Blue heliotrope (Heliotropium amplexicaule)

WEED ALERT: REGIONALLY PROHIBITED WEED
If you see this plant contact your council weeds officer, the NSW Invasive Plants & Animals Enquiry Line 1800 680 244 or email weeds@dpi.nsw.gov.au

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Impact

Blue heliotrope is extremely drought-hardy, which increases its ability to persist and spread, and has made it a major agricultural weed in NSW. Blue heliotrope competes with desirable pasture plants and causes toxicity to stock. It is widespread and adaptable to a wide range of soil and climate types. It occupies more than 110 000 hectares in NSW.

Toxicity

Blue heliotrope contains pyrrolizidine alkaloids (PAs). These PAs are also found in common heliotrope (Heliotropium europaeum). The amount of PAs in blue heliotrope is much higher than in common heliotrope.

Heliotrope is not very palatable to livestock, and consequently tends to be avoided; however, some individuals continue to eat it indiscriminately. Heliotrope will be eaten if no other feed is available.

Continual ingestion by livestock of large amounts of heliotrope plants (either fresh or dried), or of their seeds as contaminants in stock feed, can cause liver damage and reduced productivity (see Table 1). In order of susceptibility, horses, pigs, cattle, sheep and goats can all be affected, with horses being the most susceptible.

All affected livestock species may become jaundiced and experience varying degrees of photosensitisation.

Table 1. Summary of livestock toxicity symptoms

Animal Clinical Symptoms Production Effects Pathology
Horses Weight loss, dull, depressed, uncoordinated, wander aimlessly. Can develop respiratory difficulties. Death  Reduced productivity  Liver damage and secondary brain damage
Pigs Death   Liver, kidney and lung damage
Cattle Depressed, unpredictable bouts of aggression. Death Reduced productivity Liver damage and secondary brain damage
Sheep, Goats Can accumulate copper, which can cause sudden death when released. Reduced productivity Liver damage

Distribution

Blue heliotrope is a native of South America, and was probably introduced to Australia as an ornamental plant in the latter part of the 19th century. It was first reported in NSW in 1908 in the Hunter Valley, and since then has colonised large areas in NSW.

Distribution Maps

Spread

Blue heliotrope is adapted to a wide range of habitats, and can reproduce from both seed and root fragments. Blue heliotrope spreads aggressively, as it produces many sticky seeds that adhere to animals and machinery. Seed can pass unharmed through the digestive tracts of most animals. Blue heliotrope can also regenerate from root fragments. It is most commonly spread by road graders, farm machinery, livestock, humans and the movement of water along watercourses.

Flowering is largely dependent on rainfall, but usually starts in November and continues through summer until March. In frost-free areas, the plant is capable of growing and flowering at any time of the year after rain. Established plants produce a flush of new growth in spring and autumn, flowering profusely at these times. In warmer areas, plants may flower and set seed as early as July. The fruit develops into two nutlets, each containing two seeds.

The plant is frost-susceptible, dying off in winter and regenerating from the vigorous root system in the following spring.

Description

Blue heliotrope is a hairy, summer-growing, prostrate perennial herb, 15–30 cm high and 30–200 cm in diameter.

Blue heliotrope belongs to the Boraginaceae family which includes forget-me-nots (Myosotis spp), comfrey (Symphytum officinale), Paterson's curse (Echium plantagineium) and yellow burrweed (Amsinckia spp).

Stems

It has many hairy, branched stems radiating from a woody rootstock, and is highly aromatic.

Blue heliotrope has a strong, slender taproot that can be very woody. It generally extends to over 1 m, but has been observed at up to 2 m throughout the soil profile, with a complex system of lateral roots occurring at several depths.

Leaves

The leaves are alternate, dull green, soft and tapered at both ends.

Flowers

The flowers are bluish-purple with yellow centres. They grow in dense clusters along one side of a coiled stalk, often referred to as a fiddle neck.

Habitat

Blue heliotrope is often found along roadsides, in waterways, on non-arable country, in degraded pastures and on fallowed cultivation.

Major infestations occur in areas receiving more than 500 mm of rainfall per year, although it is also established in low-rainfall areas, such as the western districts of NSW.

Acknowledgements

Prepared by Annette McCaffery, Alyssa Schembri and Annie Johnson, NSW Department of Primary Industries, July 2008.

The authors would like to acknowledge the work done by Royce Holtkamp, Jim Dellow, Graeme Kelso and Barney Milne, NSW Agriculture, and the comments made by Rob Walker, Royce Holtkamp and Col Mullen regarding the technical content of this publication.

References

Da Silva, E. 1991. The ecology and control of blue heliotrope (Heliotropium amplexicaule Vahl). Final Report to the Wool Research and Development Corporation, 33 pp. 

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Control

Eradication of blue heliotrope is difficult. The effective control of this weed will usually involve a combination of the following options.

Pasture management

Overgrazing, which reduces competition from pasture, is a major cause of heliotrope infestation. Managing grazing pressure is critical to the control of this weed. Maintaining a vigorous summer-growing perennial pasture to out-compete blue heliotrope provides effective long-term control.

It is necessary to reduce the weed density using systemic herbicides before sowing a competitive perennial pasture. Advice on pasture management can be obtained from your local agronomist.

Grazing management

Where large infestations of blue heliotrope occur, sheep and goats can be used to manage heliotrope, provided a different group of animals is used each year.

The sheep rumen has a great capacity to degrade most of the poisons present in the plant. The merino has the greatest tolerance of heliotrope, but adult wethers should be used rather than breeding ewes or juveniles. British breed crossbred sheep are less selective grazers than merinos, and are more frequently affected by heliotrope poisoning.

Anecdotal evidence suggests that supplementing sheep with molybdenum and sulfate can reduce the chronic health effects of heliotrope poisons. The combined effect of molybdenum and sulfate is to reduce the accumulation of copper in the animal’s liver.

The aim of this practice is to either improve the short-term heliotrope tolerance of crossbred sheep or to allow the same group of merino sheep to be used to graze the plant over two or three successive seasons.

Correct grazing management to reduce PA toxicity is even more critical if Paterson’s curse is also present. In this situation, stock can be exposed to PAs during summer from the heliotrope and during the cooler months from the Paterson’s curse, increasing the risk of toxicity occurring from prolonged grazing.

Horses, pigs and cattle should never be used in the grazing management of blue or common heliotrope.

Cultivation

Cultivation gives short-term control of blue heliotrope, but also has the potential to spread the problem. To reduce the establishment of new plants from root fragments, it is best carried out after application of a systemic herbicide. Follow-up seedling control is essential.

Biological control

Biological control, if successful, has the potential to reduce the long-term economic and environmental costs of traditional herbicide control methods for blue heliotrope. There has only been one biological control agent released in Australia for blue heliotrope. The blue heliotrope leaf-beetle (Deuterocampta quadrijuga) was first released in Australia in 2001. At high densities, leaf-beetles can completely defoliate blue heliotrope, with both the larvae and adults feeding on the leaves. The blue heliotrope leaf-beetle has the potential to build up population levels rapidly, as each beetle lays several hundred eggs.

Chemical control

Systemic herbicides play a critical role in the control of blue heliotrope, by helping to destroy their root system. Only a registered herbicide, used according to the directions on the label, should be used to control a weed. 

To improve the effectiveness of chemical control, herbicides should be applied to blue heliotrope when it is actively growing and commencing flowering (late February to March). Avoid spraying stressed plants.

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 12286 Expires 3/10/2015
Metsulfuron-methyl 600 g/kg (Brush-off®)
Rate: 10 g per 100 L of water
Comments: Plus 0.1% surfactant. Spot spray. Apply when plants are actively growing spring to autumn.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High


2,4-D 300 g/L + Picloram 75 g/L (Tordon® 75-D)
Rate: 1.0 L per 100 L of water
Comments: Grass pastures only. Spot spray. Apply to young actively growing plants.
Withholding period: 1-8 weeks (see label).
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Dicamba 500 g/L (Kamba® 500)
Rate: 130 mL per 15 L of water
Comments: Knapsack spray.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Dicamba 500 g/L (Kamba® 500)
Rate: 0.6 L per 100 L of water
Comments: High volume spot spray.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Dicamba 500 g/L (Kamba® 500)
Rate: 8.8 L/ha
Comments: Boom spray. Apply to young, actively growing plants.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Fluroxypyr 200 g/L (Staraneā„¢ )
Rate: 1.0 L per 100 L of water
Comments: Spot spray. Apply during flowering.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Fluroxypyr 333 g/L (Staraneā„¢ Advanced)
Rate: 600mL per 100 L of water
Comments: Spot spray. Apply during flowering.
Withholding period: 7 days.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 500 mL per 100 L water
Comments: Treat at flowering.
Withholding period: Where product is used to control woody weeds in pastures there is a restriction of 12 weeks for use of treated pastures for making hay and silage; using hay or other plant material for compost, mulch or mushroom substrate; or using animal waste from animals grazing on treated pastures for compost, mulching, or spreading on pasture/crops.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Tebuthiuron 200 g/kg (Graslan®)
Rate: 0.5 g /m2
Comments: Do not use within 30 m of trees. Do not apply to areas greater than 0.5 hectares in size.
Withholding period: Nil.
Herbicide group: C, Inhibitors of photosynthesis at photosystem II (PS II inhibitors)
Resistance risk: Moderate


Triclopyr 300 g/L + Picloram 100 g/L (Grazon® DS)
Rate: 500 mL per 100 L of water
Comments: Apply at flowering in a minimum spray volume of 1250 L/ha.
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
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 (Weed Control) Order 2014 published in the NSW Government Gazette, detailing weeds declared noxious in New South Wales, Australia, under the Noxious Weeds Act 1993. The Order lists the weed names, the control class and the control requirements for each species declared in a Local Control Authority area.

Area Class Legal requirements
Bland 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Bogan 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Bourke 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Brewarrina 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Cabonne 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
Corowa 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
Dubbo 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
Gloucester 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Great Lakes 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Greater Taree 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Gunnedah 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
Kempsey 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Lachlan 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Mid-Western Regional 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
Narrabri 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
Narromine 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Parkes 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Port Macquarie-Hastings 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Unincorporated Area of Western Division 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Wagga Wagga 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
Weddin 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed
Wellington 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

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Disclaimers

Pasture improvement may be associated with an increase in the incidence of certain livestock health disorders. Livestock and production losses from some disorders are possible. Management may need to be modified to minimise risk. Consult your veterinarian or adviser when planning pasture improvement. The Native Vegetation Act 2003 restricts some pasture improvement practices where existing pasture contains native species. Inquire through the NSW Office of Environment and Heritage for further details.

Blue heliotrope flowers
Blue heliotrope flowers (Photo: J Edwards)

Blue heliotrope beetle (Deuterocampta quadrijuga)
Blue heliotrope beetle (Deuterocampta quadrijuga) (Photo: A Johnson)

Blue heliotrope plant
Blue heliotrope plant (Photo: J J Dellow)

Blue heliotrope rosette
Blue heliotrope rosette (Photo: J J Dellow)

Heliotropium amplexicaule - Blue Heliotrope
Heliotropium amplexicaule - Blue Heliotrope (Photo: John Hosking)

Heliotropium amplexicaule - Blue heliotrope
Heliotropium amplexicaule - Blue heliotrope (Photo: John Hosking)

Blue heliotrope flower head
Blue heliotrope flower head (Photo: Auld & Medd)

Blue heliotrope biological control agent larvae feeding on flower head
Blue heliotrope biological control agent larvae feeding on flower head (Photo: J Kidston)