Tom's Blog

Thursday, July 19, 2012

The Bradley Method: An interesting approach for control of invasive plants

Back in 2002 I published a short article on the "Bradley Method" for invasive plant control in Plants out of Place (PooP), the newsletter of the Invasive Plants Association of Wisconsin (IPAW). In those years, circulation of PooP was fairly limited and although my article has been picked up by quite a few internet sites, these are mostly outside the Midwest.Therefore I am republishing it here.

The Bradley Method for the Control of Invasive Plants

 An interesting approach to the control of invasive plants in natural habitats is the Bradley method, first developed in Australia by the late Joan Bradley and her sister Eileen. Outside of Australia it has apparently only been used in California, but it should be applicable to most parts of the world.

The Bradley method is first of all a “philosophy” of weed control.

There are three basic principles:

1) Always work away from undisturbed natural areas toward the weedy areas.

            According to the Bradleys, if native plants are given a chance they will recover the ground that has been taken from them by weeds. The principal here is to start in areas where the native plants are thriving and gradually clear into the weedy areas. Weeds do not invade readily into areas where the native plants are already well established.
            If one clears weeds in the worst areas first, this may not only be ineffective, it may be harmful. Removing weeds in such areas exposes bare ground, tipping the balance in favor of the weeds. On the other hand, weeding a little at a time within and adjacent to good stands of native plants, moving toward the worst weed areas, gives the natives a chance to move in and thrive.

2) While weeding, try to keep from disturbing the environment any more than necessary.

            Large numbers of weed seeds rain down on natural areas. If the ground is opened, these weed seeds can thrive. Undisturbed native soil, with its natural mulch, is resistant to weed invasion.

3) Do not overclear

            Leave the natural area as undisturbed as possible. If a large team of workers is available, people should spread out and weed small amounts in many places, rather than having everybody weed in one place. The total area weeded will be as large, but regeneration by native plants will be greater.

The Bradley method emphasizes that removing weeds from a natural area involves two different kinds of time, working time and waiting time. Patience is not only a virtue, it is essential.

The Bradley plan of approach

1) Start with areas where native plants are dominant. Weeds may be scattered throughout, singly or in small groups. The risk of overclearing here is nil, so this is the place to start. After clearing all the weeds, return once or twice a year and remove any weeds that were missed, or which have just grown.

2) Then move into areas of heavier weeds, where there is some native undergrowth. Choose an area of substantial growth where native plants are pushing up against a mixture of weeds and natives. Remove weeds in a strip about 10 feet across, then stop and give the natives time to move into the weeded areas. As the natives take hold, extend the strip along the boundary.

3) Maintain the advantage already gained. It is important to resist the temptation to clear deeper into the weeds before regenerating natives have become established. Weed seeds will continue to germinate in newly cleared areas, so they should be removed as soon as possible. This is more important than starting to clear new areas.

4) Be very cautious in moving into the worst areas. However ugly an area of solid weeds may look, do not start clearing it until the native vegetation has been brought right up to it.

Although Joan and Eileen Bradley were trained as chemists, their method makes very little use of herbicides. “We regenerate [native vegetation] by using methods that give us the most effective kill of weeds and the most bountiful growth of natives; that is, by skilful manual weeding. This can be laborious, and we are often asked, especially when we are having to spend a long time extracting a big weed ‘Why don’t you poison it?’ We prefer not to use poisons if we can avoid it, and we certainly condemn their indiscriminate use.”

I think the point here is to use herbicides in selective ways, rather than by broadcast spraying. Their reasoning is that herbicides are not truly selective, may have detrimental effects on the environment, and do not always work. However, they do admit that for some weeds, or for some areas, herbicides may be necessary. However, their hand weeding technique is perfectly safe, highly effective, and reliable. It does require one trait that we do not always have or want to use: staying power.
Although I have generally approached a restoration area with the Bradley method in mind, I have not always used it. The "waiting time" that the Bradley method requires is not always available. However, we have always tried to start with the "good" areas first and then move into the "bad" ones. This is the most important part of the Bradley method.
Details of the Bradley method, including many practical suggestions for weeding, have been published in a book called “Bringing back the bush: The Bradley method of bush regeneration.” Lansdown Publishing Company, The Rocks, New South Wales, Australia.
I obtained my copy from Books of Nature, P.O. Box 345, Lindfield NSW 2070, Australia.

An internet search for "Bradley Method" AND "Invasive Plants" will bring up quite a few "hits", including some further details under a Wikipedia page called "Bush regeneration". 

Finally, those interested in the broader scope of restoration ecology should look into the Australian literature. Of all the countries outside of North America, Australia is probably the most advanced. In some ways they are ahead of us.


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