Publications
The Garden
September 2004
General news
Roof-greening initiatives spring up in London
One
of Europe’s highest roof gardens is to be built in the
UK as the green roofs revolution gathers momentum. Plans to
create a ‘garden in the sky’ on the 35-storey-high
Barclays building in Canary Wharf, London, could spark a dramatic
increase in rooftop projects.
Roof-greening specialist Dusty Gedge, who is involved in the Barclays Bank garden, wants to see green roofs as the norm on new developments, schools and hospitals.
He is also working on a 248sq m (2,670sq ft) horseshoe-shaped green roof on the new Komodo dragon house at London Zoo, which is expected to be unveiled in October. It is based on soil and rubble to encourage different species of local plants, after initial planting by the zoo’s botanical staff. The project will include green walls of creepers on thin wires strung across the facade.
Green roofs also form part of one of the biggest regeneration projects in Europe - King’s Cross Central - which includes 1,800 new homes and up to 486,000sq m (5,230,000sq ft) of commercial property.
The concept of roof gardens is not new to the capital. The 0.5-ha (1.5-acre) Kensington Roof Gardens, 30m (100ft) above street level, were laid out during 1936–8. Average soil depth is 45cm (18in), with bricks and clinker over a waterproof membrane to provide drainage. Landscape architect Ralph Hancock brought in some 500 species of plants and shrubs and even imported rock from Pennsylvania for his alpine planting. Each year, 15,000 bulbs were bought and 38,000 bedding plants were laid out, which had been produced in the nursery on the roof.
The gardens were constructed around three themes: a Spanish Garden with a Court of Fountains and formal design; a Tudor Garden and Walkway built in traditional stone; and an English Woodland Garden with stream and ducks.
Sir Richard Branson now owns the gardens which are open to the public and run as an independent restaurant.
Elsewhere in the capital, new shoots are pushing up through the soil on a 460sq m (5,000sq ft) biodiverse green roof at Laban Dance Centre, in southeast London, where the roof has been left to self-colonise with a mixture of seed.
Unlike Germany and Switzerland, there are no Government incentives in the UK to encourage the installation of green roofs, but London Mayor Ken Livingstone is due to make a major announcement about roof greening shortly.
For information visit www.livingroofs.org or tel: 020 8692 2109.
There are plans to promote green roofs in the West Midlands, and the Hedgehog development of self-build houses in Brighton has adopted the trend. A roof garden of Pembrokeshire cliff fauna is planned at Haverfordwest, Wales.
Fuchsia conundrum
Botanists
are puzzling over whether a fuchsia discovered in the Andes
is a species that was believed to have died out or is completely
new to science.
It was initially thought that the plant, discovered by French plant hunter Jean-Luc Marcenac, was extinct Fuchsia summa (pictured left). However, botanists at Fuchsia Research International (FRI), who run the European Centre of Excellence for the Genus Fuchsia at Margam Country Park near Port Talbot in Wales, where the plant was sent, are now less sure of its identity.
Using micropropagation, they sliced the plant into fine slivers, which were grown in the laboratory and sent to botanical gardens worldwide.
Arthur Tickner of FRI said it could be two years before they are able to say for certain whether the plant is a new discovery. He is working closely with Professor Paul Berry of Madison University at Wisconsin, USA, one of the leading authorities on fuchsias.
Arthur says, ‘The juvenile plants are only 10cm (4in) high, so we cannot say for certain yet. We are also carrying out DNA profiling.’
Genetically modified blue rose
After
14 years of research, Suntory of Japan is said to have developed
the world’s first blue rose with Australian firm Florigene.
The as-yet-unnamed rose will not be available in the UK until
at least 2007.
Bluish roses already on the market were created through crossbreeding and cannot be called true blue, according to Suntory. The gene of the enzyme that produces the blue pigment, delphinidin, is not found in rose petals, so, using biotechnology, researchers extracted it from pansies and activated it inside the roses. Suntory says the petals of the new blue roses contain nearly 100 percent of the blue pigment. Suntory and Florigene also produced the world’s first blue carnation, ‘Moondust’,using the same technology in 1995.
Company officials admit more work is necessary to create roses with bright sky blue colours. A Suntory spokesman said, ‘We know we need to add chemical compounds to create brighter blue colours. Technologically, we are absolutely successful in creating a blue rose because of the blue pigment in the flower. But for our rose to be recognised by everyone to be blue, maybe we are only a half way there.’
Testing and inspections are expected to take two years or more, but if the genetically modified rose is launched, it could be worth 30 billion yen (£150 million).
UK’s rarest orchid stolen to order?
Specialist
plant collectors are urged to look out for an orchid that
police believe was stolen to order. The Cypripedium
calceolus (lady’s slipper orchid), valued at up
to £2,000, was taken from a golf club in Silverdale,
Lancashire in July. It is thought it was originally planted
there in the early 20th century. Now conservationists and
volunteer plant wardens face an anxious wait until next March
to see if any part of the plant’s rootstock has survived.
In the past four years, conservation charity English Nature, with the full co-operation of the site’s landowners, has been managing a sensitive visiting arrangement during May and June, enabling some 3,000 people to see Britain’s rarest orchid in flower. This year it had nine flowers and was the most vigorous it had ever been.
Several conservation organisations have been involved in a Species Recovery Programme to reintroduce plants into sites in northern England. Colin Newland of English Nature says, ‘Our firm hope is that in a few years’ time there will be several lady’s slipper orchids on view to the public’.
Onward march of the climate-change-related bugs
Pests that were once confined to glasshouses are spreading outdoors as global warming and climate change create new enemies for Britain’s gardeners.
As the RHS Advisory Service copes with an increasing number of enquiries about climate-change-related pests, the horse chestnut leaf-mining moth has been found at RHS Garden Wisley.
Since
its discovery in Wimbledon in 2002, when damaged leaves were
sent to the Advisory Service, the moth has spread to Surrey,
Hertfordshire and Oxfordshire.
The larvae feeds on horse chestnut leaves, causing them to wither and trees to produce fewer conkers.
RHS Principal Entomologist Andrew Halstead, who discovered the moth damage at Wisley, says, ‘I believe it will spread rapidly to other areas of the country. In some parts of Europe the moth can produce as many as five generations and, by late summer, foliage can be heavily marked with brown patches (above left). Hopefully, in Britain, because of the cooler climate, the moth will have fewer generations per summer and thus limit the extent of the damage.’
Little can be done to prevent the moth’s attack. It has no effective natural enemies in Europe and spraying with insecticides is unlikely to be viable, due to the size of most horse chestnuts. Trees growing in streets may be more badly affected than those in parks and gardens, due to the warmer microclimate in built-up areas.
Andrew has found a steady increase in the number of climate-change-related pests invading the UK.
Earlier this summer mottled umber moth caterpillars defoliated an area of woodland in South Yorkshire. Experts believe a combination of a mild spring and lack of predators was to blame for the freak occurrence.
Several insect pests originating from warmer climates, such as lily beetle and berberis sawfly, are now established in Britain and spreading more widely due to the higher temperatures. Reports of defoliated Berberis shrubs have been received from Middlesex, Buckinghamshire, Essex and Hertfordshire gardens.
Significant spreads of rosemary beetle have been seen in London, Berkshire, Surrey, Leicestershire, Norfolk and Cambridgeshire, and two new species of vine weevil and the glasshouse pest red spider mite are also on the increase.
In addition, a new shield bug species has been found in the UK by Max Barclay, Curator of Beetles at the Natural History Museum.
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The shield-shaped green
vegetable bug (left) is a crop pest, usually found in
much warmer climates, but three colonies are living
and breeding in London. Green vegetable bugs (Nezara
viridula) attack a broad range of crops, from soft
fruits to potatoes and beans, damaging fruit, transmitting
disease and leaving plants open to attack by other pests.
They are a particular problem in the Mediterranean,
the Middle East, Australia, North America and Africa,
and could be a significant pest if, as the evidence
suggests, they become resident in the British Isles.
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Adult green vegetable bugs have been regular stowaways in imported stocks for over 25 years, but have never bred successfully in the UK due to the colder climate. Finding young bugs, known as nymphs, in three different locations is a clear sign that the weather has been warm enough for the species to start breeding.
The green vegetable bug is similar to our native green shield bug (Palomena prasina) but is a paler green colour, narrower and longer, growing up to between 11 and 15 millimetres. Unlike the native green shield bug, adult green vegetable bugs have no brown markings and are uniformly green. Young green vegetable bugs have distinctive white-spotted backs, with red edging.
Loss of fruit yields
Research into the consequences of the recent spate of warm winters on fruit production in the UK has now been completed (see Chilling news about fruit and veg, News, April 2003, p232).
The report, published by the Government department defra, says that there is a need to undertake long-term monitoring of the effects of climate change on fruit production, and develop a better understanding of the biology of winter chill. It also recommends the long-term breeding of cultivars that will be better adapted to the expected future climate.
The results of the study show that there has been a significant reduction in winter chill and spring frost in recent years.
Predictions of the amount of winter chill suggest that by 2080 Kent will see a 31 percent decline and Tayside 20 percent. Spring frosts in Tayside have already declined by 31 percent compared to 50 percent in the West Midlands. The report also suggests that over the next 80 years Tayside’s climate will become more like Kent today.
In worst case scenarios, crops of apple, pear, blackcurrant and other affected species could rapidly decline in yield, as warmer winters retard some of the physiological functions of these plants, causing bud drop and reduced fruit set.
Paraquat withdrawn
Products containing the highly-toxic chemical paraquat, one of the world’s most widely used herbicides, are to be withdrawn from sale in the European market by 10 September.
Paraquat is one of 18 products - mainly domestic weedkillers and herbicides - that European law dictates should be withdrawn in 2004 and 2005. The move is part of an EC review programme designed to make sure that all chemicals used as ‘active substances’ in pesticides meet the ‘most up-to-date standards of human and environmental safety’.
Ingestion of small to medium amounts of paraquat can lead to development of adverse health effects within several days to several weeks including liver failure, kidney failure, heart failure and even lung scarring. Advice to gardeners is to use up any of the relevant products to avoid the need for disposal.
Products containing both paraquat and simazine will be withdrawn from sale this month; those without simazine will be withdrawn in April 2005. The last day for storage and use is 30 April 2006.
Atrazine, simazine and dichlorophen
Also due to be withdrawn this month are products with atrazine and simazine, but gardeners can use them until 10 September 2005.
A spokesman for the Pesticides Safety Directorate says, ‘The fact that there is a phase-out period to allow pesticides to be used up reflects that withdrawn products do not generally raise serious safety concerns. If there were a particular safety concern in relation to any specific product, we would issue special advice on dealing with it.’
In addition, the active substance dichlorophen has recently become unsupported in the EC review programme. The manufacturers of the active ingredient decided not to continue with its registration because its use had declined, and it is likely that the last date for sale will be spring 2005.
Bio Kills Moss on Lawns and Baby Bio Roota both contain dichlorophen.
The manufacturers of the active ingredient decided not to
continue with its registration because its use had declined.
Bio Kills Moss on Lawns will not be replaced but there are
plans to reformulate Baby Bio Roota using an alternative to
dichlorophen.
There are two ways of checking whether a particular product
is being withdrawn. Either check the registration number of
the product. A ‘brand’ may continue to be sold
under the same or a similar trade name following re-formulation
but it will have a new number. Or check the active substances
on the label for atrazine, simazine or one of the other withdrawn
substances.
Paraquat products that contain simazine include Pathclear
M10840 and M11438.
Paraquat products without simazine include Weedol M09280 and M10789.
Atrazine and Simazine products include Do-It-All Path and Patio Weedkiller M10408; Wilko Path Weedkiller M06976 and Woolworths Path Weedkiller M07456.
For the full list and more information visit www.pesticides.gov.uk or phone 01904 455775.
New initiatives at Middleton
Following a £3million rescue package (see Award, and lifeline, for Middleton, May, p332), the National Botanic Garden of Wales has introduced an adventure playground and maze to help bolster flagging visitor numbers.
Although new trustees have to be found and debts of £2.8million have to be rescheduled, the future of the garden seems secure for the next five years.
General Manager Rhodri Griffiths says, ‘At the end of the five years a sustainable future has to be in place. Part of the solution is putting in family elements. A modern botanical garden has to be a wonderful place for families to visit and also undertake scientific and educational work. It has to be a serious attraction and a scientific institution. We know what we want to do and how to do it.’
Creating a genetic resource
John Vanderplank, holder of the NCCPG National Plant Collection of Passiflora for more than 20 years, received The Brickell Award from Chris Brickell at the Hampton Court Palace Flower Show in July.
Launched last year as part of the NCCPG 25th birthday celebrations, the award recognises collection holders for their work in the conservation of plants in cultivation. It was named after Chris who was instrumental in setting up the charity. Previous recipients are Henry Noblett and the Lakeland Horticultural Society (for Astilbe) and Henry Oakeley (Anguloa, Lycaste and Ida collections).
John has 180 species and 70 cultivars of Passiflora in the collection, which he ‘aims to maintain as a genetic resource’.
The collection is based at Greenholm Nurseries in north Somerset, tel: 01934 833350.
Canna warning
Canna virus diseases could become a worldwide problem, according to Keith Hayward, holder of the NCCPG National Plant Collection of Canna. When Keith started growing cannas 20 years ago, new plants were generally healthy, but now the opposite is true.
Some cultivars tolerate infection, but badly affected plants fail to thrive and can die, especially over winter when the rhizomes are dormant.
Plants showing streaked, speckly, distorted or crinkly leaves are likely to be affected.
Collection holders trying to preserve old cultivars are particularly concerned.
For more information visit www.canna.com
RHS Journals