Montbretia (Crocosmia x crocosmiiflora)

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Impact

Montbretia grows in dense clumps and is capable of adapting to a variety of conditions. It out-competes native plants, particularly in native bushland and riparian areas. The biodiversity of ecosystems can be significantly affected by an infestation of montbretia. Dense growth of this plant along riparian areas can lead to creek bank erosion and sedimentation.

Montbretia can sometimes still be found for sale at local fetes, nurseries and markets, despite the ban on sale in NSW.

Distribution

A horticultural hybrid plant, developed in France for ornamental purposes. It is the result of the intentional cross between the plants Crocosmia aurea and Crocosmia pottsii, both of which originated from South Africa.

Montbretia is located in all states of Australia, with the exception of the Northern Territory. It is most prevalent close to highly populated city and coastal areas. It is likely that spread has occurred from inappropriate dumping of garden waste.

In NSW, Montbretia is present at various locations along the eastern coast. Isolated infestations occur in the Tablelands regions and on Lord Howe Island. It is of particular concern in the Manly and Blue Mountains areas near Sydney.  

Spread

Montbretia mostly spreads from underground runners and bulbs. Each plant can produce up to 14 new bulbs annually. These bulbs break off from the parent plant and begin to produce their own root network. This increases the size and density of an infestation. Bulbs can be transported to new locations by dumped garden waste, water and movement of contaminated soil.

Lifecycle

Flowering occurs during summer and autumn. The leaves and flowers die back in autumn after producing seeds. Foliage begins to grow from the bulbs in spring. 

Description

Montbretia is a perennial herb, usually growing to about 60 cm tall, but sometimes reaching up to 100 cm in height. The above-ground foliage is short-lived, and grows back each year from underground 'bulbs' and creeping stems (i.e. rhizomes). 

The green stems are long and strap-like. They are 30-80 cm long, 1-2 cm wide and are mostly clustered near the base of the plant. There are usually only about 6-12 leaves produced by each individual 'bulb'. The leaves are soft, and sometime droop towards the ground. They are hairless with entire margins and pointed tips.

The flowering stem of montbretia is 15-30cm long and zigzagged.

The trumpet shaped flowers are yellow to orange-red (usually orange-red with yellow centres).  The petals are 3-4 cm long and 2-5 cm wide. They have three stamens and a style that splits into three short branches near its tip. Flowering occurs mostly during summer and autumn, but also during spring in warmer climates.

The fruit are capsules (5-10 mm long) that turn from green to brown, and become shrivelled, as they mature. Seeds are usually not produced, but when present they are brown or reddish-brown in colour and flattened or triangular in shape (about 3 mm long and 1-2 mm wide).

Habitat

A weed of temperate and sub-tropical environments. It inhabits wetter grasslands, open woodlands, pastures, waterways, gardens, roadsides, waste areas, disturbed sites and railway enclosures.

References

Department of Employment, Economic Development and Innovation (2011) Montbretia: Crocosmia x crocosmiiflora, Queensland Government. Available at http://keyserver.lucidcentral.org/weeds/data /03030800-0b07-490a-8d04-0605030c0f01/media/Html/Crocosmia_x_crocosmiiflora.htm. Accessed August 2014.

Hosking JR, Sainty GR, Jacobs SWL & Dellow JJ (in prep) The Australian WeedBOOK.

James, TA and Brown, EA (2014) Crocosmia x crocosmiiflora (Lemoine ex Burb. & Dean) N.E.Br., in PlantNET - The Plant Information Network System of The Royal Botanic Gardens and Domain Trust, Sydney, Australia. Available at http://plantnet.rbgsyd.nsw.gov.au. Accessed August 2014.

Richardson FJ, Richardson RG and Shepherd RCH (2011) Weeds of the south-east: an identification guide for Australia. RG and FJ Richardson, Meredith, Victoria.

Weeds of Blue Mountains Bushland (2014) Montbretia: Crocosmia x crocosmiiflora. Available at: http://www.weedsbluemountains.org.au/montbretia.php. Accessed August 2014.

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Control

The bulbous nature of montbretia makes physical control difficult. Small infestations or individual plants may be manually dug up from the ground. All root material and bulbs must be removed.

Herbicide control

Foliar application of a registered herbicide during flowering can have some success. Best results are usually obtained using a wiper wand application over the foliage between flowering and fruiting.

Always monitor control efforts and repeat treatments as necessary.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


PERMIT 9907 Expires 31/03/2020
Glyphosate 360 g/L (Roundup®)
Rate: 1.0 L in 50 L of water
Comments: Spray between flowering and fruiting.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2020
Glyphosate 360 g/L (Roundup®)
Rate: 1 part glyphosate per 1 part water
Comments: Weed wand application.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


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Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds Act 1993.

Area Class Legal requirements
Blue Mountains 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed

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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW Invasive Plants and Animals Enquiry Line on 1800 680 244 or send an email to weeds@dpi.nsw.gov.au

Reviewed 2014