GMO Myths and Truths

5.7 Myth: Roundup is a benign herbicide that makes life easier for
farmers
Truth: Roundup causes soil and plant problems that impact yield
GM Roundup Ready crops are marketed on
the basis that Roundup is a safe herbicide that
simplifies weed control and makes the farmer’s life
easier. But recent studies show that Roundup and
glyphosate can accumulate in plants, have negative
effects on soil organisms, and harm the growth
and health even of soy plants that are genetically
engineered to tolerate it. These effects may be
partly responsible for yield decline and disease
outbreaks found in GM Roundup Ready soy and
maize.
5.7.1. Glyphosate causes or
exacerbates plant diseases
“When you spray glyphosate on a plant,
it’s like giving it AIDS.”
– Michael McNeill, agronomist and farm
consultant 97
Manufacturers claim that glyphosate kills plants
by inhibiting an enzyme necessary for plant
growth. But research shows that glyphosate has
another way of killing plants: it makes the plant
more susceptible to disease, potentially leading
to the plant’s death from the disease. Spraying
glyphosate on a plant is, as US agronomist Michael
McNeill said, “like giving it AIDS”.
One possible mechanism for this process is
offered in a study on GM RR soybeans. The study
found that once glyphosate is applied to the plant, it
accumulates in the plant tissues and then is released
into soil through the roots. There, it stimulates
the growth of certain fungi, notably Fusarium, a
fungus that causes wilt disease and sudden death
syndrome in soy plants. 98 Other studies confirm the
link between glyphosate applications and increased
infection with Fusarium. 99,100,101,102,103
Interestingly, one study found that Fusarium
colonisation of roots was greater in GM RR soy
compared with non-GM soy even when glyphosate is
not applied. The researchers suggested that this was
due to an unintended change in the GM crop brought
about by the genetic engineering process. 98
Fusarium is of especial concern because it does
not only affect plants. It produces toxins that can
enter the food chain and harm humans 104 and
livestock. In pigs, Fusarium-contaminated feed
impairs reproduction 105 and increases stillbirths. 106
Glyphosate has also been shown to increase
the incidence and severity of other fungal
diseases in plants, including take-all in wheat and
Corynespora root rot in soy. 107,108
In an attempt to combat soil-borne diseases such
as Fusarium, Monsanto markets its new Roundup
Ready 2 Yield soy seed with a proprietary fungicide/
insecticide coating. 109 In other words, Monsanto has
created a problem (fungal infection) by genetically
modifying the soy seeds and is then profiting from a
techno-fix “solution” to that problem. Such chemical
treadmills are profitable for seed and chemical
companies, but hurt farmers, consumers, and the
environment.
5.7.2 Glyphosate makes nutrients
unavailable to plants
Glyphosate binds vital nutrients such as iron,
manganese, zinc, and boron in the soil, preventing
plants from taking them up. 110 So GM soy plants
treated with glyphosate have lower levels of
essential nutrients and reduced growth, compared
with GM and non-GM soy controls not treated
with glyphosate. 111 Lower nutrient uptake may
partly account for the increased susceptibility
of GM soy to disease, as well as its lower yield.
It could also have implications for humans and
animals that eat the crop, as it is less nutritious.
5.7.3 Glyphosate impairs nitrogen
fixation
The yield decline in GM RR soy may be partly due to
glyphosate’s negative impact on nitrogen fixation,
a process that is vital to plant growth and depends
on the beneficial relationship between the soy
plants and nitrogen-fixing bacteria. In young RR soy
plants, glyphosate has been found to delay nitrogen
GMO Myths and Truths 82