Global Plant Trade Poses Increased Risk of Alien Diseases Attacking Gardens and
the Countryside
Alien pests and diseases inadvertently imported on exotic plants are threatening
the plants in our gardens and across the countryside, according to a report launched
today (Tuesday 8th July) by a scientific working group led by the Royal Horticultural
Society (RHS).
The number of plant disease outbreaks is up by 60% on last year. Increased global
plant trade, coupled with evidence of rapid climate change, suggests that the problem
will multiply.
Recent Defra reports have highlighted the worrying spread of disease on rhododendrons
in the south west of England caused by Phytophthora ramorum and Phytophthora
kernoviae, while many other diseases, including Cylindrocladium buxicola, [box
blight] which is responsible for the destruction of native box hedges, and Ophiostoma
novo-ulmi, [Dutch elm disease] are well known to the working group.
The report, Non-native diseases and the future of UK gardens, is being published
today. It proposes that the horticultural industry worldwide develops effective
systems to manage the risks that growing and trading of ornamental plants are now
creating. Suggested features of such a system would be similar to those, driven
by the supermarkets, that are now familiar in relation to food assurance schemes.
The report suggests that new quality assurance systems, driven by a voluntary code
of conduct, could sit alongside the current UK plant inspection programme and offer
further reassurances to the plant buying public. In 2005, £870 million was spent
on imported plants by the British public, three times as much as in 1988. The current
inspection scheme only applies to plants known to play host to diseases and does
not provide the opportunity to capture evidence of new diseases symptoms throughout
the plant production, transportation and selling process.
Dr Simon Thornton Wood, Director of Science and Learning at the RHS, explains, “The
current plant inspection programme works exceptionally well for diseases we already
know about. But it is the unknown diseases on plants that would not normally be
considered problematic that are the real cause for concern. Phytophthora kernoviae
and P. ramorum entered the UK because they were not known about and so not checked
for. They have wreaked havoc with cultivated rhododendrons and now threaten to spread
to our native heath land.
"However, an industry code of conduct could provide the answer, with every stage
of the production and transport process managed with disease risk in mind. We would
then be able to avoid another situation like sudden oak death or Dutch elm disease
that has changed the face of the Britain’s countryside."
Striking the balance between plant health and providing the variety of plants that
inspire this nation of gardeners, is at the forefront of the RHS' mind. The UK's
leading gardening charity believes that consumer awareness could be the key to ensuring
that a code of conduct, underpinning true quality assurance, is developed by the
plant importing trade.
Dr Simon Thornton Wood continues, "Working together gardeners can help the RHS to
track the emergence and spread of pest and disease problems and together we can
all take responsibility for the health of our gardens and the wider environment.
Everyone has an interest in ensuring that high-quality; disease-free plants arrive
at our shores and reach our gardens."
For help and advice on identifying plants pests and diseases visit www.rhs.org.uk/advice and to view a copy of Non-native
diseases and the future of UK gardens contact the RHS press office on 020 7821
3044.
A DEFRA consultation on the problem of Phytophthora is being launched at RHS Garden
Wisley on 15 July 2008.