay of others, hedges that have been lush green and vigorous for years are suddenly browning off and dying.

It seems that nature has taken a dislike to the work of man, and has reached into Pandora’s Box to unleash a deadly fungus, coming down strongly on the side of the anti Leylandii lobby.

After last year’s drought and hosepipe ban many plants, including Leylandii, have been left moisture-stressed and vulnerable to all sorts of pests and diseases. This year’s hot humid conditions have made it easy for nature to launch its attack on this already weakened coniferous man-made monster.

The pathogen in question is needle blight (Pestalotiopsis Funerea) which attacks the plant via wind blown bore spores, entering the system through wounds and damage. This makes Leylandii particularly vulnerable as gardeners clip and manicure their beloved hedges on a regular basis, providing plenty of opportunity for the infection to take hold.

At the moment there is no cure available to the amateur gardener, as none of the chemicals used by professionals are available to the gardening public.

The symptoms are brown tips, which spread into large brown patches which can encompass most of the hedge, often the sides are brown and the tops are left lush and green. However, as Leylandii rarely rejuvenate from old wood there is no chance of the hedge recovering, leaving gardeners with the expensive task of replacing their hedge.

As this disease spreads easily in warm humid conditions, delay pruning your hedge until winter and ensure you use sharp implements to decrease the surface area of the wound. Remove all clippings from the ground as the spores can be spread by water splash.

If one side of your hedge has been affected, prune out the dead wood this winter, leaving the main stem and any live shoots. Then, under plant with new Leylandii which will quickly knit into the existing frame work of the old hedge, thus avoiding having to rip up the whole thing.

If you are worried about the new plants becoming infected, use non-coniferous species like Laurel, Privet, Beech, etc, which are not affected by this particular fungus, to create a mixed or “tapestry” hedge.

Love it or hate it, the conditions created by climate change has made one of our most commonly used garden plants susceptible to the wrath of Mother Nature.

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