Sweet briar

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Sweet briar (Rosa rubiginosa)

Description | Habitat | Life cycle | Spread | Control & Management | Legislation

Sweet briar (Rosa rubiginosa) is a native of Europe that now grows throughout the world. The fruit or hips are rich in vitamin C and have been used in making syrups.

The plant is widespread in NSW but is more common in the cooler, high rainfall areas. The worst infestations are usually found on the tablelands and cooler slopes.

Sweet briar can reduce the carrying capacity of land, harbour rabbits, restrict vehicle access and restrict stock movements, especially where it occurs in clumps or patches.

Description

Sweet briar is an erect perennial shrub, commonly growing 1.5 to 2 m high but can be up to 3 m.

Many stems arise from a shallow, perennial rootstock. They are smooth when young and become rough and woody as the plant ages. They arch towards the top and have numerous backward curving flat thorns up to 1.5 cm long.

The leaves are pinnate and have an apple-like fragrance. They consist of 2 to 4 pairs of oval leaflets plus one terminal leaflet. The leaflets have serrated margins and short prickles on the leaf stems.

Flowers usually appear in late spring and are pink or white with 5 petals and long green sepals or leaflike structures at the flower base. They form in loose clusters at the ends of the branches and are also fragrant.

The fruits are orange-red in colour, oval shaped with short spines and contain numerous, yellow, irregularly shaped seeds. The sepals remain attached to the fruit.

The extensive roots are at least 1 m long and are usually confined to the top 30 cm of soil.

Habitat

Sweet briar often invades unimproved grasslands and disturbed bushland. It prefers well-drained areas of moderate fertility with little competition and light grazing. The weed can grow on most soil types.

Generally, it is confined to areas in NSW with an annual rainfall greater than 600 mm. However, in lower rainfall areas, infestations can still occur in moist gullies and protected sites.

Infestations are often heaviest in hilly and rocky country around trees on creek banks and along fence lines.

Life cycle

The seeds of sweet briar can germinate at almost any time of the year. Young seedlings are not very competitive and few survive grazing or competition from other plants.

Plants generally begin to flower after three years. This is usually in November and can continue until early summer.

Sweet briar is a deciduous plant and sheds its leaves in autumn, with new leaf and cane growth starting in spring.

Fruits mature during summer and are shed in autumn/winter after leaf fall.

The life cycle of sweet briar

Spread

Sweet briar is spread mainly by birds or animals eating the fruit and distributing the viable seed.

Fruits and seeds can also be spread by run-off in steep country along creeks and streams. The seeds can remain viable in the soil for up to 4 years.

Root pieces and disturbed crowns of sweet briar can also produce new growth or suckers.

Control and Management

The effective, long-term control of this weed may require the integration of a number of techniques including mechanical removal, pasture management, grazing management, herbicide application, regular monitoring and replacement with appropriate plants.

For invasive, woody weeds such as sweet briar, control is more effective and economical if done when the plants are young.

The control methods used will depend on the infestation size and location. For advice on the most appropriate methods for your situation, consult your local agronomist or council weeds officer.

Mechanical removal

Established plants can be removed by hand grubbing, bulldozing or tractor and chain. This is easier and more effective when the ground is wet. Deep cultivation can be effective on arable land as it exposes and kills the bulk of the root system.

However, it can be difficult if the bushes are large or dense. After the initial removal, further cultivations in summer will ensure the remaining root system is exposed and killed. Normal autumn cultivations before sowing pastures or crops will kill any remaining seedlings.

The site should be monitored regularly and any regrowth should be treated with repeat cultivations or by spraying with an appropriate herbicide once it is a sufficient size (refer to the chemical label).

Pasture management

Vigorous perennial pastures provide competition to reduce the invasion of sweet briar. In suitable sites, they should be established as soon as possible after the removal of the weed infestation but not after the application of residual herbicides.

Consult your local agronomist for advice on pasture establishment and appropriate pasture management. For further information refer to a range of NSW Department of Primary Industries (DPI) publications available at any DPI office or www.dpi.nsw.gov.au/agriculture.

Grazing management

Grazing management is also useful in controlling sweet briar. Sheep will readily graze young seedlings and help prevent their establishment.

Cattle are not as good at preventing seedling establishment and an increase in sweet briar infestations is often noticed after graziers switch from sheep to cattle.

Sweet briar is highly palatable to goats so they can be very successful in controlling infestations. They will readily graze both established plants and seedlings, continually defoliating all accessible stems and eventually ringbarking them. This kills established plants and prevents seedlings from establishing.

Chemicals

Refer to the Noxious and Environmental Weed Control Handbook for a guide to the recommended chemicals to control sweet briar.

Only use registered herbicides according to the label directions.

Herbicides can be applied to sweet briar in many different ways. The most appropriate form of herbicide application will depend on the location, size and maturity of the infestation.

Treated infestations should be regularly monitored for regrowth because seedlings, spray errors and root shoots (suckers) can occur over a period of years. Regrowth should not be treated with an appropriate herbicide until it is of sufficient size (refer to the chemical label).

Applying chemicals through foliar spraying is more effective when the plant is actively growing.

Foliar spraying is the most commonly used method of control. For effective control spray the whole bush thoroughly when soil moisture is adequate and the plant is actively growing. This will vary depending on location but is generally during late spring to early autumn. The plant should be in full leaf, prior to leaf fall (refer to the chemical label for the most appropriate time). Insufficient herbicide coverage is a common mistake and is probably the largest cause of survival.

A systematic approach is required when spraying. Spraying should commence at the top of the bush and work down to the base. Seedlings and suckers around the drip zone of the plant also need to be treated.

For effective results, DO NOT treat infestations during hot, dry, summer periods or when the plant is stressed from drought, waterlogging, cold or without leaf.

Basal bark application of chemicals should be to the complete base of every stem to a height of 30–40 cm above the ground.

This technique is less effective but is appropriate for infestations in environmentally sensitive locations. It is most suited for small bushes with stems less than 5 cm in diameter.

Spray an appropriate herbicide mixed with diesel around the COMPLETE BASE OF EVERY STEM to a height of 30–40 cm above the soil surface. Check the chemical label for the correct mixing ratio.

Ensure that stems and bark are not wet at the time of application as water will repel the diesel mixture. Basal bark treatments also work best if plants are actively growing.

In cut stump applications it is important to apply the chemical immediately to the cut stem.

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This technique is labour intensive but is also appropriate for small infestations in environmentally sensitive locations. It is most suitable for large plants with a stem diameter greater than 5 cm.

Cut each stem off 15 cm above the soil surface. Liberally apply an appropriate herbicide mixed with diesel (check the chemical labels for the correct mixing ratio) to the cut surface within 30 seconds of the cut being made.

If the herbicide is not applied immediately, the plant will heal the cut, the chemical will not be translocated through the plant and control will not be effective.

Great care must be taken when using this technique.

Many desirable trees, in particular eucalypts, are susceptible to the residual herbicides used for this control method. DO NOT use these chemicals within a distance of at least twice the height of adjacent desirable trees or shrubs.

To control sweet briar, apply an appropriate residual herbicide directly under the plant near the base. The herbicide should be applied under the soil to prevent degradation by sunlight and possible contamination of surface run-off after rain. It is most effectively applied when the soil is moist.

Deep-rooted plants may need to be retreated after 2 years if they are still partially green.

Legislation

Sweet briar is a are declared Class 4 weeds under the NSW Noxious Weeds Act 1993.

As a Class 4 weed, the growth and spread of the plant must be controlled according to the measures specified in a management plan published by the local control authority.

The Noxious Weeds Act 1993 is enforced by the local control authority, usually local government.

The responsibility for control of noxious plants and appropriate disposal of weed plant material on private land rests with the owner or occupier of the land. Failure to do so could result in the local control authority issuing a weed control notice, court action and a fine.

Local control authorities must control noxious weeds on land under their control adequately to prevent the infestation of adjoining land. The community can assist the control of this weed by notifying the local control authority of any known infestation of sweet briar on public land.

Acknowledgements

Authors: B. Clements District Agronomist, Bathurst
J.J. Dellow former Weeds Agronomist, Orange Agricultural Institute
A.C. McCaffery former Project Officer (Weeds), Orange Agricultural Institute

The authors would like to acknowledge the comments made by Tony Cook and Clare Edwards regarding the technical content of this publication.

Information for this Primefact was taken from:

• Sweetbriar. Second Edition. AgFact P7.6.19.
• Parsons W.T. and Cuthbertson E.G. (2001). Noxious Weeds of Australia. 2nd Edition.
• Sweet Briar (Rosa rubiginosa L.). DPIWE Information Sheet. Agdex 647.