Weeds reduce farm and forest productivity, they invade crops, smother pastures and in some cases can harm livestock. They aggressively compete for water, nutrients and sunlight, resulting in reduced crop yield and poor crop quality. In the case of livestock burrs in wool can diminish the quality of fleece, wild garlic can taint meat and milk, they can infect the udders or cows and kill horses and some weeds, such as ragweed, cause asthma in humans. Weeds are common on all 485 million acres of U.S. cropland and almost one billion acres of range and pasture. Since weeds are so common, people generally do not understand their economic impact on crop losses and control costs. In 1991 alone, the estimated average annual monetary loss caused by weeds with current control strategies in the 46 crops grown in the United States was $4.1 billion. If herbicides were not used, this loss was estimated to be $19.6 billion. Losses in field crops accounted for 82% of this total. Another source estimates that U.S. farmers annually spend $3.6 billion on chemical weed control and $2.6 billion for cultural and other methods of control. The total cost of weeds in the United States could approach $15 to $20 billion dollars.[1]
Pesticides are defined as “chemical substances used to prevent, destroy, repel or mitigate any pest ranging from insects (i.e., insecticides), rodents (i.e., rodenticides) and weeds (herbicides) to microorganisms (i.e., algicides, fungicides or bactericides).” Over 1 billion pounds of pesticides are used in the United States each year and approximately 5.6 billion pounds are used worldwide. In many developing countries programs to control exposures are limited or non-existent. Consequently; it has been estimated that as many as 25 million agricultural workers worldwide experience unintentional pesticide poisonings each year. In a large prospective study of pesticide users in the United States, the Agricultural Health Study, it was estimated that 16% of workers had at least one pesticide poisoning or an unusually high pesticide exposure episode in their lifetime.[2] Pesticides are necessary to the health of our agricultural systems but agricultural scientists and genetic engineers are constantly working on ways to reduce the use of pesticides and create better products.
Outside of drought and hail, insects and weeds are the worst threats to agricultural crops, so it’s not surprising that weeds were the first to be studied by genetic engineers. In the 1980s, Monsanto already produced the powerful herbicide Roundup. It works by disrupting the action of an enzyme that is found in almost all plants but not in humans. The problem was how to apply Roundup to the plants you don’t want and keep it off the plants you do – get it on the weeds while keeping it away from the crops. That’s tough to do, so farmers were using Roundup early in the growing season to kill weeds that sprouted before the crops, and then switching to less powerful herbicides after the crops germinated. Genetic engineers wondered if they could find a gene that would allow crops to survive and even thrive when they are exposed to Roundup. The reasoning was that the pesticide worked on enzymes, and enzymes are proteins that are produced by genes – therefore, there might be a gene that could protect the crop from the pesticide.
In the early 80s, workers at a Roundup manufacturing plant in Louisiana noticed that bacteria were breaking down the chemical residue left over. Scientists took 20 different bacteria from the waste facility and found one of that was totally immune to the effect of Roundup or other glyphosate pesticides. From here the biotechnology team worked to get that gene into plants. In 1987, Monsanto started field trials with GMO biotech plants. It took until 1996 to complete the tests, get the regulators to approve of the new hybrids and introduce to the world “Roundup Ready Soybeans.” Farmers could now plant the soybeans, wait for the weeds and the crop to come up and spray once with Roundup. The weeds would die, and the crops would grow without the pressure from competing weeds.[3]
Roundup Ready crops have changed the face of farming since the 1990’s. Farmers can control weeds effectively, creating more productive farms, generate better revenue while not having to use copious amount of different pesticides throughout the growing season in order to be successful.
[1] “Introductions to Weeds: What are They and Why do we Care.” Penn State Agriculture Extension. https://extension.psu.edu/introduction-to-weeds-what-are-weeds-and-why-do-we-care. 2009
[2] Pesticides Use and Exposure Extensive Worldwide. Journal of Environmental Health. M. Alavanja. 2009
[3] “Bt and Roundup Ready Crops.” https://livinghistoryfarm.org/farminginthe70s/crops-3/the-gmo-age-begins/bt-roundup-ready-crops/