We need a holistic and systems-based agroecological approach - not agriculture as a war on the land and people.
The main props of modern industrial agriculture, synthetic fertilisers and pesticides (both herbicides and insecticides) emerged from the World Wars of the 20th century.
They emerged from war and their use is a continual war - on the land, the soil, biodiversity and people. The impacts include illness and many deaths among people, and the destruction of the life of the soil, water, plants and insects.
In December 2011, the Permanent Peoples Tribunal indicted six major pesticide producers, Monsanto, Dow Chemical, BASF, Bayer, Syngenta and Dupont for violating human rights to life and health, and destroying biodiversity. 
A product of war, for war on the land
One of these agricultural weapons, 2,4-D (2,4-Dichlorophenoxyacetic acid) was first discovered during World War Two when, as reported by Orvin Burnside in The History of 2,4-D and Its Impact on Development of the Discipline of Weed Science in the United States: 
" ... both United States and England scientists initiated secret biological warfare research on plant growth regulators with the objective of destroying enemy crops.
"Kraus at the University of Chicago had observed since 1936 that certain growth regulators were phytotoxic (28). Kraus was aware of the inadequacy of existing herbicides, and in 1941 he was first to propose that growth regulators might work as herbicides, because they often killed test plants."
Like its more potent relative, 2,4,5-T, 2,4-D is a synthetic auxin, or plant hormone that acts as a selective weedkiller. And as Burnside explains, 
"In November 1942, the United States Army began developing Camp Detrick (later renamed Fort Detrick) in Frederick, Maryland, as the center for research and testing of chemicals for biological warfare with special emphasis on crop destroying chemicals."
This research, authorised by the US Chemical Warfare Service, included investigating the use of 2,4-D and 2,4,5-T.  After the war, Dow Chemical Company and Union Carbide acquired patents on some formulations of 2,4-D and the process of commercialization began.
Later of course, 2,4,5-T and 2,4-D, produced by Monsanto and Dow Chemical, were used in combination as Agent Orange and massively sprayed in Vietnam to defoliate the forests.
Escalating agricultural warfare
Yet the US and Brazil are currently considering whether to approve GM crops that tolerate 2,4-D. How can this be? The reason is simple and shocking. It is because current GM crops, the majority genetically engineered to be tolerant to the herbicide glyphosate and first launched in 1991, are now failing.
The main reason is that many weeds have developed the ability to tolerate applications of the herbicide. This was of course predictable. The spraying of millions of gallons of toxic chemicals, often from the air, forces weeds to adapt or die, so they adapt.
Pesticide use in Argentina has increased massively, "from nine million gallons (34 million litres) in 1990 to more than 84 million gallons (317 million litres) today". 
Over the same period, Brazil, where GM crops are grown on 36 million hectares, has become the world's largest user of agrochemicals. And herbicide use in the US has increased by an estimated 239 million kilograms.
During this time, several different kinds of weed resistant to glyphosate emerged, increasing year on year until now some 20-25 million hectares of US farmland may be affected.
The response has been to use older and more toxic herbicides such as 2,4-D in tank mixes of agrotoxics and to develop new 'stacked' GM seeds with several traits for resistance to different herbicides.
Dow Agrosciences seeks to release 2,4-D resistant crops ...
Now Dow Agrosciences, offshoot of the company that originally commercialised 2,4-D, seeks to release genetically engineered soybean and corn resistant to 2,4-D in Brazil, Argentina and the US.
It is estimated that releasing the 2,4-D products could increase the volume of herbicide sprayed, possibly by up to by 50%  - even though 2,4-D has negative impacts on crops, ecosystems, animals and people.
It is persistent in certain conditions, some formulations are very toxic to fish. It is highly volatile and implicated in cases of pesticide drift and destruction of other farmers' crops and of course to biodiversity. 
... and a new herbicide for a GM crop / herbicide package
Dow also seeks approval for its new herbicide Enlist Duo, which combines glyphosate and 2,4-D. 
By doing this, it opens up the opportunity, long profitably exploited by Monsanto, to retain control of the system by creating packages of products under restrictive grower contracts that place responsibility on the grower, limiting the liability of the company, and increasing profits and control.
Violation may lead to legal action and severe financial sanctions. See this fairly typical agreement that regulates farmers use of a Dow Agro product. 
US prepares to release crops tolerant to 2,4-D and glyphosate
On 28th April 2014, the US Environmental Protection Agency said it was planning to grant approval to Dow Agroscience's new herbicide Enlist Duo. 
This follows the indication from the US Department of Agriculture in January 2014  that it was minded to grant approval to Dow's proposed GM crops resistant to 2,4-D and glyphosate. Together they are called the "Enlist Weed Control System".
Ironically, in their petitions seeking ‘nonregulated' status for these crops in the US, Dow Agrosciences cited many problems with glyphosate to bolster their claims for 2,4-D. Yet there are already weeds in the US that are resistant to 2,4-D. 
Both glyphosate and 2,4-D have negative impacts on the environment and human health. What impacts they may have when used in combination has not been investigated.
Many adverse health impacts
These are numerous - and include the potential to cause birth defects and other developmental disorders (endocrine disruption), cancers, respiratory and allergic reactions, and to reduce the effective operation of the immune system. 
There are many different manufacturers and formulations of 2,4-D and some products have been found to contain significant levels of dioxin, even though it was assumed that this problem had been solved, following the scandal of Agent Orange. 
This sorry tale of a return to persistent old toxics for GM crops highlights the fact that industrial monocultures are the wrong kind of agriculture.
Real farming is multifunctional within the functions of the ecosystem. We need a holistic and systems-based agroecological approach - not agriculture as a war on the land and people.
Petition: Tell the USDA: Don't Approve New GMO 'Agent Orange' Crops! (Organic Consumers Association).
Helena Paul has worked for 25 years on issues including indigenous peoples' rights and tropical forests; oil exploitation in the tropics; biodiversity, including agricultural biodiversity; patents on life and genetic engineering (GE); and corporate power. She helped co-found GM Freeze and Genetic Engineering Network in 1999 and has been chair of the former ever since.
She has co-authored a number of papers on agriculture, climate change and biodiversity, and the book Hungry Corporations: Transnational Biotech Companies Colonise the Food Chain (Helena Paul and Ricarda Steinbrecher, Zed Books 2003).
This article is based on part of an essay written for a book entitled 'The Chains of War - nuclear weapons, militarisation and their impact on society', edited by Angie Zelter, to be published by Luath during 2014.
1. International people's tribunal indicts Monsanto, Dow Chemical and others for pesticide deaths, injuries, 8th December 2011, http://www.downtoearth.org.in/content/international-peoples-tribunal-indicts-monsanto-dow-chemical-and-others-pesticide-deaths-inj
2. Orvin C. Burnside, The History of 2,4-D and Its Impact on Development of the Discipline of Weed Science in the United States Chapter 2, Phenoxy Herbicides. http://www.24d.org/abstracts/chapter2.pdf
4. Archives Search Report Findings for Field Testing of 2,4,5-T and Other Herbicides, Fort Detrick: http://www.detrick.army.mil/responsible/ArchivalReport2012.pdf
5. Tom Fawthrop, Agent Orange Victims Sue Monsanto, Special to CorpWatch 4.11. 2004: http://www.corpwatch.org/article.php?id=11638. The Legacy of Agent Orange: http://home.clara.net/heureka/gaia/orange.htm
6. Michael Warren and Natacha Pisarenko, Argentines link health problems to agrochemicals , Associated Press/Aurora Advocate, October 18, 2013: http://www.auroraadvocate.com/ap%20financial/2013/10/18/argentines-link-health-problems-to-agrochemicals
7. Impacts of genetically engineered crops on pesticide use in the US - the first sixteen years: Charles M Benbrook: http://www.enveurope.com/content/24/1/24
8. More information available at the US Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) at http://www.aphis.usda.gov/.
It is also worth consulting Pesticide Action Network UK on 2,4-D at: http://www.pan-uk.org/pestnews/Actives/24d.htm and on dicamba at: http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC32871
10. Example of a fairly typical GM crop grower agreement http://www.dowagro.com/na/usa/en/traitstwd/das_tech_use_agreement.pdf
13. Impacts of genetically engineered crops on pesticide use in the US -- the first sixteen years: Charles M Benbrook: http://www.enveurope.com/content/24/1/24
14. The Risks of the Herbicide 2,4-D by Testbiotech, Genewatch UK and Pesticides Action Network (PAN) Europe, January 2014: http://www.genewatch.org/uploads/f03c6d66a9b354535738483c1c3d49e4/Risks_of_herbicide_2_4_D.pdf