The Food Journal and Food, Nutrition & Science

An alliance between The Lempert Report and The Center for Food Integrity

Why Do Farmers Spray Chemicals on Crops?

Why Do Farmers Spray Chemicals on Crops?

The Food Journal

March 12, 2015

Growing the food and fiber we need is a challenge. The UN Food and Agriculture organization IPPC Secretariat estimates that 20-40 percent of our global crop is lost due to plant pests and diseases.

Worldwide there are about 250,000 species of plants. Three percent of these or 8000 species are weeds. Of these 8000 weeds 200-250 are major problems for our food supply. Weeds have many characteristics, but producing lots of weed seed and having their seeds survive in the soil are two examples of the problems they cause. For example, pigweed produces as many as 117,000 seeds from each weed. Some weed seed, under the correct soil conditions, can stay buried and survive for up to 40 years. In the United States each acre of our cropland has between 50-300 million buried weed seeds. 

Why Do We Spray?

Farmers spray to mitigate crop damage caused by pests. A pest is any biological organism, including weeds, pathogens, and arthropods, that interferes with the production of crops affecting quality and/or yield. Insect pests can have large and irreversible effects on crops and yields, which can impact consumers through higher crop prices. 

Much like we take steps in our gardens to keep our plants free from pests and disease, farmers utilize crop protection products (herbicides, insecticides, fungicides, etc.) to help control the thousands of weed species, harmful insects, and plant diseases that can afflict crops. Whether organic or conventional, farmers face these challenges each growing season. 

The need to utilize crop protection products can vary by climate, environment, and geographical location so each farm poses different needs in the spectrum of crop protection products. In order to understand how and why certain crop protection products are used, it is important to understand the science behind how and why they work. Pesticides work in many different ways by affecting their target, whether it be a weed, pest, or disease. 

“These different ways in which pesticides work are called ‘modes of action,’ and it is typically through these modes of actions that pesticides are classified. The importance of knowing the mode of action needed will allow you to utilize crop protection products successfully. Farmers only utilize the modes of action they need for any given situation. Oftentimes farmers will consult a professional called an agronomist to make recommendations or suggestions,” says Jennifer Dewey Rohrich of Rohrich Farms in South Central North Dakota, where she farms wheat, corn, soybeans and sunflowers with her husband, his father, and his brother along with their families.

Not only do farmers have to fight weeds that steal nutrients, sunlight and water from our crops, but other things want to eat our food too. Many insects eat plants. There are over 500,000 insect species that feed on growing green plants. Most are butterflies, moths, beetles and sucking insects. Other pests cause harm while the food is being stored or transported.  

There are all kinds of pests, and there are treatments applied to protect the food and fiber grown from them eating and damaging the crop. This includes Algicides (algae), Antimicrobials (bacteria and viruses), Biocides (microorganisms), Miticides (mites), Fungicides (fungi), Insecticides (insects), Nematicides (nematodes), and Rodenticides (mice and rodents).

What Would Happen If We Didn’t Spray?

In 2003, it was estimated that if we didn’t use herbicides to kill the weeds it would have cost us $21 billion dollars. Of this, $7.7 billion would have been spent on other forms of treatment, and we would have lost $13.8 billion because of less yield or crop being produced.

“Without the use of crop protection products, overall food production would decline, and many of the fruits and vegetables we enjoy in the store would be in short supply. Because crop protection products can help improve crop yields and supply, this help keeps our food at a stable price in the grocery store. Crop protection products don’t only affect food crops though; production of certain fibers and oils would also be affected, as crops like cotton are highly susceptible to pests and disease,” says Dewey Rohrich.

All farmers want to prevent insects from harming their crops, adds Katie Sawyer, a fourth-generation farmer in Central Kansas who, along with her husband Derek, grows corn, soybeans, wheat and grain sorghum on their irrigated and dryland farm. There are techniques farmers can use to help keep insects out of fields, says Sawyer, but once they are present and inflicting damage on crops, pesticides are the only effective tool to eliminate them.

Robert Bowling, Ph.D., Texas A&M Agrilife Extension Entomologist says that without pesticides, farmers would depend on more labor intensive and expensive techniques to manage pests. Some of these are hand weeding fields, crop rotations, and mechanical pest suppression in the absence of sprays. In some instances farmers would experience significant yield reductions from pests when management alternatives to sprays are unavailable. The absence of effective spray options would severely limit production and would reduce the number of acres a farmer could manage.

“Farmers would experience a reduction in food quality in the absence of sprays. This could impact the nutritional quality, safety, and quantity of food available to consumers while increasing the cost of perishables. Consumers would have to accept holes, discolorations, and other blemishes on fruits and vegetables in the absence of sprays. On-farm profit margins would shrink forcing some farmers to seek alternative means to support their families. Furthermore, production costs would increase, and those costs would eventually be passed on to consumers,” says Bowling. (See full interview)

How Do Farmers and Farmworkers Protect Themselves?

Dewey Rohrich says that farmers don't have a jug labeled "pesticides" that goes on anything and everything. The truth about the crop-protection products they use on the farm is that they use specific chemicals labeled for very specific uses and at very specific amounts. The products they use for crop protection vary depending on crop, soil, crop rotation, current condition of the crop, pests, and moisture. The choices they make regarding what to spray are careful, calculated, and measured out. It is not something they do haphazardly or thoughtlessly like many websites will suggest.

“We are a third generation farm and want to continue striving to preserve the land quality for our future generations. This wouldn’t be possible if we abused the resources allowed to us. If farmers were to overuse things such as crop protection products, this could hurt their land. Bad, toxic, or depleted soil doesn’t grow crops. We rely on the health and safety of our land in order to continue farming each year,” says Dewey Rohrich.

On the farm, farmers like Jennifer Dewey Rohrich and Katie Sawyer take precautions when applying pesticides. Personal Protective Equipment (PPE) such as long sleeves/pants, gloves, and safety glasses are used as per pesticide label requirements, and if there is a risk of inhalation, a disposable respirator is used as well.

Employee training is extremely important when it comes to using pesticides. Workers are protected under the Worker Protection Standard as well as the Hazard Communication Standard, which requires employers to disclose any toxic or hazardous substances in workplaces. This also requires any employee unrestricted access to Material Safety Data Sheets for any chemicals utilized as well as appropriate training to understand potential safety risks. There are also field re-entry intervals put in place as per pesticide label requirements. 

“Technology has allowed for precision spraying so that only the necessary amount of pesticides is applied to only the areas of the field that are damaged by the insects. We contract with companies who use precision spray rigs to apply pesticides. They survey the field and crop damage and are exact, within less than an inch, with their application. By only applying the minimum amount, this reduces the potential for run off and adverse affects to the soil,” says Sawyer. 

Farmers routinely use specialized nozzles to control individual droplet size thereby reducing the potential for spray drift, adds Bowling. Adjusting ground speed and pressure also minimizes off-target movement by pesticides. Environmental factors that could increase the probability of spray drift, some of which include wind speed and air inversions, are carefully monitored before and during spray applications to fields. Adjustable spray booms are commonly used to adjust the height of spray applications above the canopy to minimize the time required for pesticides to contact their intended targets. Also, spray equipment and technologies are constantly changing to make pesticide applications safer to the environment, handlers, and applicators while minimizing off target movement of these applications.

Bowling continues, “The safe use of chemicals starts with training employees about pesticide safety including, but not restricted to, handling, application, and cleaning spray equipment. Farmers take great care when applying chemicals to their crops not only for environmental considerations but to ensure surrounding crops and off target organisms are not adversely affected by off-target movement by pesticides.” 

What About Organics?

Many consumers believe that organically produced food does not use pesticides of any type. That isn’t true. This type of production agriculture also seeks ways to protect the food and fiber from pests but uses products that are derived from natural sources rather than those that are synthetically manufactured. Being organically produced does not mean the products are pesticide or chemical-free. USDA lists these substances on their website

“Organic farmers face the same challenges and have the same goals as conventional farmers: keep crops free of pests and deliver the highest quality product possible. But because organic farmers do not use GMO seed technology, their crops do not have any built-in resistance to insects and they must, instead, rely only on pesticides to defeat insects,” says Sawyer.

In terms of the bottom line, many organic growers spend some of the money that might be spent on pesticides in conventional growing on human labor and other inputs, says Dewey Rohrich. They utilize techniques like harrowing and cultivating, flame weeding, and actually physically hoeing weeds out of fields – techniques that typically aren’t used in a conventional method of production. Like a conventional farmer, on the other hand, organic producers utilize cover crops to suppress weeds or establish a good crop rotation to build soil health. For any farmer, healthy plant roots equal healthier plants, which in turn are better able to ward off pests and for conventional farmers, and it can minimize the usage of certain pesticides. 

Dewey Rohrich also says that organic farmers can use hybrids that are naturally pest resistant. This could be helpful in the case of row crops like field corn, barley, field peas, grasses and alfalfa because these crops have very few options for pesticide sprays.

“There are certain spray formulations, classified as organic, used by organic farmers. These sprays are commonly used to suppress certain arthropods and pathogens that damage organic field crops, fruits, and vegetables. Organic farmers would experience similar consequences as those mentioned for conventional farmers in the absence of sprays to control or suppress agricultural pests,” says Bowling.

What Should Consumers Know?

Farmers can gain consumers’ trust through transparency and thorough explanation of their methods. They have to demonstrate to consumers that they analyze the use of all forms of technology on their farms and that all decisions are made with the consumer and environment in mind, says Sawyer.

Also, pesticides developed for commercial use are much safer than those used in the past, says Bowling. For example, many products are designed after “natural” pesticides such as pyrethroid insecticides that are modeled after pyrethrins and neonicotinoid insecticides tailored after nicotine, an insecticidal product found in tobacco. Pyrethrins are natural, plant derived products. Others mimic certain biological activities of some insects that disrupt normal growth and development of the target pest, such as insect growth regulators. These products tend to be specific to a pest or group of pests and have little to no impact on non-target organisms. New insecticides being developed have targeted sites of activity and are more pest specific thereby minimizing the impact on non-target organisms. Many of these products tend to compliment biological control.  

Farmers also consider activity by non-target organisms prior to making insecticide applications. For instance, when honey bees are active, farmers may delay application, use products that are pest specific, or spray early in the morning or late at night when bees are not active.  

In all cases the use of these chemicals, whether synthetic or natural, is regulated by EPA. The EPA states:

“For many years, we have enjoyed the benefits of using pesticides to control weed, insect, fungus, parasitic, and rodent pests. Recently, both the public and the press have increasingly focused on the negative impacts of agricultural, urban industrial, and residential chemicals. However, there are also substantial benefits to society, including:

    •    Pesticides are the only effective means of controlling disease organisms, weeds, or insect pests in many circumstances.

    •    Consumers receive direct benefits from pesticides through wider selections and lower prices for food and clothing.

    •    Pesticides protect private, public, and commercial dwellings from structural damage associated with termite infestations.

    •    Pesticides contribute to enhanced human health by preventing disease outbreaks through the control of rodent and insect populations.

    •    Pesticides are used to sanitize our drinking and recreational water.

    •    Pesticides are used to disinfect indoor areas (e.g., kitchens, operating rooms, nursing homes) as well as dental and surgical instruments.

    •    The pesticide industry also provides benefits to society. For instance, local communities and state governments may be partially dependent upon the jobs and tax base that pesticide manufacturers, distributors, dealers, commercial applicators, and farmers provide.”

Does Public Opinion Matter?

Bowling says farmers want to provide safe, high quality agricultural products to consumers. Products and technologies adopted by farmers originate from rigorous scientifically-based research to ensure they perform in a manner that minimizes environmental and non-target impacts while maintaining production goals. Commercializing new agricultural pesticides, biopesticides, or biotechnologies takes seven to 10 years of comprehensive, rigorous research to ensure their safety to the environment and humans. The EPA allows a public comment period on products, technologies, and regulations prior to their commercialization. Public opinion can alter the time required for EPA approval of any new product.

Sawyer adds, “Farmers are mindful of the short and long-term impacts of all of their actions, including pesticide use. While we are cognizant of public opinion and take that into account when making decisions, farmers are the true experts of crop production. They have access to data, information and studies that are not widely reviewed by the general public. That applies both to the use of pesticides and seed technology that allows us to dramatically decrease our use of pesticides.”

Dewey Rohrich points out that consumers have the ability to potentially vote in legislation that can hinder farmers or potentially help them to continue to farm the land they have for generations. Therefore, public opinion has a direct impact on laws and regulations that affect farmers. 

“This is one of the reasons why I strive so hard to have so many conversations about what it is we do in agriculture. As farmers, we want consumers to know what we are doing and why we make the choices we do on our farm. We don’t want our methods to be somehow secretive. The more they know about what we do, the more they can make informed decisions at the voting box. I strive to be open, honest, and transparent about what goes on at our farm even if it means discussing a hot button topic like pesticides as I am doing right now,” says Dewey Rohrich.

Interview on Pesticides with Robert Bowling, Ph.D., Texas A&M Agrilife Extension Entomologist

Why do farmers spray?  

Farmers spray to mitigate crop damage caused by pests. A pest is any biological organism, including weeds, pathogens, and arthropods, that interferes with food quality and yield.  

What would farmers have to do if they didn't spray, and what impact would it have on their ability to farm? What would happen to organic farmers?

Farmers would depend on more labor intensive and expensive techniques to manage pests such as manual labor for weeding fields, crop rotations, and mechanical pest suppression in the absence of sprays. In some instances farmers would experience significant yield reductions to pests when management alternatives to sprays are unavailable. The absence of effective spray options would severely limit production goals and would restrict the number of acres a farmer could manage. Farmers would experience a reduction in food quality in the absence of sprays. This could impact the nutritional quality, safety, and quantity of food available to consumers while increasing the cost of perishables. Consumers would have to accept holes, discolorations, and other blemishes on fruits and vegetables in the absence of sprays. On-farm profit margins would shrink forcing some farmers to seek alternative means to support their families. Furthermore, production costs would increase, and those costs would eventually be passed on to consumers. 

There are certain spray formulations classified as organic used by organic farmers. These sprays are commonly used to suppress certain arthropods and pathogens that damage organic field crops, fruits, and vegetables. Organic farmers would experience similar consequences as those mentioned for conventional farmers in the absence of sprays to control or suppress agricultural pests.

How can we best explain how pesticides work in organics to consumers? 

Progressive or unexpected pest outbreaks in production fields (either conventional or organic farms) can occur at any time during the production season. Remedial action often is required to manage outbreaks before causing economic injury or loss to the crop and producer. Pesticides are used to preserve the quality and yield when outbreaks occur in the absence of alternative management practices.

What are “restricted use” pesticides, and what does that mean?  

Restricted use pesticides (RUP) are strictly for retail sale to, and use by, certified applicators or persons under their direct supervision and only for those purposes covered by the applicator's certification. When a pesticide is classified as restricted, the label will state "Restricted Use Pesticide" at the top of the front panel. Below this heading may be a statement describing the reason for the restricted classification. There are various reasons determined by the U.S. Environmental Protection Agency (EPA) why a particular pesticide is classified as restricted. These criteria involve the EPAs determination that the pesticide may be hazardous to human health or to the environment even when used according to the label (Source: Frederick M. Fishel, University of Florida IFAS Extension).

What special equipment or precautions do farmers take when they use chemicals?  

Safe use of chemicals starts with training employees about pesticide safety including, but not restricted to, handling, application, and cleaning spray equipment. Personal protective equipment (PPE) such as face shields, boots, googles, and rubber gloves are used to minimize a person’s exposure when handling pesticides. Farmers take great care when applying chemicals to their crops not only for environmental considerations but to ensure surrounding crops and off target organisms are not adversely affected by off-target movement by pesticides. Farmers routinely use specialized nozzles to control individual droplet size thereby reducing the potential for spray drift. Adjusting ground speed and pressure also minimizes off-target movement by pesticides. Environmental factors that could increase the probability of spray drift, some of which include wind speed and air inversions, are carefully monitored before and during spray applications to fields. Adjustable spray booms are commonly used to adjust the height of spray applications above the canopy to minimize the time required for pesticides to contact their intended targets. It should be noted that spray equipment and technologies are constantly changing to make pesticide applications safer to the environment, handlers, and applicators while minimizing off target movement of these applications.

How does public opinion shape how farmers use science? 

Farmers want to provide a safe and high quality product to consumers. Products and technologies adopted by farmers originate from rigorous scientifically-based research to ensure their performance in a manner that minimizes environmental and non-target impacts while maintaining production goals. Commercializing new agricultural pesticides, biopesticides, or biotechnologies takes seven to 10 years of comprehensive, rigorous research to ensure their safety to the environment and humans.  

Rules and regulations enacted by the USDA and EPA provide for public and environmental safety of products and technologies approved for commercial farm use. The EPA allows a public opinion period on products, technologies, and regulations prior to their commercialization. Public opinion can alter the time required for EPA approval of any new product. The EPA will review any products or regulations when public concerns surface about their environmental fate or potential negative impacts on non-target organisms. Additional academic and independent research is required to investigate these concerns to verify or refute claims.

How safe are the pesticide applications we use today compared to those used in the past? 

Pesticides developed for commercial use are much safer than those used in the past. For example, many products are designed after “natural” pesticides such as pyrethroid insecticides that are modeled after pyrethrins and neonicotinoid insecticides tailored after nicotine, an insecticidal product found in tobacco. Pyrethrins are natural, plant derived products. Others mimic certain biological activities of some insects that disrupt normal growth and development of the target pest such as insect growth regulators. These products tend to be specific to a pest or group of pests and have little to no impact on non-target organisms. New insecticides being developed have targeted sites of activity and are more pest specific thereby minimizing the impact on non-target organisms. Many of these products tend to compliment biological control.  

Integrated pest management (IPM) is a program that utilizes various tactics such as plant genetics, biological organisms, and cultural practices for managing crop pests. Sprays are employed when pest populations reach a research-based economic threshold. Chemical control is employed only after all alternative IPM practices have been exhausted. The program tolerates certain low levels of pests below a threshold. IPM does not replace insecticide use but improves the effectiveness or reduces the overall use of pesticides.

Farmers also consider activity by non-target organisms prior to making insecticide applications. For instance, when honey bees are active farmers may delay application and use products that are pest specific when available or spray early in the morning or late at night when bees are not active.  

How can we show consumers that there are safety protocols in place for farmworkers, and how can we gain their trust on these issues?  

The USDA, EPA, and state agricultural departments have specific protocols for commercializing and utilizing pesticides. These regulations can be accessed by the Internet or through your Department of Agriculture office. 

Where do genetically modified seeds fit into all of this? Could seeds engineered to resist certain pests and blights reduce our need for pesticides?  

Genetically modified seed is considered an IPM tactic under genetic resistance. Insecticidal proteins found in GM plants are derived from the same organisms found in commercial Bt spray formulations used by homeowners, some conventional farmers, and widely used by organic farmers. This is another management strategy utilized by farmers to manage insect pests such as corn borer, rootworm, and cotton bollworm. GM seeds providing resistance to insect pests has reduced insecticide use by 123 million pounds (http://www.enveurope.com/content/24/1/24). Although herbicide use has increased with the introduction of herbicide tolerant crops, it should be noted that this technology has permitted farmers the ability to reduce reliance on tillage for managing weeds. Conservation tillage practices preserve soil moisture while reducing wind and water erosion as well as decreasing water and chemical runoff. Conservation tillage also reduces air pollutants that are associated with wind-borne soil particles. Conservation tillage also reduces the carbon footprint of agriculture.