RHS Cardiff Show On The Lookout For Pests
The Royal Horticultural Society will be calling on Welsh gardeners to plot pests
when they hold their annual show in the parklands of Cardiff Castle April 16-18
www.rhs.org.uk/cardiff
The RHS is currently conducting a nationwide survey to plot the spread of four of
the UK’s most troublesome, non-native, invasive garden pests, and will be in Cardiff
later this month to ask Welsh gardeners to get involved, as there is little information
about the spread of these pests and their impact on the environment in Wales.
The RHS Show Cardiff is a co-production with Cardiff Council and features the best
of the spring blooms from nurseries across the UK, with ideas and inspiration for
the growing season ahead.
The RHS survey aims to record the distribution of four species of garden pests,
and determine their rate of expansion across the UK, providing valuable research
data for RHS scientists. The four pests under investigation are:
Lily beetle (Lilioceris lilii) – the third most troublesome pest
in the UK in 2009.* Lily beetle adults and larvae defoliate lilies and fritillaries.
It became established in Surrey in the late 1930s and until the 1980s remained confined
to South East England. Over the past two decades the beetle has spread rapidly and
is now found throughout much of England, with more scattered records in Wales, Ireland
and Scotland.
Rosemary beetle (Chrysolina americana) – The Rosemary beetle was
first reported outdoors in Surrey in 1994. It is now common in parts of England,
with scattered reports from the rest of the UK and Ireland. The adults and their
grey grubs defoliate rosemary, lavender and some other related plants.
Berberis sawfly (Arge berberidis) – The caterpillar-like larvae
of Berberis sawfly defoliate some Berberis, especially Berberis thunbergii, and
Mahonia species and hybrids. This insect was first reported from Essex in 2000,
and has spread rapidly across much of England although it’s not yet known to be
in Wales.
Hemerocallis gall midge (Contarinia quinquenotata) – Hemerocallis
gall midge was first reported in Surrey in 1989. It has spread throughout England
and into parts of Wales and Scotland. Larvae of the 2mm long midge develop within
the flower buds, causing them to become abnormally squat and swollen. Damaged flower
buds dry up and fail to open.
Andrew Halstead, RHS Principal Entomologist, says: “Wales is an under-recorded area
of Britain and the support of Welsh gardeners is vital for us to get a true understanding
of the distribution of these pests.”
“Adult Berberis sawflies start emerging in late April and both adult rosemary beetles
and lily beetles should be visible on sunny days throughout that month. Hemerocallis
gall midge is a tiny fly that is likely to be missed by most people, but the abnormally
swollen flower buds are easy to spot, although not until late May to early July.”
Gardeners can find out more about the survey and submit their records at
www.rhs.org.uk/science/plant-pests.
In addition to RHS expertise on hand, the Cardiff event features show gardens created
by the finest Welsh horticultural talent, the ever-popular schools wheelbarrow competition
supported by Legal & General, and numerous plants and accessories for sale. There
are nature trails, street entertainers and live music throughout the weekend. The
beautiful parklands site also contains a Craft Village and a taste of Welsh produce
in the Café Quarter.