Author: andy.winfield

A portrait of a boy and his plant

Posted on by andy.winfield

By Nicola Temple

On the 12th of February 1809, Charles Darwin was born in a large Georgian house, known as The Mount, in Shrewsbury. As a biologist, I am very familiar with the works of Darwin. And when I conjure an image of this man in my head it is of him in his 60s, bald on top and with a formidable beard. However, on a recent visit to the University of Bristol Botanic Garden, the curator, Nick Wray, showed me a portrait I had never seen before.

The portrait was completed in 1816, just before Darwin turned 7 years old and he is with his sister Catherine. It is a magnificent piece done using chalk on paper, by the artist Ellen Wallace Sharples (1769-1849), who was settled in Bristol at the time – not far from the Botanic Garden in Clifton [see note 1].

Nick pointed the portrait out to me because he is interested in the plant that Darwin is holding in the portrait. Children would have often been given something to hold while sitting for a portrait – it gave them something to do with their hands to prevent fidgeting. While Catherine has a posy of flowers in her hand, Charles is holding a clay pan on his knee with a plant in full bloom. This would have been no small feat for a child.

The portrait painted by Ellen Wallace Sharples in 1816
of Charles and Catherine Darwin.

Nick recognised the plant held by Darwin as almost certainly Lachenalia aloides (the opal flower), which is a native to the Western Cape of South Africa. Nick informed me that Cape flora were very in vogue during this period. The collecting activities and botanical observations of horticulturist-explorers, such as W. Paterson, Francis Masson, Robert Gordon, W.H.C. Lichtenstein, John Barrow and William Burchell, created a voracious appetite among Europeans for the curious plants of the Western Cape, while established trade routes enabled their transport back to Europe. So it is very likely that the children of a wealthy family would have been given such exotic pieces to hold rather than a favourite toy.

The artist almost certainly painted the portrait at the Darwin’s family home, The Mount. Records show that their impressive house had equally impressive gardens, including a conservatory and hothouse. The Lachenalia aloides likely came from one of their own glasshouses. Grown correctly in a cool frost free glasshouse, this little plant flowers from February-March. In a warm glasshouse it would flower earlier.

In an article written for the Garden History Society by Susan Campbell (Vol. 40, No 2 Winter 2012), she lists the plants cultivated at the Mount, including those growing in the Conservatory and Hothouse. In these lists, one species of Lachenalia is mentioned, Lachenalia pendula, which is now known as Lachenalia bulbifera. This species is almost always red in colour with the robust flower spike leaning to one side. However, yellow tipped orange forms have been recorded in the wild. Whether the plant in the portrait was misidentified in the original plant list or it was correct and an unusual orange and yellow form was cultivated, we shall never know. On examining the portrait carefully, its habit, erect inflorescence and the colour of the flowers, suggests the plant was wrongly identified and should be Lachenalia aloides. Nick goes onto suggest that, “the presence of this Cape bulb flowering in this portrait is evidence that the chalk picture was made around the 12 February 1816, Charles Darwin’s seventh birthday. The picture may have been commissioned deliberately to commemorate the occasion”.

About Lachenalia aloides

There are about 110 different species of Lachenalia, 80 of which are found in the Cape region of South Africa. L. aloides has a number of different varieties, all of which grow on granite or sandstone outcrops. The flowers can vary quite a bit in their colour. Some plants have flowers that are nearly entirely yellow, while others are magenta at the base turning yellow and then to green.

The Lachenalia genus are geophytes, which means that they spend part of the year dormant as a fleshy underground structure, such as a bulb, rhizome or tuber. South Africa is a global hotspot of geophyte diversity. There are 2,100 species across 20 different families in the area and 84% of them are endemic.

Lachenalia aloides is naturally pollinated by sunbirds, which use their long curved bill to access the nectar at the base of the tubular flowers. It was widely-thought until fairly recently that sunbird-pollinated plants had almost always evolved perch-like structures to make feeding for the sunbird easier. However, L. aloides has no such structure and the sunbirds simply sit on the ground to feed on the flowers – an observation that has been made with other low-growing sunbird-pollinated species.

Lachenalia in the Botanic Garden

Lachenalia aloides is in bloom at the
Botanic Garden right now if you want to
have a look at this interesting South African bulb.

The Botanic Garden has some specimens of Lachenalia aloides and other Lachenalia species in the glasshouses and, much like the plant Darwin is holding in the portrait, they are currently in bloom. The portrait would have been painted around this time of year, when there would have been very few plants in bloom. This further supports Nick’s conclusion regarding the species.

The Lachenalia story was one aspect of a lecture titled The Origin & Diversity of Flowering Plants, which was given recently by Nick Wray to the members of the annual Darwin Festival, held each February in Shrewsbury. The audience, made up of academics, ecologists, naturalists and keen amateur and professional gardeners, were taken through the flower pollination syndromes, illustrating the diversity that has evolved over millions of years. Nick discussed the work of the Angiosperm Phylogeny Group (APG) work, the planting of the APG III displays at the Botanic Garden and the difficult task of cultivating Amborella trichopoda and its place at the base of the extant living Angiosperm phylogenetic tree. The talk was illustrated by plants that were brought from the Botanic Garden. This created a lot of interest and added to the sense of place as the talk was held in the Shrewsbury Unitarian Church where Darwin’s mother took him and her other children to worship until Charles was thirteen. When, with an eye to his future university life, Darwin would have to attend a Church of England Church to ensure he would be eligible for a university course as students from Unitarian families would not be admitted.

The group were very appreciative of Nick’s talk and plan to make a summer visit to the Botanic Garden to enjoy the garden and explore its various evolution displays.

Notes:

1. Ellen Wallace Sharples met her husband in Bath where he was her tutor. After they married, the couple travelled back and forth a couple of times between England and America. When Ellen’s husband died in 1810, she moved to an apartment in Clifton with her two children (also artists) in 1811. She made her living doing portraits, as did her children. When she died in 1849, she left a substantial sum to the Bristol Academy which was instrumental in financing Bristol’s first art gallery, now the Royal West of England Academy.

Sources:

Campbell, S. 2009. ‘Sowed for Mr C.D’: The Darwin family’s garden diary for The Mount, Shrewsbury, 1838-65. Garden 
     History 37 (2): 1-16.
Campbell, S. 2012. ‘Its situation…was equisite in the extreme’: ornamental flowers, shrubs and trees in the Darwin 
     family’s garden at The Mount, Shrewsbury, 1838-65. Garden History 40 (2): 1-32.
Procheş, Ş., Cowling, R.M., Goldblatt, P., Manning, J.C., Snijman, D.A. 2006. An overview of the Cape geophytes. 
     Biological Journal of the Linnean Society 87: 27-43.
Turner, R.C., Midgley, J.J. 2016. Sunbird-pollination in the geoflorous species Hyobanch sanguinea (Orobanchaceae) 
     and Lachenalia luteola (Hyacinthaceae). South African Journal of Botany 102: 186-9.

Bumblebees who brave the winter

Posted on by andy.winfield

By Nicola Temple

This past weekend, my family and I met with friends in the village of Shipham, in Somerset, for a walk. It was torrential rain, yet we were determined. We dressed ourselves and three children under the age of 10 in waterproofs and set out. We arrived at a local country pub, not more than 3 km away, resembling drowned rats. And as a Canadian living here in the UK, I still marvel at the fact that nobody took one bit of notice at the state of us. It’s what you do. You get wet. You find a pub. You hunker down for a hot Sunday lunch. And you hope it tapers off before you have to head out again. (It didn’t.)

Pollinators, at least of the flying insect variety, aren’t terribly keen on this kind of weather either. Most hunker down for the winter months as there is generally not a lot of nectar to forage this time of year anyway. How they do this depends on the species. Honeybees reduce the colony to a minimal size and rely on their honey stores to see them through, while they dance in order to regulate the temperature of the hive. Most bumblebee colonies die out completely and the queens that mated at the end of the season find a place to hibernate. Solitary bees may hibernate as adults or as larvae, emerging only when the weather conditions are suitable. To each their own.

Martin Cooper spotted this buff-tailed bumblebee queen
foraging on his Mahonia flowers in Ipswich on a sunny
January day in 2015.
Photo credit: Martin Cooper [via Flickr CC]

However, there is one flying pollinator that can be spotted this time of year here in Bristol, and indeed, other warmer regions of the UK. It is the common buff-tailed bumblebee (Bombus terrestris). This species was first spotted during the winter of 1990, in Exeter. Sightings have been increasing ever since and include nest-founding queens, workers and males, suggesting this is a winter generation of the species.

The mated queen will emerge from her subterranean dormant state (diapause) during warm winter weather and set about establishing a new colony. The potential cost of waking up early is that the warm weather could be short-lived and temperatures could plummet. The benefit, of course, is that there’s nobody to compete with for food. If successful, the queen can establish a colony before the other pollinators even wake up from their winter nap.

Introduced plants provide winter forage

Of course, there is potentially another cost to emerging early – there could be nothing to eat. Bees are able to forage at temperatures around 0oC, but if there aren’t enough plants in flower, they won’t find the pollen and nectar needed to sustain the colony. Few native UK species flower in winter, but species introduced by avid gardeners to bring some winter colour to the garden, also bring some much-needed food to the buff-tailed bumblebee.

Researchers at Queen Mary University of London and The London Natural History Society, conducted a study of buff-tailed bumblebees foraging in London parks and gardens during winter about ten years ago. They wanted to see just how much food the bees were finding as food is directly related to the success of the colony.

The researchers found that there was plenty of forage to sustain the colonies and, in fact, the foraging rates they recorded near the end of winter were equivalent to peak foraging rates found in the height of summer. This doesn’t mean that the winter-flowering plants, such as the evergreen shrubs of the Mahonia spp., are providing more pollen and nectar than all the plants in the height of summer. But it does mean that each flower might have more pollen and nectar available because there aren’t other pollinators out and about also using the resource. The bumblebees, therefore, don’t need to go as far to find an equivalent amount of food and so they can collect it at a faster rate.  

Strategies for tolerating cold

Buff-tailed bumblebees aren’t as tolerant to cold as some other bee species; workers will freeze solid at about -7.1oC while queens freeze at -7.4oC. The bumblebees can obviously find warmth in the colony, but they need to forage and therefore be able to tolerate short spells of cold during the winter months. They may even need to tolerate cold temperatures for up to 24 hours as bumblebees often overnight away from the colony when they are unable to return from foraging.

Researchers from the University of Birmingham looked at the different cold tolerances of this bumblebee species a few years ago. They found that 50% of workers died after being exposed to 0oC for 7.2 days while queens could last over 25 days at this temperature – likely due to their fat reserves. However, as the forage study showed, the bees seem capable of finding food sources closer to the colony during winter months, which may reduce the likelihood of them having to endure cold temperatures for a lethal period of time.

These bumblebees may also have adopted some strategies to help reduce their possibilities of freezing. Pollen is an ice-nucleating agent in that it promotes the development of ice at higher temperatures. Other insects have been observed to expel any ice-nucleating agents from their gut when they experience low temperatures to avoid freezing. While this wasn’t observed in the bumblebees, it is a strategy that individuals might employ when caught out in the cold.

The more frequent observation of buff-tailed bumblebees in winter is thought to be a result of warmer autumn temperatures brought about by climate change. In a study from 1969, researchers reported a 6-9 month dormancy of all bumblebees in southern UK, so in a relatively short period of time there has been a considerable change in their seasonal pattern. There seems to be some flexibility in these patterns among bumblebees and for now, establishing winter colonies seems to be working for the buff-tails. However, with so many of our pollinators under threat, there is obviously also concern among the scientific community that more frequent extreme weather events could also spell disaster for these colonies that have selected to brave the winter months. As gardeners, we can perhaps do our bit by planting some winter forage species.

This year, the University of Bristol Botanic Garden will embrace a pollinator theme, with the aim of highlighting some of the lesser-known pollinators that are so important here in the UK. We love our pollinators, but research is still revealing so much about their unique and complex relationships with plants. So watch this space as we share some of these wonderful stories through our blog. We will also be posting pictures of pollinators we see in the Botanic Garden on our Twitter feed and Facebook page. But to see these pollinators in action, take some time to visit the Botanic Garden. Make space in your busy schedule to watch nature at its best – it’s worth it.

Sources:

Alford DV (1969) A study of the hibernation of bumblebees (Hymenoptera: Bombidae) in Southern England. Journal of 
     Animal Ecology 38: 149-170.
Owen EL, Bale JS, Hayward SAL (2013) Can winter-active bumblebees survive the cold? Assessing the cold tolerance of 
     Bombus terrestris audax and the effects of pollen feeding. PLoS ONE 8(11): e80061.          
     doi:10.1371/journal.pone.0080061
Stelzer RJ, Chitka L, Carlton M, Ings TC (2010) Winter active bumblebees (Bombus terrestris) achieve high foraging 
     rates in urban Britain. PLoS ONE 5(3): e9559. doi: 10.1371/journal.pone.0009559 

‘Tis the season…or is it?

Posted on by andy.winfield

By Helen Roberts

As I sit at my desk this morning, staring out the window, the weather is dire. There is slanting torrential rain and high winds, a typical December day perhaps.
Here in the UK, the seasons are changing and we are experiencing extremes of weather. For example, we have had wetter, milder winters in the southwest over the last couple of years along with increased flooding, particularly on the Somerset Levels. And then there was the very slow start to spring this year, with temperatures well below average in April. This was followed by a very hot end to the summer and warmer-than-average temperatures throughout autumn.
These changes to the seasons are linked to global climate change and are throwing the UK’s wildlife into disorder and affecting the fine balance of habitats and ecosystems. This is not a good scenario for biodiversity in the UK. Seasonal timing is off. When seasons start and end is shifting, and the length of the season itself is changing, making ‘growing seasons’ a more fluid concept. There is also increased risk for most gardeners of a ‘false spring’. Many plants and animals are changing their geographical ranges in order to adapt to these changes.
One of the most significant effects has been the disruption of lifecycle events and these are manifesting themselves in different ways. Bird migration, insect emergence, incidence of pests and diseases and flowering times are being thrown out of kilter.  
Researchers from the University of East Anglia recently analysed 37 years worth of data from the UK Butterfly MonitoringScheme (UKBMS) and found that extreme weather events were causing population crashes of butterflies. Uncommonly high rainfall events during the cocoon life stage affected 25% of UK butterfly species. And more than half of species were affected by extreme-heat during the overwintering life stage, possibly due to the increased incidence of disease or the effect of a ‘false spring’, causing butterflies to emerge too early only to be decimated by a return to cooler temperatures.
Warm temperatures are not all bad for butterflies though, as they will benefit from hot temperatures over the summer months when they are in their adult form and resources are plentiful. However, if populations crash more frequently than they expand, these extreme weather events could threaten UK butterflies.
The spider orchid (Ophrys sphegodes).
Photo: Jacinta Iluch Valero via Flickr [Creative Commons]

Changes in seasonal timing are also knocking the relationships between plants and animals out of sync, including the delicate balance between plants and pollinators. Thiscan be detrimental to the balance of entire ecosystems. An elegant study carried out by scientists from Kew and the University of East Anglia found that earlier springs brought about by rising temperatures are affecting the relationship between a rare spider orchid (Ophrys sphegodes) and its sole pollinator, the solitary miner bee (Andrena nigroaenea).   

This particular orchid has a flower that resembles and smells like a female miner bee and it uses this deceit in order to lure the male miner bee in. The male attempts to mate with the flower and by doing so, pollinates the flower. The plant has evolved to flower at the same time as the male bees emerge, but before the females do.
What the researchers discovered, by looking at the data set going back to 1848, was that rising temperatures are causing the relationship between orchid and bee to break down. Although rising temperatures cause both the bee to emerge and the orchid to flower earlier, the effect on the bees is much more pronounced. The male bees emerge much earlier and the orchids now flower as the female bees emerge. This means the males are not “pseudocopulating” with the flower because the real thing is already available and so the rare spider orchid is having fewer pollinations.
However bleak this picture may seem, plants and animals do have the ability to adjust to seasonal changes caused by climate change, it is just whether they can adapt quickly enough for these intricate ecological relationships to remain intact.
Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.


References

Nematodes: the natural nemesis to slugs and other garden pests

Posted on by andy.winfield

By Alida Robey

Nematodes pop up from time-to-time on gardening programmes, but usually as something of an afterthought: “Oh, and of course if you don’t want to use pesticides you can always try nematodes.” A certain air of mystique has surrounded nematodes for some years now, but these environmentally friendly pest controllers warrant far more consideration than a mere afterthought!
Nematodes are in fact one of the most successful and adaptable animals on the planet. They are second only to the insects in their diversity of species, geographic spread and the range of habitats they can occupy. There are more than 15,000 known species of nematodes, more commonly known as roundworms, and likely thousands more that are yet to be described.
There are parasitic nematodes that live in the gut of animals, humans, birds and mammals. Other species are free-living in the soil, feeding on bacteria and garden waste. Some are parasitic on plants and may cause disease and crop devastation. But, as a gardener, I’m most interested in those species that are free-living in healthy soil and those that parasitise common garden pests.
Free-living garden nematodes are microscopic thread-like worms, which are scarcely visible without a microscope. (This is in marked contrast to the 9 metre long species, Placentonemagigantissima, which can be found in the placenta of the sperm whale!). In good nutritious soil there could be as many as 3 billion individuals per acre. They eat fungi, bacteria and algae. So, much like ordinary earthworms, they have a useful role in decomposing and recycling nutrients.

Biological control with a specific target

Parasitic species have an equally important role in the garden. With such a diversity of species, it is not surprising to find that there are nematodes that specifically parasitise slugs, ants, vine weevil, leather jacket, chafer grub – you name it! This means that a slug nematode won’t have any impact on anything but slugs – this isn’t always the case with other biological controls and rarely the case with chemical controls.
A wax moth pupa can be a host to thousands of
nematodes. The parasitised cadavers can be placed in
orchards to protect crops from pests such as citrus root and black
vine weevils.
Photo credit: Peggy Greb, US Department of Agriculture
It works like this: the juvenile nematodes are in the soil looking for a specific host. Once found, the nematode enters the body of the host and gives off  bacteria inside the host’s body. These bacteria multiply and cause blood poisoning and, eventually, death. The nematodes then feed on the body of the creature and multiply, sending a new generation off into the soil to find another host. When hosts are scarce, the nematodes naturally die off.

The practicalities of using nematodes

As nematodes are living organisms they have a very limited shelf life. They therefore need to be bought online, stored according to instructions and used very soon after delivery.
There are several UK suppliers of nematodes.
It is important to choose the correct nematode species for the right type of pest and to use them in the right conditions. The soil temperature has to be above 5oC (and remain so) and they should be applied only when the pests or their larvae are active. Nematodes are also light sensitive, so use them early morning or dusk, when light levels are low.
They come as a thick paste in a little sachet, which you need to dilute with water. Repeat applications may be needed.

The specifics:

Ants : Drench the nests between April and September.
Chafer grubs: Apply nematodes in August and early September.
Fruit flies, carrot root fly, onion fly, gooseberry sawfly and codling moth: All of these pests can be treated with a generic nematode mix called Nemasys Natural Fruit and Veg Protection Pest Control. You can use it as a general treatment after planting out and when the soil has warmed up, or to target specific pests when you see them, such as gooseberry sawfly caterpillars. These (and other caterpillars) need to have direct contact with the spray while they are on the leaves.
Leather jackets:  These are the larvae of the crane fly or daddy longlegs and attack the roots of grass in the lawn. Treat with nematodes in the autumn, when the adult daddy-long-legs are laying.
Slugs:  The nematode for slugs was discovered by scientists at the University of Bristol! An application early in spring will tackle the young slugs growing under the ground, which are feeding on humus. A single application should last for at least 6 weeks, which allows time for tender seedlings and young plants to get established. They can be applied until early Autumn.
If using on potatoes, apply them 6-7 weeks before harvesting , when the tubers are most likely to be eaten by slugs.
Slug nematodes are very efficient, enjoying the same wet environment so loved by the slugs themselves.
Vine weevils: An application in March will give much greater control of larvae when they are present – either March to May, or from July to October.
I have heard the anecdotes from many gardeners who have had good results using nematodes for ants, vine weevils and slugs. But in May 2016, the Royal Horticultural Society and BASF, the only UK manufacturer of nematodes, announced a one-year research project to put slug nematodes to the test.
So in May 2017, we should see just how well this little creature stacks up against the chemical and other treatments in tackling arguably our most annoying garden pest.

Alida Robey has a small gardening business in Bristol. For several years in New Zealand she worked with others to support projects to establish composting on both domestic and a ‘city-to-farm’ basis.

What lies below: how soil bacteria fight off sticky roots

Posted on by andy.winfield

By Nicola Temple

The first horror film I ever watched was Invasion of the Body Snatchers. The film was already dated by about 30 years when I saw it and so aspects seemed silly rather than scary. Yet, those alien plants still managed to evoke nightmares in my pre-teen imagination. Antagonistic plants have cropped up in numerous films over the years – from the musical menace in Little Shop of Horrors to the Devil’s Snare that entangles Harry Potter and his friends. Yet, the cinematic nightmare of being entwined and strangled by the (not so) local flora is based in some truth…if you’re a microbe.

Soil is alive with microbes – on the order of 100 million cells per gram of soil. Some of these are friendly microbes and some are less so. So, as plant roots seek out water and nutrients within the soil they must also be wary of what they encounter. The root tips are sheathed in specialised cells known as root border cells and these are the front line of defence. These cells launch themselves from the root tips and through the release of various chemicals, help to manipulate the environment around the extending root tips. They can attract and stimulate growth of helpful microbes and repel or inhibit the growth of others. 

Earlier this year, researchers at the University of Wisconsin, USA looked closely at how the root border cells of peas and tomatoes interact with the bacteria Ralstonia solanacearum.
R. solanacearum is a pathogen that affects a number of economically important plants, including potatoes, tomatoes, peppers, bananas and tobacco. It follows the chemical signals sent out by plant roots and finds natural openings or wounds within the root in order to invade the plant. Once inside, the bacteria replicate rapidly and take up residency in the xylem of the plant. Eventually, they block this important transport system of the plant and cause it to wilt and die.

A false coloured electron micrograph showing bacteria (blue)
tangled in the DNA-based trap (yellow).
Photo credit: Tran et al.
The Wisconsin researchers found that when the root border cells of both the peas and tomatoes encountered R. solanacearum, they released DNA. Surrounded by stands of sticky DNA, the bacteria become entangled. Unable to move, the bacteria die. It truly is the stuff of horror films.
Other friendlier species of bacteria didn’t induce this projectile DNA trap from the root border cells, which suggests that they are able to recognise the threat of R. solanacearum.

However, as is almost always the case with nature, there is always a counter attack. The researchers discovered that only 25% of the bacteria were dying in the plant’s sticky trap, so how were the rest managing to escape?

The Wisconsin group found that when R. solanacearum encountered the DNA, it triggered a release of an enzyme that cuts DNA. In other words, they were using molecular scissors to cut their way out of the trap.

And so the evolutionary arms race continues. It is those individual bacteria that produce more of the defensive enzyme that will escape the traps and replicate. Perhaps over evolutionary time, those that have limited capacity to produce the enzyme will be weaned out of the population, forcing the root border cells to improve their offensive game.

For scientists, this detailed understanding of how hosts interact with different pathogens could help them to develop disease-resistant plant varieties of these economically important crops.

For me, this insight into the quiet battles being fought below the ground give me an even greater appreciation for the fruits and vegetables I harvest from my small little garden – they have been hard-won!

The paper referred to is:
Tran TM, MacIntyre A, Hawes M, Allen C (2016) Escaping Underground Nets: Extracellular DNases Degrade Plant Extracellular Traps and Contribute to Virulence of the Plant Pathogenic Bacterium Ralstonia solanacearum. PLoS Pathog 12(6): e1005686. doi:10.1371/journal.ppat.1005686

Nicola Temple is a science writer and co-author or the book ‘Sorting the Beef from the Bull: The Science of Food Fraud Forensics’ . She dabbles in her small veg patch and regularly contributes to the University of Bristol Botanic Garden blog.

Botanical treasures on the beach

Posted on by andy.winfield

By Helen Roberts

Beachcombing is fun no matter what your age. Shells, pieces of driftwood and cloudy coloured glass somehow find a way into pockets, rucksack compartments and lunchboxes. A holiday to Slapton, in the South Hams, over the summer cemented our family’s curiosity in scouring the beaches. But whilst beachcombing, I was also similarly intrigued by the plants growing in this environment.

The coast here has a constantly shifting flora highly specialised for growing in difficult conditions. There is a shingle ridge that runs parallel to the shoreline, dividing the lake (Slapton Ley) from the sea. The plants that I discovered along the ridge path that runs northeast from the village of Torcross looked so intrinsically a part of the place, that to me they amplified the essence of this unique shingle coast.

All of the species on the shingle ridge have evolved ways of coping with difficult coastal conditions. The plants here are frequently subjected to saline spray and blown salts, high winds, exposure to hot summer temperatures and low soil humidity. The physical makeup of the shingle (it is a mix of flint, chert and quartz intermixed with some finer material) means that the substrate is very free draining and this results in the acute leaching of nutrients.

Thick leaves and deep roots

Most species that grow here have developed a cuticle (the protective film covering the leaf) that resists the entry of salt water or the leaves are sclerophyllous (thick, waxy and leathery). Often leaves are succulent and allow more effective retention of water.

Giant leaved sea kale (Crambe maritima)
Photo credit: Peganum [via Flickr CC BY-SA 2.0]

White hairs on the leaf surface, which give a silvery hue, are also adaptive in preventing evaporation as they trap moisture, conserving water within their microclimate. The yellow horned-poppy (Glaucium flavum) has hairy sclerophyllous leaves. This is a toxic but striking perennial, with bright yellow flowers that later produce a stunning display of long horned seedpods. This plant has an extremely deep root system in order to access water deep down, but this also helps with stability during high winds.

Other plants on the shingle bar include the beautifully architectural rock samphire (Crithmum maritimum) and the giant leaved sea kale (Crambe maritima), the latter becoming popularised through its abundance in Derek Jarman’s extraordinary shingle garden near Dungeness. Sea kale taproots reach depths of up to 2 metres, providing them with a significant anchor in coastal winds.

Lying low

Restharrow (Ononis repens) is a common beach dweller.
Photo credit: Matt Lavin [via Flickr CC BY-SA 2.0]

Some plants have adapted a slightly different approach to coastal living. They nestle down as low as they can and spread horizontally to reduce the amount of surface area exposed to the hammering winds. The small fleshy leaves of the sea campion (Silene uniflora) are closely packed and the plant grows in low mats. It is only the flowering branches, with their pretty white flowers and inflated bladders, much like calyx, that dare poke their heads up into the wind. Restharrow (Ononis repens) is an attractive low creeping aromatic herb with hairy stems and small pink pea-like flowers. The evaporation of essential oils released by aromatic plants is thought to cool the environment around the plant and thereby protect it from periods of extreme heat. Restharrow also has an extensive root system. Other species like chicory (Cichorium intybus), viper’s-bugloss (Echium vulgare), thrift (Armeria maritima), wild carrot (Daucus carota) and bird’s-foot-trefoil (Lotus corniculatus) all grow on the shingle ridge and are highly prized by pollinating insects.

These species have adapted to this environment. Although the ridge is only a narrow two metre strip of shingle, it displays a wonderful mosaic of disturbed ruderal* vegetation that forms a linear ribbon of interesting shapes, forms and flowers. Observing this particular plant habitat has helped me in the development of my own gravel garden at home. Some of these species are better suited to a garden environment and so I will begin with these. Although, more often than not it’s a matter of trial and error when trying to take plants outside of the conditions in which they thrive. Beth Chatto’s famous mantra, ‘Right plant, right place’ springs to mind and is always in my thoughts when I am planting my own garden or designing for other people.

*Ruderal is a term in botany that refers to plants that grow on waste ground or among rubbish.

 Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

The wondrous creatures that share our gardens part 2: feathers and fur

Posted on by andy.winfield

By Alida Robey

This week’s post continues to separate the facts from the fallacies concerning the creatures that cross our paths while we garden. In my last post I looked at invertebrates and this week, I look at creatures with feathers and fur.

Is that little robin back again this year?

Robins live just over a year.
Photo credit: Linda Stanley [via Flickr CC by 2.0]

Unfortunately, this is highly unlikely. Robins are relatively short-lived birds, with an average lifespan of 1.1 years. The oldest known robin lived to 12 years. Compare this with blackbirds (2.4 year average; 20 year max) or starlings (2.5 average; 22 year max). This sadly means that the robin you see in your garden year after year is unlikely to be the same one.

How long do foxes live?

Whilst in captivity, foxes can live as long as 14 years, but they usually live 5 years in the wild. In rural areas where fox control is practised, up to 80% of the fox population may be less than 1 year old.

Foxes can dig their own dens, but sometimes they prefer to simply renovate vacated rabbit holes, or even co-habitate with badgers, amicably occupying the other end of their sett.

Foxes have been known to travel 5-10 miles from their den on their nocturnal hunt for food.

If you are troubled by foxes – and increasingly in urban areas such as Bristol this can be the case – I am reliably informed that rural chicken keepers get the males in their family to take a pee around the hen house. This being one of the best-known deterrents to these wily poachers!

Are moles really blind?

Moles can create havoc in the garden.
Photo credit: Stephan Caspar [via Flickr CC BY-NC 2.0

Moles can be the bane of your life if you get them tunnelling in your lawn or garden. These amazing little creatures can shift twice their body weight in soil in a minute, which amounts to 540 times their body weight in a day. This can have a rather disruptive effect on your lawn if you are unfortunate enough to have them as neighbours – and given there are 35-40 million of them in the UK, the chances of that are fairly high! Moles are solitary except when mating and they only surface at night to forage for food and nesting material. They live mainly on worms, grubs and larvae.

Contrary to the popular myth, moles are not blind. They have very small eyes as they spend so much time tunnelling. Their eyes are light-sensitive, but don’t detect colour; they rely heavily on sound and smell. They are the only mammal that lives totally underground. Their blood composition allows them to cope with significantly less oxygen than other mammals require.

How far do hedgehogs travel? 

Hedgehogs travel up to 3 km a night in search of food. They can swim and even climb the lower branches of hedges in search of bugs and caterpillars. Their spindly little legs can help them reach speeds of up to 4.5 mph if they need to, which is more than twice my average pace as a steady walker (with significantly longer legs)!

Hedgehog numbers are in decline.
Photo credit: Milo Bostock [via Flickr CC BY 2.0]

We do love hedgehogs, yet we don’t seem to love them enough, as their numbers are in drastic decline due to human lifestyle choices. Whilst hedgehogs can live 10 years with a bit of care and attention, their average life in today’s urban environment is only  2-3 years with 20% of baby hoglets dying before they even show their little noses out of the nest. A large number then die during their precarious first hibernation. Roadkill, pesticides and urban development contribute to mortality, so less than 0.4% ever reach 10 years of age.

A hedgehog diet is mainly slugs, snails and beetles, but they also eat worms and spiders, and occasionally carrion and birds eggs. Milk and bread that is left out for these carnivores can actually be fatal to them. And to dispel yet another myth, hedgehogs do have fleas, but these are a variety exclusive to hedgehogs and will not transfer to pets or humans. It is also the case that if you should try to treat any hedgehogs you find with other animal flea treatment you will again almost certainly  kill the poor hedgehog.

Hibernation gets the hedgehog through winter when the availability of its normal diet is scarce. To cope, its body temperature drops from 35 degrees Celsius to around 4 degrees Celsius. It breaths only every 6 seconds and drops its heartbeat to one tenth the normal rate. A hedgehog can lose around half its body weight in the process of getting through the long cold winter.

The stark fact is that without drastic measures by householders and others, hedgehogs are heading rapidly towards extinction having fallen in number from some 30 million in the 1950s to 1.1 million by 1995 and further loss since then means there are now fewer than a million left in the UK.

Slug bait and pesticides kill hedgehogs, so if you want to do your bit, then please do consider nematodes and other hedgehog-friendly pest control methods. Nematodes can be bought online and simply watered onto your garden a few times a year. Doing so as an alternative to slugbait should help both your bird population and any of the few remaining hedgehogs in the country – both of which will help reduce slug devastation in your garden. Worms, birds, hedgehogs and many other wild creatures perform vital ecosystem services for us – they are workers in our gardens and countryside. The more we protect them, the more help they give. So when you are fighting the battle to take control of the  unruly creatures in your garden remember to keep some room for ‘the wild side!’

Alida Robey has a small gardening business in Bristol. For several years in New Zealand she worked with others to support projects to establish composting on both domestic and a ‘city-to-farm’ basis. 

The Svalbard Global Seed Vault: a safe haven for seed

Posted on by andy.winfield

By Helen Roberts

Svalbard is a group of Norwegian islands located in the high Arctic and only 1,300 km from the North Pole. It is breathtakingly beautiful. The landscape is stark, unforgiving and wholly memorable. I visited these islands more than 16 years ago as part of a 6-week science expedition – I was part of a botanical group looking at the exceptionally low-growing Arctic Willow. 
Memories of that place are still strong today. Its beauty and sense of isolation is unique. The humdrum of everyday life is simply stripped away here. You are left with the landscape, weather and incredible flora and fauna. Although life became simple, the vastness of the place was exhilarating and I felt totally and utterly free. 
The stark landscape of Svalbard
Photo credit: Paul Williams [via Flickr CC BY-NC 2.0]

The Arctic is an ideal refuge for seeds

Within this unforgiving landscape, nestled deep within a mountainside, is a seed bank of global importance. It holds 12,000 years of agricultural history and contains the world’s largest collection of crop diversity. 
The Global Seed Vault is the brainchild of renowned scientist Cary Fowler, a former executive director of the Global Crop Diversity Trust. It started as a simple idea back in the 1980s in the spirit of global collaboration, and finally came to fruition in 2008 when the building was completed. However, building the collection within is ongoing.
Svalbard Global Seed Vault
Photo credit: Amber Case [via Flickr CC BY-NC 2.0]
The facility currently holds about 850,000 different varieties of seed and acts as the back up for seed banks across the globe. This is a collection that is vastly important for food security and the safeguarding of crop diversity. Those 850,000 packets of seed represent more than 5,000 species and nearly half of the world’s most important food crops, from cereal and rice to unique varieties of legumes. The seed deposits come from over 60 different institutions and represent nearly every country in the world. 
The chosen location of the global seed vault is an interesting story. It needed to be located somewhere safe from both potential natural disasters and human conflict. Svalbard itself is a safe place to store seed both in terms of physical and social factors. Svalbard’s remoteness ensures an extra layer of security, while its geological stability and location, 130m above sea level, means the vault would be safe even in the worst-case scenario of sea-level rise. The storage facility is buried 150m deep into the side of a mountain where there is no radiation and where humidity levels remain low. The mountain also acts as a natural freezer, reducing the facility’s reliance on mechanical refrigeration. The local infrastructure on Svalbard is also very good despite its remoteness – Svalbard is serviced by regular scheduled flights.
Svalbard itself is also politically very stable and military activity is prohibited in the region under the terms of the Treaty of Svalbard of 1920. The local government is highly competent and Norway has long been recognised as a key country in the international efforts to conserve Plant Genetic Resources for Food and Agriculture (PGRFA). 

Building and running the vault

The Global Seed Vault is built to store up to 4.5 million different varieties of seed. Constructed to be highly functional, the rectangular edifice emerging from the side of the mountain is stark but architecturally beautiful. The structure is energy efficient; insulated by the mountainside, it maintains an ambient temperature of -7°C and therefore only needs a further temperature drop to -18°C to reach the recognised standard temperature for the storage of viable seed. 
The vault was built and paid for by the Norwegian government to provide a service to the world community. The structure took 12 months to build and cost NOK 50 million (approximately £4.6 million). The facility runs as a partnership between the Government of Norway, the Nordic Genetic Resource Centre (NordGen) and the Global Crop Diversity Trust. Operations regarding the vault are administered and controlled by an international advisory council of experts representing the Food and Agriculture Organization of the United Nations (FAO), national gene banks, the Consultative Group on Agricultural Research (CGIAR) and the Governing Body of the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA). 

Inside the building

Some people are lucky enough to visit the seed vault on the rare occasions that you can gain access inside. I had to see the interior of the facility via a virtual tour. 
The front entrance is understated, although to gain access you have to go through half a dozen locked doors, each requiring a different key. Although, security appears minimal, it’s not. The facility is under constant surveillance by Staatsbygg, the government of Norway’s property manager and developer;  security cameras and sensors are located throughout the building. There is some natural security, of course, as the roaming polar bears outside outnumber the human population of Svalbard. 
From the entrance lobby, a 150m long tunnel extends into the mountain before reaching the three main storage chambers. At the moment, only one storage chamber is in use, in time the others will be filled as more seed varieties are deposited. 
Seed is only deposited three times a year and this is the only time when the vault is opened. 

Making a deposit

The metal shelves inside the Global Seed Vault.
Photo credit: Dag Terje Filip Endresen
[via Flickr CC BY-NC 2.0]
On arrival to Svalbard, seed lots are x-rayed and taken to the vault by NordGen staff members. The seed boxes containing the seed, which have been carefully placed in 3-ply aluminium packages, are then wheeled by trolley to the main storage chamber within the vault. Each package will contain on average 500 seeds. 
The seed lots are placed on simple metal shelving and are assigned bar codes to allow easy retrieval. They are catalogued using an information system called the Seed Portal of The Svalbard Seed Vault. This allows depositors to submit seed inventories and the general public to look at basic information about the seed that is stored within. Storage is free to depositors and they control access to the deposits. It is an International Black Box system, which ensures that only the depositor can access the raw seed and open the boxes. 

The most recent seed deposits

Last year, the first tree seeds were deposited from Norway and Finland. In February, pine and spruce seed was taken to the vault for storage from the Norwegian Forest Seed Center and the Finnish gene reserves forests of Lappträsk and Puolango, and Filpula and Lovisa. This deposit provides a back-up in the event that global climate change, forest management techniques and other factors, such as pests and disease begin to compromise the genetic diversity of these forests. It is a method of conserving the existing genetic resources and enabling long-term monitoring of the genetic variation within these forests, including any changes that occur because of tree breeding. This long-term tree seed project involves the countries of Finland, Denmark, Sweden, Iceland and Norway. 
The last deposit of seed was on 26th May 2016, with deposits from Germany, Thailand, New Zealand and the World Vegetable Center in Taiwan. Germany placed over 6,000 accessions into the vault of a number of different crop varieties, New Zealand deposited a number of varieties of sheep food including rye grass and white clover, Thailand deposited some 20 samples of very special chilli peppers and the World Vegetable Center deposited 1,200 seed lots from a number of different nations. 

Our agricultural future

The importance of this seed vault is apparent; it ensures the survival of the world’s most important crop species. Some seed varieties within the depths of this safe haven can survive for up to 4,000 years. In terms of food security, that is long term planning for human agriculture. 

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.


References:

Doomsday Vault Opened for Syrian Seeds: 
What is NordGen?:
Croptrust: 
Forest seed destined for Svalbard:
Forest tree seeds arrive at Svalbard’s ‘Doomsday vault’:
Arctic seed vault ‘key to future global crops’:
Storing the World’s Seeds in a Frozen Mountainside:
From sheep food to chili peppers – seed deposit at Arctic Vault takes the world one step closer to future food security: 
In the vault: David Osit:
Svaalbard Global Seed Vault:

The wondrous creatures that share our gardens part I: The creepy crawlies

Posted on by andy.winfield

By Alida Robey


As I peacefully garden, random thoughts about the wildlife I encounter waft through my head. How far does a hedgehog travel in a night? If you throw a snail over the fence, is it likely to find its way back into the garden? How long do worms live?  Rather than continue repeating this cycle of speculation,  I decided to get to the bottom of these little mysteries.

Do those snails make it back over the fence?

There are 43,000 species of Gastropoda (the taxonomic group better known as slugs and snails). There are 220 non-marine species of these mucous crawling critters living in the UK, so it’s small wonder we have such problems with snails in our gardens. Snails can live up to three years. Each snail has both male and female sex organs (they are hermaphrodites) and mating occurs when two entwined snails each shoots a small sperm-carrying dart at the other; each then goes off to lay about 40 eggs.
Garden snail.
Photo credit: Daniela [via Flickr, CC license]
And that burning question….what happens to all those snails that I catapult over my fence? Well yes, snails can happily find their way back over fences and walls, up to a distance of 10 metres. Professor Dave Hodgson, Professor of Ecology, University of Exeter, revealed this fact when he used LED lights and UV paint to track the movement of snails at night in a British garden. The study revealed that snails can travel distances of up to 25 metres during a 24-hour period and reach top speeds of one metre per hour. So you will need to do more than lob them discretely over the wall if you are hoping to do more than just make them work a bit harder for their supper! 

What is the lifespan of a slug?

Most slugs evolved from snails, losing their shells through evolutionary processes over time.
Depending on the species, slugs can live between 1 and 5 years. If you are squeamish about slugs, count your blessings you don’t live in North America where there is the banana slug, which grows to 10 inches long!
The banana slug (Ariolimax columbianus).
Photo credit: Oregon Department of Agriculture [via Flickr, CC license]
Much as we may berate slugs, they do serve an important function in nature, munching up rotting debris and recycling the nutrients back into the food chain. 
However, they also like to munch the tender leaves and stalks of our most treasured little seedlings, and it is for this reason that many British gardeners are keen to shorten the lifespan of these troublesome pests. Use of slug baits is highly controversial and there is insubstantial and conflicting information regarding how these poisons affect other creatures, such as birds and hedgehogs, which are natural predators of slugs. 
Despite being in widespread use, slug pellets are considered by some to be a relatively ineffective method of slug control, some say killing no more than 10% of the slug population in the average garden. Slug pellets fall into 2 main types; those containing metaldehyde or the less common methiocarb.
Metaldehyde is the most common and less toxic form of slug poison and if not taken in too large quantities less likely than methiocarb products to be fatal to other animals – the suggested dose being one pellet every 10 cm (4”). 
Methiocarb is about ten times more poisonous than metaldehyde, and therefore of greater danger to other animals. It breaks down more slowly too, making it a longer lasting hazard in the environment with the potential to affect more animals (targeted or not).
The RHS has some research underway that is due to report in December 2017 on the relative effectiveness of different methods of slug and snail control, including the use of nematodes. This research will help them improve their advice about slug and snail control. 

Does cutting a worm in half make 2 worms?

Sadly no – but thankfully at least one half should still survive. 
Earthworms
Photo credit: Wormwould [via Flickr CC by-NC 2.0]
I always say the common earthworm is the hardest worker in the garden, and Charles Darwin called them ‘nature’s ploughs’. They do an extraordinary job of aerating and fertilising the soil, pulling leaves down beneath the ground at a rapid rate and bringing valuable minerals to the surface with their wormcasts. One acre of land can hold around 3 million earthworms, which are capable of bringing around 9 tonnes of soil to the surface through their wormcasts in just one year. The tunnels they make and live in can go as deep as 1.8 m (6 ft), which enables them to find moisture in times of drought. Worms are capable of digesting even leaves that are generally poisonous, owing to the presence of a chemical in their gut called drilodefensins. Scientists at University College London identified this molecule, which breaks down the toxic chemicals plants produce to deter herbivores. Without this ability, leaves would pile up on the surface of the soil.

Ladybirds
Photo credit: danielweiresq
[via Flickr CC by-NC 2.0]

How many spots does a ladybird have? 

Well, actually, there are 40 different species of ladybirds in Britain, with differing numbers of spots and some have yellow wing cases rather than red – the invasive harlequin ladybird (Harmonia axyridis) can also have a black wing case. And no, ladybirds do not gain more spots as they get older. The ladybird is a most welcome addition to the garden as its larvae munch their way through vast quantities of aphids prior to pupating.  However, they have to eat heartily as aphids are so fast at reproducing, they get through three generations for every single generation of ladybird. For this reason, the ladybird’s ability to truly help control aphid infestations has been brought into question.

Is the common wood lice harmful to plants?

An unfortunate name for a little creature that is more closely related (admittedly from way back), to crabs and lobsters! It quietly beavers away eating rotten wood, fungi and garden debris and protects itself from drying up by only coming out from under stones and logs at night. 
Woodlice
Photo credit: Mark Hilditch [via Flickr CC by-NC 2.0]
Woodlice cause little or no damage to plants. Large numbers can be found in compost heaps, where they help break down the plant material and are a useful part of the composting process. But you may well have seen what you think is the same thing around your house. This is a slightly different species of wood louse to the garden variety and is called the pill bug.  It can be distinguished from the woodlouse by its tendency to roll into a tight ball when threatened. Pill bugs are not thought to do any harm in the house although their presence may indicate an issue with dampness, as this is their preferred environment.

How can you tell  the difference between toads and frogs?

I have often wondered how to tell which was which. Frogs generally have a wet, smoother skin, while that of toads is dry and ‘warty.’ Toads walk rather than leap and are less nimble movers than frogs. I regularly help with a garden in Herefordshire where I am frequently surprised by the lump of soil that turns out to be a toad that then ambles off unsteadily down the garden – a frog would have leapt off at the least disturbance. 
Toads return each year to the same pond to spawn their eggs – as many as 7,000 in a sitting.
Frogs come in a much wider range of colours than the steady brown toad with its darker brown blotches; they can be anything from yellow, brown, orange, red, grey, and different shades of speckling. 

What ARE Nematodes?

Caenorhabditis elegans is a nematode that is studied
extensively by scientists.
Photo credit:snickclunk [via Flickr CC by-NC 2.0]
Nematodes are microscopic worms that are naturally present in the soil. They can be purchased in concentrated volumes as biological pest control. There are specific nematodes for each different  garden ‘pest’ such as slugs, vine weevils, ants, chafer grubs, leatherjackets, caterpillars, codling moth etc. An advantage of nematodes is that they don’t persist in the environment like chemicals do – when their prey item depletes, they naturally die off to natural population levels. 
As this is a ‘live’ product, it is currently only available from online suppliers as nematodes have to be used within a few days of purchase. They are sent in a little pack that resembles fresh yeast and one simply has to dilute this to the required level and then water them into the garden. I have used nematodes myself very successfully and believe that with increasing regulatory pressure on toxic sprays and treatments that are harmful to pollinators and other wildlife, nematodes are the way of the future for pest control.
Please leave a comment if you have any questions about the wildlife you encounter in your garden and we’ll do our very best to find an answer. Part 2 will have some common questions about our furred and feathered garden friends.
Alida Robey has a small gardening business in Bristol. For several years in New Zealand she worked with others to support projects to establish composting on both domestic and a ‘city-to-farm’ basis. 

Know your knotweed advice

Posted on by andy.winfield

By Nicola Temple

Researchers at the University of Exeter‘s Penryn campus have had a comprehensive look at Japanese knotweed (Fallopia japonica)  guidance from a range of sources on the web, including government sites, environmental NGOs, weed control companies, the media and the property market. They’ve found that this advice is often contradictory and even misleading.

A Japanese knotweed contaminated area in Hertfordshire
is identified with signage.
Photo credit: Peter O’Connor via Flickr [CC By-SA 2.0]
Japanese knotweed was introduced to the UK as an ornamental in the mid-1800s. It quickly became a problem plant, spreading swiftly and widely across the UK. This brutish invasive can penetrate building foundations and drains and is estimated to cost the UK economy £165 million a year.
The plant can grow from very small fragments of rhizome that weigh as little 0.01 g [1]. The rhizome material is capable of surviving for three months in a salty environment, which allows it to spread in coastal regions. Disturbing the rhizomes underground only promote growth and cutting the material above ground stimulates new above ground stems. It is the very definition of nuisance.

Japanese knotweed and the law

Two pieces of legislation were enacted to  provide the legal teeth needed to help control Japanese knotweed [2]. Under the Wildlife and Countryside Act 1981 (Section 14), it is illegal to plant or otherwise cause Japanese knotweed to grow in the wild. Offences can carry a maximum £5,000 fine or six months in prison, or both, in magistrates court. A Crown Court can impose an unlimited fine or maximum prison sentence of 2 years, or both.
The second piece of legislation is under the Environmental Protection Act 1990 (Section 33), where it is classed as ‘controlled waste# and must therefore be disposed of according to the Environmental Protection Act (Duty of Care) Regulations 1991. If you keep, treat or dispose of knotweed in a manner that is likely to allow it to spread, a magistrates court can impose a maximum fine of £20,000 or prison sentence of 6 months, or both. A Crown Court can impose an unlimited fine or maximum prison sentence of 2 years, or both.
Allowing Japanese knotweed to spread to your neighbours can also be considered a private nuisance. Failure to control this plant on your land could therefore result in a prosecution or community protection notice.

Mixed messages

Japanese knotweed growing along a fence in East London.
Photo credit: Gordon Joly via Flickr [CC licence BY-SA 2.0]

The research, published today (4th July) in the journal Applied Ecology, included a content analysis, which objectively describes written, spoken and visual communication, and allows researchers to quantify different types of content. This is a method often used in social research, but rarely applied to ecological questions, such as invasive plants. The results showed that there is conflicting advice out there, particularly about the disposal of Japanese knotweed, which could result in people taking the wrong course of action that leads to the unlawful and environmentally harmful spread of the plant.
“It is important to provide clear advice about the waste disposal of Japanese knotweed,” explained Beth Robinson, a PhD researcher in Exeter’s Environment and Sustainability Institute and lead author of the study, “as it can regrow from small fragments of rhizome and incorrect disposal of waste material can result in further spread of this plant.”
Even government websites were found to have conflicting and unclear information. The researchers point to Devon and Cornwall councils as both having valuable and accurate information about knotweed management. However, most of us are likely to consult the website of our own local council with the assumption that the information they provide is accurate.
“We recommend that local and national authorities collaborate and work towards disseminating more consistent messages,” said Robinson.
A tendency by the media to sensationalise the risks associated with this invasive plant can lead to unnecessary anxiety and expenditure.  An extreme example of this was headlines in 2013 such as ‘Murder andsuicide by husband driven mad over knotweed‘. Stories such as this make it sound as though the plant might have a psychoactive effect – driving people mad by its sheer presence, when indeed there are serious underlying mental health issues.
The Exeter researchers stress that Japanese knotweed needs to be dealt with on a case by case basis. While some knotweed invasions do require professional assistance, small-scale occurrences in domestic gardens may be effectively controlled and disposed of responsibly by the homeowner.

Visit the Cornwall Council website for some reliable information about Japanese knotweed and its management. 


The paper in Applied Ecology is titled ‘Weeds on the web: conflicting management advice about an invasive non-native plant’ and is authored by Beth S. Robinson, Richard Inger, Sarah L. Crowley and Kevin J. Gaston.


Sources:

[1]     Macfarlane, J.S. (2011) Development of Strategies for the Control and Eradication of Japanese Knotweed [MPhil Thesis, University of Exeter] <https://ore.exeter.ac.uk/repository/handle/10871/11862>

[2]     Cornwall County Council (2016) ‘Japanese Knotweed Legal Issues’ [website accessed 4/7/2016] <https://www.cornwall.gov.uk/environment-and-planning/trees-hedges-and-woodland/invasive-plants/japanese-knotweed/japanese-knotweed-legal-issues/>