Author: Jason Deveau

  • Compulsory, Standardized Sprayer Inspections

    Compulsory, Standardized Sprayer Inspections

    Spring always brings renewed interest in sprayer calibration. This is good, because a well-maintained and calibrated sprayer will protect crops more effectively and efficiently, as well as reduce the potential for off-target drift and point source contamination.

    Presently, there is no nationally-recognized standard for sprayer calibration in either Canada or the United States. As a result there are many methods, some more stringent than others, spanning activities relating to seasonal maintenance through to precise diagnostic measurements. This means an operator can be in compliance with programs such as CanadaGAP (a food safety traceability standard for fruit and vegetables), and yet only perform the most rudimentary adjustments.

    I was first made aware of “compulsory inspections” in 2009 when I started noticing certification stickers on certain European import airblast sprayers. Some Ontario tender fruit and grape growers familiar with the European standards asked why we didn’t enforce standardized calibration program as they do in Europe. I was surprised to hear a farmer ask for more paperwork, so it made me wonder, are Canada and the US overdue for a change?

    All sprayers, from large, commercial field and airblast sprayers, to the more humble home-grown sprayers (see below) benefit from regular servicing and calibration. And yet, sprayer calibration in Canada and the US remains largely voluntary and highly variable depending on the size of the operation, sprayer design and the willingness/skill of the operator.

    Canada and the US: Then

    In the mid 1980’s, University of Nebraska engineers and Successful Farming Magazine published a study showing that un-calibrated spray applications were costing US farmers ~$1,000,000,000 per year. The article was infamously called “The Billion Dollar Blunder”. You can download the original journal article describing the survey here.  It was estimated that fewer than 5% of applications were within 5% of the desired rates. Spray overlaps and poor calibration resulted in over-applications of more than 20%.

    At the time it was eye-opening and received a lot of attention. In 2006 the original study was revisited (see here), and even with advances in precision application, there was a disappointing lack of improvement. Bill Casady, University of Missouri Extension agricultural engineer, estimated that if 20 minutes of calibration can save 5% on 500 acres in an application sprayed at $25/ac ($61.75/ha), then the 20 minutes of effort worked out to $1,875 / hour. Now that’s a solid return on investment!

    Belgium: Then

    Belgium recognized and addressed this issue more than twenty years ago. In 1995, following the lead of the Netherlands and Germany, Belgium’s Ministry of Agriculture mandated that all spraying equipment (save backpacks) be inspected every three years. At the time, other countries such as Sweden, Hungary and Austria had similar, albeit voluntary, programs.

    Belgian farmers received letters asking them to make their sprayers available for testing by a Ministry-appointed institution, in locations no more than 10 kilometers from their operations. The institution’s trained technicians would subject the sprayers to a regimented, standardized inspection. When the equipment met the standard, they would receive a permit in the form of a sticker (see below) attached to the sprayer. The growers paid for this service, based in part on the size of the sprayer.

    In order to introduce the process to the Belgian farmer, a short documentary was produced. If you would rather not watch the preamble explaining why the prudent use of chemistry is critical to agriculture, and get right to the sprayer inspection process, skip ahead to 3:35.

    What follows is a brief outline of that 1995 process, which I’m told is similar to the process currently used in Belgium:

    1. Administrators perform visual checks to assess the general condition of the sprayer (e.g. obvious maintenance, safety and operational issues).
    2. Boom balance (where applicable), hinges, boom ends and boom sturdiness is checked.
    3. Nozzle spacing and orientation of nozzle bodies is inspected.
    4. All points of filtration are inspected.
    5. For boom sprayers, a spray pattern distribution used to be performed, but it wasn’t diagnostic enough. Instead, a pressure gauge / nozzle combo is used in each position to check for pressure fluctuation, and to ensure each tip had a flow rate within 5% of the average and no more than 10% deviation from the manufacturer’s rate.
    6. For airblast sprayers, the overall output of the sprayer is measured to determine nozzle wear using individual collectors clamped onto each position.
    7. For sprayers with rate controllers, calibrated collection bags are attached to a few nozzles and the sprayer drives a 100 metre course while spraying. The actual output is compared to the expected.
    8. Finally, the farmer receives a report outlining issues that need to be remedied before the sprayer is certified.

    SPISE: Today

    Today, collaborating European countries are members of SPISEStandardized Procedure for the Inspection of Sprayers in Europe. Established in 2004 by founding members from Belgium, France, Germany, Italy and the Netherlands, the SPISE Working Group aims to “further the harmonization and mutual acceptance of equipment inspections”. They also work to continually improve the inspection / calibration process.

    Their website hosts a number of sprayer-related resources, but the SPICE Advice handbooks are perhaps most valuable to the sprayer operator. Click either image below to download them as PDF for airblast or field sprayers:

    This more current video by AAMS-Salvarani goes though the inspection and adjustment process for airblast sprayers. While there is no mention of air speed adjustments, many of the steps in this video correspond with the airblast adjustments relating to Crop-Adapted Spraying which has proven very successful in Canada.

    Canada and the US: Tomorrow

    Regular, third-party mediated inspections offer many potential benefits to the average operator. But, in order to realize gains in crop protection and environmental stewardship, perhaps there are two programs required: One to certify the sprayer and the other to certify the sprayer operator.

    1. A sprayer inspection program would focus on sprayer maintenance rather than calibration. Maintenance occurs at regular intervals to ensure spray equipment is operating optimally. Calibration is an ongoing process intended to match the sprayer to the conditions in which it’s operating, and that requires an educated sprayer operator.
    2. Sprayer operator education programs such as Ontario’s Grower Pesticide Safety Course, or Penn State’s Pesticide Applicator Certification Course already exist, but they are not offered in every state or province, and they are often voluntary or perhaps specific to a particular expertise (e.g. not applying to custom applicators or airblast operators).

    They could start as voluntary, pay-for-service pilot programs to see if operators appreciate how much better their sprayers are functioning, and to quantify how much waste is been reduced. They wouldn’t necessarily have to be government-run; Industry or Academia may be better conduits. So, what would be required to develop and implement these two programs?

    • We would need to agree on a robust and generic sprayer inspection protocol. We have several European examples to draw on.
    • We would need to agree on the minimal content for a sprayer operator course. Again, we have many to draw on, with the obvious understanding that the core curriculum would be amended to reflect various state and provincial requirements.
    • We would need a trained, third-party organization to take responsibility for overseeing and implementing the two programs.
    • And, of course, we would need the funds to initiate both programs before they would eventually become self-sustaining.

    So, are we dreaming in Technicolor? If responses to this article are any indication, there are those in western society that lash out at the idea of mandatory requirements. But there are supporters, too. Maybe we can learn from those European countries that have been doing this for more than 20 years.

    Thanks to Jan Langenakens of aams for reviewing this article, and providing the videos.

  • Optimizing Sprayer Air Settings – Part 2

    Optimizing Sprayer Air Settings – Part 2

    This is part two of a two part article on how to optimize the match between the sprayer air and the target canopy. You can find the first part here. For a more fulsome description of the process, consult chapters 3, 9, 10, and 11 of Airblast101.

    A close up of an airblast gear box. There are usually two options – high or low.
    A close up of an airblast gear box. There are usually two options – high or low.

    Evaluating air energy – Ribbon test part 2

    Air behaviour can change radically between stationary operation and driving. We learned in part one of this article that slower travel speeds increase the throw and the spray height. The simplest way to monitor where air is going is for a partner to watch the leaves in the target canopy. Leaves that are ruffling indicate that air is reaching them.

    A more informative method, and one that works during dormancy, requires a length of flagging tape tied to the end of a long stick. The partner (wearing eye and ear protection) can move the ribbon around in the air wash, extending it into areas of interest. The ribbon’s behaviour will indicate gaps, the air angle and relative air energy. The ribbon can be interpreted using the following figure.

    Work with the sprayer oriented to blow into any crosswind. Extend the ribbon into the sprayer air while the sprayer is stationary, or preferably, while driving. The ribbon’s behaviour will show what you couldn’t otherwise see. Here are a few possible outcomes: A. The angle and air energy are appropriate while the sprayer is stationary. B. The air energy is not sufficient to reach the tree top when the sprayer is driving. C. Obstructions or deflector misalignment can create gaps. D. Air is angled too low for the target canopy.

    Evaluating canopy penetration – Ribbon test part 3

    This final diagnostic accounts for the influence of any intervening canopy (or canopies for multiple-row strategies). It confirms that the air energy has the potential to carry droplets the full extent of the swath. Evaluating one side will give you a lot of insight but if you have the time it’s better to do both sides. Since most sprayers have at least some imbalance in air handling, the results may surprise you.

    1. Choose a canopy that is upwind and on the lift side of the sprayer (if applicable).
    2. Move the sprayer a distance into the row to allow it to reach target speed and to avoid wind effects on the periphery.
    3. Attach 25 cm (10 in.) lengths of flagging tape on the far side of the target canopy. Do this at the top, middle and bottom of the canopy. In tall canopies this might require a ladder, telescoping pole, or sections of galvanized pipe to raise the ribbons.
    4. With deflectors/spray outlets adjusted and the desired fan gear (or fan speed) selected, start the air without spraying and bring the sprayer up to the target travel speed. A partner wearing eye and ear protection will stand in the next alley and observe the ribbons as the sprayer passes (preferably recording a video for the operator).
    Three ribbons are positioned on the far side of the upwind target canopy. In this case, an every-row traffic pattern is depicted. The observer watches or records the ribbons as the sprayer drives past with the air on (not the spray). For an every-row traffic pattern, the air energy is too high if the ribbon strains at 90⁰. It is ideal for the ribbon to briefly flutter (0⁰-60⁰). If the ribbon does not move (0⁰), the air energy may still be sufficient as long as it penetrates to the centre of the canopy. This is often the case with particularly dense/wide trees like nuts and citrus.
    Tying flagging tape in trees to indicate prevailing wind and to calibrate airblast air settings.
    Tying ribbons on the up-wind side in an apple orchard just past green-tip. The red vest has lots of pockets to hold supplies and sprayer operators can see it clearly for safety. The Hawaiian shirt is because it was a Friday.

    Repeat this process this for EACH significantly different crop sprayed with the sprayer. As with air direction settings, multiple set-ups might be needed to reflect each block, or you might choose to group of similarly-sized blocks and calibrate air to the worst case scenario. Record the set-up for each sprayer/block combination and keep a copy in the tractor cab(s).

    Interpreting the ribbon tests

    Interpreting the ribbons is not always straightforward. When they don’t behave as anticipated they may be indicating one or more of the following problems:

    1. The air angle is incorrect.
    2. The air energy is too low.
    3. The air energy is too high.

    There might be a single cause or several contributing factors. As you diagnose and attempt to correct these problems be aware that addressing one may create others. If the problem cannot be corrected, the sprayer configuration (or design) may be inappropriate for the canopy or the environmental conditions.

    Ribbons that don’t point from the sprayer to the canopy may indicate a misalignment of spray outlets or deflectors. The bottom of the air should align with the bottom of the target. More critically, the top of the air should slightly overshoot the top of the target. We want to avoid spray drift, but we must account for wind speed increasing with height and vertical booms that rock on uneven alleys. If the spray does not slightly overshoot the top of the target, it may miss it entirely.

    Adjusting horizontal alignment, when possible, can significantly impact sprayer performance. It can be tricky to optimize the angle because it represents the sum of several complicated interactions. Air outlets on wrap-around sprayers may be positioned too close to the target canopy to permit a ribbon test. However, you can still use the ribbon-on-a-stick technique to visualize how the air is behaving. Consider the following when positioning air outlets on either side of a canopy:

    Unresponsive ribbons are often observed during a ribbon test. Depending on where the ribbon is located, this may or may not indicate a problem. Ideally, the top ribbon should always move in response to sprayer air. In larger canopies, this location represents the greatest distance sprayer air must travel and the highest wind speed it will encounter. The middle and bottom ribbons may or may not move in response to sprayer air. This is common in larger, denser canopies. To confirm this, an observer would have to stand at the trunk and watch the leaves rather than the ribbons.

    Shingling and canopy distortion

    When possible, do not position laminar air outlets in direct opposition. The convergence creates a high pressure zone that reduces spray penetration. Laminar flows will deflect unpredictably around this pressurized area and carry droplets back out of the canopy. Unless the canopy is narrow and sparse, turbulent air handling systems do not typically create this problem. In both cases, canopy penetration is improved when fans are staggered and/or are angled slightly forward or backward.

    When too much air is vectored directly at the canopy face, it may close and compress that canopy rather than penetrate it. This is more likely when air is high energy, has a narrow air wash or is more laminar in nature. When leaves shingle, the overlap blocks spray and creates resistance to sprayer air. Air will then take the path of least resistance and either deflect around the canopy or channel through any openings. Shingling can be corrected by angling air outlets slightly forward or backward. A little goes a long way as small changes can have big effects.

    Dr. Bernard Panneton (formally with the Horticultural R&D Centre, Agriculture and Agri-Food Canada) performed a series of experiments exploring the relationship between potato canopies and wind and his observations extend to all broad leaf crops. Bernard showed that as wind speed increased, the percent of leaf surface area exposed to spray also increased, but only to a point. If the wind got too fast, the percent of leaf surface exposed to spray dropped significantly: ~20% less!

    His interpretation was that low to moderate air speeds just ruffled the leaves, exposing their broad surfaces to spray more consistently. When air speed became excessive, leaves and twigs aligned with the wind, exposing only their thin edge to spray. The take home lesson is that spray will be more likely to impinge on all target surfaces when air speed and volume are calibrated correctly.

    Bernard summed this article up succinctly: “More air is not better!”

    Potato canopy distortion in an air tunnel. Research by Dr. B. Panneton.

    Video summary

    We’ll finish the article with a light-hearted video describing how the process works. It doesn’t explore the second ribbon test, but that’s more of a concern with distant targets or alternate row spraying strategies where the sprayer must penetrate one or more canopies in a single pass.

  • Optimizing Sprayer Air Settings – Part 1

    Optimizing Sprayer Air Settings – Part 1

    This is part one of a two part article on how to optimize the match between the sprayer air and the target canopy. For a more fulsome description of the process, consult chapters 3, 9, 10, and 11 of Airblast101.

    Why is air so important?

    Air handling is the most important and least understood mechanical system on a sprayer. Most air-assisted sprayers for three-dimensional perennial crops produce droplets that are Medium or smaller according to the ASABE S572.3 droplet size classification standard. These small droplets have very little mass relative to their surface area, so they don’t have much kinetic energy. Without air to impart speed and direction, most droplets would never go where we want them to. In addition, air opens and moves a canopy, exposing otherwise hidden surfaces to the droplets it’s carrying.

    Imagine throwing a feather. Now imagine throwing it as hard as you can. It may travel a little farther, but not much relative to the extra effort. Even then, an errant gust of wind might change its direction entirely. Similarly, we cannot rely on hydraulic pressure to propel small droplets. This is the primary reason for the “air” in air-assist spraying.

    Air-assist spraying attempts to replace the empty air within a canopy with droplet-laden air (and then get it to stay there). If we don’t have enough air energy, we won’t displace enough empty air and the throw will fall short. Likewise, if we have too much air energy, the throw will extend beyond the the target, wasting spray and likely compromising coverage. Ultimately, we want the air to expend all its energy, spreading, stalling and depositing droplets inside the target canopy.

    Travel speed

    Travel speed can have a significant impact on work rate. However, the effect of travel speed on air behaviour (and ultimately coverage) should be the sprayer operator’s primary concern. There will always be a trade-off between travel speed, coverage and work rate. Travel speed is the first and easiest adjustment to throw, spray height and canopy penetration. Just as travel speed modifies the liquid rate per row, it also modifies air energy per row.

    Environmental and canopy conditions

    Whenever calibrating or adjusting a sprayer, it is critical to do so in the crop, in environmental conditions you would typically spray in. You would not expect a sprayer to achieve the same results in high winds in a dormant vineyard as it would in calm conditions in a mature citrus orchard.

    I recommend using a handheld weather meter because local weather reports often don’t match the conditions in the planting. For temperature and relative humidity, take readings in the shade. For wind conditions, face into the prevailing wind and hold the meter as high as you can. Wind speed increases with height and we want to evaluate the most challenging part of the target – the top third of the canopy.

    Evaluating vertical air angles – Ribbon test part 1

    The air angle (or direction relative to the target) is the first concern. Research has shown that low profile radial airblast sprayers without effective straightening vanes or deflectors make the air go up on one side and down on the other. In extreme situations, this might compromise the spray job (e.g. miss the lower portion of the target on one side of the sprayer) or it might simply waste spray and stir up debris. Here’s how you can see if this is happening on your sprayer:

    1. Park the sprayer in an alley between the rows.
    2. Affix 25 cm (10 in.) lengths of tape along the air outlets. Tie them to nozzle bodies or use duct tape to position them so that they stand out in the sprayer-generated air.
    3. Bring the fan(s) up to the desired speed but do not spray. Stand back behind the sprayer and use the ribbons to extrapolate the air angle relative to the target canopy. Look for asymmetries and wasted air (i.e. angled above the canopy or into the ground.)
    The ribbons on the LPR sprayer in this photo are twice as long as they should be, but fortunately it was a calm day. Note the angles of the lower ribbons compared to the “ideal” broken white lines. The asymmetry corresponds to the misaligned bottom right deflector. Observe the ribbons while adjusting deflector positions. Any ribbons above the upper broken white lines indicate wasted air energy (and likely spray). Large upper deflectors, positioned horizontally, would reclaim wasted air and focus it into the crop.

    By observing the ribbons, you can extrapolate where deflectors or fan heads should be aimed. Air should be adjusted to slightly over- and under-shoot the target canopy. For ducted outlets, such as low profile Turbomist sprayers, the air outlet is not a uniform width – it’s widest about half-way down. Using ribbons to extrapolate air direction, aim the widest part of the outlet at the densest part of the canopy. This automatically repositions the booms as well, facilitating the next calibration step where we turn off nozzles that will significantly over- or under-shoot the target. This is discussed in another article.

    Using a piece of scrap wood with a ribbon on the end to demonstrate how deflectors would channel air on a Florida airblast sprayer. Once convinced, this grower fabricated and installed deflectors and has been very pleased with their performance.
    Using a piece of scrap wood with a ribbon on the end to demonstrate how deflectors would channel air on an Economist airblast sprayer. Once convinced, this grower fabricated and installed deflectors and has been very pleased with their performance.
    When repositioning the air outlets on a Turbomist with no towers, aim the widest part of the outlet towards the densest part of the canopy, then turn off unneeded nozzles. Lubricate the nuts and bolts that hold the outlet bands tight.
    When repositioning the air outlets on a Turbomist with no towers, aim the widest part of the outlet towards the densest part of the canopy, then turn off unneeded nozzles. Lubricate the nuts and bolts that hold the outlet bands tight.

    Video Extras

    These videos are a bit long-in-the-tooth now, but the concepts are still sound. If you hear anything in the videos that contradicts what’s written in the article, go with the article. Live and learn. Thanks to Penn State, the University of New Hampshire and Chazzbo Media for producing these 2014 videos.

    This article will conclude in the second half:
    Optimizing Sprayer Air Settings – Part 2

  • Simple Statistics for Growers

    Simple Statistics for Growers

    In North America, winter is agriculture conference and lecture season. Growers are inundated with graphs and charts and left to make sense of what they’re seeing. It might be an agrichemical rep promoting a new pesticide or a seed dealer comparing yields. Maybe an equipment dealer is illustrating return on investment. Even university researchers and government extension specialists have been known to flash the occasional graph from time to time.

    Without a basic understanding of how data can be abused, we are at the mercy of those presenting the data. So, in 2012, I was asked to develop a talk that would give growers a basic grounding in descriptive statistics. More to the point, it would empower a grower to raise their hand and ask questions if they felt a presenter was talking out of their… *ahem*.

    • Did the researcher do their stats correctly?
    • Is the data clear and easy to understand?
    • Is the presenter skewing something to make us see what they want?

    Since writing it, I’ve been asked to deliver this talk to several grower groups, which is surprising because very few people love statistics. Now that we’re all webinar-savvy, I took the opportunity to update the presentation and record it.

    The video is only 15 minutes. When you’re done I hope you’ll appreciate that it’s OK to be skeptical of data. Ask questions and dig deeper.

  • Homemade Air-Assist Tower Retrofit

    Homemade Air-Assist Tower Retrofit

    It was Saturday morning in April, 2016 when I received an email from Steven Bierlink, an orchardist in Washington State. He was curious about the impact of air induction nozzles on lime-sulphur applications (intended to thin apple blossoms). Work-life balance notwithstanding, I happily grabbed a hot cup of coffee and we got on the phone. It was a great conversation.

    The top two nozzles are capped in this orchard (targeting 10' and below). It's very evident that the top two nozzles are not in use.
    The top two nozzles are capped in this orchard (targeting 10′ and below). It’s very evident that the top two nozzles are not in use.

    It turned out Steve, like many growers, also had a knack for metal working. Displeased with his Rears sprayer’s performance, he told me he’d replaced his classic radial air outlet and curved boom with a ducted tower assembly, very much like the H.S.S. sprayer had just been introduced to North America.

    I asked if he would share his story and a few photos of how he did it and he didn’t disappoint! What follows is a photo journal of how he designed and built his new sprayer. He wrote:

    Sorry it’s taken me so long to get back to you. Spring is like a tornado and there’s just no time to get things done! Here’s a quick/not so quick rundown of the process:

    1 – I started by cutting the horizontal supports that attach the fan box to the front deflector wall. I plugged all the old holes with nuts and bolts to keep the air going where I wanted it.

    1) Fan box cut away from deflector wall. Holes filled with bolts.
    Fan box cut away from deflector wall. Holes filled with bolts.

    2- I then got a 10″ wide sheet of 16 ga cold-rolled steel from a local HVAC guy. I marked out where I wanted to attach it, drilled and tapped the holes, and attached using only stainless hardware. I marked out for a total of 8 holes per side evenly spaced, and drilled them out with a 4” hole saw. I then cut 3″ long sections of 4″ diameter thin-wall pipe (about 0.125” thick) and welded them flush with the inside.

    2) Welded pipe outlets for air.
    Welded pipe outlets for air.

    3 – I had several conversations with the local HVAC guy about turning vanes, nozzles, cubic feet/min. and wind speeds. The reason I decided to use hose after all these conversations is because there are no 90° angle turns. Those turns during testing severely decreased wind speeds because of the turbulence it caused. The hose is standard 4″ suction hose for woodworking chip/dust collection. Together, we came up with a 1.5” x 8” outlet to use. The numbers written on the outlet are average wind speed with 10 feet of hose attached at the desired tractor rpm’s.

    3) Commercial woodshop hose and air outlets.
    Commercial woodshop hose and air outlets.

    4 – Initially I was set on having the same distance of hose for each outlet, like headers for an internal combustion engine. I let that go since volume matters so much more in this situation and there is no “real” back pressure pressure to be concerned about. This was the initial drawing:

    4) Early sketch of equal hose lengths and positions.
    Early sketch of equal hose lengths and positions.

    5 – My measured dimensions showed the rectangular tower frame would fit through my tightest V-trellis, but only if I drove 0.5 mph and who is going to do that!? So, I needed to rethink it, break it down, and redo it. I decided on a partial, center-mast design.

    5a) Original tower frame would not clear the V-trellis. A center-mast solved the issue.
    Original tower frame would not clear the V-trellis. A center-mast solved the issue.
    5b) The top of the mast can be removed and the hoses disconnected and just left to hang. This allows me to hit 12' tall V-trellis easily, as well as 14' vertical trees all the way to the top.
    The top of the mast can be removed and the hoses disconnected and just left to hang. This allows me to hit 12′ tall V-trellis easily, as well as 14′ vertical trees all the way to the top.

    6 – After putting everything together I realized the air volume wasn’t always balanced across the each outlet. This was because the bend in the hose was too sharp and too close to the outlet. This REALLY MATTERS because if the air volume is too “heavy” on one side of the outlet, it doesn’t capture and carry the spray consistently. I corrected it by attaching support rods to increase distance between bends and outlets to about 18”.

    6) Gradual angles on hose prevented uneven air from the outlets.
    Gradual angles on hose prevented uneven air from the outlets.

    7 – On the painted, final design, you might notice lowest nozzle is angled. This is because I’ve noticed that foliar applications don’t often hit the lowest branches. I angled one outlet upwards to correct this. I notice in your article on the H.S.S. sprayer that the Woolly Apple Aphid nozzle does the same thing. I feel like I need to meet these people; we have incredibly similar ideas!

    7) Lowest nozzle and air outlet angled up to better hit lowest branches.
    Lowest nozzle and air outlet angled up to better hit lowest branches.

    8 – I used TeeJet’s ¼ turn AIC air-induction flat fan nozzles. They’re molded into the cap, so they are always oriented the right way. I set the nozzle bodies outside the air outlets to reduce turbulence in the airflow. It also makes servicing cleaner and easier. I also ended up adding some shielding around the lower nozzles just in case someone loses focus and runs into something.

    8a) Shields prevent physical impacts to AIC (air induction) nozzles. Coverage map was created for 55 gpa in a 6'x14' vertical planting.Shields prevent physical impacts to AIC (air induction) nozzles. Coverage map was created for 55 gpa in a 6'x14' vertical planting.
    Shields prevent physical impacts to AIC (air induction) nozzles. Coverage map was created for 55 gpa in a 6’x14′ vertical planting.
    8b) Close up of nozzle location versus air outlet.
    Close up of nozzle location versus air outlet.

    I asked Steve to stay in touch and let me know how his spraying season goes with the new sprayer. I’ll add to this article as he checks in and lets us know how the sprayer holds up and what changes, if any, he wants to make in the future.

    July 2016 Update

    As promised, I checked in with Steve to see how the sprayer was holding up. Here’s what he had to say:

    “It’s awesome. Works fantastic. Very effective in windy weather without having to worry about drift. Also, it works perfectly for sunburn protectants because of how directed the application can be. It has held up well considering how many acres its gone through this year.”

    Of course, there are always a few hiccups. I’ll interject here to suggest that what Steve is about to note about thinning is not a reflection of his design. I believe many orchardists experience the same difficulties with their conventional towers, too. Steve continued:

    “A few downsides I’ve noticed throughout the season: For blossom thinning (lime sulfur), gallonage is critical to get the stamen of the flower burned sufficiently to prevent fertilization. Even when spraying ~100 gallons per acre with this sprayer, it wasn’t enough to effectively blossom-thin the fruit. Part of this may be because I’m now distributing the spray evenly through the entire canopy, rather than spraying up through the canopy below. Another downside is the droplets’ tendency to accumulate in the lower portions of the tree (since every droplet doesn’t hit foliage), and over-apply in those areas. My Sevin/NAA application this year definitely prove this theory as my lower branches were over-thinned.”

    So, what’s the final word on this cool sprayer mod?

    “Overall, it’s great, and with a few tweaks this winter will be even better.