The rise of the superweeds; we brought it on ourselves

Those of us who garden as a hobby are familiar with the frustration of trying to get ahead of the weeds that compete with our flowers, vegetables and shrubs. With work we are able to more or less stay ahead of weeds at least in smaller, restricted areas and for most of the growing season our crops survive. 

For farmers, especially those tending large, industrial type farms, weeds have always been an enemy that threatened their livelihood and in recent years the threat has become much worse. The weeds seem to be winning. 

An analogous problem has been going on in medicine for the past 75 years. With the development of antibiotic drugs, many diseases were either conquered or controlled, at least for the time being. But excessive and often indiscriminate use of antibiotics has reduced their effectiveness in killing bacteria, with more and more new drugs being developed to replace the older, less effective ones. But the bacteria seem to evolve to survive the antibiotics faster than the new medicines are developed to kill them.

Pesticide use (both herbicide and insecticide) really took off after World War II. The common existing herbicides, while effective at controlling weeds, tended to be too toxic for the crops being planted in the same locations and dangerous for the farmers applying them. In 1976, the giant chemical company Monsanto introduced Roundup, an herbicide containing glyphosate, its proprietary herbicidal product, and not long after they introduced Roundup Ready crops, patented seeds that grow into plants genetically engineered to be tolerant of glyphosate. Now crops could be sprayed without damage after plants had emerged from the ground. Roundup in its various formulations has been the world’s best selling weed killer for most of the past 40 years. 

Roundup Ready seeds proved to be a hit with farmers from the start. In the United States, by 2014, 94% of the planted area of soybeans, 96% of cotton, and 93% of corn were genetically modified varieties, mostly Roundup Ready seeds.

Herbicide resistant crops have become a big business. Farmers are required to purchase the seeds exclusively from the purveyor and face legal challenges if they save and replant the seeds from the crop they may have previously planted.

Herbicide resistant crops have certain advantages. They are less expensive to produce. They enable farmers to till the soil less often, leading to better water retention, reduced runoff, and less greenhouse gas emissions. Manufacturers claim better soil health as a result (although this is vigorously challenged by organic growers who claim that pesticide residue always has untoward effects). 

But within a few years, herbicide resistant seeds were causing problems. Farmers were using more and more glyphosate to control the ever more resistant, difficult to control, weeds that were evolving in their fields. Many started  to add dicambra and 2 4-D, a major herbicidal component of Agent Orange, (used to defoliate Viet Nam), and other chemicals to their sprays. 

Globally, hundreds of different weeds have developed resistance to hundreds of different weedkillers. In the United States, 43 different weeds are known to have developed strong resistance to glyphosate. 

In addition, climate change has become a serious factor in the development of superweeds. Mounting evidence suggests that temperatures of 90 degrees F or above can make some herbicide resistant weeds even more resistant and cause other weeds to be less sensitive to certain chemicals. Many superweeds grow faster and bigger because of the warmer climate and because of increased CO2 in the atmosphere. Together with herbicide resistance, increasing climate change will make superweeds even more difficult to control.

Perhaps the best way to combat superweeds is to return to more traditional , and more expensive, methods.They include crop rotation, planting cover crops, and in some cases hand pulling and removal of weeds. Persuading Midwestern farmers to do this,with miles and miles of fields growing corn and soybeans for animal feed, may be difficult. The movement has begun however with organic and small farms growing diverse assortments of crops, mostly for people, not livestock. Despite many limitations, organic herbicides are becoming more popular, but generally work best only on newly emergent seedlings and are no match for the current generation of superweeds.

Monsanto was acquired in 2018 by Bayer, the German pharmaceutical manufacturer. In the 10 months following Bayer’s acquisition of Monsanto, its stock lost 46% of its value because of investor apprehension concerning the 11,200 lawsuits filed against its subsidiary. In June 2020, Bayer agreed to settle over 100,000 Roundup lawsuits, agreeing to pay $8.8 to $9.6 billion to settle those claims, and $1.5 billion for any future claim. Many other suits are still pending. 

The U.S. patent for glyphosate expired in 2000 and similar products are being manufactured by others worldwide.

 Architect and landscape designer Mac Gordon lives in Lakeville.