Competition

As a seedling, serrated tussock is a weak competitor. Maintaining a healthy ground cover of desirable species is the key for long term management and control. Competition should be made an integral part of any control program.

Competitive techniques comprise cultivation, pasture establishment and renovation, grazing management, and afforestation. 

Cropping forms strong competition with serrated tussock seedlings. - Source: DEPI Victoria 

Cultivation (cropping)

Cultivation on its own is a short term method to control serrated tussock and reduce the seed bank. For long term control, sow cultivated areas to crop or pasture. Cropping can be an alternative to grazing, provide an alternative source of income, and reduce the soil seed bank.

Prior to sowing a crop, a soil test should be conducted to determine fertiliser, lime, and gypsum requirements. If suitable, land can be continually cropped or sown to pasture after a couple years of cropping rotations. Specific advice on suitable crops for your location, crop varieties, sowing rates and crop nutrition may be obtained from your local agronomist.

Cultivation is suitable for:

Arable, agricultural land, where the pasture is rundown and requires renovation.
Note:
1. New areas may require high spray inputs to effectively kill high densities of serrated tussock.
2. Do not heavily graze pastures that contain only serrated tussock.

Advantages to cultivation

• Continued cultivation kills serrated tussock plants.
• Cropping rotations provide strong competition with emerging serrated tussock seedlings.
• Reduces the serrated tussock seed bank.
• Forage crops may be used in a cropping rotation as grazing feed.
• Cropping may provide income.

Disadvantages to cultivation

• Disturbance of the soil caused by ploughing will result in a mass germination of serrated tussock.
• Cropping requires high labour and cost inputs, particularly if changing land-use from solely grazing.
• Ploughing around rocks and obstacles can be a problem as tussock seedlings can remain trapped, causing a re-invasion.
• Cultivation areas still need to be spot treated along fence lines and areas not able to be cultivated.

Warning: Cultivating or cropping native pasture may be illegal depending on federal and state legislation. Do not destroy native pastures by any means unless prior approval has been given by a relevant government authority.

A densely growing pasture with good ground cover is crucial for maintaining sufficient competition against serrated tussock. - Source: DEPI Victoria 

Pasture Establishment and Renovation

Pasture establishment can be the complete re-sowing of a pasture following a cropping rotation or the renovation of an existing pasture to increase the density of desirable pasture species.

Serrated tussock is very vulnerable at the seedling stage as it is slow growing and susceptible to high competition levels. When there is limited bare ground available and higher competition or water and nutrients, serrated tussock plants have difficulty surviving past the seedling stage. Having a strong, competitive pasture is a long term control measure that targets this feature.

Improving the productivity of land by using fertiliser and introduced pasture species can help reduce the incidence of serrated tussock invading.

Pasture establishment or renovation is suitable for:

• Introduced pastures that are in a degraded state and require complete re-establishment to be competitive with serrated tussock.
• Mixed native and improved pastures that require the addition of desirable species following treatment of serrated tussock to improve the health and competitive value of the pasture.
• Steep or rocky land with vegetation that requires improvement to be more competitive with serrated tussock. Specialised equipment is required for sowing pasture in these situations.

Advantages to pasture establishment and renovation

• A densely growing pasture with good ground cover is crucial for maintaining sufficient competition against serrated tussock.
• Improving pastures may help to increase the carrying capacity and productivity of a property in the long term.

Disadvantages to pasture establishment and renovation

• Grazing is limited on newly established pastures particularly if they have been aerially sown.

Managing pasture cover and density through grazing, whether on native or introduced pastures will help to out compete serrated tussock. - Source: DEPI Victoria  

Grazing management

Grazing and pasture management is the total process of ensuring pasture persistence and ground cover, maintaining soil nutrition for growth and organising livestock to make the best use of the pastures grown. It is about managing the frequency (how often the stock are removed) and intensity (how hard and how many) livestock graze pasture (MLA 2008).

Good grazing management is necessary to maintain pasture cover and density to effectively compete with serrated tussock. Total grazing impact includes domestic livestock and both native wildlife and introduced feral grazers.

Serrated tussock seedlings are slow growing and relatively weak competitors; however, if they are able to survive to maturity, they may dominate the grassland indefinitely, requiring active removal. It is cheaper and easier to stop serrated tussock seedlings from establishing.

Grazing management is suitable for all pastures on all land-uses.

Introduced pastures

A mix of perennial and annual, grass and legume species, in a pasture will help provide a strong pasture base to manage.

The density of the pasture is the key. Ideally maintain a ground cover of at least 90−100%, and pasture density of at least 1200 kg DM/ha (about 4 cm high). This will help to reduce the establishment of serrated tussock from the soil seed bank and minimise the chance of new infestations developing from windblown seed.

Focus management on continually improving the quality of pasture by promoting the growth of desirable species that will minimise serrated tussock invasion. Strategic fencing of larger paddocks and rotational grazing of these paddocks are tools that may help to achieve a highly productive and competitive pasture. Doing this will also increase productivity and profits (MLA 2003).

Strategic grazing management must be used as one component of an integrated management plan. Always monitor pastures for serrated tussock seedlings and follow up with spot spraying or chipping.

Native pastures

Native pastures may contain all native species or a mix of native grasses, subterranean clover and annual grasses—modified native pasture.

Long-term grazing management strategies are essential to encourage the growth of native species. Graze the pasture for short periods of time followed by long periods of rest to allow native grasses to regenerate and set seed (deferred grazing).

The optimum duration of these phases will vary and should be decided on the basis of regular inspection of the pasture and the stock. Pastures should be grazed only if they will recover rapidly. If pastures are not growing in summer they should not be grazed hard, even for short periods.

The optimum density of a native pasture to prevent serrated tussock seedling recruitment is greater than 800 kg of perennial grasses per hectare (pasture about 5 cm high over summer) and 90–100% ground cover. Rotational grazing will help maintain adequate levels of dry matter and ground cover.

In modified native pastures, regularly fertilise to boost clover growth and rotationally graze to help keep a balance of native grasses. Paddocks managed in this way can become very productive yet sustainable.

Further advice may be obtained from an agronomist.

Advantages to grazing management

• Rotational grazing may increase the productivity of a pasture in the long term and improve returns when compared to set stocking (MLA 2003).
• Having a healthy vigorous pasture is more likely to withstand invasion from serrated tussock and other weeds.
• Rotational grazing to maintain a good ground cover with a variety of perennial grass species is also regarded as good soil carbon management which may have positive implications in the future.

Disadvantages to grazing management

• May need to increase infrastructure, such as fencing and watering points, to gain maximum benefit.
• May require additional labour.

If using herbicide in conjunction with grazing management it is important to observe withholding periods and manage stock around this.

Planting trees or shrubs, for conservation or commercial purposes, is one way to manage serrated tussock in steep gorge country.- Source: DEPI Victoria 

Afforestation

Areas such as steep gorge country can provide ideal habitat for serrated tussock to dominate.

An escarpment dominated by serrated tussock may be a seed source, infecting neighbouring properties. Such areas are difficult to manage due to their aspect and limited options for control.

Planting trees or shrubs, for conservation or commercial purposes, is one way to manage serrated tussock in these areas.

In the long-term, trees and/or shrubs may reduce serrated tussock dominance by:

• providing competition for light and nutrients—a plantation of trees can form a canopy that will help out-shade the tussock, reducing its dominance
• reducing seed spread by altering wind convections.

If commercial farm forestry is not a feasible option, consider retiring the land from all forms of agricultural production and increase the biodiversity value of the property by planting native trees and shrubs, or allow natural regeneration.

Afforestation is suitable for:

• Steep escarpments and ridges, erosion prone soils, creek valleys and other inaccessible areas.
• Windbreaks or shelterbelts along property boundaries. Plant trees of differing heights to capture seed heads and reduce spread.
• Areas with a large, dense serrated tussock infestation, and where soil fertility and rainfall is not suitable for establishing a strong vigorous pasture.

Tree establishment is a complex procedure. If considering a farm forestry operation, involve a farm forestry adviser in the process as they can advise on site preparation, fertiliser and herbicide requirements, species of tree to plant and ongoing management.

Fence off plantations, or provide protection, from rabbits and grazing stock while trees are establishing. These animals will interfere in growth and development of saplings—stock can remove entire plants, while rabbits eat new growth. Firebreaks will also need to be made.

Continue to chip or spot spray serrated tussock plants with herbicide until trees have grown and the canopy has closed. Pine plantations can take up to 4 years to suppress the growth of serrated tussock and up to 10 years to kill it (Campbell and Vere 1995).

Always continue with a control program in areas of the property that have not been planted to trees.

Advantages to afforestation

• Plantations may significantly reduce severe serrated tussock infestations.
• Farm forestry can be income producing, turning unproductive land into productive land.
• May double as a windbreak for reduction of serrated seed blowing into or out of the property.
• May provide shelter for habitat, encourage biodiversity and increase the environmental health of a paddock.
• Trees planted in a linear design, at least ten metres in width, may be eligible for future carbon credit schemes.

Disadvantages to afforestation

• It can take many years for a canopy to develop and suppress the growth of serrated tussock.
• Labour intensive and costly to initiate.
• If trees are harvested, for example, for commercial purposes, there is a risk of serrated tussock invading once the trees are removed.
• Difficult to drag a spot spraying hose amongst the trees.

More detailed information and advice on competition can be found in the National Serrated Tussock Best Practice Manual.