nvasive weeds are an increasing problem in the UK sectors. The majority are alien but the most widespread damaging weed in agriculture, forestry and amenity is a native 'primitive' plant called Pteridium aquilinum otherwise known as bracken.
Bracken is a native species, originally being a shade loving plant like all other pteridophytes (ferns). Clearance of Britain's wildwood unleashed bracken into the wider environment and being able to cope with high light regimes it became a highly successful invasive weed. Creation of heathland by early agricultural communities for manageable livestock grazing gave bracken an 'escape route' from its niche forest and woodland environments. Bracken remains the primary obstacle in the restoration of significant tracts of land to 'authentic' lowland heath in England.
Bracken already covers around 7 per cent of the UK land area and the area covered is growing by 3 per cent every year. Bracken continues to overwhelm upland pasture at an alarming rate causing health hazards for sheep, cattle, farmers and hill walkers through poisonous alkaloids and disease-carrying ticks.
Bracken is the most difficult to control native UK weed and needs a multi-task approach requiring consecutive years of herbicide application to kill and eradicate the aerial fronds and underground rhizomes.
Such an approach has been devised by Micron Sprayers who specialize in application equipment for the control of weeds using highly targeted applications posing minimum risk to the environment compared with standard high volume overall applications, whether by lever-operated knapsack sprayers or power sprayers and leading to a risk of run-off and/or the pollution of water supplies.
The first phase of bracken control entails primary spraying or wiping, hitting bracken as swift and hard as possible over the widest area in the shortest time. A hand-held low volume sprayer called the ULVA+ and a vehicle-towed weed wiping applicator, the WeedSwiper, are ideally suited to this task.
The Micron ULVA+ Bracken Pack comes with a range of appropriate feed nozzles, calibration beaker, 5 protective masks and full instructions for bracken control. Micron Micropak backpacks (5 or 10 litres) are available to reduce the number of refilling operations required.
The ULVA+ offers fast treatment of large areas of bracken in a very short space of time. Its advanced spinning disc technology atomizes liquid into spray droplets of the right size to guarantee cost effective coverage using minimum spray volumes over a spray swath up to three metres wide.
A single operator can treat one hectare of bracken in just over 2 hours. Being battery-powered the ULVA+ does not require pumping which makes it the ideal choice for treating bracken on hillsides and open moors and other areas difficult to access and dangerous to treat with vehicle mounted sprayers. The ULVA+ is lightweight, easy to carry and use while being robust and simple to maintain. High work rates and low volumes used make the ULVA+ a highly cost effective option for primary spraying of bracken.
The Micron WeedSwiper is a non-drip weedwiper working off a 12 volt power supply and designed in different formats for mounting on a tractor or towed behind by, for example, by a quad bike (ATV) or a pick-up truck. The WeedSwiper allows safe and effective application of total non-selective herbicides, e.g. Roundup ProBiactive (glyphosate), using minimal amounts of herbicide (only that wiped directly onto the bracken) and without risk of run-off or dripping onto non-target plant species including pasture grass.
All units can be folded and operated at narrower widths than their maximum working width, and have a simple boom and break-back return system e.g. the 3 metre unit allows application to 1, 2 or 3 metre widths. The WeedSwiper's Hydrostat electronic control system regulates the supply of herbicide wiped onto bracken fronds by switching the pump on and off in response to changes in the amount of herbicide in the pad. The pad is continually saturated for maximum effective transfer of herbicide to the fronds, but never becomes over-saturated thus avoiding dripping irrespective of travel speed or weed density.
Sensors in the contact pads and Hydrostat control system automatically control fluid flow to the pads which are made of strong and tufted material with excellent fluid retention properties.
The 150mm (6 inch) deep pads provide a three-dimensional reservoir of active ingredient and a large herbicide transfer area to ensure each targeted bracken plant receives a sufficiently high dose of active ingredient on contact with the pad. Pad height can be adjusted to suit a range of variables including the terrain and height of bracken above valued plants below including grass. All units are supplied with pad covers to prevent accidental contamination and to safeguard operator safety.
Despite its reputation as an invasive weed there are many situations where targeted treatment is an essential requirement in bracken control. This includes sensitive conservation areas like woodland where measured amounts of bracken are a vital part of the life history of rare butterflies like the pearl bordered fritillary. Spot applicators are very useful for heather reclamation from areas of sparse bracken and for treating advancing fronds which are always a priority in stopping bracken encroachment (with the ULVA+ suitable for treating the periphery of large areas of encroaching bracken - or clumps when this sprayer is used in placement mode).
Spot-application is essential for treatment of sparse bracken as the second phase of a bracken clearance programme. Bracken fronds always re-grow after primary spraying or wiping and subsequent spot-applications are the recommended means of dealing with these small fronds in the years following initial treatment to avoid overuse of chemicals and environmental risk. Clearance of entrenched bracken with complex rhizome structures may require some 6 to 10 years of repeated, spot-treatment every year to stop re-growth.
Precise spot application can be secured using the hand-held Micron PrecisDos, which comes with a choice of quality nozzles and a 5-litre backpack, or by using Micron Microwipe. The Micron PrecisDos delivers small metered volumes and doses to make this spot-treatment of bracken as easy and as less tiring as possible. A team of 4 people equipped with PrecisDos, and working a 12m width, can treat an acre of rough ground in around 20 minutes making the system practical and most cost effective even in remote areas.
With the hand-held Micron Microwipe operators simply walk through moving the Microwipe over target bracken fronds to deliver a lethal dose by direct contact of the herbicide-containing rope wick and the bracken frond surface. This delivers a lethal dose of herbicide onto and into the fronds but nowhere else, making Microwipe ideal for safe despatch of bracken sparsely spread in swards.
Further information and details from:
Micron Sprayers Limited, Bromyard Industrial Estate, Bromyard, Herefordshire, HR7 4HS. Tel: 01885 482397.