A deadly new plant disease that has caused widespread devastation on the continent is expected to arrive in the UK soon.

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The “unprecedented” disease, Xylella fastidiosa, doesn’t just attack one type of plant but can kill hundreds, and the Royal Horticultural Society (RHS) has warned the quintessential UK garden, bursting with a wide variety of flowers, fruit and vegetables, could be lost to it in 2018.

Gerard Clover, head of plant health at the RHS, says: “Xylella is a game-changer for gardeners and the horticultural industry, and it’s vital we understand its potential impact.

“Unusually, the disease threatens not just one host but hundreds of different types of garden plants, and its impact has been felt dramatically in France, Spain and especially Italy, where entire groves of ancient olive trees have been wiped out.

“The question is not ‘if’ but ‘when’ the UK will have its first outbreak of Xylella, and the industry and public must be prepared for the far-reaching impact of it,” he adds.

Here are 10 things you need to know about this new garden killer:

1. Xylella fastidiosa is a bacterium which restricts water movement in plants, resulting in eventual death.

2. Most pests and diseases are plant-specific, but Xylella affects more than 350 different plant species.

3. The disease is spread by insects including leafhoppers and froghoppers.

4. It threatens to arrive in the UK from the continent through the importation of infected plant material.

5. Garden favourites including lavender, hebe, rosemary and flowering cherry are at high risk because of their popularity, susceptibility to different strains of the disease and association with outbreaks on the continent.

6. Xylella is difficult to identify, meaning it could advance unnoticed. Infected plants either show no symptoms or exhibit ones which may be confused with other common problems such as drought or frost damage.

7. If found in the UK, all host plants within 100m would be destroyed.

8. There would also be restrictions on movement of plants within a 5km radius for five years, “striking a death knell” for surrounding nurseries and garden centres, warns the RHS.

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9. The RHS is calling on gardeners and the industry to future-proof gardens by purchasing host plants that are UK-sourced and grown – that is, propagated from seed in the UK or grown in the UK for a minimum of 12 months. They are also advised to maintain varied plantings, and report potential cases of Xylella to Defra.

10. To help reduce the risk posed by Xylella, the RHS is adopting new principles across its gardens, shows and plant centres, including holding imported semi-mature trees in isolation for at least 12 months prior to planting, using UK-grown and sourced plant material wherever possible, and developing a list of RHS-approved suppliers that meet specified plant health criteria.