BY：Vince M. Davis
Introduction
Glyphosate resistant crops, first released in 1996, have been the most rapidly adopted
agriculture technology by the farming community in the U.S. The technology was rapidly
adopted because weed management systems were drastically simplified. Weed management
was simplified because glyphosate is a highly efficacious, non-selective postemergence
herbicide for control of annual and perennial weed species, and when used in conjunction
with glyphosate-resistant crops, a high-level of crop safety was ensured. Additionally,
glyphosate is also safer for the environment, safer for humans and animals, cheaper, and
slower to develop resistance in comparison to many other herbicide options. All of those
reasons have contributed to make glyphosate an herbicide that growers and applicators prefer
to use.
Unfortunately, in part due to its’ own superior postemergence weed control efficacy and
low cost, glyphosate has been relied upon too much in many glyphosate-resistant cropping
systems. This ‘over-reliance’ on a single weed control strategy has created a ‘shift’ in the
problematic weeds in many fields to become dominated by species where glyphosate is less
efficacious, as well as infested with weed biotypes which are resistant to glyphosate.
Currently, there are 21 weed species Worldwide documented with biotypes that are resistant
to postemergence glyphosate. Some of these weeds like horseweed, giant ragweed, common
ragweed, waterhemp, Palmer amaranth, and johnsongrass (just to name a few) infest millions
of acres of corn, soybean, and cotton across the U.S. Additional management, additional
herbicides, and subsequently additional costs have been the result of this progression.
One additional result of the increased glyphosate-resistant weeds in glyphosate-resistant
cropping systems Worldwide has been the need for newer technologies to aid in weed control
to ensure sustainability of our primary commodity crop production across the U.S. A couple
of those developed technologies are crops with genetically modified traits which will allow
them to be resistant to growth regulator herbicides in addition to glyphosate. The growth
regulating herbicides of primary utility for these crop traits are 2,4-D and dicamba.
Dicamba-resistant Soybean
Monsanto Company, St. Louis, MO, is developing the addition of dicamba tolerance to
the Genuity.Roundup Ready 2 Yield.Soybean platform which will offer growers an
additional tool for flexible and effective weed management along with the increased yield
opportunity of Roundup Ready 2 Yield.Once approved, the dicamba tolerant technology
will enable the use of dicamba and glyphosate tank-mixes for preplant burndown, at planting,
and in-season applications adding considerable weed control value to the well-established and
effective Roundup Ready® system. Monsanto and BASF are working together to develop
innovative dicamba formulations for use with these herbicide-tolerant cropping systems, and
both companies are working together to develop robust Best Management Practices for the
use of dicamba over Dicamba tolerant soybeans. Dicamba tolerant soybeans are projected to
be commercialized in the middle of this decade, pending global regulatory approvals with
initial product launches in the U.S. and Canada.
2,4-D-resistant Crops
Dow AgroSciences has developed traits conferring herbicide tolerance in plants. This
technology was originally referred to as Dow AgroSciences Herbicide Tolerance (DHT)
traits, and is now referred to as Enlist™ Weed Control System. In soybean, the trait will
provide tolerance to pre-emergence and post-emergence applications of 2,4-D. In corn, the
trait will provide tolerance to pre-emergence and post-emergence applications of 2,4-D and
post-emergence applications of quizalofop, an ACCase – inhibitor grass herbicide. In
conjunction with the Enlist crop traits, Dow AgroSciences is also developing new and novel
proprietary technology that will significantly reduce the physical drift and volatility of 2,4-D
relative to current DMA and ester 2,4-D herbicide formulations in the market. This new
technology will be used to create proprietary pre-mix formulations of 2,4-D + glyphosate
having improved compatibility and cold storage stability characteristics. Dow AgroSciences
is also committed to providing comprehensive stewardship guidance for deploying this
technology. Enlist technologies are also projected to be commercialized in the middle of this
decade, pending global regulatory approvals.
Thoughts about Growth Regulator Resistant Crop Adoption in Wisconsin
I agree these growth regulator resistant technologies will offer many plausible and
important weed control benefits. However, the adoption and acceptance of these technologies
may once again stretch the entire crop production community to revolutionize. The benefits
with these pending technologies will include increasing broad-spectrum postemergence weed
control options, particularly for broadleaf weeds. Similar to glyphosate, the growth regulating
herbicides are also relatively cheap, and weeds are slow to develop biotypes with resistance.
However, growth regulator resistant weeds have been documented in a couple unique
situations, so like glyphosate, it can happen when the herbicide is used too often.
The adoption of these technologies also bring much concern about the potential for these
herbicides to be used more often, and as a result, find their way to sensitive vegetation which
was not an intended target. Growth regulating herbicides cause plant symptoms that are
highly visible which can lead to easy detection of off-site movement. There are three
common ways these herbicides will move off-target including failure to properly clean spray
equipment (which is very difficult in relation to other herbicides), particle drift during
herbicide applications, and volatilization, or movement of vapor off the target after spray has
deposited on the target surface. In summary, these technologies bring with them both
opportunity and challenges for weed management systems which will be discussed.
References
Johnson, W.G., V.M. Davis, G.R. Kruger, and S.C. Weller. 2009. Influence of glyphosateresistant
cropping systems on weed species shifts and glyphosate-resistant weed
populations. Eur. J. Agron. 31:162-172.
Seifert-Higgins, S. 2010. Weed management systems in dicamba-tolerant soybeans (DTS).
Proc. of the 2010 North Central Weed Science Soc. 65:91.
Simpson, D.M. 2010. Future of 2,4-D – New uses and new technologies. Proc. of the 2010
North Central Weed Science Soc. 65:180.
Introduction
Glyphosate resistant crops, first released in 1996, have been the most rapidly adopted
agriculture technology by the farming community in the U.S. The technology was rapidly
adopted because weed management systems were drastically simplified. Weed management
was simplified because glyphosate is a highly efficacious, non-selective postemergence
herbicide for control of annual and perennial weed species, and when used in conjunction
with glyphosate-resistant crops, a high-level of crop safety was ensured. Additionally,
glyphosate is also safer for the environment, safer for humans and animals, cheaper, and
slower to develop resistance in comparison to many other herbicide options. All of those
reasons have contributed to make glyphosate an herbicide that growers and applicators prefer
to use.
Unfortunately, in part due to its’ own superior postemergence weed control efficacy and
low cost, glyphosate has been relied upon too much in many glyphosate-resistant cropping
systems. This ‘over-reliance’ on a single weed control strategy has created a ‘shift’ in the
problematic weeds in many fields to become dominated by species where glyphosate is less
efficacious, as well as infested with weed biotypes which are resistant to glyphosate.
Currently, there are 21 weed species Worldwide documented with biotypes that are resistant
to postemergence glyphosate. Some of these weeds like horseweed, giant ragweed, common
ragweed, waterhemp, Palmer amaranth, and johnsongrass (just to name a few) infest millions
of acres of corn, soybean, and cotton across the U.S. Additional management, additional
herbicides, and subsequently additional costs have been the result of this progression.
One additional result of the increased glyphosate-resistant weeds in glyphosate-resistant
cropping systems Worldwide has been the need for newer technologies to aid in weed control
to ensure sustainability of our primary commodity crop production across the U.S. A couple
of those developed technologies are crops with genetically modified traits which will allow
them to be resistant to growth regulator herbicides in addition to glyphosate. The growth
regulating herbicides of primary utility for these crop traits are 2,4-D and dicamba.
Dicamba-resistant Soybean
Monsanto Company, St. Louis, MO, is developing the addition of dicamba tolerance to
the Genuity.Roundup Ready 2 Yield.Soybean platform which will offer growers an
additional tool for flexible and effective weed management along with the increased yield
opportunity of Roundup Ready 2 Yield.Once approved, the dicamba tolerant technology
will enable the use of dicamba and glyphosate tank-mixes for preplant burndown, at planting,
and in-season applications adding considerable weed control value to the well-established and
effective Roundup Ready® system. Monsanto and BASF are working together to develop
innovative dicamba formulations for use with these herbicide-tolerant cropping systems, and
both companies are working together to develop robust Best Management Practices for the
use of dicamba over Dicamba tolerant soybeans. Dicamba tolerant soybeans are projected to
be commercialized in the middle of this decade, pending global regulatory approvals with
initial product launches in the U.S. and Canada.
2,4-D-resistant Crops
Dow AgroSciences has developed traits conferring herbicide tolerance in plants. This
technology was originally referred to as Dow AgroSciences Herbicide Tolerance (DHT)
traits, and is now referred to as Enlist™ Weed Control System. In soybean, the trait will
provide tolerance to pre-emergence and post-emergence applications of 2,4-D. In corn, the
trait will provide tolerance to pre-emergence and post-emergence applications of 2,4-D and
post-emergence applications of quizalofop, an ACCase – inhibitor grass herbicide. In
conjunction with the Enlist crop traits, Dow AgroSciences is also developing new and novel
proprietary technology that will significantly reduce the physical drift and volatility of 2,4-D
relative to current DMA and ester 2,4-D herbicide formulations in the market. This new
technology will be used to create proprietary pre-mix formulations of 2,4-D + glyphosate
having improved compatibility and cold storage stability characteristics. Dow AgroSciences
is also committed to providing comprehensive stewardship guidance for deploying this
technology. Enlist technologies are also projected to be commercialized in the middle of this
decade, pending global regulatory approvals.
Thoughts about Growth Regulator Resistant Crop Adoption in Wisconsin
I agree these growth regulator resistant technologies will offer many plausible and
important weed control benefits. However, the adoption and acceptance of these technologies
may once again stretch the entire crop production community to revolutionize. The benefits
with these pending technologies will include increasing broad-spectrum postemergence weed
control options, particularly for broadleaf weeds. Similar to glyphosate, the growth regulating
herbicides are also relatively cheap, and weeds are slow to develop biotypes with resistance.
However, growth regulator resistant weeds have been documented in a couple unique
situations, so like glyphosate, it can happen when the herbicide is used too often.
The adoption of these technologies also bring much concern about the potential for these
herbicides to be used more often, and as a result, find their way to sensitive vegetation which
was not an intended target. Growth regulating herbicides cause plant symptoms that are
highly visible which can lead to easy detection of off-site movement. There are three
common ways these herbicides will move off-target including failure to properly clean spray
equipment (which is very difficult in relation to other herbicides), particle drift during
herbicide applications, and volatilization, or movement of vapor off the target after spray has
deposited on the target surface. In summary, these technologies bring with them both
opportunity and challenges for weed management systems which will be discussed.
References
Johnson, W.G., V.M. Davis, G.R. Kruger, and S.C. Weller. 2009. Influence of glyphosateresistant
cropping systems on weed species shifts and glyphosate-resistant weed
populations. Eur. J. Agron. 31:162-172.
Seifert-Higgins, S. 2010. Weed management systems in dicamba-tolerant soybeans (DTS).
Proc. of the 2010 North Central Weed Science Soc. 65:91.
Simpson, D.M. 2010. Future of 2,4-D – New uses and new technologies. Proc. of the 2010
North Central Weed Science Soc. 65:180.
Yangzhou pioneer chemical CO.,LTD
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