Fuchsias are being hit by a ‘devastating’ new pest that is set to spread throughout Britain.

Fuchsia gall mite, which was unheard of in the UK before 2007, has become widely established along the south coast – and is heading north.

Fuchsia gall mite damage (credit: RHS)

The news comes weeks after B&Q and Thompson & Morgan stopped selling busy Lizzies – another popular bedding plant – because it has been ravaged by impatiens downy mildew.

Tiny fuchsia gall mites have a big impact on the growth of fuchsias. Critters feed on shoot tips and flower buds, leaving both distorted. Affected plants are unable to produce normal leaves and flowers.

“RHS principal entomologist Andrew Halstead described the pest as “devastating” and said he expected it to spread nation-wide.

“Unfortunately there are no effective pesticides for garden use,” Andrew explained.

“Because the damage cannot be controlled, it may lead to a decline in the popularity of this valuable garden plant.”

The emergence of fuchsia gall mite came to light in the Royal Horticultural Society’s annual survey of Britain’s top plant pests (see below). Fuchsia gall mite is a new entry, at number six.

Also making its debut is leek moth, a problem that can also affect onions and shallots. Two generations of caterpillars are produced in summer, but the second, in late-July to August, is most troublesome.

Young caterpillars mine leaves and bore into stems of leeks and bulbs of onions and shallots. Infested leeks often become infected with secondary rots and die.

Leek moth is mainly found in Southern England and South Wales, but is spreading north.

The RHS pointed out that allium leaf miner, although not in its top 20 list of pests, is an increasing worry. Slugs and snails took the number one pest slot, held by viburnum beetle in 2011.

TOP PESTS OF 2011

1: Slugs/snails

2: Cushion scale

3: Vine weevil

4: Ants

5: Viburnum beetle

6=: Fuchsia gall mite

6=: Cypress aphid

8=: Leek moth

8=: Chafer grubs

8=: Mealybugs

8=: Brown scale