Category: Boom Sprayers

Main category for sprayers with horizontal booms

  • Testing the Effectiveness of Sprayer Rinsing Methods using Dicamba

    Testing the Effectiveness of Sprayer Rinsing Methods using Dicamba

    This work was performed with Mike Cowbrough, Weed Management Specialist (Field Crops) with OMAFA.

    The unprecedented number of dicamba drift complaints in the United States has proven to be a polarizing issue in the agriculture community. The debate continues as to the relative influence of contributing factors.

    The sensitivity of soybeans to trace amounts of dicamba has been known for more than 50 years (Wax et al. 1969). Research has shown that less than 0.2% of the highest recommended use rate can cause a 10% yield loss in non dicamba-tolerant soybean (Robinson et al., 2013). Many horticulture and ornamental crops are equally sensitive to low doses of dicamba.

    Relative volumes of Callisto (33% field rate), Roundup (6% field rate) and Xtend (0.16% field rate) known to cause 10% yield loss in conventional soybean.

    The inherent volatility of the active, and its subsequent potential for off-target movement, is also well known. Research has shown that XtendiMax, Engenia and FeXapan are far less volatile than their predecessors. However, research has also shown that there is some degree of volatilization for 36 hours following application, peaking 6-12 hours after treatment (Mueler, 2017). Studies by Jacobson et al. (2014) showed dicamba present in the air 60-72 hours after treatment.

    While sensitivity and volatility are suspected of being the primary culprits, there are other factors that contributed to the estimated 3.6 million acres of soybean reported damaged in the United States in 2017 (Bradley, 2017):

    • inappropriate sprayer set-up,
    • physical drift,
    • the use of older dicamba chemistries, and
    • contamination of filling or spray equipment (aka carry-over)

    The Experiment

    In 2017, we decided to learn more about sprayer contamination. The following is a summary of the labelled cleaning protocol. It’s noted that rinsate disposal must comply with local regulations:

    1. Drain sprayer immediately after use.
    2. Flush all inner surfaces with water.
    3. Fill sprayer with an ammonia-based solution and soak overnight.
    4. Concurrently, remove and soak strainers, screens and nozzles.
    5. Circulate solution for 15 minutes and flush through the boom for one minute.
    6. Drain sprayer, replace strainers, screens and nozzles, and flush once more with water.

    This thorough protocol is not unique to dicamba, and historically has not been followed by sprayer operators. Instead, operators choose cleaning methods that reflect the risk of damage and the time and effort required to clean the sprayer. The majority flush with water, may or may not perform serial rinses and may or may not address dead end plumbing. Where possible, operators schedule sprays that present the least potential for carry-over damage (e.g. moving into corn following soybean). There is no way to know for certain that the sprayer is sufficiently cleaned.

    Sprayer

    Our research sprayer had a tank capacity of 60 L and was calibrated to deliver a spray volume of 15 gallons per acre. RoundUp Xtend was added at the highest labeled rate of 2 L/acre (consisting of glyphosate at 1,200 gae/ha and dicamba at 600 gae/ha). We reserved the solution for reuse by collecting spray in jugs.

    Rinses

    Serial rinse

    On a typical sprayer, the capacity of the clean water tank is ~10% that of the product tank. To perform a triple rinse, the operator introduces 1/3 of that volume to the product tank through a washdown nozzle, circulates for 10 minutes, and then sprays the product tank empty. This is repeated two more times to empty the clean water tank.

    Our intent was to scale the process in the same ratio using the research sprayer. That would mean using a 6 L volume of clean water to represent 10% of the 60 L product tank. It follows that we would have to perform three, 2 L rinses.

    However, that was insufficient volume to engage the pump and still provide enough rinsate to spray in our trials. We calculated the minimum required volume to be 8 L per rinse. We circulated for 5 minutes through a washdown nozzle. Following our third rinse, we noted that the rinsate still smelled of dicamba, and elected to run a fourth 8 L rinse. Rinsate was collected from multiple nozzles spaced evenly along the boom.

    We then opened the suction filter and the two line filters and poured the remaining solution into a bucket. We topped the volume up to 8 L with clean water and scrubbed the filters with a brush.

    Continuous rinse

    The continuous rinse process continually introduces clean water via the washdown nozzle via a dedicated pump. Concurrently, the product pump sprays from the nozzles and circulates via the agitation/bypass line. We used 32 L of clean water (a volume equivalent to that used in the serial rinse) and collected rinsate in four, 8 L volumes.

    Rinsate was collected from multiple nozzles spaced evenly along the boom. We then opened the suction filter and the two line filters and poured the remaining solution into a bucket. We topped the volume up to 8 L with clean water and scrubbed the filters with a brush.

    Continuous rinse using 1% ammonia solution

    We followed the continuous rinse process, as previously described, in order to collect the filter residue.

    Possible artifacts

    The limitations involved in scaling down introduce two potential artifacts to this experiment. First, the ratio of clean water to product volume is high compared to typical practices for both rinses. We estimate the volume remaining in the sprayer when “empty” did not exceed 4 L.

    Second, continuous rinsing was sampled in batches, which means the fourth and final volume collected represents an average of the active remaining in the system rather than the final concentration. As such, it would likely be more concentrated than what truly remained in the sprayer.

    Application

    Rinsate was applied to glyphosate tolerant soybean on 30” rows. Rinsate was applied at 20 gpa using a handboom with AIXR 11002 nozzles. Ontario locations were Ridgetown, Elora, Winchester and Woodstock.

    Results

    Crop Injury

    Regardless of rinse procedure, crop injury was greatest after the first rinse cycle and diminished after each subsequent cycle (Table 1). The first half of the continuous rinse procedure caused greater injury than the serial rinse, but injury was equivalent for the final half. Crop injury was less when rinsate was applied to soybeans at an early vegetative stage (V2) compared to when rinsate was applied to soybeans at later vegetative stages (V5-V6) or the early reproductive stage (R1).

    Table 1: Visual Injury (%) of soybean 14 days after the application of rinsate that was collected from two different sprayer cleanout procedures.

    TreatmentEloraRidgetownWinchesterWoodstock
    % Visual Injury at 14 days after application
    Crop stage at applicationV5V2V6R1
    Weed-Free Control0000
    RU Xtend100100100100
    Serial Rinse # 110075100100
    Continuous Rinse # 1 (25% water)10095100100
    Serial Rinse # 275659090
    Continuous Rinse # 2 (50% water)85709595
    Serial Rinse # 355506075
    Continuous Rinse  # 3 (75% water)55506075
    Serial Rinse # 425102535
    Continuous Rinse # 4 (100% water)25102535
    Filters – Serial Rinse15301025
    Filters – Continuous Rinse15301025
    Filters – Continuous with 1% ammonia25452035

    We were surprised to observe dicamba injury even in the final stages of both rinse procedures. This reinforces how sensitive soybeans are to low doses of dicamba and demonstrates the importance of following the labelled water – ammonia – water sequence.

    When comparing damage from filter residue (following a continuous rinse) the rinsate extracted using a 1% ammonia solution was more injurious than rinsate from plain water. Cundiff et al. (2017) found no difference between the use of water or water-and-ammonia when cleaning out a sprayer. We speculate that the ammonia was more effective at removing dicamba from the sprayer, or it increased the residue’s potency.

    Soybean yield

    Yield losses appeared to mirror visual injury; as dicamba injury decreased, so did soybean yield loss. Yield losses were observed following application of all rinsate treatments, which is understandable given that dicamba injury also occurred following the application of all rinsate treatments.

    Yield losses were greater in the first half of the continuous rinse protocol, but were par with the serial rinse for the second half (Table 2). Yield losses were observed following the application of rinsate collected from filters, demonstrating the importance of following a thorough sprayer decontamination that addresses dead-end plumbing, filters and nozzles.

    Table 2: Yield (% of weed-free control) of soybean following the application of rinsate that was collected from two different sprayer cleanout procedures.

    TreatmentEloraRidgetownWinchesterAverage
    Yield (% of weed-free control)
    Crop Stage at applicationV5V2V6V2-V6
    Weed-Free Control100100100100
    RU Xtend0000
    Serial Rinse # 1044115
    Continuous Rinse # 1 (25% water)01304
    Serial Rinse # 233651036
    Continuous Rinse # 2 (50% water)2261328
    Serial Rinse # 374896676
    Continuous Rinse  # 3 (75% water)72895776
    Serial Rinse # 486968689
    Continuous Rinse # 4 (100% water)86978289
    Filters – Serial Rinse939610096
    Filters – Continuous Rinse87979593
    Filters – Continuous with 1% ammonia79859285

    Other observations

    1- Dicamba injury delayed soybean maturity and date of harvest by over 14 days at the Elora site. Delayed maturity was observed at the Winchester locations as well.

    2- Heavy rainfall shortly after the application of rinsate at the Winchester location caused water ponding. Since dicamba is very water soluble, crop injury and yield loss was higher in areas in the trial where water ponded after application.

    3- Dicamba injury appeared to accentuate other stress symptoms at the Elora site, specifically potash deficiency. In the absence of dicamba injury, soybean plants did not exhibit potash deficiency symptoms.

    Take Home

    • Continuous rinsing was as effective as four low-volume rinses.
    • Plots sprayed with the cleanest water rinsate (both protocols) averaged 11% lower yields than unsprayed plots.
    • Filter rinsate (following continuous rinse with water) resulted in an average 7% yield loss.
    • Filter rinsate (following continuous rinse with 1% ammonia) resulted in an average 15% yield loss.

    Citations

    • Bradley, K. 2017. “A Final Report on Dicamba-injured Soybean Acres”. University of Missouri Integrated Pest Management online. https://ipm.missouri.edu/IPCM/2017/10/final_report_dicamba_injured_soybean/
    • Cundiff, G.T., Reynolds, D.B. and T.C. Mueller. 2017. Evaluation of dicamba persistence among various agricultural hose types and cleanout procedures using soybean (Glycine max) as a bio-indicator. Weed Science. 65(2), pp. 305-316.
    • Jacobson, B., Urbanczyk-Wochniak, E., Mueth., M.G., Riter, L.S., Sall, J.H., South, S. and Carver, L. 2014. “Field Volatility of Dicamba Formulation MON 119096 Following a Post-Emerge Applciation Under Field Conditions in Texas”. Monsanto Report Number MSL0027193.
    • Mueller, T. 2017. “Effect of adding Roundup PowerMax to Engenia on vapor losses under field conditions” (Presentation).
    • Robinson, A.P., Simpson, D.M. and W.G. Johnson. 2013. Response of glyphosate-tolerant soybean yield components to dicamba. Weed Science. 61(4), pp. 526-536.
    • Wax, L.M., Knuth L.A., and Slife F.W. 1969. Response of soybean to 2,4-D, dicamba, and picloram. Weed Sci 17, pp. 388-393.
  • Application Recordkeeping: Focus on Environmental Conditions

    Application Recordkeeping: Focus on Environmental Conditions

    Note: This article was written by Bob Wolf of Wolf Consulting and Research, and first appeared as an NDSU Extension Service publication. Bob has agreed to reproduce the article on our website.

    When applying crop protection products, a good steward is one who can identify and record the environmental factors that may negatively impact making an application; particularly, the possibility of spray drift.

    New label language states: “Avoiding spray drift at the application site is the responsibility of the applicator.” A wise sprayer operator must possess the ability to assess the environmental conditions at the field location to determine how best to spray the field, or maybe decide it would be best not to spray that field, or part of that field, at that time. Instruments that assess environmental conditions are available to assist applicators in making good decisions.

    Making the correct measurement is the critical first step. Record the information measured to document the application conditions. Quality records help mitigate against any misapplication allegations, such as a drift complaint. Many of the items listed below are based on past legal experiences with applications involving spray drift litigation.

    The following guidelines should help you measure and accurately record environmental conditions at the application site.

    1- Document any instrument used by recording the manufacturer and model number. Accurate portable weather instruments are recommended. Portable weather instruments are available that log and store data, and aid in auditing and recordkeeping. Some will have Bluetooth/wireless capabilities.

    2- Environmental measurements include wind speed and direction, temperature, and relative humidity.

    3- At a minimum, record data at the start and finish of the job. Consider more often as conditions change or for a job that lasts over a longer period. For example, make observations when tank refilling for larger fields. Time stamp all observations with a.m., p.m., or military time.

    4- Take meteorological readings as close to the application site as possible. Be advised that the weather data received via a smart phone or local weather station may not be accurate for the location being sprayed.

    Note the specific location where the measurement was made, such as GPS coordinates, field entry point, field location, etc. Check the label to see if it requires a specific observation location in relation to the treatment area.

    5- Make all measurements as close as possible to the nozzle release height (boom height) and in an area not protected from the wind by the spray machine or your body. For aerial applications, six feet is suggested when using a hand held instrument.

    6- Record wind speed averaged over a 1 to 2 minute time span. Note the time the observation was recorded. Most instruments give an average over a period of time. Make sure the instrument’s anemometer is facing directly into the wind.

    Do not record winds as variable or with a range i.e. 4 to 8 mph – an average gives a better indication of the transport energy. Light and variable winds, where directions may change several times over a short period, can be more problematic than higher speed winds in a sustained direction. Observe any label restrictions on wind speed.

    Wind direction requires a similar averaged measurement. Record direction in degrees magnetic from a compass (0-360°). The use of alphabetic characters, i.e., N, S, NW, to indicate wind direction is discouraged. The key for determining direction is to have an accurate assessment method: trees moving, dust, smoke, a ribbon on a short stake, etc. Face directly into the wind and record the direction from which the wind is coming. A ribbon on a stake with the ribbon blowing directly at your body is a simple fail safe approach. Movement of smoke, particularly from moving aircraft, or dust may help determine direction.

    7- Record temperature and humidity since they can be helpful in determining temperature inversion potential. It may be advisable to record both temperature and humidity well before and after the application for this purpose. In fact, recording a morning low and an afternoon high would be useful regarding determining the potential for an inversion. Take temperature measurements with the instrument out of direct sunlight. Shade the instrument with your body or spray equipment. This is especially critical if you are trying to assess temperature differentials for determining if an inversion is in place.

    8- Be alert to field level temperature inversion conditions which typically occur from late afternoon, can be sustained through the night, and into the next morning. Beware, inversions can start mid-afternoon. Observe conditions such as the presence of ground fog, smoke layers hanging parallel to the ground, dust hanging over the field/gravel road, heavy dew, frost, or intense odors (i.e., smells from manure or stagnant water from ponds are held close to the surface when inversion conditions exist). Inversions commonly occur with low (less than 3 mph) to no wind speeds. Spraying in calm air is not advised. If a mechanical smoker is used note wind direction and smoke dissipation with a time stamp.

    9- Note any variances due to terrain or vegetation differences, tree lines, buildings, etc.

    10- Initial or sign all recordings to indicate who made the observation(s).

  • Spray Coverage in Carrot, Onion and Potato

    Spray Coverage in Carrot, Onion and Potato

    This research was performed with Dennis Van Dyk (@Dennis_VanDyk), vegetable specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs.

    Prior to 2017, Syngenta introduced the UK to the Defy 3D nozzle, which is a 100° flat fan, designed to run alternating 38° forward or backward along the boom. They prescribed a boom height of 50 to 75 cm, 30-40 psi, and travel speeds of 10 to 14 km/h in cereals and vegetables. Compared to a conventional flat fan, they claimed that the angle and Medium-Coarse droplets promise less drift and improved coverage.

    In 2017, Hypro and John Deere began distributing the Defy 3D in North America. Our goal was to explore coverage from the 3D in vegetable crops. We compared the nozzle’s performance to common grower practices in onion, potato and carrot in the Holland Marsh area of Ontario.

    Experiment

    We used a technique called fluorimetry. A fluorescent dye (Rhodamine WT) was sprayed at 2 mL / L from a calibrated sprayer based on protocols generously provided by Dr. Tom Wolf.

    Tissue samples from the top, middle and bottom of the canopy were collected from random plants.

    The samples were rinsed with a volume of dH2O and this rinsate was then tested to determine how much dye was recovered.

    The tissues collected were dried and weighed to normalize the samples to µL of dye per gram dry weight to allow for comparison.

    In addition, we used water-sensitive paper as a check in key locations in the canopy to provide laminar and panoramic coverage. Papers were digitized and coverage determined as a percentage of the surface covered.

    In carrot and onion, we compared a hollowcone, an air-induction flatfan, and alternating 03 3D’s at 500 L/ha (~40 cm boom height, ~3 km/h travel speed, ~27ºC, 3-9 km/h crosswind, ~65% RH).

    In potato we compared the alternating 05 3D’s to a hollowcone at 200 L/ha (~55 cm boom height, ~10.5 km/h travel speed, ~22ºC, 6-8 km/h crosswind, ~65% RH).

    Water-sensitive papers were originally intended as a coverage check, and not as a source of analysis, but their use revealed interesting information. The following images are the papers recovered a single pass in each crop.

    Carrot

    Onion

    Potato

    Results

    The following table represents the percent coverage of these paper targets. Papers were digitized using a WordCard Pro business card scanner and analysis made using DepositScan software. This table is small, but you can zoom in for a quick comparison. The following three histograms show the same data graphically for carrot, onion and potato, respectively. Remember, this only represents a single pass, so don’t draw any conclusions about coverage yet.

    Carrot

    Onion

    Potato

    It was interesting to note differences in coverage observed on the papers versus the results of the fluorimetric analysis. It was anticipated that while water-sensitive paper serves for rough approximation of deposition, fluorimetry would be far more accurate. This is because of the droplet spread on the paper, and the evaporation and concentration of a spray droplet en route to the target. Again, here is a small table, and again, the next three histograms show the same data graphically for carrot, onion and potato, respectively.

    Carrot

    Onion

    Potato

    Observations

    While water-sensitive paper is an excellent diagnostic tool for coverage, fluorimetry allows for greater resolution. The high variability in coverage meant little or no statistical significance, however the means suggested the following:

    • In carrot, the 3D deposited more spray at the top of the canopy.
    • In onion, the hollowcone spray had a higher average deposit, and penetrated more deeply into the canopy.
    • In potato, the hollowcone deposited more spray at the top, with little or no difference mid-canopy.

    Each nozzle performed well at the top of the canopy, which is quite easy to hit. Certainly they exceeded any threshold for pest control. With the possible exception of hollowcone in onion, nozzle choice had only minor impact on mid-bottom canopy coverage. And so, if coverage is not a factor for distinguishing between these nozzles, we should consider drift potential. Due to the comparably smaller droplet spray quality, the hollowcone is far more prone to off target movement. This leads us to select the AI flat fan or the 3D as the more drift-conscious alternatives.

    Future analysis would benefit from a larger sample size to reduce variability, and the inclusion of an air-assist boom to better direct spray into the canopy.

    Applitech Canada (Hypro / SHURflo) is gratefully acknowledged for the 3D nozzles. Thanks to Kevin D Vander Kooi (U of G Muck Crops Station) and Paul Lynch (Producer). Assistance from Will Short, Brittany Lacasse and Laura Riches is gratefully acknowledged. Research made possible through funding from Horticultural Crops Ontario.

  • The Vermorel Nozzle – Humility in the Face of History

    The Vermorel Nozzle – Humility in the Face of History

    It’s a rainy Friday in 2017 and I decided to deal with the articles, factsheets, manuals and other sprayer-related documents that have been piling up on my desk for a year.

    My filing strategy is based on some advice I got from Dr. Bernard Panneton (Application Tech Guru) back in 2009. He said to read each document and then file them according to content, not by author or date. That way when I need something, I can search up the subject and find everything that might be relevant. More than 1,200 files later, the system works. No Dewey Decimals in my office, thank you.

    What I’ve noticed as I sift through this eclectic pile of wisdom, is that many of the application methods I experiment with, or generally promote, are rarely entirely novel. Crop protection has evolved considerably (think pulse width modulation, crop sensing and remote piloted aerial application systems), but the fundamentals of spraying haven’t changed that much.

    Case in point.

    I just found a photocopy of a 1906 book called “Ginseng – It’s Cultivation, Harvesting, Marketing and Market Value, with a Short Account of Its History and Botany“. Great title. We obviously appreciated florid language in technical manuals 100 years ago. Here’s an excerpt that caught my eye:

    “When applied to plants, the finest nozzle obtainable must be used. The Vermorel is perhaps the best. Now make no mistake: this spray must be a spray, not a dribble, nor a drizzle, nor a squirt, but a mist. It must look like a little fog at the end of the hose and must reach every part of the plant, particularly the undersides of the leaves, mind, just enough so it won’t trickle off.”

    Poetry. And to make my point, it’s similar to what I’d tell a ginseng grower today. Granted, I’d lead them into a lower-range-of-Medium droplet size and help them achieve the described coverage using drop arms. But what on Earth is a “Vermorel nozzle”? That’s not one I have in my motley collection.

    I turned to Virginia Tech’s Museum of Pest Management. I hope they’ll forgive me for lifting their content, but it’s too wonderful not to share. They note the contributions of Charles Valentine Riley. Born in London, England in 1843. He was a multi-talented Renaissance man. He was a pioneer of entomology in the United States and is often referred to as the founder of biological control in America.

    Charles Valentine Riley

    Two of his greatest contributions to pest management included founding the field of biological control and the invention of the Riley spray nozzle (1889). The Riley nozzle was sold as the Vermorel nozzle. It produced a fan pattern and was the primary nozzle used in pesticide application in the United States and Europe well into the 20th century. The auspicious Mr. Riley died in a bicycle accident in 1895.

    The Vermorel nee Riley Nozzle

    It was Riley’s nozzle, and the invention of some other early European pesticide application devices, that inspired W.B. Alwood (publisher of orchard spraying techniques c.1899) to import these devices and adopt them to Virginia conditions. The rest is history.

    I tell you this because of what I found beneath the book touting the Vermorel; A 2015 TeeJet brochure for their TXVK hollow cone nozzles. I’m aware that the engineering behind the TXVK molded poly body and ceramic orifice is considerable compared to the humble Vermoral. But on closer inspection the fundamental designs aren’t so different. That realization both surprised and pleased me and compelled me to write this article.

    I’m not certain what my point is. I suppose it’s just good to be reminded that the next time you want to invest time, money and effort into a “new idea” you might consider a little historical research. Odds are, you’re not the first person to recognize the problem, or propose a solution. A little time in the archives also instills respect for those that were there first. Let’s not waste time repeating their efforts, but stand on their shoulders and advance what they’ve already pioneered.

    And if anyone has one of Riley’s Vermorel nozzles, I’d love to add it to my collection. Drop me a line.

  • The Misplay of our Generation

    The Misplay of our Generation

    We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run.

    –Amara’s Law of Computing

    We tend to overestimate the effect of a stewardship mistake in the short run and underestimate the effect in the long run.

    –Wolf’s Adaptation of Amara’s Law to Agricultural Stewardship

    August 9, 2017

    Since June of 2017, we’ve been hearing reports of widespread dicamba damage symptoms in soybeans throughout the US mid-south and midwest. It appears that millions of acres could ultimately be affected, and yield impacts are unknown at this time.

    For those new to the issue, dicamba is a broadleaf herbicide in the Group 4 mode of action group, a benzoic acid. It’s an important tool for herbicide resistance management for weeds like palmer amaranth (Amaranthus palmeri) and waterhemp (A. tuberculatus), populations of which have become resistant to Group 2 (ALS inhibitors), Group 5 (triazines), Group 9 (glyphosate), Group 14 (PPO inhibitors) and Group 27 (HPPD inhibitors) in some places.

    Dicamba is a volatile herbicide, discovered in 1942 and first registered in the US in 1967. Its primary use was in corn and other cereal crops, lawns, and rights of way, at comparatively low doses, and relatively early in the season.

    Calling a pesticide volatile means it can evaporate after application, either from a liquid or a dry deposit, for hours or sometimes days after application. The resulting vapor cloud can move unpredictably, depending on atmospheric conditions, and affect plants long distances away. Higher temperatures increase vapor loss.

    Starting this year, dicamba-tolerant soybeans and cotton (Xtend varieties) were sprayed with new lower-volatility formulations of dicamba, XtendiMax, Engenia, and FeXapan, to control certain broadleaf weeds (including the Amaranth species above) without harming the soybeans. Problem is, dicamba can harm non-Xtend soybeans and other plants, even at very low doses. And these registrations were for applications that occurred later in the season, at higher doses than before.

    I usually don’t get involved in people’s decision about whether to spray, or what to spray. But I do get involved when it comes down to how to spray. That’s my job. The real question to me is “can this product be used safely in cotton and soybeans?” Right now, the jury’s out on that one.

    In my business, our guiding principles are what some people have called the “Three Es of Application”, Efficacy, Efficiency, & Environment.

    We use sprays to control pests. That’s the only reason. We have to apply them so that they work, or else it’s a wasted effort. That’s the efficacy part. We also need to use our resources, time, money, etc., efficiently so the whole process doesn’t bankrupt us and we have time left for other important tasks.  That’s efficiency. And finally, we need to protect the environment, and that means making sure the product lands where it’s intended.

    None of these three priorities trumps the others. All need to be met to the best degree possible. And due to ever-changing conditions, we will typically change our approach to emphasize one or two of these three over the others, to have a working system.

    Simply put, pesticides belong on target surfaces covered by the swath of the sprayer, and nowhere else. If they do move elsewhere (something we’ve come to view as inevitable), regulators conduct risk assessments to ensure that this movement does not result in harm. If harm is possible, mitigating tools such as application timing, product rate, spray method, and buffer zones may be imposed. If those tools aren’t enough to ensure safety, regulators deny product registration. That’s their job.

    But even if no harm is done by trespass, the products still need to be on-target. That’s stewardship. It’s a principle whose adherence gives license for a technology to be used. It gives others faith in our competence. Practicing this principle when it’s easy prepares us for hard times.

    I respect our regulatory process, and know it to be increasingly conservative with regards to risk the less data there are. I worked for the PMRA (the Canadian pesticide regulatory agency) as an application expert for five years. I know the system isn’t perfect and can make mistakes.  I know the system can be political. Usually it’s by being too careful. With dicamba, it looks like the opposite happened.

    The reason we’re seeing dicamba leaf cupping everywhere isn’t because all applicators suddenly forgot how to spray. They didn’t suddenly get reckless. They didn’t wilfully ignore all the training that the dicamba manufacturers and state and provincial governments developed in preparation for the product launch.

    Instead, dicamba drift reports arose from a combination of extreme sensitivity and easily identified symptoms, as well as an unexpected (by some) amount of vapor drift. Even good applications appeared to create problems. Despite warnings from local experts, regulators and registrants didn’t see it coming.

    Experienced agronomists have suggested that the observed dicamba trespass of 2017 implicates both temperature inversions and vapor drift. And although the new product labels advise against spraying under inversion conditions, they don’t say a word about vapor drift, the conditions that give rise to it, or how to protect against its occurrence. Not one word. I’ve searched the Xtendimax, Engenia and FeXapan labels. Nada.

    Seems that the regulators and registrants felt confident enough in the reduced volatility of dicamba, based on their internal empirical data and modeling, that they didn’t need to mention it on the label. Calling that a mistake is an understatement.

    I’d call it the biggest spray application misplay I’ve ever seen.

    A part of the problem may be the enormous scale on which this new use of dicamba was introduced, over 25 million acres of Xtend crops. Scale-up errors are common in many industries. Emergent properties related to scale can’t readily be predicted by empirical data and models. Especially when the underlying data are scant.

    So what to do? The continued success of agriculture depends to continued access to safe crop production tools. Irresponsible use threatens that. And by irresponsible use, I don’t just mean application. I also mean registration, promotion, sale, and support. The whole stewardship package.

    When problems occur, we need to be quick on our feet to acknowledge them, to support those affected, and to try to understand the cause and prevent the situation from continuing or getting worse.

    The current industry response appears to be the exact opposite. What I’ve seen is full of denial, downplaying, innuendo, blaming, and entrenchment.

    Why is such an important issue in pesticide stewardship handled so poorly?

    The immediate victims of this situation are the producers that depend on new technologies. But the long-term victim is agriculture as a whole. The lack of humility and leadership by many of the proponents of this technology, those with no small financial stake in its continued use, hurts not just them, but all of us involved in farming. This is not stewardship. It’s not license. It’s short sighted and reckless.

    Over my career, spray application has generally become safer for the operator and the environment. A big part of our success has been the adoption of low-drift nozzles, the de-facto standard for modern pesticide application. The development of less toxic and less persistent pesticides has also been very important. We can avoid a lot of problems with good chemistry. I’ve been proud to tell this story.

    I want to stay proud of our story. And in this case, that requires admitting to mistakes that were made and taking corrective action that is in the best interest of our entire industry. Agriculture will persist longer than company brands and titles. It takes priority.

    It’s still too early to fully understand all the reasons for the widespread dicamba damage. But it’s not too soon to say that much of this could have been prevented with a smaller rollout, with greater collaboration with government and university experts during registration, and with more honest information on dicamba volatility on product labels. Call it Volatility Humility.

    We’ll all pay for the mistakes that were made. We’ll likely have more stringent and expensive registration protocols. More restrictive application parameters. Strained relationships. More distrust of agriculture.

    And as always, an ounce of sweet prevention would have been much better than the pounds of bitter cure that will surely be required to make this right.