Control of Bracken (Pteridum aquilinum) with Roundup Pro Biactive

 

Bracken, Pteridium aquilinum, is widely distributed throughout the UK being by far the commonest fern. Today bracken, in the UK for example, covers over 8% of the country, an area of 11,000 sq.km.  It is spreading at 1-3% per year, the rate of spread is faster than all the programs in place to control it, and it is encroaching on to grazing ground, forestry and amenity areas, reducing bio-diversity.

In many areas bracken has spread from its traditional niche on the shoulders (upper slopes) of the hills. Expansion from these areas has been at the expense of open heather moor, semi-improved grassland, grass heath and wooded areas. Frequently bracken forms almost pure stands, so thick that it is essentially a monoculture, the shading being so severe that little or nothing can grow beneath it.

To further exacerbate the problem, bracken provides a refuge for sheep ticks and thus Louping Ill and the more serious Lyme disease, its spores are considered carcinogenic and it is poisonous to cattle and horses, giving rise to 'bracken staggers'.

Successful control of Bracken can be difficult. The main reason for this is the extensive underground rhizome network. This network consists of two rhizome types: storage rhizomes (70-80% of total rhizomes), which contain large carbohydrate reserves, and frond bearing rhizomes carrying a large number of frond-forming buds.

Control methods

Repeated cutting will weaken the rhizomes. Asulox may be sprayed overall without damage to grass and can be sprayed from a helicopter, but it only controls frond-bearing rhizomes, there are LERAP restrictions for use near water courses and it is very costly. 

 

Control with Roundup Pro Biactive

 

Timing of control is critical. Successful control using Roundup Pro Biactive is dependent upon the timing of the treatment in relation to the movement of nutrients and dry matter between the underground storage rhizomes and the fronds. As the fronds develop in spring the reserves in the storage rhizomes diminish. Once the fronds are fully expanded, the products of photosynthesis will start to be translocated down to replenish the underground reserves. Treatment of the fronds as they approach full size in July-August will remove resources from the system and will prevent its replenishment thereby successfully reducing the vigour/viability of the bracken. In essence, the underground rhizomes are starved of resources.

 

Overall Spraying

 

Overall spraying is appropriate for large areas and thick stands. In many instances little or no other plants will be growing beneath the bracken canopy, and, in any case, the bracken fronds will intercept almost all of the herbicide spray. Apply Roundup Pro Biactive as soon as the fronds have fully expanded, usually early July-August. Later timings up to mid-September can still give satisfactory results but must be pre-senescence of the foliage. (In any case it is unwise to carry out treatment when ripe carcinogenic spores are in the air.) Treated fronds will die back within four weeks of treatment, the Roundup being translocated down into the rhizome network killing both frond forming and storage rhizomes.

 

Weed Wiping

 

Small areas or isolated plants may be controlled by pulling or cutting as the fronds are fully expanded but a second effort may be required to deal with any re-growth, usually 6-8 weeks later. Alternatively, a hand-held weed wiper may be successfully used to apply Roundup Pro Biactive, at full frond expansion.

 

Large areas, especially scattered populations or patches in grassland, moorland or heath land, may be effectively controlled using tractor/quad bike-trailed weed wiper. Use of such applicators will ensure superior, cost-effective control of the bracken whilst leaving grass, heather and other plants unharmed.

 

The new generation of trailed and rotary weed wipers, such as the C-Dax Eliminator, Logic Contact 2000, WeedSwiper or the Carier Rollmaster or Rotowiper make efficient selective application of Roundup Pro Biactive, possible over large areas.

 

The bracken should be ‘wiped’ at full frond expansion but before they start to turn brown and die back. Optimum control is achieved during July/August. Later timing up to mid-Sept can still give satisfactory results but must be pre-senescence of the foliage. Do not treat when the fronds are wet or rain is imminent. Always ensure a height differential of 10cm between the bracken and the grass to maintain selectivity.

With large plants in dense stands the amount of Roundup Pro Biactive that can be successfully applied to the fronds, whether using an overall spray or a weed wiper, may not result in a total kill and some re-growth may be seen in the following year. The best levels of control are seen where Roundup Pro Biactive is used as part of a long-term management programme with 2-3 treatments over a period of up to 5 years.

 

Livestock

If the bracken is being controlled in an area accessible to livestock the animals should be kept away from the treated area whilst spraying and for 7 days where spraying is overall, and until the spray has dried on the leaf where spot treatment or wiping is carried out. However, it must be noted that treated bracken may become palatable and is of course poisonous. So it may be prudent to exclude stock until the foliage has completely died down if the bracken takes up a large proportion of the available grazing area. This is also important if other poisonous weeds like Ragwort, Cowbane, Hemlock or Hemlock Water Dropwort are present in the treated area.

Rates, Timings and Water Volumes

Method	Dose Rate of Roundup Pro Biactive	Dose Rate of Roundup ProBiactive450	Application Advice
Overall Spray	5l/ha in 80-250 litres water	4l/ha in 80-250 litres water	Spray at full frond emergence, usually late July/Early August.  Before sporulation and senescence
Hand-held weed wiper	1 part Roundup in 2 parts water	1 part Roundup in 3 parts water	Usefull method for small areas of re-growth and inaccessible areas

Spot treatment in knapsack sprayer

 

Most knapsack sprayers are supplied with a set of 4 deflector nozzles giving different swath widths but all delivering 200l/ha water at 1 bar pressure and a walking speed of 1 metre per second

 

Area Sprayed	Dose rate of Pro Biactive	Dose rate of ProBiactive450	Volume of Water
50 Square Metres	25 ml	20 ml	1 litre
500 Square Metres	250 ml	200 ml	10 litres
1,000 Square Metres	500 ml	400 ml	20 litres