Often times when people talk about using chemicals on the farm,
they use the word "pesticides." To people outside of agriculture,
pesticides tend to be the lump all category for any and all
chemical compound we spray on our crops. And honestly, that is far
from the truth. We don't have a jug labeled "pesticides" that goes
on anything and everything. In agriculture, we call any sort of
chemical we use on the farm crop protection products.
The truth about the crop protection products we use on the farm
is that we use specific chemicals labeled for very specific uses
and at very specific amounts. I've written before that as farmers
have a choice in what seed to select. We also have a choice
when it comes to what we put on our crops. It varies depending on
crop, soil, crop rotation, current condition of the crop, pests,
and moisture. The choices we make for what to spray is careful,
calculated, and measured out. It is not something we do haphazardly
or thoughtlessly like many other websites will suggest.
In the agriculture world, we typically categorize crop
protection products under many different types. I want to share
with you those different types, why we use them, and how they
affect the crops on our farm. In order to understand how and why we
use certain chemicals, it is important to understand the science
behind how and why they work. Think of it like this, if you were
looking to clean your floor, you wouldn't use the soap formulated
to clean your dishes. You would use whatever is specific to that
I have done my best to break this down in the simplest terms I
can. I understand this is a hot topic and I ask that if you choose
to comment, please be respectful.
Much like your home or garden, controlling weeds is important to
ensure your crop grows. Since the 1940's, a new breed of herbicide
was born that allowed for relatively low rate of chemical applied,
using low volumes of water, and are selective meaning that we can
kill the weed without harming the crop plant.
Herbicides work in several different ways by affecting their
target weeds: destroying cell and tissue, preventing cells from
dividing so the plant cannot grow, promoting uncontrolled growth
that kills the plant, or by disrupting vital enzyme systems within
We call these different methods modes of action and it is
through these modes of action herbicides are categorized. For
example, glyphosate (Roundup) is a mode of action that inhibits an
enzyme, which is vital for plants to make particular amino acids.
Without these amino acids, the plant dies. Animals do not require
this which means glyphosate has relatively low toxicity to mammals,
insects, and fish.
Herbicides are also categorized by what we call a mode of
uptake. Not all herbicides reach the plant in the same method. Some
herbicides act on the plant when they first touch it, some
herbicides are absorbed from the soil by the roots, and some
herbicides enter the plant by absorption through the
Insecticides are chemicals used to control insects by killing
them or preventing them from engaging in behaviors that are
destructive to crops, like eating them. Many insecticides act upon
the nervous system of the insect by inhibiting or blocking
Much like herbicides there are varying modes of entry to
insecticides to work. Residual insecticides remain active in
amounts sufficient to kill pests for a specific amount of time.
These residual insecticides act by keeping a toxic residue on a
surface that the insect will come in contact with.
Contact insecticides control the pest on contact and are applied
directly to the insect, which is killed after it comes in contact
with the insecticide. Very little toxic residue remains on a
surface after spraying a contact insecticide. Think about when you
fog for mosquitos or flies.
Systemic insecticides enter the insect's host plant and
translocate throughout the host plant. When an insect feeds on the
host, it ingests enough insecticide to be lethal. And finally
stomach poisons are insecticides eaten by an insect so that the
poison enters the stomach and is then absorbed into the body.
Insecticides are also classified by their chemical basis. These
are big, scientific words but here are several of the
classifications: organophosphates, carbamates, miticides,
pyrethoids, and neonicotinoids. If you are interested in reading
more about these classifications,
here is a great write-up.
Disease is a major source of crop and plant damage that can be
caused my fungus. Fungicides are used to control fungal disease by
specifically inhibiting or killing the fungus causing the disease.
In contract with human medicines, most fungicides need to be
applied before the disease occurs or at the first appearance of
symptoms to be effective. And also unlike humans, the damage caused
by diseases on plants often does not go away, even after the
pathogen is killed. Fungicide can only protect new uninfected
growth from disease, so you can see why fungicides play an
important role in crop protection.
Like insecticides and herbicides, there are different
classifications of fungicides. Contact fungicides remain on the
surface of plants while Systemic fungicides are absorbed into the
plant. There are also different modes of action. Fungicides kill
fungi by damaging their cell membranes, inactivating critical
enzymes, or by interfering with key processes such as energy
production or respiration.
Knowledge of exactly how an herbicide, insecticide, and
fungicide is affects its' target is helpful and critical for
selecting products. Products are not just selected at random, but
as I said before, are carefully chosen with many factors taken into
consideration. Often times, farmers will consult a professional
agronomist to make pesticide recommendations. Knowing the mode
of action determines how the pesticide will affect the target.
Sometimes different modes of action are needed in successful and
effective crop protection. One of the reasons we rotate our crops
is so that our soil isn't getting the same modes of action year
Please remember that we are all people, no matter what side of
the fence we are on. Whether we are organic farmers or a
conventional farmer or anyone in between, we are all people. We
have families, friends, and people we are about. We are all
passionate about the food we eat and how it ends up on our tables.
We all care about the health and safety of those we love…farmers
are no exception.
Look at this list, look at the choices we are offered as
farmers. Let's celebrate that choice. Let's celebrate that farmers
are given choices so we can produce the very best crops we possibly
can so that you, the consumer, can have choices when it comes to
the food you find in the grocery store and beyond. And finally,
let's all work together, have conversations, and further research
so that more people across the globe can be given those choices
Jenny Dewey Rohrich is a self-proclaimed country girl. Born
and raised in Northern California and growing up in her parent's
butcher shop and deli (chicolockersausage.com), agriculture has
always been close to her heart. She recently followed her heart all
the way to the rural prairies of North Dakota where she is now
married to a Sunflower farmer and works at his Ag supply business.
Jenny and her farmer still cannot believe they found found love via
Twitter and their life became a true modern day love story. Besides
spending time with her farmer, Jenny can be found with a camera in
hand capturing the world around her, loves the challenges of
bringing culture to the North Dakota prairie through a variety of
culinary creations, and using her interior design degree to flip
their bachelor pad into a home in their small town of Ashley
(population 800). All of this and more can be found on her blog: prairiecalifornian.com. You can also find her