Archive | July 2013

Corn Wars

An article by Dan Charles for The Salt on Bt resistance in the corn belt actually does a good job of identifying the problem as an issue created by poor crop and pesticide management rather than blaming biotech. The insinuation is the title, but not the reporting. The comment section is a battle of bumperstickers vs. balance.

In May, Andrew Kniss asked the world to stop using the term “Superweed” and brought some perspective to the role of biotech in herbicide resistance.

Most of the time, the term superweed is associated in some way with herbicide resistance. So if we define superweed as a weed that has evolved resistance to herbicides, we can then test the hypothesis that “GM crops have bred superweeds.” (ASIDE: The way this statement is phrased, there’s no way it can possibly be true, because crops don’t “breed” weeds. There are some rare cases where crops and weeds cross pollinate, but those have not resulted in any herbicide resistant weeds to date. For the sake of argument, we’ll assume Ms. Gilbert really meant “GM crops have significantly increased the development of superweeds.”) Dr. Ian Heap has developed and maintained a website to document new cases of herbicide resistant weeds, and we can use the data at that site to get an idea of whether this statement is true or false using our definition of superweed.

If GM crops have contributed significantly to the development of herbicide resistant weeds, we would expect the number of unique instances of these superweeds to increase following adoption of GM crops. The figure below illustrates all unique cases of herbicide resistant weeds between 1986 and 2012. I have fit a linear regression to the data from 1986 to 1996 (time period before widespread GM crop adoption) and another regression to the time period 1997 to 2012.


The slope of the linear regression is an estimate of the number of new herbicide resistant weeds documented each year. In the eleven year period before GM crops were widely grown, approximately 13 new cases of herbicide resistance were documented annually. After GM crop adoption began in earnest, the number of new herbicide resistant weeds DECREASED to 11.4 cases per year. The difference in slopes between these two time periods is probably not very meaningful from a practical standpoint. But based on the best data available, we can be quite certain that adoption of GM crops has NOT caused an increase in development of superweeds compared to other uses of herbicides.

Perhaps this definition of superweed is too broad. Let’s define it instead as only “glyphosate-resistant” weeds. The first glyphosate-resistant weed was documented in 1996. This is approximately the same time GM crops were first being introduced into the market. But this first superweed evolved in Australia, where no GM crops were grown. So it is obvious that GM crops are not necessary for glyphosate-resistant superweeds to develop. Certainly, adoption of Roundup Ready crops (the dominant GM herbicide resistance trait) has increased the use of glyphosate in cropland, and therefore increased selection pressure for glyphosate-resistant weed populations. But even so, there are currently more instances of glyphosate-resistant weeds in non-GM crops/sites than in GM crops. The following chart (from illustrates the number of cases of glyphosate-resistant weed species in various crops/sites.


The only 3 GM crops on the chart are soybean, corn, and cotton. All of the other bars represent non-GM systems. If we add up the number of herbicide resistant species in GM crops and compare it to non-GM crops/sites, we should expect GM crops to have a higher number if GM crops are the primary contributor to evolution of superweeds. However:

  • 35 species of glyphosate-resistant weeds are present in GM crops (soybean, corn, cotton).
  • 40 species of glyphosate-resistant weeds are present in non-GM crops/sites (orchards, grapes, roadsides, wheat, fencelines, fruit, barley).

So again, there appears to be no strong difference between GM crops and other sites where glyphosate is used. So this data again suggest that GM crops are not any more problematic than other uses of glyphosate for selection of superweeds.

Barley and Lentils Back in the Day

A new paper [paywall] in the journal Science reports that recent archeological findings show that agriculture had started in Iran on the far edge of the Fertile Crescent 12,000 years ago. The Los Angeles Times:

For decades, archaeologists believed agriculture took root in a part of the Fertile Crescent called the Levant, which includes present-day Israel, Lebanon and Jordan, as well as parts of Syria, Iraq, Saudi Arabia and other countries. From there, it was thought to have spread eastward to present-day Iran.

“The eastern Fertile Crescent has been treated as backwater,” said Melinda Zeder, a senior scientist at the Smithsonian Institute’s Program in Human Ecology and Archaeobiology, who was not involved in the study. Now, the understanding that people in the Zagros grew and ground cereal grains as early as their counterparts in the Levant has “democratized this situation where everyone in the region was involved,” she said.

The Salt:

riehl4hrThere were stone tools, too: things that looked like sickles, and mortar and pestles, some clearly used for grinding food. And then there were the grains and seeds — hundreds of them, charred but otherwise intact and well preserved.

Now, Conard is no botanist. He’s an expert on stone tools. But even his untrained eye recognized some of the grains.

“They look like lentils you might buy at the store, or pieces of wheat or barley you might have encountered in other aspects of life.”

He suspected he was looking at an “agricultural village,” but he sent the grains to his colleague to double check.


“That was a fantastic feeling, when I first get these plant remains under the microscope,” says Riehl, an archaeobotanist at the University of Tubingen.

She confirmed that the grains were indeed varieties of lentils, barley and peas. She also identified a range of nuts and grasses, and a kind of wheat called Emmer, known to be a commonly grown crop in later centuries throughout the Middle East.

But most of the grains Riehl looked at were pre-agricultural. “They were cultivating what we consider wild progenitors of modern crops,” says Riehl.

Here’s a recipe that combines elements of what those folks might have been eating. I cook lentils with spinach a lot, but I’ve used arugula here because our arugula is a lot closer to it’s ancient predecessor.


½ lb. chopped bacon (ends are perfect)
¼ cup extra-virgin olive oil
2 carrots, finely chopped
1 large yellow onion, finely chopped
1 tsp. cumin seeds,
½ tsp. dried thyme
12 cups chicken broth
1 cup pearled barley, rinsed
¾ cupred lentils, rinsed
Kosher salt and freshly ground black pepper
½ lb. arugula, coarsely chopped


1. Heat oil in a 5-quart pot over medium-high heat; add bacon, cook until 2/3rds done.

2. Add carrots,and onions, along with cumin, and thyme. Cook, stirring, until lightly browned, 10–15 minutes. Add chicken broth, and barley and season with salt and pepper to taste.

3. Bring to a boil, lower the heat to medium-low, and cook, partially covered, stirring occasionally, until barley is al dente about 35 minutes. Add lentils. Cook about 10 more minutes until lentils are done. Red lentils cook much faster than other lentils so adjust accordingly if you are using a different type of lentil. Stir in arugula at the end.