Serrated tussock is difficult and expensive to control. Management activities should aim to stop the plant setting seed and to exhaust the store of seed in the soil. Large infestations should be treated in manageable parcels, with regular follow up over several years.
A long-term strategic plan should be made for each infestation and this plan should fit within the broader regional control strategy. Infestations should be quantified and mapped to enable success of management programs to be measured. Sharing responsibility for the serrated tussock in your area is part of the solution. Change of land use, eg. from pasture to cropping, may be the most appropriate management option in the longer term. The best land use for the infested land should be identified in advance.
Control of dense infestations requires an integrated approach incorporating a number of control techniques. On arable lands, cultivation and cropping or pasture renovation are generally important. On poorer land, herbicides and mechanical removal are usually employed. In all cases the ultimate aims is the establishment of competitive vegetation that will resist serrated tussock invasion. Long-term control is dependent not only on killing plants, but also replacing them with improved pasture or trees and then careful management of the area to minimise re-infestation. Monitoring is an important aspect of management. Treated areas should be inspected twice a year, for 5 to 10 years or until regrowth from the soil seed bank ceases.
Be vigilant in identifying serrated tussock and take prompt action to remove or kill it when it is found. All land at risk should be checked annually for newly established plants. Isolated plants and small patches should always be chipped out or treated with herbicide as soon as they are detected.Chemical control
Under Victorian legislation, there are controls on various aspects of the uses of agricultural chemicals. It is the responsibility of chemical users to familiarise themselves with these controls. Legal use of some chemicals requires the user to possess anAgricultural Chemical User Permit (ACUP). Other chemicals have restrictions on their use in Chemical Control Areas (CCAs). Refer to theAgriculture Note: Agricultural chemical user permits (ACUP) and chemical control areas (CCA).
Choose only products registered for use on serrated tussock in your particular situation. Read the product label and follow all label instructions carefully. See your chemical retailer for further advice. Information on ACUPs, CCAs and other chemical information can be found under Chemical Use in the General Farming section under Agriculture and Food at the website http://www.dpi.vic.gov.au/or ring the Chemical Information Service on (03) 9210 9379.
- Herbicide treatment should be part of an integrated management plan involving the planting of competitive replacement species and rehabilitation. Chemical treatment without follow up work usually results in reinfestation from the soil seedbank.
- When spot spraying aim to completely wet the plant to cause run-off. Add a dye to the spray mixture to identify treated areas.
- Glyphosate is a non-selective, non-residual herbicide absorbed through the leaves. It is relatively fast acting. Unless a total kill is required, eg. as part of a pasture improvement program, an application method should be chosen that enables selective treatment of the serrated tussock eg. carpet-wiper or direct spot spraying. However, appropriate timing of applications can protect desirable species, eg. spraying after annual grasses have set seed or spraying when perennial grasses are dormant. Glyphosate is the best option if the intention is to sow a new pasture or crop.
- 2,2-DPA is a residual herbicide absorbed through leaves and roots, which is selective for some grasses at low application rates.
- Flupropanate-sodium is a selective, slow acting herbicide, absorbed through the roots, with some soil residual effect and a long stock withholding period. A major advantage of flupropanate is that some pasture species, native grasses and trees are tolerant to it, but many native pasture grasses are very susceptible. Effects of spraying may not be visible for 2 to 5 months after application and it may take up to 18 months for serrated tussock plants to die. This is a benefit in highly erodible soils as alternative species can be established to stabilise the area while the tussock degrades.
- To prevent seed set, flupropanate must be applied before July to allow time for it to act. Flupropanate soil persistence means it will kill emerging tussock seedlings for several months after application. The length of time it is active within the soil is dependent on the amount of rainfall. Always follow label instructions and note withholding periods when using flupropanate.
- Both flupropanate and 2,2-DPA kill annual grasses and some native grasses, which is why reseeding is necessary. Flupropanate is less damaging to improved perennial grasses such as phalaris, cocksfoot, fescue and ryegrass than 2,2-DPA. Phalaris is the most tolerant pasture species to flupropanate. Grazing down pastures before spraying, or spraying in summer when improved pasture species are dormant or not actively growing, and spraying at the correct rate will minimise pasture damage.
Repeated treatment of a weed with herbicides from the same ‘mode of action’ group can result in the selection of plants that are herbicide resistant. Serrated tussock populations resistant to flupropanate were discovered in 2002 in Victoria, but it is not known how widespread the problem might be. To avoid the development of resistant strains, rotate between products from different mode of action groups and employ non-chemical management methods in an integrated strategy.
- Use a program of cultivation and cropping followed by establishment of improved pasture. Cultivation and cropping can be used to control existing infestations as well as reducing the seed bank. The program involves burning in late winter followed by ploughing to a depth of 10 to 20 cm. Serrated tussock seedlings cannot emerge when seed is buried deeper than 2 cm.
- Mouldboard and disc ploughing are the most effective methods. Chisel ploughing is not effective. Paddocks are left fallow and cultivated again in late summer to kill new serrated tussock and other weed seedlings. Cropping programs should be conducted for two years before establishing improved pasture.
Improved perennial pasture is an effective long-term management regime for serrated tussock after initial infestations have been killed. Serrated tussock seedlings will reinvade improved pasture; however, they are weak and can be smothered by vigorous, actively growing perennial pasture species. Phalaris and cocksfoot are two of the most competitive pasture species. Both these perennial grasses are deep rooted and drought tolerant, and therefore more persistent than perennial ryegrass in areas with dry summers. Suitable subclover species also need to be included in any pasture mix.
Successful pasture establishment relies on following proven techniques and not taking any short cuts. The steps for successful pasture establishment are:
1. Start planning 12 months ahead and seek advice.
2. Conduct a soil test.
3. Control rabbits.
4. Determine the most appropriate method of sowing.
5. Begin weed control the year prior to establishing an improved
6. Remove excess pasture trash.
7. Order chemicals, seed and fertilisers and organise contractors
8. Spray with herbicide to achieve a total weed kill.
9. Control redlegged earth mites and pest insects.
10. Treat pasture seed with appropriate seed dressings.
11. Select recommended pasture species.
12. Sow seed and fertiliser in May.
13. Check the pasture for weed germination and insect attack.
14. Spell pasture until well established.
- Good pasture cover (70%) and avoidance of overgrazing is important to prevent serrated tussock taking over. Grazing management is one element that helps promote healthy and productive pastures.
- Annual applications of phosphorous-based fertilisers like superphosphate are required, plus other nutrients required to remedy deficiencies. Soils tests and plant tissue tests can determine nutrient deficiencies.
The basic steps in a grazing strategy to control serrated tussock are as follows.
1. Monitor paddocks for seedling appearance.
2. Maintain grazing pressure until pasture dry matter falls below 1000 kg/ha (approx. 30% bare ground) then remove stock. Note: Phalaris will tolerate heavy stocking over summer, but cocksfoot will send up green shoots in response to summer rainfall and if continually grazed the plants will die.
3. Crash graze to remove excess feed if dry matter is greater than 1000 kg/ha.
4. Start rotational grazing.
5. Use rotational grazing throughout winter.
6. Maintain pasture height at 6 to 10 cm to shade out serrated tussock seedlings by either rotational or set stocking grazing.
Trees can provide a physical barrier to intercept wind blown seed heads and they can function as a competitive species to kill and suppress serrated tussock. The most effective species are those that create heavy shade, eg. radiata pine.
On non-arable land where pastures are difficult or impossible to establish, dense tree plantings can be an effective long-term method for controlling serrated tussock. Examples are stone barriers, steep escarpments, erosion prone soils, creek valleys and other inaccessible areas. Tree plantations can be established as a commercial venture but they also provide the benefits of shelter, wood, habitat and aesthetic value.
The successful establishment of a tree plantation requires planning similar to the establishment of any other crop. Site preparation and continued management are essential in achieving a healthy plantation.
Steps for successful tree establishment (winter planting) are:
1. Seek advice and plan at least 12 months ahead.
2. Control weeds in the year prior to planting.
3. Select and order trees for the site well in advance.
4. Control vermin.
5. Rip the site in late summer.
6. Control weeds prior to planting.
7. Plant in winter.
8. Continue to monitor for weeds, vermin and otherpests.
Serrated tussock is a difficult weed to control and requires long-term management plans. Management activities should include prevention and control works and replacement with appropriate competitive vegetation if long-term control is to be achieved. In management plans, it is important to build in short-term wins to maintain enthusiasm and confidence. The number of heavily infested properties in Victoria has been falling, significant numbers of previously infested properties are now free the weed, and major landscape renovation projects are under way in the worst affected areas. Don’t give up, be vigilant and protect your investment.
Serrated tussock can be beaten!
(For more information, refer to the DPI website)