Weeding to restore and protect your patch
This is the text of a brochure available from Friends of Grasslands.† Contact Us for printed copies.
A key aim of Friends of Grasslands (FoG) is to encourage good management of sites containing natural temperate grasslands, grass woodlands and grassy forests (grassy ecosystems).
While good patches of remnant grassy vegetation will often resist weed invasion, invariably some areas within a patch will be invaded by weeds, and there will always be some weeds that creep into better areas of vegetation.
Therefore weed management is a key focus for FoG, particularly informing FoG members of good weed management practice.
What you can do to be a weed manager
There is no easy way to become a good weed manager, but learning about and practising good weed management can be very satisfying especially as it can result in saving precious plants and animals.
Good weed management requires personal commitment, time and often money to learn how to identify plant species, to understand their life cycle, to know what herbicides, methods and equipment to use, to develop a weed strategy applicable to your patch, to seek training, and, if appropriate, to obtain funding and/or organize outside help, so that you know what to do and how to do it effectively and safely.
Joining a group that is looking after a patch or two, can help you to start to learn how to become an effective weed manager.
Weed management is an essential component of protecting and managing our grassy ecosystem patches. Therefore it is essential to gain some understanding of what grassy ecosystems are, why they are important, how they function, and what can be done to restore and manage them. Part of this is to start to learn how to identify both the indigenous plants (native plants that grow in a particular ecosystem), and introduced plants (weeds) in remnant patches, and their ecology.
Most serious weed control efforts require knowledge of herbicides, even if these are to be used sparingly in spot spraying situations for example. This can only be achieved by obtaining proper training and practice in their use. Without such training, volunteers can use some herbicides safely (e.g. cutting and daubing) if done under supervision. Some people prefer not to use herbicides and to manage areas using other methods (e.g. Bradley Method).
What is a weed?
There are agricultural and environmental weeds, and many plants fall into both categories. Agricultural weeds may compete with crops or pasture, may be unpalatable or even toxic to animals. Environmental weeds are those which out-compete native vegetation, gradually replacing them. They might also provide habitat for feral animals which in turn out-compete or prey upon native animals. Removing environmental weeds may therefore assist native vegetation to regenerate and perform important eco-system functions, remove a threat to patches of rare or threatened plants, and assist pressed native fauna to rebound.
Developing a weed strategy
Weeds can be daunting but with a good strategy and persistence even the worst-affected weed areas can rebound. Developing a realistic plan is the first step.
You need to:
- Clearly define your objectives, perhaps prioritising for the noxiousness of the weed;
- Survey and map the weed areas;
- Find out what resources are available, how they might be augmented, and prioritise the tasks to be done;
- Select and acquire tools (e.g. spray packs), and determine treatment;
- Acquire training to ensure that you can be effective and safe; and
- Monitor what you do so that you will discover what works and what does not work, and be prepared to adapt or try new methods.
Determining your objectives can only be done when you understand what weeds you have, how you can control them, what options and resources are available, and the time horizon.
You need to be realistic and often focusing on one or two weeds will bring early success which will encourage more ambitions weeding work to be approached.
Knowing what weeds you have and where they are is essential. This will help you to determine what resources are required over what time, and also provide valuable information to later monitor your progress.†
Understanding the life cycle of each weed species can greatly assist in controlling it. There are many aspects to this.
Stop plants seeding
The first consideration is to stop plants from seeding, e.g. poisoning, grazing, slashing or cutting before seeding. Slashing or cutting may stop seeding, retard or delay it, or have little effect Ė this may also depend when slashing or cutting is undertaken in relation to the life cycle.†
If plants have already produced seed, removing the seed from the plant, and taking the seed away to be burnt or safely disposed of, may be a good control technique.†
Killing of plants by pulling, chipping or digging them out, or poisoning them is usually desirable. Leaving dead plants in place, if without seed, may be desirable to stop erosion or opportunities for new plants to establish.
Stop plants re-growing
If not totally killed or removed some plants will re-grow. However, setting back plant growth may be sufficient if good follow up is planned.
Poison may not be effective if the plant is not actively growing (if the conditions are too cold/hot or too dry), and killing many small plants which might die anyway (e.g. going into a drought) may not be the best use of resources.
Types of Weeds
There are numerous weed species that have invaded grassy ecosystem remnants. These may be classified as:
Woody weeds in grassy ecosystems include willow (Salix spp.) along water ways, introduced pine (e.g. Pinus spp.), hawthorn (Crataegus spp), African boxthorn (Lycium ferocissimus), sweet briar (Rosa rubiginosa), blackberry (many Rubus spp.), African olive (Olea europaea ssp. africana), privit (Ligustrum spp.), etc. These threaten grassy ecosystems in different ways and may also present other environmental threats such as taking too much water.
There are many deliberately and accidentally introduced grasses, including African lovegrass (Eragrostis curvula), Chilean needle grass (Nassella neesiana), serrated tussock (Nassella trichotoma), phalaris (Phalaris acqatica), Yorkshire fog grass (Holcus lanatus) wild oats, etc. These grasses tend to become dominant. Some may be of poor nutritional value to stock, and/or not grazed by introduced or native animals. Some are considered a fire risk.
There are many deliberately and accidentally introduced forbs, including infamous plants such as Bathurst burr (Xanthium spinosum,) Patersonís curse and viperís bugloss (Echium spp.), St Johnís wort (Hypericum perforatum), thistles, mullein, etc. These become dominant and compete successfully against native plants. To a degree they may be controlled by grazing but some are toxic for stock.
Methods of weed control
Appropriate grazing management can be very effective in determining what grows and where it grows. Therefore, properly designed grazing can be a good tool to manage some weeds, especially grasses and forbs. On the other hand ill considered grazing can promote weed growth and destroy biodiversity in grassy ecosystem patches.
Mowing and slashing can also be a method of pasture management and weed control. Likewise such methods can have the opposite effect - changing the balance between native and introduced plants and spreading weed seed on mowers.
Fire can be a management tool to promote grassy ecosystem conservation, but it can also have deleterious effects and open up areas for weed invasion.
Use of poison can be an effective method of control. Methods of control include boom spraying, spot spraying, cutting and daubing, Ďkiller tongsí, and tree injection with general or selective herbicides. However, poisons can have many deleterious effects and knowledge and care is required in their use.
Other methods such as biological control, grazing by goats, solarisation, hot water application, cultivation, reafforestation, and mulching might also be considered in some circumstances. ††
The Bradley sisters in the 1960s are credited with pioneering the science of bush regeneration through their insights into weeding in which they used simple tools, weeding in and around areas of good native vegetation and allowing them to expand and replace weed-infested areas, and persistence. Many of the principles they propounded should be included in any approach to weed management especially in remnant vegetation.
A case study - Old Cooma Common
In May 1999, FoG received a Threatened Species Network Grant to establish a reserve to preserve a natural temperate grassland remnant which contained the threatened species Monaro golden daisy (Rutidosis leiolepis), at Old Cooma Common.The grant included money for fencing, weed control, signage, and some publicity. This site has become a flagship for conservation of natural temperate grassland in the Monaro.
The chief woody weed was hawthorn, and to a lesser extent blackberry, briar rose, and some tree plantings. The chief grass weed was African Love Grass and occasional serrated tussock, while invasive forbs were St Johnís wort, vipers bugloss, and onion weed.
While weeding seemed an overwhelming task, it was decided to focus on woody weeds, St Johnís wort, and African lovegrass. The woody weeds were removed during volunteer working bees and the level of skill was commensurate with the task. The spraying of African love grass and St Johnís wort was subcontracted. The weeds have been greatly reduced, being replaced with native grasses and forbs. The reserve, which has since been established, now looks much better.
Unfortunately, lack of skills and resources to manage weeds remain limiting factors.
How can FoG help
FoG can help through its plant surveys Ė helping land managers to identify their plants and how to manage them, through its workshops and newsletters, and through its program of site visits. All these activities assist members to understand how to identify plants and to understand their ecology. Also, through its on-ground work, FoG members have learnt many skills associated with weed management. FoG also monitors what larger agencies are doing to manage weeds, and encourages them to undertake effective management. Through its public education, FoG encourages greater public awareness of weed management.
There are now many useful references and weed identification books. Some that are very useful are:
Robin A. Buchanan Bush regeneration, recovering Australian landscapes, 1991, published by the Open Training and Education Network, ISBN 0 7240 7877 0.
NSW Agriculture Noxious and environment weed control handbook 2004-2005, a guide to weed control in non-crop, aquatic and bushland situations.
Weeds of the Monaro, a guide to identification and control, 2004, Excell Printing, Pambula.
Joan Bradley Bringing Back the Bush, the Bradley method of bush regeneration,1991, Ure Smith Press.
To contact FoG: Contact Us