Jeremy Clarkson's right: getting trees from abroad can be fatal

And the Daily Mail? Well, I’m not often in accord with that organ either. But, and it must be some bizarre effect of the spirit of this time of year that - within a matter of days - I found myself in total agreement with Mr Clarkson.

He highlighted the dangers of continuing to import trees and shrubs from abroad.

And I was also grateful for the informative Mail article on the bacterial disease Xylella.

Xylella has been identified as the cause of death of olive trees in southern Italy.

Both illuminated the extreme dangers of imported diseases which are even more likely to affect the UK as our climate warms.

We all know what Dutch Elm Disease has done to our once majestic native tree. Sixty million have been lost and suckers from the roots succumb to the infection transmitted by the beetle once they reach a certain size.

The remaining Preston Twin elm in Brighton has just recently been in the news having caught the elm disease which killed its sibling.

The amazing tree, said to be the oldest elm in the world, is suffering and its days could be numbered, despite the efforts of arboriculturists.

Its plight is one of the most dramatic and upsetting illustrations of what a tiny boring bug and bacteria can do to our countryside.

Another is ash dieback, a result of fungus imported on shipments of timber from south-east Asia.

Experts reckon it will kill eight out of ten of our ash trees and have a dramatic impact on the many species which rely upon it.

An example of ash dieback.

Another of my favourite trees, the horse chestnut, which beckons in summer with its narrow bell-shaped clusters of flowers is in gradual, painful, decline — victim to a grub the size of a grain of rice.

The leaf miner sucks out the goodness of foliage from within. Autumn comes very early and the tree fails to flourish. The miner has only been here since 2002, an import from southern Europe, but has already done great damage.

There are many more blights that have come and countless are waiting in the wings.

Among them is the serious forestry pest, the eight-toothed spruce bark beetle, which has the potential to cause significant damage to the UK’s forestry and timber industry.

The emerald ash borer has killed billions of ash trees in the US. If it gets here, it will do the same to our already vulnerable ash populations.

But one of the biggest threats, as the Mail points out, is the bacterium Xylella fastidiosa. It is native to the Americas where it causes disease in many important crops including citrus, coffee and grape vines.

Xylella was absent from Europe until just eight years ago when it was identified as the cause of death of olive trees in southern Italy.

There are now major outbreaks on ornamental plants in southern France, Ibiza, Mallorca and Menorca, southern Spain and now Portugal.

Xylella infects a wide range of plants including many popular species grown in gardens, such as cherry, hebe, lavender and rosemary.

The bacterium causes a variety of symptoms which can include leaf scorch, wilt, dieback and, ultimately the death of whole gnarled, ancient, olive groves. which have provided joy and a livelihood to generations.

Xylella is transmitted between plants by insects which feed on sap and, of course, when infected plants are traded. That is where we can play a part in keeping out yet another unwelcome visitor.

The Royal Horticultural Society has taken a lead and banned olive trees from its shows.

We can follow by responsibly sourcing one of the most popular non-native trees for our gardens by asking its provenance – whether it came from one of the disease hotspots - and most certainly not bringing anything back from abroad ourselves.

UK-grown plants or seeds pose a very low risk. Plants established in gardens for more than five years which have been previously healthy are also low risk.

DEFRA has stepped-in and placed heavy restrictions on import of a whole host of plants that may carry the disease. It is vitally important because it is a bacteria that could add our iconic English oak to the tree casualty list. Happy Christmas..!

RICHARD'S TOP TIPS:

• Leave the faded flower heads on hydrangeas until spring. They provide insulating frost protection to the swelling buds further down the stems.
• Dig over empty borders and prepare your soil for next year’s planting — if the soil is not too cloying. If it is too wet spread manure or seaweed on the surface and dig over when conditions are right.
• Group potted plants together in a sheltered spot in the garden to protect them from the harshest winter weather. There’s some safety in numbers.
• Get pruning — wisteria, fruit trees, roses and Japanese maples are just some of the plants that benefit from a winter prune.
• Stone fruits should not be pruned until the summer.
• Spread fresh gravel or grit around alpine plants.
• If you haven’t done so already, cut down dead asparagus foliage and the top growth of Jerusalem artichokes. Order your asparagus crowns now for planting in spring.

Are you an Isle of Wight gardener with a question for Richard? You can email him on: richryde@tiscali.co.uk