Saturday, June 25, 2011
Posted by Andrew King at 10:49 PM
Corrigans city farm, Blackpool: Japanese knotweed, a noxious weed: "These noxious weeds go by numerous other names, including Polygonum cuspidatum (one of its scientific names). But no matter what you call ..."
Posted by Andrew King at 1:56 PM
These noxious weeds go by numerous other names, including Polygonum cuspidatum (one of its scientific names). But no matter what you call them these plants deserve the title of "killer bamboo." It is effectively a giant herbaceous perennial which grows at an alarming rate of up to 10cm per day in any type of soil. It forms dense clumps of up to 3m (10ft) in height. Japanese Knotweed thrives on disturbance and spreads by natural means and by human activity. Very small fragments of rhizome (underground stems), as little as 0.7g - approximately the size of a fingernail - can produce fresh new plants. But it is below ground where this invader causes the biggest problems, as each stand creates a rhizome network that can extend to 3m in depth and 7m in all directions. This makes it a serious threat to construction where it can have devastating consequences damaging foundations, drains and other underground services.
Japanese knotweed plants were introduced from Japan first into Ireland the U.K., then into North America in the 19th century as a landscaping ornamental (alas, there is no accounting for some peoples tastes!). Japanese knotweed soon spread like wildfire, a mad killer taking on a life of its own, independent of its human sponsors. A common habitat for Japanese knotweed is sunny, moist areas, including riverbanks, roadsides and, yes, your lawn and garden. Japanese knotweed is often spread via landfill: all it takes is one fragment of one root, furtively submerged within a pile of fill dumped onto an unsuspecting ditch and, next thing you know, a burgeoning menace is gaining a foothold. Before you know it, all other plants are crowded out by this highly successful competitor for landscaping space, resulting in a monoculture.
Luckily, Japanese knotweed is not inclined to occupy forested areas. Rather, it typically takes advantage of areas disturbed by humans, areas affording not only ample sunlight but also friable soil for its invasive roots. If you already have a patch of Japanese knotweed at the edge of the woods on your property, whatever you do, do not begin clearing the wooded land until you have completed the eradication of this killer bamboo. You'll only invite it to spread, if you clear land adjoining the currently infested area. Eradication of an entrenched stand of Japanese knotweed, however, is easier said than done. You can slash Japanese knotweed to the ground, but they come back. You root them out and destroy by fire on a would-be funeral pyre; but it is only you who feel lifeless, fatigued from all your labours. Why, Japanese knotweed even mocks concrete, bursting up through any available crack in a driveway or path with its incredible tenacious strength.
But is killing knotweed a realistic goal? Is it possible to kill the Japanese bamboo and reclaim your lands? Well, for those who would like to free up some landscaping space for a garden by killing an well-established stand your hope resides in different tactics, as part of a multipronged strategy, carried out diligently over a long campaign. There is hope for your garden, but you'll have to be persistent with your tactics and wage a smart war. And if you'll settle for just suppressing the enemy at first, using landscape fabrics or even old carpets, you can at least reclaim the war-torn land for the short term, while you maintain the siege that will (hopefully) kill Polygonum cuspidatum for the long term.
Begin by investing in some plastic , with which you'll cover your patch of Polygonum cuspidatum and smother it. Invest the money in the biggest you can find, the outlay will save you a lot of labour. If the landscape area from which the Japanese knotweed emerges is covered in the early spring with plastic or carpet, the Japanese knotweed's growth is immediately impeded.
The covered knotweed will still make a protest. It is not for nothing that in Japan, home of this killer bamboo, Japanese knotweed is referred to as itadori, which means "strong plant." With their Godzilla like strength, the new shoots will act like tent poles, pushing your coverings up. But you can then simply trample them down by walking over them. What growth does occur under these will be unsuccessful, deprived of sufficient sunlight. Make sure your covers overlap each other considerably, and are weighted down all along the seams and the outskirts; or else the sun-seeking shoots will be pushing through the gaps in no time. This is why buying the largest covers you can find, is a good investment.
One reason why I would say that this covering tactic is perhaps the most powerful of your options is the fact that, during carrying out this, the piece of your lands can be reclaimed for above-ground gardening uses. For example, you could apply an attractive mulch on top of the covers, and display containers in this area. You could even build raised-bed gardens right on top of the covers. No matter how long it takes the Japanese knotweed down below to be smothered, your raised beds will be safe: the covers act as a protective barrier against incursion.
Knotweed can be suppressed (but not eradicated) by cutting it back all the way through the summer, so that its photosynthesis is never allowed to operate at high levels. Since cuttings will easily sprout new roots and re-entrench themselves in the landscape or garden, pick up the cuttings and bag them afterwards. Don't rely on the cutting method in isolation, though. Cutting back Japanese knotweed regularly is a tactic only meant to be used in conjunction with injections of weed killer into the cane stumps. But this is a lot of work, and certainly not my preferred method.
Finally, dig into the ground where the bamboo shoots come up most vigorously in your garden. In these areas you will probably discover the rhizome-clumps from which spring the knotweed's roots and shoots. In stands of Japanese knotweed that have flourished for many years, these rhizome-clumps are very woody and quite easily reach widths of a foot or more. The rhizomes can be dug up and bagged. Do not, however, expect immediate results from implementing this tactic. For no matter how careful you are, some of the rhizome roots will snap off. And from even the tiniest root of Japanese knotweed left in the ground, a new plant will eventually emerge. But remember: this is a long-term war. In this case, the nourishment your enemy requires to fight you most vigorously is stored in its rhizomes. Think of the rhizomes as strongholds. Although enemy soldiers will fan out and hide after their stronghold has been destroyed, the loss of the stronghold makes their long-term success more difficult.
There is hope on the Horizon though: http://news.bbc.co.uk/2/hi/8555378.stm
“A tiny Japanese insect that could help the fight against an aggressive superweed has been given the go-ahead for a trial release in England.”
Since Japanese knotweed was introduced to the UK it has rapidly spread, and the plant currently costs over £150m a year to control and clear.
But scientists say a natural predator in the weed's native home of Japan could also help to control it here.
The insect will initially be released in a handful of sites this spring.
This is the first time that biocontrol - the use of a "natural predator" to control a pest - has been used in the EU to fight a weed.
Wildlife Minister Huw Irranca-Davies said: "These tiny insects, which naturally prey on Japanese Knotweed, will help free local authorities and industry from the huge cost of treating and killing this devastating plant."
A little known fact is though that it is edible and likened to rhubarb! Here is a link to a site, I may just try some! Why not, it’s very nutritious, has many medicinal uses and also contains an organic pesticide; this is well worth a visit! Highly interesting!
Posted by Andrew King at 1:51 PM
Friday, June 17, 2011
Common namesGiant hogweed, The Hog, giant cow-parsnip and cartwheel flower.
A Brief History:
Heracleum mantegazzianum was first recorded on the seed list of the Botanic Gardens at Kew in 1817. A likely first incidence of introduction in the wild was 1828 in Cambridgeshire. The plant then spread through the greater part of Europe by 1900, mainly vectored by those most potent agents in the circulation of invasive plants; namely, gardeners and plantsmen. Here is Gertrude Jekyll, (probably the most influential gardener of the twentieth century), in a couple of articles written for "Country Life". These articles begin in the 1890's, but were mainly written after 1912.
"For cool, quiet places where there is a backing of copse, there should be free planting of the giant Heracleum mantegazzianum, with its very large leaves and branches of white bloom four feet across. It is a distinct improvement on the older kind of giant Cow Parsnip, Heracleum giganteum, for the leaves are larger and a glossier green, more deeply slashed and more sharply toothed, and the massive bloom is larger altogether."
In another article:
"Prominence would be given to the fine Heracleum Mantegazzianum, a notable improvement in all ways on the older Heracleum giganteum, give it the appearance of a specially proud and sumptuous plant. It is a native of Abkhasia, a small Russian province on the Black Sea at the foot of the Caucasus." Quite correctly, Miss Jekyll ascribes the source of the new plant to the western Caucasus.
Giant hogweed does what invasive plants do. Its height, spread and capacity for producing dense stands of plants, cuts out around 80% of daylight reaching lower growing species. Many of these are out competed as the plants germinate or start vegetative growth very early, and grow with alarming rapidity. This lost of plant diversity leads to subsequent loss of the other organisms that depend on that very diversity. Like Japanese knotweed, (Which I will be covering in my next blog) its size and alien appearance, whilst sometimes breathtaking, does not look well with the visual congruity in our rural areas.
This mammoth plant grows from the seed to build an enormous rosette of foliage, with leaves up to 3 metres long.
When it has enough energy stored in its rootstock, it thrusts up its tall flower stem to hold multiple umbels of flowers, which can generate as many as 100,000 seeds. In extremely poor growing conditions it will delay the flowering stage until it is big enough to make a good job of it. This may take 12 years or so. Under more sympathetic conditions, flowering is from between the 3rd to the 5th year of life. The plant is usually monocarpic, and its life ends when seed has been set. It is reported that some individuals form perennating crown buds arising from the rootstock, and that ancillary flower stems can be produced in seasons succeeding to the main flowering.
Its main claim to notoriety is in its ability to produce a virulent contact dermatitis on the human skin, (Phytophotodermatitis) when conditions of strong sunlight and high temperatures and humidity combine with skin exposure to sap.
The chemicals causing this unpleasant syndrome are known as Furocomarins which are also found in other members of the Apiaciae and some other plants. Symptoms consist of intense reddening and extensive blistering, dark pigmentation of the skin, and a discoloured scarring, which remains noticeable for a very long time. Sap splashed in the eyes can have particularly bad consequences.
Organic Control Methodssafety of the operators affecting the control of this plant is the first concern when instituting a control programme. Long gauntlet gloves, waterproof overalls and boots and eye protection must always be worn. Where strimmers and powered cutters employing high-speed blades are used, suitable protective masks should be worn to prevent atomised sap being inhaled.
Unless circumstances dictate that the control method is cutting of the umbels, all other control methods should be started early in the growing season.
Perhaps most surprisingly enough I have found out, sheep and cattle can be used to graze the plants, and will develop a distinct liking for it, making substantial control possible. Introduction of animals early in the season on sites where there is still a mixture of vegetation, or performing a pre-grazing cut to encourage a mixed sward, reduces the possibility of initial rejection by the animals, or of toxic effects being experienced. Breeds with dark skin on exposed areas and external mucus membranes are unlikely to suffer phytophotodermatitis. (The nostrils, eyes, anus, genitals and udders of the grazing animals should however be monitored,) and any animals adversely affected, removed to clean pasture.
Mechanical methods include cutting the root of the plant at a depth greater than 10cm below ground level, using a sharpened spade or similar implement. The above ground plant parts are then pulled and spread to dry. This is a no-argument method for small infestations.
Mowing conducted 3 times in the growing season for a number of years will exhaust the seed-bank and finally the more mature plants, and can eliminate infestations. Competing grass swards should also benefit and become denser.
Posted by Andrew King at 7:01 PM
Wednesday, June 8, 2011
Corrigans city farm, Blackpool: Equisetum, control methods: "Field Horsetail Biology and Control methods This perennial plant belongs to the Equisetaceae , Equisetum or horsetail family. Equisetum c..."
Posted by Andrew King at 7:42 PM
Field Horsetail Biology and Control methods
This perennial plant belongs to the Equisetaceae, Equisetum or horsetail family. Equisetum comes from Latin, equus meaning horse and seta meaning brittle, referring to the barren stems that supposedly resemble a horse’s tail.
Some other common names are joint grass, mare’s tail, horse pipes or snake grass. There are several members of this family that are native to the northwest.
Members of the Equisetaceae family are prehistoric plants, as are ferns, which may provide a clue as to why and how they have been around so long. This plant spreads by spores located on the cones and has an extensive creeping rhizome system that penetrates to great depths in the soil.
Field horsetail, Equisetum arvense L. is a perennial with aerial stems and underground tuber-bearing rootstocks which has dimorphic stems: a fertile cone-bearing stem which arises in early spring is flesh-colored and ½ to 1 foot tall with cones ¾ to 1½ inches long; a sterile or vegetative stem arises after the fertile stem and is 1 1/5 to 2 feet tall with many whorls of slender, green jointed branches.
Giant horsetail, Equisetum telmateia Ehrh resembles field horse tail but is much more robust with sterile stems over 1½ feet high and cones which are 1½ to 4 inches long.
Smooth Scouring Rush, Equisetum laevigatum A. is a tenacious perennial plant with deep, spreading rootstock. Stems are rough (high silica content), jointed and hollow. Leaves are scale-like appendages located at stem nodes. Fertile stems have a terminal spore-producing cone. Field horsetail produces whorls of branches at each stem node while Scouring Rush is coarse with evergreen stems and very apparent bands at the base of each collar. Field horsetail is adapted to wet areas, while Scouring Rush can establish either along stream banks or in relatively dry soils. Field horsetail is a noxious weed that has survived millions of years to become one of the most tenacious weeds today. It is toxic for horses, sheep and cattle when consumed. Horsetail is difficult to eradicate despite a gardeners best efforts. It spreads by spores carried by the wind every spring and by its tubers. It thrives in wet soils, which is why it is commonly found near rivers, lakes roadsides and ponds or poorly drained ground. This perennial weed has a deep and extensive root system and easily survives cold winters;
Some steps to help eradicate this thug of weeds
Wear your gloves and dig up a small horsetail plant with a spade, making sure to get all the roots. Even the smallest piece of rootstock will grow into a horsetail plant. without delay collect it in a plastic bag, knot it securely and dispose of appropriately. Not on the compost heap!
Chop or mow horsetail weed to ground level if the plant is large or covers a vast area. Put the foliage in a plastic bag and dispose of appropriately.
Break the thick stem or slash it with a sharp knife or shovel in several places. Make sure the gashes are deep enough and bruise the plant. Douse the plant in commercial weed killer that contains glyphosate,( I know, but it is effective, and I am going against my principles, but as a spot weedkiller I’ll excuse myself this is the last result) pouring directly over and around it. The weed killer will penetrate the gashes and eventually kill the horsetail plant. Treat any new growth promptly, and reapply the herbicide later in the season, or early next season to eradicate it permanently.
A much more ecologically friendly approach, is to pour vinegar directly over the horsetail plant and the soil around it on a dry day to eradicate it from your lawn. Horticulture vinegar is stronger than household vinegar and kills young plants immediately. Reapplication may be required the next day and for a few days after for mature plants .
The long-term control of Equisetums has been very difficult due to their tenacious root systems and high silicone content. An integrated control approach can help alleviate the problem. Improve drainage and encourage growth of a healthy perennial grass cover. Cut or burn fertile stems prior to spore formation to reduce spread potential. Porous landscape fabrics or black plastic mulch effectively prevent Equisetum growth. Smother the horsetail plants as an alternative to applying weed killer to it. Spread a plastic sheet or a 1/2-inch thick cardboard over the mowed plant and poke holes in it to allow mulch to penetrate. Spread a thick layer, at least 5 to 6 inches, of pine bark or mulch over the sheet; leave it for four to five months. The plants will compress under the weight and eventually die due to lack of oxygen.
(Sawdust or bark mulches are ineffective. Deep cultivation can be effective in the short term. Be aware that rhizomes cut into very short pieces will regenerate. Shallow cultivation and dragging the rhizomes are not advised.)
Posted by Andrew King at 7:41 PM