Preventing and Controlling Weeds

Prevention

Paterson's Curse
A close up of the flowers of Paterson's Curse, Echium plantagineum.
The cost of controlling a weed pest is at least 100 times greater than preventing the pest from establishing itself in the first place. Prevention is the best form of defence against weeds.

There are some easy steps you can take to help prevent weeds becoming established in your area.

Learn to identify the environmental weed problems in your area
This website contains identification information for many of the most significant environmental weeds in Tasmania.

If you have environmental weeds on your property, replace them with bush-friendly plants
There are many safe alternatives that can do all the things weed species can do - look stunning, provide shade, screening, attract birds, look after themselves - without being weeds. These can be local natives or plants from overseas. The key is that they don't escape and cause havoc elsewhere.

Don't dump garden clippings, cuttings and other green waste in the bush or along roadsides, and don't put pond or aquarium plants in waterways or down drains
Dumping is a major source of weed spread. Take waste to an appropriate disposal site (ie a tip), or compost it and turn it back into the garden. Good composting will destroy the reproductive capacity of many weed plants, and return much of the goodness they may have sucked out of the soil. Most of our worst water weed problems have resulted from the dumping of aquarium plants.

Ask your local nursery for advice about environmental weeds and bush friendly plants
Many plants that we know are environmental weeds are no longer available from nurseries. This is because consumers made it clear they did not want to buy plants that could damage the landscape they loved, and because most of the nursery industry adopted a responsible attitude to plant sales. If they don't know or care, buy your plants from someone who does. Not only will you be buying good plants, you will send a clear message as well.

Educate your family and friends about environmental weeds
Don't be afraid to spread the word! Many people who have environmental weeds on their property don't actually like them. Talking with others can provide the information and inspiration required to tackle the problem.


Control

Control of environmental weeds in the home garden is relatively straightforward, but may require a combination of techniques. It may also need to be staggered to avoid a significant aesthetic impact.

In bushland situations, weed control can be very complicated, with the approach depending on the weed(s) present, the size and density of the infestation, the terrain, the proximity to other vegetation, and other land uses. Most importantly, it will depend on the resources that are available for tackling the problem. Unless you are experienced, it is important to get expert advice. This is likely to save wasted effort and ensure that you get the best possible result.

You will also need to consult your local council to make sure your planned activities don't breach any by-laws. Not only is this a legal requirement, but it also helps forge productive links between the community and councils/state agencies. Land managers are often only too happy to provide resources - expertise, equipment, herbicide, mapping tools - to help in the battle.


Basic steps

If you think you might have environmental weeds growing in your garden, arrange to have the plants identified.
Unfortunately, weeds don't come with identifying labels, and many closely resemble non-weedy plants. Check first.

Consider all the possible control options, and seek to use an integrated approach that takes into account local conditions.
There is usually a range of options available for controlling environmental weeds. Which method(s) you choose will depend on the location and type of infestation. Integrated weed management means that you may choose a combination of methods to get the best weed control result. Control options include:
  • Hand pulling
Plants with shallow root systems, and the seedlings of larger plants, can be pulled out quite easily. This is best done when the soil is moist. Grubbing with a hoe or mattock may also be best for smaller plants. Always wear gloves to protect your hands from spines, bristles or irritating sap. For most weed species plants that have not developed seeds can be pulled out and left. They will rot away where they are left, but be sure that the root system is clear of the ground, and that at least a good part of any taproot has been removed. Some plants, such as periwinkle, will readily re-sprout from stem and large root pieces. These species, and any plant that contains seed, should be disposed of differently. Depending on the situation, disposal options include deep burial, bagging and leaving to rot, or burning.
  • Mechanical removal
This is not always a solution in itself, and follow-up is often required. A wide range of garden tools is available to help prune back unwanted trees and shrubs. Removing plants in stages can lessen the visual impact, and may also reduce the amount of regrowth from seeds and roots as there is still competition for light, moisture and nutrients. Try to avoid unnecessary soil disturbance, as this can promote erosion and weed seed germination.

Any form of mechanical weed control will involve some element of personal risk. Only those qualified and appropriately licensed should undertake work with heavy machinery, chainsaws etc.
  • Chemical control
Get professional advice and always read and follow the label instructions for any chemical application. Herbicide control can only be undertaken using chemicals registered for particular weeds and situations. Obey restrictions on the use of chemicals near waterways and take care around sensitive vegetation, orchards, crops and domestic situations. Never spray on very hot or windy days. Always wear appropriate clothing and protective gear.

This website does not provide details of specific chemical treatments. This is for several reasons. Firstly, new herbicides are introduced, older ones may be withdrawn and registrations change. Information not only becomes outdated very quickly, but it may cause an unnecessary risk. Secondly, every situation is slightly different, and the best method for weed control at one site may not be appropriate at another. To overcome these problems it is best to seek professional advice before undertaking any unfamiliar weed control work involving herbicides. This advice is free, and may save you time and money in the long run, as well as ensuring you have the best available safety information. Contact details for organisations are provided
  • Environmental management
This involves changing environmental conditions to disadvantage the weed. In a pasture situation, for example, changing the soil pH levels may impede the growth and spread of Spanish heath, while assisting the growth of grasses. In the bush, such changes may harm native plants as well, but there are some management techniques that can be successful. Fire can be used to reduce weed mass, stimulate weed seed germination and/or aid native plant recovery. Fire must always be used with caution and permission must be sought from the land owner.

Always check first with your local council AND the Tasmania Fire Service regarding when, where and what you may burn.

Other management changes may include altering the timing of annual maintenance activities, preventing the leaking of septic tanks or sewers, diverting drainage and revegetation with native species to increase competition for weeds.

Whatever approach you take, make sure you don't do anything that has undesirable consequences for areas adjacent to the unwanted plant. This means:
  • getting advice on the best techniques to use
  • using chemicals safely so that off-target damage does not occur
  • avoiding the wholesale removal of plants used as habitat by native birds and animals
  • avoiding soil disturbance or creating bare areas that may promote erosion
  • informing adjacent landholders and other stakeholders - their support will help you and they may have valuable local knowledge

Whether you are tackling a single plant in your garden or a large infestation, you need to look after yourself and everyone else involved. This means:
  • having a plan. There are very few, if any, magic solutions in weed control - you must expect a long battle, but good planning will make it shorter and more enjoyable.
  • being aware of your physical and knowledge limitations and seeking appropriate help. Before tackling a big weed problem, have a practice on a few weedy plants to gain an understanding of what is involved.
  • having the right equipment for the job (including safety equipment), and making sure it is in good working order
  • Reading and understanding the instructions on chemical labels
  • not trying to do too much in one go. Weed removal can be slow, and setting realistic goals is vitally important to maintaining enthusiasm for the task. Breaking a large task into smaller chunks is one way of giving yourself a real sense of achievement.
  • thinking the task through. "How are we going to deal with all the weeds we've just cut down?"

All of the above considerations are made easier by joining or forming a community group. Landcare, Coastcare and a variety of other groups are the driving force behind environmental weed control work. They have a wealth of experience, and can provide access to the variety of local and national assistance programs that exist. Believe it or not, being part of a group can actually make weed control fun.


Now find out more about plants known to be causing a weedy environmental problem in Tasmania.

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