Technical Case study
Rates and water volumes Problem
Common Ragwort (overall or spot spray)
Dose Rate
5 l/ha Roundup Pro Bio in 80-250 litres of water. 4l/ha Roundup Pro Biactive 450
Common Ragwort (hand-held weed wiper)
1 part Roundup Pro Bio in 2 parts water 1 part Roundup Pro Biactive 450 in 3 parts water
The Crown lands of the New Forest National Park are managed by the Forestry Commission, and with considerable populations of ponies and cattle grazing in the forest, controlling ragwort is an important task.
The Forestry Commission’s Open Forest Manager Dave Morris explains: “We tend to use the ‘historic’ method of hand pulling during the summer months. We have done a small trial with herbicides, but our policy is to avoid chemicals if possible.”
Dave comments that ragwort is not a problem year-on-year but some years, such as 2012, the workload is considerable.
“We draft in labour for a period of six weeks to hand pull the ragwort, using teams of contractors, volunteer rangers and our own staff.”
Although the open forest totals 18,000ha, Dave explains that ragwort tends to grow in specific habitats, such as old airfelds or the edge of roads, and is not prevalent on the open heath.
“We target our resources to pull and bag the ragwort, which is then collected and taken to specific disposal points for composting, where there is no likelihood of livestock encountering the dying plants. We avoid burning as the fire risk is already high at that time of year.”
He adds that, by pulling the ragwort before heading takes place, there is no risk of seeds blowing and reinfesting the forest.
“I would say that we are on top of the ragwort, and have controlled its spread, but there are no plans for eradication. We recognise that there are some species, such as the cinnabar moth, that use ragwort, and we have a policy to leave any plants that have the caterpillars on them.”
Dave points out that there is increasing pressure from environmental groups to preserve ragwort, and that it is a delicate balance between maintaining habitats and avoiding infestation where ponies and cattle graze.
“The New Forest is an SSSI, so we have clear guidance on habitats from Natural England and accept the need for management,” he concludes.
Application tips
Spray at flowering, but before seed set. Ragwort plants can be cut or pulled 5 days after spraying, allowing grazing to recommence. Any remaining roots will die off
Useful method when working in inaccessible areas
Most knapsack sprayers are supplied with a set of four deflector nozzles giving different swath widths but all delivering 200l/ha of water at 1 bar pressure and a walking speed of one metre per second
Spot treatment in knapsack (Standard 200 l/ha nozzles) Area sprayed
Volume of Roundup Pro Bio/Pro Biactive 450
50 square metres 500 square metres 1000 square metres 25ml/20ml 250ml/200ml 500ml/400ml
directed knapsack sprayer fitted with a sprayer hood or guard. Apply Roundup Pro Bio at a rate of 5.0 l/ha or Roundup Pro Biactive 450 at 4.0l/ha. There must be enough actively growing leaf above ground to absorb sufficient product to kill the underground roots. Avoid spraying whilst the stem is extending rapidly as the sap flow is against the direction of movement down to the roots and poor control may occur. Apply from when they have produced a
flowering stem, but before seed are set. Plants in the first year rosette stage may also be spot treated, but they may be hard to spot amongst taller grasses. Ragwort plants can be cut or pulled five
days after spraying, allowing grazing to recommence. Any remaining roots will die off - always wear gloves when handling ragwort.
Volume of water 1 litre 10 litres 20 litres
2) Using a handheld or trailed weed wiper will allow selective control of taller plants in grass or turf. When using a hand-held weed wiper, the rate of application is one part Roundup Pro Bio to two parts of water or one part Roundup ProBiactive 450 to three parts of water. The latest generation of trailed rotary and tractor mounted weed wipers make selective application of Roundup Pro Biactive possible over large areas. Application is typically 1 part Roundup Pro Bio to 10-20 parts water (or 1 part Roundup ProBiactive 450 to 12 -25 parts water) according to the weed wiper manufacturer’s instructions.
3) As part of a reseeding programme to establish a new grass sward. Roundup is applied overall to destroy the whole sward prior to re-seeding.
Ragwort after three weeks with leaf material removed before it dies to allow horses to go back and graze, showing how careful spot treatment can cause minimum damage to surrounding grass
136 I PC JUNE/JULY 2014
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