Weed Management Systems

Associated Press, 2017a

Associated Press, “Arkansas governor approves board’s limits on dicamba use,” The Washington Times, January 4, 2017.

SUMMARY:

Reports that Gov. Hutchinson has approved the Arkansas State Plant Board’s proposal to limit when and where dicamba can be sprayed in the upcoming planting season.  It includes a requirement for a 1 mile buffer zone before spraying dicamba, except on pasture or rangeland. FULL TEXT

Barber, 2017

Tom Barber, “Dicamba Drift and Potential Effects on Soybean Yield,” AGWatch Network, July 7, 2016.

SUMMARY:

Tom Barber, an Extension Weed Scientist at the University of Arkansas, posts a chilling overview of what he has observed in soybean fields in several parts of the state. His piece “Dicamba Drift and Potential Effects on Soybean Yield” contains an ominous warning – “We have observed a 10% [soybean] yield loss from dicamba at rates as low as 1/1024X of the labeled rate” – a very low level of drift and/or movement following volatilization.  Barber also warns that low rates of dicamba drift/movement onto soybeans, especially later in the crop’s growth cycle (i.e. R3-R5) can result in carryover of dicamba in the seed…triggering problems if the soybeans are used for seed in the next year and increasing dietary exposure levels.  FULL TEXT

BASF, 2016b

BASF Press Release, “Engenia herbicide from BASF now registered by EPA,”  Farm Industry News, 2016.

SUMMARY:

BASF press release about EPA approval of Engenia herbicide for dicamba-tolerant soybean and cotton.  Includes claims of a 70% reduction in volatility.  FULL TEXT

Beck, 2018

Madelyn Beck, “Federal Suit Alleges Companies Knew Dicamba Would Drift, Monsanto Created Monopoly,” KUNC Radio, August 8, 2018.

SUMMARY:

Describes court documents filed August 2018  on two “master complaints” in the dicamba drift Multi District Litigation (MDL) pending in federal court.  The first complaint is a crop damage class action, and the second alleges antitrust violations.  Lawyers representing the plaintiffs allege that defendants Monsanto and BASF are “commercializing a product that literally destroys its competition.”  FULL TEXT

Begemann and Skiles, 2017

Sonja Begemann and Susan Skiles Luke, July 10, 2017, “Arkansas, Missouri Ban Dicamba,” AgWeb.

SUMMARY:

Effective just after midnight on July 11, Arkansas finalizes a 120-day emergency ban on dicamba sales and use.  Missouri also banned dicamba the week before, with the intent of re-opening sales once the investigation into complaints of damage from dicamba drift is complete. The Missouri Soybean Association is quoted as saying that more than 200,000 acres of soybeans are affected in the state.  In a statement, Monsanto stressed the importance of “following label and local requirements” for their Roundup Ready Xtend Crop System of dicamba-resistant soybeans. The article lists the number of complaints of dicamba damage in Arkansas as “nearly 600,” up from the 500 reported on July 6, 2017.  FULL TEXT

Begemann, 2017

Sonja Begemann, “Dicamba Damage Watch,” July 6, 2017, AgPro.

SUMMARY:

Describes the symptoms of dicamba damage – cupped and wrinkled soybean leaves – and other culprits that could be the cause such as other herbicide damage, pests such as aphids and various plant diseases.  It can take 7 to 21 days for dicamba damage to appear, and it will only be evident on new leaves, not those present when the drift occurs.  Percentages as low as 0.06 to 1.9% can cause damage resulting in yield loss. FULL TEXT

Behrens et al., 2007

Mark Behrens, Nedim Mutlu, Sarbani Chakraborty, Razvan Dumitru, Wen Zhi Jiang, “Dicamba Resistance: Enlarging and Preserving Biotechnology-Based Weed Management Strategies,” Science, 316, 2007, DOI: 10.1126/science.1141596.

ABSTRACT:

Abstract: The advent of biotechnology-derived, herbicide-resistant crops has revolutionized farming practices in many countries. Facile, highly effective, environmentally sound, and profitable weed control methods have been rapidly adopted by crop producers who value the benefits associated with biotechnology-derived weed management traits. But a rapid rise in the populations of several troublesome weeds that are tolerant or resistant to herbicides currently used in conjunction with herbicide-resistant crops may signify that the useful lifetime of these economically important weed management traits will be cut short. We describe the development of soybean and other broadleaf plant species resistant to dicamba, a widely used, inexpensive, and environmentally safe herbicide. The dicamba resistance technology will augment current herbicide resistance technologies and extend their effective lifetime. Attributes of both nuclear- and chloroplast-encoded dicamba resistance genes that affect the potency and expected durability of the herbicide resistance trait are  examined.  FULL TEXT

Benbrook Consulting Services, 2016

Benbrook Consulting Services, Use of Dicamba on Crops as Surveyed by the National Agricultural Statistics Services (NASS), 2016.

SUMMARY:

Table detailing NASS reports of dicamba use (percent of total crop) and application rates.  FULL TEXT

Benbrook, 2012

Benbrook, C, “Impacts of Genetically Engineered Crops on Pesticide Use in the U.S. – the First Sixteen Years,” Environmental Sciences-Europe, 2012, 24:24.

ABSTRACT:

BACKGROUND: Genetically engineered, herbicide-resistant and insect-resistant crops have been remarkable commercial successes in the United States. Few independent studies have calculated their impacts on pesticide use per hectare or overall pesticide use, or taken into account the impact of rapidly spreading glyphosate-resistant weeds. A model was developed to quantify by crop and year the impacts of six major transgenic pest-management traits on pesticide use in the U.S. over the 16-year period, 1996–2011: herbicide-resistant corn, soybeans, and cotton; Bacillus thuringiensis (Bt) corn targeting the European corn borer; Bt corn for corn rootworms; and Bt cotton for Lepidopteron insects.

RESULTS: Herbicide-resistant crop technology has led to a 239 million kilogram (527 million pound) increase in herbicide use in the United States between 1996 and 2011, while Bt crops have reduced insecticide applications by 56 million kilograms (123 million pounds). Overall, pesticide use increased by an estimated 183 million kgs (404 million pounds), or about 7%.

CONCLUSIONS: Contrary to often-repeated claims that today’s genetically-engineered crops have, and are reducing pesticide use, the spread of glyphosate-resistant weeds in herbicide-resistant weed management systems has brought about substantial increases in the number and volume of herbicides applied. If new genetically engineered forms of corn and soybeans tolerant of 2,4-D are approved, the volume of 2,4-D sprayed could drive herbicide usage upward by another approximate 50%. The magnitude of increases in herbicide use on herbicide-resistant hectares has dwarfed the reduction in insecticide use on Bt crops over the past 16 years, and will continue to do so for the foreseeable future. FULL TEXT

Benbrook, 2016a

Charles M. Benbrook, “Trends in glyphosate herbicide use in the United States and globally,”  Environmental Sciences Europe, 2016, 28:3, DOI 10.1186/s12302-016-0070-0.

ABSTRACT:

BACKGROUND: Accurate pesticide use data are essential when studying the environmental and public health impacts of pesticide use. Since the mid-1990s, significant changes have occurred in when and how glyphosate herbicides are applied, and there has been a dramatic increase in the total volume applied.

METHODS: Data on glyphosate applications were collected from multiple sources and integrated into a dataset spanning agricultural, non-agricultural, and total glyphosate use from 1974–2014 in the United States, and from 1994–2014 globally.

RESULTS: Since 1974 in the U.S., over 1.6 billion kilograms of glyphosate active ingredient have been applied, or 19 % of estimated global use of glyphosate (8.6 billion kilograms). Globally, glyphosate use has risen almost 15-fold since so-called “Roundup Ready,” genetically engineered glyphosate-tolerant crops were introduced in 1996. Two-thirds of the total volume of glyphosate applied in the U.S. from 1974 to 2014 has been sprayed in just the last 10 years. The corresponding share globally is 72 %. In 2014, farmers sprayed enough glyphosate to apply ~1.0 kg/ha (0.8 pound/ acre) on every hectare of U.S.-cultivated cropland and nearly 0.53 kg/ha (0.47 pounds/acre) on all cropland worldwide.

CONCLUSIONS: Genetically engineered herbicide-tolerant crops now account for about 56 % of global glyphosate use. In the U.S., no pesticide has come remotely close to such intensive and widespread use. This is likely the case globally, but published global pesticide use data are sparse. Glyphosate will likely remain the most widely applied pesticide worldwide for years to come, and interest will grow in quantifying ecological and human health impacts. Accurate, accessible time-series data on glyphosate use will accelerate research progress.  FULL TEXT