DRAFT: FOR DISCUSSION

Guideline For the containment of Olive Hymenachne (Hymenachne amplexicaulis) to Genuine Grazing Systems

Preamble Hymenachne (Hymenachne amplexicaulis) or olive hymenachne is an invasive semi-aquatic grass, officially released in Australia in 1988 as dry season cattle fodder for use in ponded pasture systems. It quickly escaped from the production systems it was intended, invading wetlands, watercourses, water storages and irrigation channels and drainage lines in agricultural situations such as sugar cane.

Hymenachne is regarded as a ‘conflict species’ as it has both beneficial and detrimental impacts. Landholders planted hymenachne in good faith, on the advice of well-meaning governments as a source of dry season cattle fodder. Hymenachne has shown to be valuable to cattle production in purpose-built ponded pasture systems in Queensland and on alluvial flood plains of the Northern Territory. Unfortunately, hymenachne has escaped from such intentional plantings to wetlands, watercourses and other wet areas and now many landholders are reluctant to instigate control due to perceived production benefits. However, cattle will largely ignore hymenachne when other food sources are available, and, wet areas need to dry sufficiently for cattle to access and graze hymenachne. Vast stands of hymenachne go untouched by cattle in tropical areas. Therefore, its value outside of ponds and flood plains is questionable at best.

In Queensland, hymenachne is declared as a Class 2 pest under the Land Protection (Pest and Stock Route Management) Act 2002. Under this legislation, landholders must take reasonable steps to keep their land free of hymenachne. It is also an offence to introduce, supply or release a Class 2 pest in Queensland.

In the Northern Territory, hymenachne is declared as a Class B weed under the Weeds Management Act 2001, which means that its growth and spread must be controlled. It is also declared as a Class C weed, which prohibits its introduction into the Northern Territory.

This guideline sets out actions for containing the extent of existing olive hymenachne infestations that are a component of legitimate pasture production systems. Olive hymenachne is known to be used in ponded pasture systems in Queensland and on floodplains in the Northern Territory. All other infestations other than these are outside the scope of this guideline and must be dealt with as per relevant legislative provisions.

Aims of Guideline • A means of complying with State and Territory legislation to prevent the spread of hymenachne

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• Ensure no new plantings of hymenachne • Advise expectations for containment of hymenachne to existing pondage and floodplain grazing systems • Prevent spread of hymenachne within or from infested properties • Eradicate or contain ‘escaped’ infestations

Principles of Guideline • No new plantings • Existing plantings used in genuine grazing systems contained to pondage or floodplain situations • Containment protocols implemented

Guideline – in Practice • Eradicate outlier infestations not used in grazing systems • Contain hymenachne used in pondage to ponds • Contain hymenachne used in seasonal floodplain grazing to floodplains • To contain hymenachne to floodplains, contain on property (paddock scale), by means such as, but not limited to: o Preparing management plan ▪ Identifying spread pathways ▪ Maintain 50m buffer on external fence lines, creeks and drainage lines ▪ Encourage strong grass pasture (no KTP grasses) in buffer zones ▪ Spell stock being moved to clean areas • Regularly and following rainfall and flooding events, as access permits, monitor eradication sites for new growth and containment sites for escapees. • Spray any plants growing outside managed grazing systems, with the aim of treating plants prior to seed set • Manage grazing intensity within grazing systems to reduce seed set • Promote responsible pasture management in accordance with this code

NOTE: research is being undertaken through 2011 and 2012 on methods to contain invasive plants (including hymenachne) through a CSIRO led, Rural Industries Research and Development Corporation (RIRDC) funded project. This document is intended to be dynamic and best practice containment methods will be incorporated as they evolve.

Definitions 1. Contain: infestations of olive hymenachne are not to expand beyond their current level (current level may be taken to mean from the date of endorsement of this guideline). 2. Eradicate: to remove all olive hymenachne plants and seeds from a designated area. 3. Escapees: any plants growing in buffer zones or otherwise outside the extent of the production system. 4. Genuine grazing system: a. For ponded pastures: the practice developed by pastoralists to create an environment by either the construction of banks or the

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modification of naturally wet areas, in which fresh water is impounded or used primarily to grow suitably adapted plant species and produce fodder for grazing1. b. For floodplain systems: i. restricted to those pastoral properties in the Northern Territory that undertook plantings of olive hymenachne prior to its declaration under the Northern Territory Weeds Management Act 2001 on alluvial floodplains and that form the basis of cattle fattening or breeding enterprises2. ii. Where a floodplain extends beyond the boundary of a pastoral property, the olive hymenachne must be contained within the boundaries of the pastoral property. The only exception is where a floodplain spans more than one pastoral property and all pastoral properties meet part 1.b.i of this definition. 5. KTP grasses: The five high biomass grasses listed as Key Threatening Processes under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. The five grasses being: gamba grass (Andropogon gayanus), para grass (Urochloa mutica), olive hymenachne (Hymenachne amplexicaulis), mission grass (Pennisetum polystachion) and annual mission grass (Pennisetum pedicellatum).

1 Definition taken from the Cabinet approved Queensland Government Policy for Development and Use of Ponded Pastures 2 The Weeds Management Branch of the Northern Territory Department of Natural Resources Environment The Arts and Sport (NRETAS) should be consulted for a listing of those pastoral properties that meet this definition.

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