Chemical weed control kills the susceptible weed bio-types leaving the resistant ones, which carry-on the generation of resistant bio-types, in the coming seasons. Because farmers are commonly adopting the chemical mode of weed control rather than integrated weed management, are we not committing a blunder by over reliance on herbicides alone for weed control?
this is a simplistic point of view. Besides for the one hand, using herbicides can induce the accumulation of resistant weeds, for the other their proper use can help in controlling weed. Just to better explain: the induction of herbicide-resistant weed-biotypes is stimulated when low doses of the herbicide is used, which allow some plants to survive, and when always the same class of herbicide is used, which allow the selection of herbicide-resistant weed-biotypes.
In addition, although integrated weed management systems (IWMS) are better to control weed, especially with a long-term view, farmers usually are not able to put it in practice. And in addition they observe the highly and rapid outcome of the herbicide treatments, so they neglect the IWMS. Thus, just to spread the IWMS experimental farms, able to run long term experiments, are pivotal, as well as political and social decisions to foster such a enlightened example. The latter features usually don't exist.
I agree with Sergio. It is too simple say that herbicides induce resistance, you have to consider how do you use them, you can also rotate the active ingredients. Obviously the proper use of herbicides requires an adequate level of skills
By this way we are inadvertently breeding for super weeds that will require newer and higher doses of cocktails of herbicides and increasing farmer dependency on them. Alternative to that is mechanized hill planting and early mechanized row weeding along with one manual weeding (close to crop establishment) (wherever feasible). Better use integrated weed management practices to keep the weed pressure low. Rotate the options based on situation and resources at hand.
Use better varieties that have higher early vigor and faster establishment.
Control chemical pollution of our water systems, environment and human health-Think Green.
Dr Pardeep, it is just like pesticidal resistance, there should not be contineous use of the same weedicide, if you have option then you you should use alternatively and make rational use
Continuous selection pressure definitely leads to selection and survival of resistant weed populations, inadvertantly ending up with survivors having greater tolerance to herbicides
Sergio made a very good point about proper use of herbicides as a measure to delay evolution of resistance in weed species. If you can properly rotate herbicide chemistries and apply them at proper rates and timings, the risk of herbicide-resistant weed evolution will be similar to the level of predominance of a specific weed species in fields where single cultural weed control method is practiced.
For example, crop rotation can help manage weeds. However, some weed species such as Phalaris minor in rice-wheat cropping systems will become predominant and menacing. Similarly, mowing tends to shift weed spectrum from annual and tall weed species to perennial and prostrate weed species.
In the recent era of herbicide-resistant crop varieties, weed control has become easier than ever for the growers; specifically for growers with big land holdings. However, key to the sustainable weed control, as we all know, is to mix different weed control practices to reduce selection pressure for one or few particular weed species.
Pure reliance on herbicides is definitely not recommended. "Chemical weed control" in your question is too broad to be generalized. One should be more specific as to address a specific herbicide or herbicide family. Then, one can refer to the list of herbicides which have caused more weed resistant cases and find his/her appropriate answers. After all, integrated weed management is the way to avoid weed resistance.
The following paper provides an excellent perspective on how to avoid increasing the prevalence of herbicide-resistant weeds. The first thing to avoid, in answer to your question, is relying solely on one herbicide mode of action because the selection pressure is intense.
Jason K. Norsworthy, Sarah M. Ward, David R. Shaw, Rick S. Llewellyn, Robert L. Nichols, Theodore M. Webster, Kevin W. Bradley, George Frisvold, Stephen B. Powles, Nilda R. Burgos, William W. Witt, and Michael Barrett. 2012. Reducing the Risks of Herbicide Resistance: Best Management Practices and Recommendations. Weed Science. Special Issue 31-62.
Article Reducing the Risks of Herbicide Resistance: Best Management ...
By and large selection of incorrect herbicides, inappropriate dose,wrong timing are major reasons apartfrom other factor like agroclimate conditions, type of weed flora and other vegetation and cross compatibilty with other flora for crossing purpose.
continuous use, at elevated doses does bring about herbicide resistant plants, I have seen it myself in the use of Glyphosphate in the control of wees grass
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