Why Do We Spray?

There was a time, not too long ago, that June and July were relatively quiet months on the farm. Once in-crop weed spraying was finished, work in the fields was essentially completed. Farmers were able to spend their summers getting ready for harvest, taking care of unseeded low-lying areas in their fields, and attend weddings and other social events.

Summer this year has been a whirlwind so far. In-crop spraying was completed about two weeks ago (mostly), but fungicide season has only just gotten started. Every sprayer is rolling full out on whatever fields are ready to spray, and farmers are busy checking the rest of the fields to see if they are ready. It is not unheard of to spray 40,000 acres per season, per sprayer.

Perhaps I should explain what I mean by “in-crop spraying”. After seeding is complete in late May to mid-June, crops must all be sprayed to kill weeds. Make no mistake, this is a critical application, as a crop left to fight weeds on its own can be quickly overwhelmed by competition. Thanks to genetic modification, many of our crops are easy to deal with, such as corn, soybeans and canola. Some are also very competitive, like wheat and barley. However, crops like peas and lentils, even with proper herbicide application, can easily be outcompeted by difficult weeds like kochia, wild buckwheat, wild oats, etc. Spraying these crops is a big project and it takes many hours on the sprayer; but it is not the final application of the year.

As soon as the weeds are taken care of, crops are carefully monitored for disease and insects. Most diseases need wet, humid air and warm temperatures for optimum growth and infection. These diseases are mostly fungi, with a wide variety of species infecting each crop. In wheat, tan spot can be very damaging to the leaves, removing photosynthetic area and replacing it with tan-coloured spots. In canola, white mould can devastate yield potential, choking off the stem and starving the plant. In other crops such as lentils, some diseases can virtually kill an entire field in a matter of days (e.g. Anthracnose).

From the outside looking in on agriculture, you may wonder why we spray so many chemicals on our crops. We would not spray fungicides if we didn’t need to. These are expensive products that require many hours on the sprayer to apply, and many of them have extremely tight application windows. Also, during the summer months, I can guarantee you every farmer would rather be at the lake than spraying non-stop.

Take Fusarium Head Blight (FHB) for example, caused by Fusarium graminearum. This disease, if left unchecked, infects the seeds of durum, wheat and barley, elevating levels of a vomitoxin called deoxynivalenol (DON). As the name suggests, this toxin induces vomiting and can be dangerous if consumed in high enough levels. Therefore, if our grain is infected with FHB, it will be worth a lot less to try and sell. Would you want to eat bread or pastries or drink beer infected with this? It is a difficult disease to control, and we check our durum daily to try and catch the optimal window for fungicide application, which is about a two-day opportunity while the head is flowering. A wheat head that has completed flowering, and therefore moved past its application window, is shown below:

Nikon J1 July 351

We sprayed this crop to protect it from FHB, as climatic conditions are perfect for its development. Unfortunately, we also had to apply a product that everyone hates: chlorpyrifos, also known by its brand name, Lorsban. This product is an insecticide, and yes it is somewhat hazardous. We applied it to protect our crop from the dreaded grasshopper. These verocious insects can eat a lot of material very quickly. To compound the problem, we also found some of these bugs:



This little bug on the wheat head is called the orange blossom wheat midge, a nasty little insect that lays its eggs in the florets of wheat and durum, which hatch later on and chew on the developing kernel. Like FHB-damaged kernels, this also causes grade loss.

Spraying insecticides is not a fun job, but sometimes it is necessary to protect the massive investment we put into our crops every year. We avoid spraying them as much as we can, but you do not have to worry about their safety. There is no kernel, or any form of it, in that wheat head yet. Lorsban has a residual of about 7 days. This plant is at least 40 days from harvest. All of our insecticides, indeed all of our chemicals, have a regulated pre-harvest interval to ensure no residue remains at harvest. Furthermore, scientists have developed economic thresholds to determine when it is worth spraying insecticides to prevent unnecessary spraying. Believe me, if I didn’t believe this our food was safe after spraying with insecticides, would I really be out there spraying it? Would I eat it with my family?

The reason I have covered this in such detail isn’t to tell you how tough farming is. I love farming, and I couldn’t think of a career I could enjoy more. I tell you this so that you may know why we do the things we do. Contrary to popular belief, we don’t smother our crops with pesticides; we target herbicides (kills weeds), fungicides (kills fungi) and insecticides (kills bugs) to specific fields that require them. Someday, maybe we will have better tools that allow us to reduce pesticide use (genetic engineering is by far the best path forward for this), but for now, these are the best options we have. And the reality is, for the most part, they have been proven safe by journal article after peer-reviewed journal article.

That’s my rant for today. Hopefully I can get back on this blog more often in the future, as fungicide season will only last another week or so. I am looking forward to its conclusion. It has been a busy spray season!

Oh, one more point, in case you were wondering how the “summer of storms” has progressed since my last post about it. Immediately after that post, some fields got 3 inches of rain. Yeah. Not good. But things have improved since, and because of near ideal weather in the past two weeks, we are now looking at the potential for a very nice crop. Our fingers are crossed!

If you disagree with me about pesticides and their safety, please comment, and I’ll be happy to discuss it with you. This is a subject I take very seriously, and I have done a great deal of research on it.

14 Thoughts

      1. Pretty regularly, but depends on the crop and depends on the year. On wheat on our farm, we will spray before seeding to clean up weeds, then again at the seedling stage for the same thing. Then, if conditions warrant, we will spray a fungicide for disease control. Occasionally, if there is insect pressure, we may need an insecticide, but this will be on limited acres. Then, on some wheat acres, we may spray before harvest to dry down any weeds. Other crops in this area will be somewhat similar, but if it’s dry, the fungicide and preharvest may not be needed.

  1. Hi Jake,
    Enjoyed reading your blog! I have a question I hope you can help with. I live about 45 miles southwest of Chicago and my son recently started attending a school in rural Newark, IL I believe to the south of his school’s parking lot are soybean and corn crops. He has PE class outside near this daily. Could you please enlighten me as to when spraying any pesticides fort these crops would likely be done? During the school months? Please advise!

    1. There are a few components to this question and I’ll do my best to answer them individually. First, I should point out that spraying really goes on throughout the growing season. Weed control begins before planting and continues into early summer. Following this, farmers will probably spray for disease and will apply fertilizer (on corn, anyway). If there are insect problems, that usually occurs either very early, later in summer or early fall.

      So, spraying more or less goes on throughout the year. But, most of these chemicals are quite mundane in nature. Weed control products (like roundup) and disease control products have been shown to be very non -toxic, and I wouldn’t worry much about them. Insecticides, on the other hand, are often quite toxic products.

      Farmers use application equipment that is highly specialized for applying chemicals. Their machines are designed to minimize drift, and they are very effective at it. Plus, farmers will rarely spray in wind.

      To summarize, 90% of the chemicals farmers spray are very safe. I work with them every day. The few that are not are still safe as long as your son doesn’t go into the treated field for a day or two after application. I doubt the school would have the kids directly in the field anyway.

      There is a lot of hype about the dangers about farm pesticides, but the reality is that these products are highly regulated, non volatile chemicals that farmers apply with all safety considerations in mind. Like I said, I spend a lot of time with pesticides and I would have no concerns about my children being near fields. Let your son go out and enjoy being outside.

      I thank you for taking the time to read my blog, and to ask questions about the chemicals we use. I hope I answered your question, but if not, let me know! Thanks.

  2. Do you spray your wheat crops with Roundup or a (chemical relative )to “kill the wheats growth” and dry it out before harvesting? And do you think any of the modern day spraying of wheat has
    compromised the wheat’s quality because I am curious if there is a link with all of these people becoming gluten intolerant?…It is very common now and it makes sense to link sprays with Celiac disease. Do you know any research that has been done by a non-biased source?

    1. Sometimes we spray our wheat to kill it before harvest, yes. This is referred to as a “pre-harvest” application. We probably do that on 25-50% of our acres per year because it allows us to get the fields harvested faster. Some years we do more, some less, depending on the weather.

      The chemical kills the plant in the same way it kills anything else – glyphosate inhibits the production of amino acids in the plant, slowly shutting it down. The key thing with a pre-harvest is timing. The plant must be physiologically mature at time of application, or yield loss can occur. At this stage, and especially with the slowness of the kill, there is simply no way glyphosate can interfere with the production of proteins. If it did, it would cost us, as we get paid for the protein content of the wheat.

      Gluten, a protein itself, would therefore be totally unaffected by the pre-harvest application. Remember, in a way, we have always done some sort of pre-harvest, whether by sickle or chemical, and the effect on the plant is essentially the same.

      As for the link between gluten and changes in incidence of Celiac disease, I think this is a discussion larger than I can go into here. Suffice to say, for now, that I believe the hype over gluten sensitivity has been much over done. Watch for a blog post on this subject in the near future, as I believe this is a discussion merits further research. I think it needs to wait until after harvest though!

      I appreciate your question and I love seeing a request for journal articles. Not enough people reference this valuable resource. Stay tuned for more on this subject!

      1. Wow! I thought I lost your link in my favorites but thank heavens I found you again! Whew!
        I was so curious about your answer:)!
        I do agree that the Gluten thing is much over done. Overdone by who…I am not sure yet?
        For people who are suffering health wise and their doctor diagnoses them with Celiac disease my heart break bad for them because I LOVE bread. I love to bake etc.
        I am a Fitness and Wellness teacher in Colorado at the high school level and I don’t want to teach students misinformation. My main goal is to inspire them to think outside the box and to always ask WHY questions!! Facts are great but statistics and studies can be manipulated. Doing things the way they have always been done leads nowhere. I hope the students I have now would aspire to be farmers of the future that will do things not only differently but truly better for all in the future. Change is good and change usually makes money. My very personal spiritual belief is: making food is hard for a reason…
        It’s not just a burden or hard work it’s going to be truly painful God said. It hits farmers deep in the pocketbook. So to make it easier and more rewarding farmers in the past have reverted to hiring migrant workers, spraying, planting GMO’s etc. Now I tried to grow an organic garden last year and it was overwhelming to say the least. The weeds were prolific!!! Food production is hard for many reasons. I feel like people should all be in charge of growing their own food sometimes. They would realize how cheap they are truly getting the food at the store and how much time they can spend doing other things vs. preparing to plant, planting, tending, harvesting, and storing the food they eat. Really if I was a farmer I would be sick of being the only ones in society paying for Adam’s bad choice! I would have tried to make it easier on myself and more profitable for my family no doubt!
        Wow I really got off on a tangent!
        I guess the wheels of economy and society are already spinning so it’s hard to change anything without causing the wheels to fall off altogether.

        Looking forward to reading more information from you:)

      2. How do you address the vineyards nearby? Roundup does in fact overspray as well as dicamba
        and 2-4d

      3. We don’t have any vineyards within a 1000 miles of our farm. Regardless, good sprayer nozzle technology and proper chemical management prevents drift.

  3. Hi Jake,
    Thanks for the article. It has been over 5 years since you posted it so, I hope you see and can answer this question: What did farmers do to control weeds and kill their wheat before these chemicals were as widely available as they are today.

    1. Hi Jay, thanks for the question! In the 1960’s 2,4-D was released, which was the first broad spectrum herbicide you could use in wheat for killing weeds. Roundup (glyphosate) was released in the 70’s. These herbicides were extremely expensive in those days, so they were relegated to spot treatments in the fields. Before herbicides, farmers used tillage (rip a shovel through the ground), which was extremely destructive to soil health. Herbicides changed all that, which allowed a revolution in soil health, which continues to this day.

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