The Asian Invasion
Posted by Toni Jux on Tuesday 15th November
A recurring nuisance to gardeners across Britain has been the introduction of a fairly persistent little weed known as Japanese Knotweed. Originally introduced by the Victorians as an ornamental garden perennial, this invasive plant broke into the news recently for completely undermining the structural stability of one Hertfordshire couple’s home, along with its retail value.
Matthew Jones and Sue Banks were told that, after a particularly virulent specimen of Fallopia Japonica had burrowed through the concrete of their living room wall, the financial worth of their property had fallen by a quarter of a million pounds.
The Environment Agency recognises Fallopia Japonica as a national threat to garden welfare, as it rivals bamboo in its growth rate, and most rabbit warrens in its ability to procreate! The species can increase in length by over 10 cm a day and, as the Hertfordshire case demonstrates, is not discouraged in the least by hardened materials such as paving, brickwork or even solid concrete.
In 2009 a government study revealed a potential cure to the weed, a jumping louse of similar origins to the weed itself, known as Aphalara Itadori, which was believed would see the decline of the plant with a mass devouring of its sap. This study aptly referred to the Knotweed as a real life equivalent of a Triffid and, as such, a menace to horticultural society - able to grow up to 7 metres horizontally and 5 metres underground. It is completely regenerative from any particle exceeding the dimensions of a drawing pin and capable of drowning smaller flowers and native species in its foliage. However, the government body was understandably reserved about releasing Britain’s first deliberate biological control, particularly in the wake of the North Australian Cane Toad disaster. Questions were raised as to how our environment might sustain the jumping lice, were they successful in wiping out Knotweed.
Fast forward to today and, while the louse is yet to be released on a mass scale, there are still a variety of different techniques that the environment agency recommends should you notice your own garden falling prey. Of course the first step is decisively identifying the menace in time to combat it - first and foremost the rate of expansion will be unlike most anything else you’ve come across, marching forward like a lush green platoon it will conquer new ground daily.
The foliage itself is shovel shaped and will be supported on a cane similar to bamboo. Finally, you have the white flowers produced September – October and the trademark colourful autumn foliage.
However, patience must be exhibited when the specimen is discovered as the agency insists that successful termination of the plant will derive from correct timing, regardless of technique. Their website suggests action in late summer when the underground rhizomes are far more susceptible to herbicides and physical damage. However, when it comes to cutting, it important to remember the durability of the plant and the risk that dispersing even the smallest clipping can pose.
Studies have shown that a 1cm section of rhizome can produce a new plant in 10 days, and that rhizome segments can remain dormant in soil for twenty years before producing new plants, so extreme care must be exercised when trying to eradicate it. As such, it is necessary to gain the agency’s permission before undertaking knotweed control, so that they might outline the proper method for disposing of the cuttings produced. The number of specialised domestic facilities in existence are a tribute to the tenacity of the species and thus how seriously its disposal must be taken.
As a householder you are responsible for the control of Knotweed as, although it is not an offence to have it on your land, to allow it to spread to a neighbouring property could constitute a ‘private nuisance’ under common law. Also, to cause it to spread through improper removal or disposal is illegal. If you are in any doubt, it would be best to contact the agency, or your local authority for advice on control or disposal.
By Josh Ellison
Something Fungal This Way Comes
Posted by Toni Jux on Friday 4th November
The gardening headlines this week have been plastered with the threat of two new diseases that could potentially devastate Europe’s indigenous tree population.
In southern France, along the famous Canal du Midi, a plan has been in motion since last winter that will see the felling and destruction of 42,000 plane trees in the region. This is due to the arrival of Ceratocystis platani, a disease that, since the 1970’s, has been blitzing across Europe, originating in Italy. It is believed the blight, endemic to North America, was brought across the ocean by U.S. soldiers in World War Two. While the Midi, perhaps due to its recently endowed world heritage title, is certainly the most noticeable among the losses, the disease has also become prevalent in Switzerland, Germany and Greece, where it now threatens a vast percentage of the original Plane population.
The Canal, a world renowned tourist attraction, was originally designed as an economic conduit that allowed the merchants of old to bypass the treacherous Atlantic Ocean en route to the Mediterranean Sea. However, in a somewhat ironic twist, the original species of Mississippi Plane that has successfully adapted to this affliction is being imported in great numbers in order to replace one of the Canal’s main attractions. Unfortunately, while Toulouse can cater to their favoured humid environment, it is unclear whether this species will be viable to supplement the depletion that chillier areas of the continent have suffered.
The threat does not stop in Toulouse however - given the virility of the affliction, tree pathologist Steve Woodward (University of Aberdeen) agrees that it poses a grave threat to the urban based Planes of cities like Paris and London. It is the Plane that so commonly and attractively lines our city streets.
“We are talking about a massive disaster here if it continues to spread,” he says.
The disease is a fungal infection that, once exposed to the roots of the organism, will completely overrun it within 3-5 years, and due to the damage this causes to the plants' integrity, it is imperative that it be removed, lest it should fall and endanger passers-by in doing so. The disease is characterised by cankerous sores appearing on the inner bark of the tree, as well as an accelerated decline in both the quality and density of the plants foliage. No wound to the outer bark is too great or small to escape it and contact equals instant infection.
In addition to this threat from abroad, a new menace has been identified in rural Devon as a potential watershed moment for the diminishment of our domestic Yews and Lawson Cypresses in the form of Phytophtora lateralis. Identifiable by the patchy colouring of its trunk, a tree will also often exhibit slightly lighter foliage in places followed by out of season autumn colours. The tree will succumb soon after as this foliage deterioration signals that the tree has become totally infected.
While certain soil drenches can be utilised in the earlier stages of the disease, these will likely prove ineffective once it has advanced past the root structure; aside from which, use of these drenches on a mass scale would likely cause further environmental concerns and prove something of a pyrrhic victory.
Due to this increasing encroachment of pests and diseases, a body has been established to specifically target incoming detriments to our native plant life. This group, known as the Tree Health and Plant Biosecurity Action Plan, has been allocated seven million pounds (£7m) with which, over the next three years, they will attempt to exert a tighter control on the intrusion of foreign fungi and pathogens that threaten the endemic population.
"If we don't act now, we could end up with a similar situation to the 1970s when more than 30 million trees in the UK died [as a result of] Dutch elm disease." - says Environment Secretary Caroline Spelman.
The key responsibilities of the plan will include the monitoring of exotic plants allowed to cross British borders, as well as increasing the knowledge and awareness of currently existing domestic threats.
By Josh Ellison
