Fuchsia gall mite and leek moths enter RHS top 10 pests list

Slugs and snails have taken the top RHS pest enquiry slot for 2011 after having lost first place to viburnum beetle in 2010.

The humble slug tops the RHS pest chart once more - image: RHS
The humble slug tops the RHS pest chart once more - image: RHS

Usually they are the number one problem with 2010 being a slight variation.

This year’s RHS list has two pests that are in the top ten for the first time.

Fuchsia gall mite, at number six, was unknown in the UK before 2007. It was discovered when a sample from a Hampshire garden was sent to the RHS Members’ Advisory Service for identification. Since then it has become widely established along the south coast and is moving northwards.

"This is a devastating pest of fuchsias that will probably eventually spread throughout Britain," says RHS Principal Entomologist Andrew Halstead. "Unfortunately there are no effective pesticides for garden use. Because the damage cannot be controlled, it may lead to a decline in the popularity of this valuable garden plant."

The other new entry, at number eight, is leek moth. Although mainly a problem on leeks, it also affects onions and shallots. The moth produces two generations of caterpillars during summer. The second generation in late July–August is particularly troublesome. The young caterpillars mine the leaves but later they bore into the stems of leeks and the bulbs of onions and shallots. Infested leeks often become infected with secondary rots and die.

Leek moth is mainly found in the south of England and South Wales but, like fuchsia gall mite, is also spreading northwards. Another pest affecting leeks and allied vegetables is allium leaf miner. This small fly was first discovered in the Wolverhampton area in 2003 and is now widespread in the Midlands and is also present in northeast Surrey.

Although currently not a top-20 pest, enquiries about allium leaf miner are increasing. "These two pests will make the cultivation of leeks, onions and shallots difficult," says Halstead. "There are currently no suitable pesticides for use on these plants in gardens and allotments. Growing the plants under fine insect-proof mesh to prevent egg-laying moths and flies alighting on the foliage is the only remedy." 

2011


2010

1

Slugs/snails

1

Viburnum beetle

2

Cushion scale

2

Slugs/snails

3

Vine weevil

=3

Cushion scale

4

Ants

=3

Chafer grubs

5

Viburnum beetle

5

Harlequin ladybird

=6

Fuchsia gall mite

6

Vine weevil

=6

Cypress aphid

7

Lily beetle

=8

Leek moth

8

Horse chestnut scale

=8

Chafer grubs

=9

Glasshouse red spider mite

=8

Mealybugs

=9

Ants

=8

Brown scale




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