Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Which direction are herbicides heading?

12.10.2011
2,4-D is coming back. What many might consider a "dinosaur" may be the best solution for growers fighting weed resistance today, said Dean Riechers, University of Illinois associate professor of weed physiology.

"Farmers can't imagine going back to 2,4-D or other auxin herbicides," Riechers said. "But herbicide resistance is bad enough that companies are willing to bring it back. That illustrates how severe this problem is."

In a recently published article in Weed Science, Riechers and his team of research colleagues suggest that tank-mixing auxinic herbicides with glyphosate may be the best short-term option available to farmers interested in broad-spectrum, postemergence weed control.

"Resistance has become a big problem," Riechers said. "In 1997, researchers predicted that glyphosate resistance would not be a big issue in Round-Up Ready crops. For the most part, they were right. But they underestimated a few weed species and resistance mechanisms."

Since the 1950s, 29 auxin-resistant weed species have been discovered worldwide. In comparison, 21 glyphosate-resistant weed species have been discovered since 1996 when Round-Up Ready soybeans were commercialized. And interestingly enough, two of the most problematic weeds in Round-Up Ready soybean and cotton – common waterhemp and Palmer amaranth – are not yet on the list of auxin-resistant weeds, Riechers said.

Ideally, chemical companies would come up with a new herbicide to fight these resistant weeds. But new herbicide development is expensive and time-consuming. Riechers said he does not know of any new compounds on the horizon.

"If we don't find completely novel and new herbicides, our next best bet is to mix glyphosate and another herbicide with relatively minor resistance problems," Riechers said. "Auxin resistance is not considered a huge problem in the United States, particularly in corn, soybean and cotton. It has only occurred in isolated incidences."

Why have the auxinic herbicides escaped the resistance problems of the more modern herbicides used today?

Riechers said there are three major reasons that help explain why resistance to auxin herbicides has not become a big problem yet. First, the auxin family of herbicides has a very complicated mode of action. In theory, a weed would have to develop a very complicated resistance method to overcome it. Riechers said the auxin herbicide family is very unusual because it has multiple target sites, which were only recently discovered.

"In addition, resistance to these compounds is rare because a plant that evolves resistance may have a fitness cost," he said. "The resistance mechanism that overcomes the herbicide could have a negative consequence to the plant in absence of the herbicide. Basically, for auxin herbicides there may be a 'penalty' to having resistance."

The third explanation is that auxin herbicides have rarely been relied on by themselves and are normally mixed with other herbicides. A good example is the frequent use of several auxinic herbicides in tank mixes for weed control in home lawncare and golf course applications.

Some farmers are concerned about going back to 2,4-D and other auxin herbicides because they are considered old compounds that tend to drift and move off-target to sensitive plants. Riechers said Monsanto and Dow AgroSciences have announced that they are working on new formulations to reduce drift, and agricultural engineers are exploring spray application technology to reduce the problems, too.

"This is a risk/reward decision," Riechers said. "If you have a huge resistance problem in your field and are concerned about losing yield, this may be your best solution for now. The alternative is to give up and do nothing. For some growers, this technology may be worth the risk because they have no other choices."

So the question remains. How long will it take for plants to form resistance to the combination of auxin herbicides and glyphosate?

"We are trying to predict the future, but all we can do at this point is speculate," Riechers said. "However, we can use the past to help us make wise choices for the future. We have resistance to almost all herbicide families now. Tank-mixing auxin herbicides with glyphosate may work for the short term, but I expect that auxin resistance will likely increase over time. Nature always finds a way."

Until the next novel herbicide comes out, Riechers said you only have to look back at what happened with glyphosate to see how important it is to be a good steward by using herbicides in a sustainable, beneficial way.

This article, "Evolution of Resistance to Auxinic Herbicides: Historical Perspectives, Mechanisms of Resistance, and Implications for Broadleaf Weed Management in Agronomic Crops," was published in the October-December 2011 issue of Weed Science. Authors include Dean Riechers of the University of Illinois, Kevin Kelley of AgraServ, William Johnson of Purdue University, and Christopher Hall and Mithila Jugulam of the University of Guelph, Ontario, Canada.

For a list of herbicide-resistant weeds, visit www.weedscience.org.

Jennifer Shike | EurekAlert!
Further information:
http://www.illinois.edu

More articles from Agricultural and Forestry Science:

nachricht Studies show integrated strategies work best for buffelgrass control
12.12.2019 | Cambridge University Press

nachricht The tips of a plant design its whole shape
09.12.2019 | Eberhard Karls Universität Tübingen

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Virus multiplication in 3D

Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.

For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...

Im Focus: Cheers! Maxwell's electromagnetism extended to smaller scales

More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?

It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Supporting structures of wind turbines contribute to wind farm blockage effect

13.12.2019 | Physics and Astronomy

Chinese team makes nanoscopy breakthrough

13.12.2019 | Physics and Astronomy

Tiny quantum sensors watch materials transform under pressure

13.12.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>