The Weed's Blog
Hi, I am Nimal, a Weed Scientist, and one who is passionate about providing everyone the best information on weeds and how wonderful these plants are. So much of negativity surrounds weeds, and much of it is misinformation. Hopefully, my blog will help people understand weeds better.
Some people, particularly in developed countries, have strong negative attitudes towards weeds, and a tendency to label potentially useful plant resources as invasive ‘aliens’, which are to be controlled at any cost. This undesirable attitude ignores the considerable evidence of beneficial uses of weed species to many societies over a long period of human history. The recent application of ‘species-focused’ weed risk assessments have contributed to the maligning of many plant taxa as ‘invaders’ in the public’s mind, undermining their worth as biological resources.
Some of the methods used in the blitz against weeds, including the excessive use of herbicides, have resulted in undesirable consequences, such as herbicide resistance and negative impacts on biodiversity in farming landscapes. Weed Scientists may know that weeds are only plants with colonising abilities, which have the capacity to rapidly occupy naturally disturbed; or human-modified environments. However, the lay public does not understand this. When closely examined, the evidence is clear: not all weedy taxa are bad all the time, just because they may interfere, under certain circumstances, with human interests!
To the ecologists, weeds are 'pioneers of secondary succession' and only colonizers of available habitat. As colonizing plants, they are significant components of biodiversity in most ecosystems, occupying ecological niches that are perhaps unsuitable for other plants at a given time. Fast-growing weeds prevent bare soil from erosion by wind and water, and also improve soils by conserving water and nutrients, and adding organic matter. Weeds maintain the biological diversity of farming landscapes, providing food and shelter for a variety of animals. Insects, which pollinate crops, extensively use weeds as a source of nectar when crops are not in flower.
In Europe, there is increasing recognition of the benefits of agro-ecological approaches to farming, including crop rotations, and balancing biodiversity and crop production. Farmers are encouraged to limit weed management measures to allow populations of beneficial organisms, such as natural predators of aphids (i.e. ground beetles, spiders) to develop, thereby reducing reliance on aphicides. Weeds also attract crop pests; and there is evidence that pest populations in some crops are much lower in ‘weedy fields’ than in ‘weed-free’ crops. As many of our primary crops have ‘weedy-relatives’, the genes present in weeds appear crucial for future evolution of crops, particularly to confer ‘hardiness’ (ability to tolerate variable environmental conditions). The core issue for sustainable agriculture is the balance between adequate weed control, including the prevention of weed-seed build up, and to ‘live with some weeds’ to support biodiversity and other known benefits.
Many colonising taxa are worthy resources in diverse areas of human interest, not just because of agro-ecological benefits and utilization potential. Some species contribute to aesthetic pleasure, as part of ‘wild nature’, while others provide culinary delights for humans, and are important as food sources for both vertebrate and invertebrate animals. Global research on pharmacological values of weedy taxa is quite intense, and many weeds with medicinal values continue to be used either as traditional ‘herbal’ remedies, or extracted for secondary metabolites. The colonising strengths of several species are being used in the remediation of water and terrestrial environments to scavenge soil pollutants.
Globally, there is considerable interest in using the large biomass produced by these species as raw materials for countless house-hold products, including bricks, paper and furniture; and as future bio-fuels. In addition, there are many opportunities for using colonising plants in phyto-remediation, or in creating more sustainable farming systems. There are also significant prospects to further exploit chemical warfare between plants (allelopathy) to search for new bioactive chemicals, and for the use of allelopathic plant residues within low input agricultural systems. Exploiting various uses of weeds as bio-resources meets many of the criteria of the current ‘Green Movement’, in terms of being environmentally friendly materials, which can be utilized for human welfare, as opposed to being discarded as useless.
Therefore, within the field of Weed Science, a fresh look at weeds is essential. Perhaps a new and bold paradigm should be ‘co-existing’ or ‘living with weeds’, recognising their intrinsic worth as part of biodiversity, and the many possible uses as bio-resources. Studies must re-focus on improved understanding of weeds, not just for the sake of controlling them, but for their ecological role, as well as social and economic benefits. The next generation of Weed Scientists must improve on our understanding of environmental, ecological or social factors that create unwarranted disturbances, in which colonising species dominate our landscapes. This would lead to more effective weed management through mitigation of such factors. It would also reduce the current confusion and negative attitudes towards weeds.