Weed management paradigms and the needs for research

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Dr Stephen Johnson

Managing Editor, Plant Protection Quarterly, Orange NSW, Australia.

Cite this article as:

Johnson, S.B. (2012). Weed management paradigms and the needs for research. Plant Protection Quarterly 27(4), 118.

To end this year, this issue of Plant Protection Quarterly has a third Biology of Australian Weeds article on Polygala myrtifolia L. (Adair et al. 2012), two contributions from the Weed Society of Victoria seminar series ‘Weedy interactions: from sub-microscopic to species and communities’ held earlier this year (Pratley 2012, Cousens et al. 2012) and the annual index.

Weed management – alternate paradigms

Herbicide use in primary production, particularly in conservation tillage agriculture in Australia, is fundamental. The use of glyphosate is one of the key drivers behind the success of these systems: there are no ready herbicide alternatives (Pratley 2012). Any threat to the continued use of glyphosate is therefore of great concern. This is at least one reason why there are concerted efforts to ensure the long-term sustainability of glyphosate use, in keeping resistance to a minimum (e.g. Preston 2012); and in promoting this weed management tool as one of many techniques that can be used in an integrated weed management programs (McGillion and Storrie 2006).

The use of allelopathy may offer another management tool. In saying this, allelopathic interactions are often subtle, where undesirable plant species are suppressed via competitive interactions rather than removed completely via herbicides (Pratley, 2012). That paper summarises increasing evidence that rice (Oryza sativa L.), wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) varieties differ significantly in their ability to suppress some weeds in crop. A concerted research effort is needed to understand the broader area of rhizosphere science, and specifically to better quantify, and selectively breed for allelopathic enhancement of superior yielding varieties of these crop species. The alternate paradigm needed is not only that ‘chemical farming’ has all the current answers, but that continued research needs to continue on as many alternate weed management tools as possible.

Understanding the biology of weeds is a continued key to best management

Understanding the biology and ecology of a weed species will result in better management (e.g. Adair et al. 2012). Application of information contained in each of the 61 Biology of Australian Weeds series has proven this across multiple situations, times and locations. The human beneficiaries of such research have little doubt that understanding a fact as basic as, for example, ‘seed longevity will be exhausted in the soil after 5 years’ is critical to an eradication effort and in defining the timeframe in which this is to occur. For the weed manager involved, such information is a crucial to the success of managing the weed species.

Critics of such research rightly ask how multiple case studies, each on a different species in a different primary production, environmental and/or societal systems advance our understanding of the basic biological principles and science behind such plants? Often, such applied research sheds little extra light on the larger more basic bigger picture questions like ‘How does this better help us to understand what a plant is?’ or ‘What does this tell us about why some plants become invasive while others do not?’. The truth is that sometimes this research does not shed light on the more basic biological principles.

The paradigm that needs to be accepted here is that sometimes research (applied) is funded and performed to determine specific biological information so that better management can result. Having said this, there should be no shortage of funded basic research aimed specifically at understanding many of the basic biological, ecological, physiological and competitive processes and interactions that are not currently well understood. Rather than being competitive , basic and applied research should coexist like the two sides of a coin. Without basic research, applied research is unlikely to be able to apply known and understood concepts so that new management approaches advance integrated weed management practices.


Adair, R.J., Shackleton, A., Stajsic, V. and Gajaweera, R. (2012). The Biology of Australian Weeds 61. Polygala myrtifolia L. Plant Protection Quarterly 27 (4), 119-30.

Cousens, R., Williams, K., Kennedy, D. and Maguire, S.G. (2012). Just how bad are coastal weeds: assessing geo-eco-psycho-socio-economic impacts. Plant Protection Quarterly 27 (4), 137.

McGillion, T. and Storrie, A. (eds) (2006). Integrated weed management in Australian cropping systems – A training resource for farm advisors. (Cooperative Research Centre for Australian Weed Management, Adelaide, South Australia). 248 pp. [Also available from http://www.glyphosateresistance.org.au/manual.html (accessed 11 December 2012)].

Pratley, J.E. (2012). Allelopathy – a fancy name or a potential weed management tool? Plant Protection Quarterly 27 (4), 131-6.

Preston, C. (2012).  The Australian glyphosate sustainability working group. http://www.glyphosateresistance.org.au/ (accessed 11 December 2012).


First published online: December 15, 2012