RHSScience issue 16 — april 2013. photos . New RHS climate mike

sleigh ( change survey drought

In conjunction with the University of Reading, the ); RHS has launched a survey to better understand carol how gardeners are reacting to changes in the UK sheppard climate and to discover whether they have been ( provided with the knowledge they need to plan flood

their gardening in the future. )

This survey is intended to provide the material for the follow-up to the RHS’s 2002 report ‘Gardening in the Global Greenhouse’, which discussed potential challenges that gardens and gardeners in the UK were likely to face, based on climate change projections. survey will help us understand the perceived effects The 2002 ‘Gardening According to more recent climate models, the of climate change and the individual’s response to in the Global projections have changed. Thus UK gardeners may well those changes, a vital part of the new report and Greenhouse’ have to prepare for a different set of climatic conditions. for new adaptation strategies in UK gardening report predicted practices.” n extremes of Says Claudia Bernardini, who is leading the project weather and for the RHS, “We need to plan and prepare for what ► To take part in the survey, go to http://blogs. more exotic plantings. future changes might bring. The findings from this reading.ac.uk/crg/climate-change-and-gardening

Andrew Halstead garden fauna. Following a fewer than 13 talks on subjects has left the building recent promotion, as Principal ranging from “bugs that bite After 41 years at Wisley, Andrew Scientist Plant Health, he also back” to honeybee anatomy. Halstead has hung up his pooter took on responsibility for Wisley’s and Tullgren funnels for the last pathology section. Andrew’s farewell party on time and said goodbye to RHS March 28 at Wisley was well . A familiar figure on the Advisory attended by colleagues past and stand at RHS shows, Andrew present. “This is truly the end of Andrew came to Wisley as an has always maintained an an era,” said John David, Acting entomologist in 1972, under Chris active media presence. He is Head of Science. “Andrew’s Brickell’s directorship. During also well known as a speaker on remarkable knowledge, his time at the RHS, Andrew horticultural matters to clubs experience and unique sense of dealt with enquiries concerning and societies in the region, as humour will be missed by all who For more information: not only invertebrates, but also well as staff: during his last three had the privilege of working with ► [email protected] birds, mammals and other months at the RHS, he gave no him.” n

Published 2013 by RHS Science | RHS Garden Wisley | Woking | Surrey GU23 6QB | Registered charity no: 222879 / SC038262

All text & images © RHS 20122013 except where otherwise stated april 2013 nscience news

In brief The 27th edition of RHS Plant Finder will be published online and in bookshops on April 11, RHS-sponsored student Lucy Wenger (see issue 15, p.5) listing a total of 77,160 has been awarded an MSc in Plant Diversity (with Merit) for plant names, together with her work on Cordyline. She has now taken up a position at the details of 555 nurseries. Eden Project, St Austell.

Britain’s best gardening annual, providing Thisessential numberinformation for over twoof decades nurseries

Includes over 75,000 plants, updated annually, with more than 4,300 new plants Funding successes for Plant Soils Interactions. representsin this edition a welcome increase All the information you need – instantly: contact details, websites, opening times, maps, The RHS has made a successful bid for a Biotechnology and onand themail-order 2012details for figure. Says 555 nurseries Lists more than 5,000 newly revised Biological Sciences Research Council (BBSRC) Industrial CASE CompilerAward of Garden JudithMerit plants Merrick, “It is “the ultimate guide to plants and where to find them” PhD studentship. CASE (‘Collaborative Awards in Science and of particularBBC Gardeners' World satisfaction that UpdA ted AnnUALLy, thIs Is A recoGnIsed AUthorIty on cUL pLeAse never Use tIvAted pLAnt noMencLA Engineering’) studentships are training grants intended to allow top- we have Anarrested oLd edItIon tUre: the decline quality bioscience graduates to undertake research which will lead in nursery numbers£15.99 this year. to a PhD. Undertaken in collaboration with the University of Reading We hope that this upward and Defra, the PSI studentship will examine the effects of different trend can be maintained for organic materials on soil carbon balance and soil microbiology, and future editions.” will utilise the current Organic Matter experiment at Deers Farm, Wisley. “Examining these interactions will offer a unique insight into A significant change in this edition is the removal the value of soil management for gardeners,” says Principal Scientist of the double year date on the cover, which had (Horticulture) Paul Alexander. “Organic matter is widely used by caused much confusion in the past, and the adoption gardeners to improve soil quality, but it could also help sequester of a single year. The 27th edition will therefore be carbon, potentially helping to mitigate climate change.” RHS Plant Finder 2013. This should be clearer for gardeners in the long run, and could also help sales, Meanwhile, Tijana Blanusa has been awarded funding from the as there was some evidence that the double date European Institute of Technology Climate-KIC programme for a gave the impression of a biennial publication. 3-year PhD studentship which will start in October 2013. Based at the University of Reading, this project will investigate the The new edition also reflects the results of the use of grey and recycled water in water management of plants recent Award of Garden Merit (AGM) review, as well and its effect on the provision of multiple ecosystem services as the new RHS hardiness ratings system. It includes (specifically cooling, rainfall and pollutant trapping). Tijana 4,300 plants new to Plant Finder, the most widely was also successful in securing funds for two undergraduate offered of which are: summer studentships for 2013 from the University of Reading’s Undergraduate Research 1.= Geranium ‘Azure Rush’ Opportunities Programme (UROP). These 2.= Cirsium rivulare 'Trevor's Blue Wonder', will investigate emissions of volatile organic 2.= Rosa Boscobel (‘Auscousin’) compounds from green roof species and 4.= Choisya × dewitteana ‘Aztec Gold’ opportunities for green roof food production. 4.= Rosa Heathcliff (‘Ausnipper’)

4.= Rosa Tranquillity (‘Ausnoble’)

c

a Left, Stachys byzantina ‘Big Ears’. New RHS research

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s

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e will examine the possible contribution of volatile

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p a r

d organic compounds emitted by green roof species such Above. RHS Senior Designer Mark Timothy has created a as Stachys byzantina to climate change, and whether this affects brighter jacket design for the new edition, which should their value as temperature-lowering plants in the urban environment. help to distinguish it from previous “double date” editions.

2 RHS SCIENCE science newsn issue 16

RHS helps make sense photos . carol

of plant science sheppard Access to the knowledge of RHS scientists is now

possible through an online plant sciences expert ( inset panel. Twenty-three other leading horticultural ); research institutes including the James Hutton neil

Institute, Rothamsted Research and Cambridge hepworth and Warwick universities complete the panel, which was set up through the charity Sense about Science (SAS). Anyone can submit their plant science-relevant questions to the panel; with Above. Sarah Al-Beidh, Science & Advice KTP Associate, represents the RHS on the Sense about Science Plant Science panel. Recent questions the exception of general horticultural advice, no put to the panel have ranged from whether GM crops could be used to question is off limits. From GM crops and ash dieback combat climate change to why banana leaves are so big. to bees and pesticides, queries are directed to the most relevant panel member and responses are RHS organises training day made available on the SAS website and via Twitter. for amenity horticulture Sense about Science, as the name suggests, works in partnership with scientists, policy makers, press and professionals members of the public to make discussions around RHS Wisley was the venue for a training day science accessible to everyone. Says Sarah Al Beidh, in March for those who work professionally the RHS representative on in amenity horticulture, including head the Plant Science panel, gardeners, garden designers and contractors “Responses to questions involved in garden maintenance. The event Responses to questions are intended to be jargon- attracted 57 participants, including RHS are intended to be and waffle-free, but staff from Rosemoor and Harlow Carr and a jargon-free, but without without dumbing down. contingent of seven from English Heritage.

dumbing down. bob The panel is therefore a

Sarah Al-Beidh martin great mechanism for RHS The event was organised by Tony Dickerson of Advisory

“ scientists to make their (right). In a packed day, topics covered by experts included ( above plant science knowledge new pests and diseases (Andrew Halstead and Béatrice );

available more widely as well as an opportunity to Henricot, both RHS), updates on the EU Sustainable Use rhs

further develop our scientific profile.” Directive on Pesticides (John Allbutt of BritRisk), and health lindley

& safety responsibilities under criminal and civil law (Mike library Fielder, RHS). Optional mini-tours of the Wisley site over an (

Some questions answered by Sarah so far: extended lunchtime included consideration of the chemical musa

• How did lemon thyme become lemon? store, glasshouse irrigation, biosecurity and amenity weed ) • Is this the beginning of the end for the control. “This training day for professionals was a new deciduous tree, vis-à-vis global warming? venture for the RHS,” says Tony. “The content and networking • Is there any other special reason why banana opportunities proved especially popular with head gardeners.” leaves are so big, except struggle for light?

► www.senseaboutscience.org For more information about RHS Science news ► [email protected]

RHS SCIENCE 3 april 2013 nhorticulture & biodiversity

Assessing the invasive threat photos . carol

of non-native bluebells sheppard

by Dawn Edwards

Botany

The perceived threat to populations of the British native bluebell, Hyacinthoides non-scripta, posed by escaped non-native garden bluebells is often Above. Native Hyacinthoides non-scripta (left, with distinctive reported. However, the RHS has concerns that this deeply curled tepal tips) and hybrid Hyacinthoides × massartiana. Uncertainty regarding the identity of non-native bluebells and levels of threat may be overstated. Certainly populations hybridisation with native populations is likely to remain until molecular of the native species at RHS Garden Wisley, markers clarify taxonomy and quantify genetic threat. which have been growing alongside non-native ornamentals for many years, do not appear to be suffering from competition or in situ hybridisation. Identifying bluebells in Britain

Native bluebells remain widespread in the countryside and whilst Native Non-native non-native bluebells have established outside gardens, fears of Pollen creamy white Pollen blue to green- the loss of native bluebells due to hybridisation and competition blue do not appear to be founded on robust research. Most non-native Flowers narrowly Flowers a more open recordings are from urban areas and edges of woodlands and it tubular with tepal bell-shape with tepal therefore seems highly probable that they are the result of casual tips deeply curled tips less recurved introductions, either as garden waste or deliberate planting. back

Difficulties in assessing the distribution and interaction between Inflorescence Inflorescence is more nodding (distinctively erect with flowers bluebells are compounded by taxonomic uncertainty over the curved) at the top arranged around the identity of non-native garden bluebells. Those referred to as with most flowers stem Spanish bluebells, H. hispanica, are distinct from plants in the hanging from one wild that are known as H. hispanica. They may be horticulturally side of the stem selected derivatives or perhaps even hybrids. This in turn raises Flowers strongly Flowers have little questions over the identity of H. × massartiana, said to be the sweet-smelling scent hybrid between the native and Spanish bluebells. Hybrids show a range of intermediacy between parent Eradicating non-native plants is a costly undertaking and a species so distinguishing native from non-native bluebells can be difficult, but there are characters that assist their process of prioritisation needs to take place according to an separation. Examination should occur as flowering begins assessment of threats through rigorous scientific study. The because characters can change as they mature. RHS’s research into alien plants seeks to address this and the Society has much to offer in educating gardeners as to the For more information: correct way to dispose of garden material. n ► [email protected]

4 RHS SCIENCE public responsibilityn issue 16

Neonicotinoid insecticides, photos . bees and the EU andrew

halstead ; by Andrew Salisbury carol

sheppard Entomology ( inset ).

Decreases in bee populations are well documented and of great concern. The decline in honeybee Above. Swarming honeybees, which are in decline. Bumblebees (inset, on health results from a mixture of diseases and echinacea) are maintaining their numbers and distribution. parasites (particularly Varroa mite), and habitat loss. The widely used neonicotinoid insecticides are FAQs also under suspicion; however, there is conflicting evidence on the threat posed under normal • What are neonicotinoids? Neonicotinoids (pronounced with growing conditions. A campaign by some NGOs in the emphasis on -cot-) are insecticides chemically related to nicotine. the UK has led some DIY and garden centre chains to voluntarily remove some products. • How do they work? “Neonics” are systemic pesticides (i.e. they are absorbed by the plant and remain active in all its In a January 2013 report the European Food Safety tissues). When ingested, they block receptors in the ’s Authority concluded that three neonicotinoids central nervous system, which causes paralysis and death. (clothianidin, imidacloprid and thiamethoxam; see panel, right) posed a greater risk to bees and that • Which products contain neonicotinoids? There are four more data are needed to update risk assessments. neonicotinoid pesticides available for home garden use: acetamiprid A proposed suspension of these active ingredients (various Bug & Rose Clear products), thiacloprid (various Bayer for most uses was voted on by EU member states products), imidacloprid (Bayer Provado Lawn Grub Killer) and in March. The vote was inconclusive: 13 favoured thiamethoxam (Plant Rescue Bug Killer Ornamental Plants). restrictions, nine voted against, while Britain and four Clothianidin is used in some professional agricultural products. other states abstained. The European Commission could force restrictions through by summer 2013 • Why does the press coverage emphasise the effects unless a compromise is agreed. on bees? With the notable exceptions of Australia and New Zealand, the decline in bee numbers is almost global. This is in part The RHS is closely monitoring the situation and due to modern farming practices which result in fewer floral resources will respond swiftly to any recommendations and in the landscape. In the case of honeybees, the Varroa mite and regulations from the EU, UK government and its other parasites and diseases play a major part in the decline. Some agencies. Our aim is to always encourage the use of research indicates that, as well as their lethal effects, neonicotinoids alternatives to chemical controls where they are likely may have sub-lethal effects on bees (e.g. on homing behaviour and to be helpful. n signalling) that could lead to colony declines. However, the evidence

► For the latest Defra position, go to: www.defra.gov.uk/ that this happens in field situations is not clear. environment/quality/chemicals/pesticides/insecticides-bees For more information ► [email protected]

RHS SCIENCE 5 april 2013 nresearch update & plant health

HDC fellowship research well photos . under way rachael

tanner The RHS-HDC Fellowship has now been running for nearly six

months. Established in conjunction with the Horticultural ( measuring Development Company, the principal aim of this project is to improve the sustainability of plant production for both amateur and professional growers. Gracie Barrett took up pelargoniums her post in November and has already established her first experiment in the RHS Field Research Facility, investigating ); how various peat-free growing media interact with liquid béatrice fertilisers to influence plant quality. The experiment will run until May, and it is hoped that it will provide us with an insight henricot into how plant growth is impacted by different combinations ( of growing media and sources of nutrition. honey

fungus Gracie has also visited a number of professional nurseries and ) growing media manufacturers around the UK and Ireland. “These visits have allowed us to gain a better understanding of the challenges facing the wider horticultural sector and to appreciate that growing media are only one component of a complicated production system,” says Gracie. “The visits have also improved our awareness of the advantages and Above. Gracie Barrett measuring pelargoniums in the new disadvantages of some of the professional peat alternatives Field Research Facility. These weekly measurements will available and of the qualities required by all growers, namely allow Gracie to assess the quality of plant growth between different experimental treatments and thus help to identify consistent and reliable growing media. These findings will which growing media / fertiliser combinations give the best inform our programme of research.” plant growth.

Slugs and snails once again topped The wet weather also affected Plant Health top 10s for 2012 Entomology’s annual “top ten pathology enquiries: Plant Health Pests Diseases pests” list, generating almost twice recorded the highest number of as many enquires as the number 2 cases of Cylindrocladium blight 1 Slugs / snails 1 Honey fungus pest, cushion scale. “The dominant on box since it was first sighted 2 Cushion scale 2 Pythium 3 Vine weevil 3 Leaf spots feature of 2012 was the weather,” in advisory samples in 1998. The 4 Ants 4 Rusts said Andrew Halstead, outgoing fungus requires high humidity 5 Glasshouse 5 Phytophthora RHS Principal Scientist Plant Health. to infect and spreads over short mealybugs “This was the second wettest year distances through water splash, so 6 Soft scale 6 Cylindrocladium blight of box in the last hundred years; pests that the weather has been conducive to 7= Woolly aphid 7 Saprophytic fungi like damp conditions therefore did the disease. For the same reasons, 7= Cypress aphid 8 Volutella blight of box well. Last summer the demand for many fungal leaf spots have also 9=Fuchsia gall mite 9 Root and stem rots slug controls, especially nematodes done well. 9=Lily 10= Scabs 10= Powdery mildews used as a biological control, Right. Honey fungus topped the list sometimes exceeded supplies.” of disease enquiries.

6 RHS SCIENCE photo. national biodiveristy network / martyn hicks 7

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. ). ondon: ondon: (3): . L . ssue ollinators’ ollinators’ frica. The i in press in :145–146. : 181–184. nternational nternational nne Diamond Show, Diamondnne Show, erfect P for .) canopy as .) interceptor P ongshore thrift. 138 Garden The pril. Guypril. Barter meanwhile (Scriba) (Chrysomelidae) breeding was January in interviewed on , 4th Suppt. Quercus ilex L Quercus 128–131. (2013). 2013 Finder Plant RHS (1): 28–33. RHS. 2011–June 2012 2012. Clematis The and Checklist 2002 (2013). Holm oak ( (2013). (4):47–50. of airborneof elements trace and their accumulation the in ( Pollution litter and topsoil. Environmental 84–86. and Camellias Rhododendrons, Registrar 2012. Magnolias, 2013: coerulans Chrysolina 21 in Cambridgeshire. Coleopterist The 12 Plantsman (2012). NewClematis Registrations July Donald, (2012). D. Donald, (2012). D. Register Clematis International The campaign, and National Gardening week. Janet Gardening National and campaign, on Finder Plant was about interviewed Cubey RHS on 7 A Kent BBC Radio February 2 in on BBC Radio Mayo Simon to spoke in and also featured daffodils, about Wisley’s onMarch, 7 Revival’ Food British Great ‘The BBC2’s pea. British the great discussing part in RHSHorticultural Advisors prominent a play podcasts, gardening the new RHS series of available at: https://itunes.apple.com/gb/ iTunes from free podcast/the-rhs-gardening-podcast/id605769651 Fantozzi, F., Monaci, F., Blanusa, Bargagli, Monaci, R. F., T., Fantozzi, F., Cubey, J.J.Cubey, et al. (2013). Notes from the I the from Notes Leslie. A.C. (2013). (2013). Box Blight. Box 138 Garden The Henricot, B. (2013). RHS Science in the media the in Science RHS Halstead Andrew and pests” 2012, of on the “top 10 Kent BBC Radio A Berkshire’s BBC Radio also by new pests,covering ‘ the RHS Recent RHS Science RHS publications Recent L Armitage, (2013). D. J. Salisbury, Blue A. beetle, mint & Halstead, A.J. (2012). Whitehouse, C. (2013). Kniphofia South in A ) is a partnership of n

www.nbn.org.uk was kept busy all evening explaining the scope the explaining and busywas all kept evening

[email protected]

For more information about Science publications: about Science information more For ► The included RHS display maps animated and posters garden science” surveys invasive of “citizen promoting pests and diseases beetle, rosemary (lily beetle, berberis hemerocallissawfly, gall and midge pear as as rust), well hogweed on giant work (Heracleum recent spp.).Botany’s conservation organisations, government agencies, and government organisations, conservation biodiversity “sharing of aim the local with centres record The available”. and freely publicly anddata it making its in on gardens data biodiversity RHS provides and on pests andinvasive diseases. The NBN ( On March, 20 RHS Science part took National the in Biodiversity “Quarter Network’s of a billion records project” History Natural the at Museum.evening was The event very journalists, attended well by academics, policy makers NGOs, of and representatives and RHS Senior Entomologist left, ex- John Muggleton, SalisburyAndrew with (above, History and Natural Secretary Entomological the British of Society) science work. RHS’s the of variety Night atNight the Museum communications RHS SCIENCE