Category: Nozzles & Droplets

Articles helping with field sprayer nozzle selection

  • Boomless Nozzle Performance

    Boomless Nozzle Performance

    NOTE: This article has proved very popular, and subsequently we received emails with additional information. The article has now been expanded to include work performed by Dr. Bob Wolf et al.

    Part 1:

    Boomless nozzles are used for vegetative management activities where it’s not practical, or sometimes even impossible, to use a horizontal boom. Consider highway easements and ditches, railways, and infrastructure like buildings, powerline poles or fence posts. In these cases, the booms would hit uneven ground, trees and other obstacles. Enter the boomless nozzle.

    Unlike a typical flat fan nozzle, these nozzles direct spray laterally in one or two directions, creating a very wide spray pattern. Some field sprayers use a smaller version such as an off-centre or uneven fan to either extend the booms’ coverage (e.g. to get around fence posts) or give the pattern a discrete edge and not spray beyond the booms length.

    There are many varieties of boomless nozzle available, but they don’t give the same performance.

    Using a spray pattern table, Helmut Spieser and I compared coverage patterns from three popular tips:

    • The Boom X Tender
    • The Boom Buster
    • XP BoomJet

    The Boom X Tender

    With seven rates to choose from, this nozzle claims up to 13′ throw from tip to the edge of the swath. When we ran the tip at 40 psi we noticed a lot of inconsistency in the pattern, where it clearly had variation in flow along the swath. Note the red arrows in the image.

    2

    These inconsistencies made themselves known when we observed the pattern produced on the spray table. We achieved a 7.5′ swath at 40 psi, 16″ above the table with the XT024 (yellow) tip. The coverage wasn’t very even.

    3

    The Boom Buster

    There are fourteen nozzles to choose from, each delivering different flows and according to the manufacturer, spanning up to 31′ from the tip to the edge of the swath. An interesting feature when we ran this nozzle was that the fan extended back ~15°, which might eliminate the need for a centre nozzle if two were operated at the same time with sufficient overlap.

    4

    We achieved a 7′ swath at 40 psi, 16″ above the table and the coverage described a fairly consistent curve. It did taper at the far end, but did a respectable job. It was obvious some overlap at the 15° end would help level out the response, and when paired with a second tip facing the opposite direction, this would work well.

    5

    The XP BoomJet

    The BoomJet mounts 90º to the swath, and with five rates to choose from claims a swath up to 18.5′ from tip to edge.

    6

    We mounted the (B) 1/4XP20L (You have to specify left or right) 16″ above the table and at 40 psi we achieved a 6′ swath. There was an odd dip in the coverage pattern not far from the tip. We suspected it might be an artifact, but after multiple attempts it persisted. Other than that dip, the pattern was quite consistent. Had we adjusted the angle to reach a 7′ swath, it may have tapered as much as the Boom Buster.

    7

    Observations

    Given the range of possible rates and swath distances, the overall consistency of the swath, the conventional nozzle mount, and the 15º overlap, Helmut and I chose the Boom Buster. The BoomJet was a close second, with a consistent pattern save the odd dip, but the 90º mount while making it possible to elongate or shorten the swath was a bit finicky and could pose a snagging risk. The Boom X Tender ranked third because of the inconsistent coverage.

    Part 2:

    Nozzle mounted on the front bumper of a County Highway Spray Truck used to spray ditches in Kansas.

    Boomless nozzles are often used on all-terrain vehicles (ATV’s) equipped with small-capacity spray tanks and they’re popular for for eliminating weeds in pastures and rangelands as well as along roadsides. In 2009, Kansas State University published a factsheet evaluating the efficacy of boomless spray nozzles and describing how they can best be used. What follows is a summary of the findings from their field trials.

    Considerations for using boomless nozzles

    1. Pick a nozzle that best fits the mode of action of the herbicide being used.
    2. Select spray width to achieve uniform distribution.
    3. Both the height of the vegetation, and the prevailing wind, will interfere with the width of the spray swath.
    4. As with any hydraulic nozzle, pressure should be optimized to achieve the desired droplet size and swath width while reducing drift potential.

    Field Trials

    Applications were tested on small (growth stage prior to jointing and 4-5 inches tall) and large (growth stage after jointing and 24-30 inches tall) wheat crops planted in 20 foot wide strips. The nozzles tested were the BoomJet (XP) , Boom X Tender (XT) , Boom Buster (BB) and the Combo-Jet (WCJ). Glyphosate and paraquat were applied a typical ATV-mounted set-up. The treatments were replicated three times and water sensitive paper was used to analyze droplet size.

    The Combo-Jet nozzle group.

    Results

    The mode of action, coverage and droplet size affected the results in both short and tall wheat. As expected, glyphosate served as the 100% control and paraquat efficacy ranged depending on the nozzle (see Graph 1). The XT gave the best performance with paraquat.

    Graph 1 - Percent Control in Large Wheat
    Graph 1 – Percent Control in Large Wheat

    Spray (control) uniformity was about equal with glyphosate, but with paraquat, on a scale of 1-10 with 10 being the highest level of control, the XT and BB tied for best (Graph 2).

    Graph 2 - Spray Uniformity in Large Wheat
    Graph 2 – Spray Uniformity in Large Wheat

    Swath width was considerably less than manufacturers claimed in the tall wheat (Graph 3). Based on width of control, the WCJ had the widest swath.

    Graph 3 - Swath Width in Large Wheat
    Graph 3 – Swath Width in Large Wheat

    Swath width was somewhat less than manufacturers claimed in the short wheat (Graph 4). Based on width of control, the XT had the widest swath.

    Graph 4 - Swath Width in Small Wheat
    Graph 4 – Swath Width in Small Wheat

    Median droplet size ranged from 684 to 799 microns (Graph 5). If we assume the preferred range for coverage/weed control is 300-500 microns, all nozzles were on the high end. It should be noted that this does reduce drift potential.

    Graph 5 - Droplet Size as VMD (microns)
    Graph 5 – Droplet Size as VMD (microns)

    Percent coverage ranged from 37.5 to 27.0 for paraquat and 28 to 21.3 for glyphostate (Graph 6).

    Graph 6 - Percent Coverage
    Graph 6 – Percent Coverage

    Observations

    The wind direction and height of the spray stream likely affected the results. To achieve the manufacturer-rated swath width, nozzles would have to be mounted higher on the ATV than is practical, and this would lead to increased drift potential. It was noted that the large orifices common to boomless nozzles made it difficult to pressurize with pumps typically used on ATV’s and a more powerful pump (e.g. a roller pump) might provide better swath width.

    While there are many parameters to consider, and counter to the lab trials performed in Part 1, the results from Part 2 suggest the Boom X Tender and Boom Buster gave better overall performance.

    Checking the Boom Buster spray pattern.

    Overall Conclusions from Part 1 and Part 2

    It can be frustrating testing nozzles. What works wonderfully one day might not be worth the materials they’re made of the next. Obviously there was no clear “winner” at the end of this article, but that’s just as well, because perhaps that’s the wrong take home message.

    Instead, remember that any nozzle can be used incorrectly. Mind the pressure, swath width and environmental conditions to get the most out of whichever nozzle you choose to use. Take time to confirm that everything is working optimally, and go back to ground-proof the results so you know what worked and what didn’t.

  • What’s my Spray Quality, in 3 Simple Steps

    What’s my Spray Quality, in 3 Simple Steps

    The introduction of dicamba and 2,4-D tolerance traits in corn and soybeans was accompanied by an unprecedented emphasis on spray drift management by the registrants. Product label statements for 2,4-D choline and the new formulations of dicamba emphasize spray drift control to a greater degree than previous products.

    Spray Quality Table

    In Canada, labels make prominent reference to the appropriate “spray quality”, a term referring to an internationally standardized droplet size classification (ASABE S572.2). In this standard, the droplet size spectrum produced by a nozzle is communicated using terms such as “Medium”, “Coarse”, “Very Coarse” etc., and used to describe the potential for spray coverage and spray drift. Spray qualities are colour coded for easy recognition.

    An example of this label language is shown for Enlist Duo below:

    “Droplet Size: Apply as a coarse to extremely coarse spray (ASABE S572 Standard). Use drift reducing nozzle tips in accordance with manufacturer directions that produce a droplet classification of coarse to extremely coarse to significantly reduce the potential for drift.”

    Although spray qualities are voluntarily measured and published by most nozzle manufacturers, their appearance on the label makes their use a legal requirement. This is because the Pest Management Regulatory Agency (PMRA) conducts a risk assessment which assumes, in this case, that a Coarse spray quality supports certain calculated buffer zones (15 m in this case) to protect sensitive ecosystems from Enlist Duo damage.

    The use of coarser sprays can be used to reduce this buffer zone somewhat, in accordance with an on-line “Site-Specific Buffer Zone Calculator” published by the PMRA.

    The challenge for applicators will be to determine the spray quality of their current application method. Here’s a relatively simple three-step process to find out.

    Step 1: Identify the nozzles currently on the sprayer.

    It seems basic, but it’s surprising how many applicators can not name their spray nozzle.  If unsure, closely inspect the nozzle, looking for the manufacturer’s name, the nozzle model, and its flow rate. Most nozzles will have this information printed right on them. Here are pictures of the most common nozzles. Can’t find the info? Have a look at this article for websites with pictures.

    Major manufacturers include Hypro (John Deere via private label), Agrotop (marketed by Greenleaf in North America), Hardi, Lechler, TeeJet, Wilger, and Billericay Farm Systems (Air Bubble Jet). Manufacturers produce many models, but most are easily identified by a series of letters and numbers. For example, all nozzles will be offered in several fan angles (80º and 110º are most common), and flow rates (in US gpm).

    To be more helpful, flow rates are colour coded according to an international standard. This table shows the colours and lists flow in US units in (gpm at 40 psi) and metric (L/min at 3 bar).

    The combination of series of letters or numbers shown on nozzles follows a relatively consistent pattern: Fan angle and flow rate arranged as 11003 or 03-110. In this case, the nozzle produces a 110 degree fan and has a flow rate of 0.3 US gpm. The use of US gpm at 40 psi to designate flow rate is an international standard.

    The nozzle model is frequently inserted into this stamp, and is manufacturer specific. For example, TeeJet may include “AIXR” in its stamp, and Agrotop may include “TDXL”. Hardi’s MiniDrift is abbreviated MD. Some nozzles may not list their fan angle. Others (Air Bubble Jet) are blank, creating a mystic aura of superiority.  Others leave the information printed on the nozzle cap.

    A bit of experience is very helpful, especially with John Deere nozzles, where the nomenclature inexplicably eliminates the first digit of the 110 or 120 degree fan angle. So the JD 11004 is labelled “1004”.  That’s a bit like saying “my truck sas a 50 engine”, when you mean it has a 350. How’s a city person supposed to know you don’t mean the trusty old 250 straight 6?

    Hypro SprayIT app screenshot

    Step 2: Obtain spray quality information on the nozzle.

    Most manufacturers publish the recommended pressure range and the spray quality of their nozzles. This information can be found in their product catalogues, or on their websites, or in smartphone apps.

    Although the designation of Spray Quality is governed by an international standard that is designed to standardize droplet sizing among various labs, we do see some variation in results.  Part of this is due to the continued evolution of the standard, requiring manufacturers to re-do some tests, or at least re-analyze their data. For example, ASABE S572.3 was released in conjunction with ISO25358 which changed the boundaries for the coarser sprays. These changes are beginning to be seen in the newer catalogues.

    Turbo TeeJet Spray Quality

    Another problem is that testing is done with plain water.  It is well known that the use of certain formulations or adjuvants can affect spray quality.  Currently, the standard does not address these effects, and data should be used with some caution.

    Step 3: Identify the expected pressure for a given travel speed and water volume.

    The same catalogues or websites that publish spray quality also produce charts that list the expected spray pressures at various travel speeds and water volumes.

    Becoming familiar with using these charts enables the applicator to predict the spray pressure the nozzle will be operating at. For example, if an applicator intends to apply 10 gpa using a yellow (02) nozzle, this table shows the following: The nozzle will be operating at 30 psi at 5 mph, at 40 psi at 6 mph, at 60 psi at 7 mph, at 70 psi at 8 mph, and at 90 psi at 9 mph. The applicator should know the nozzle’s spray quality at each of those pressures.

    Nozzle sizing follows a slightly different procedure for Pulse-Width-Modulation (PWM) systems, requiring the nozzle to be over-sized about 30% or so. Since the majority of new sprayer sales now include PWM, we’ve prepared a special article just for this system here.

    Application Chart 2015 cropped

    Travel speed and/or spray volume should be adjusted to ensure the sprayer operates at a pressure which creates the desired spray quality. In other words, the pressure gauge should be used as a speedometer.  If the nozzle model or size doesn’t produce the desired results, the applicator should consider changing nozzles. Once the right combination of factors has been determined, the spray pressures that created the label-required spray quality should be noted. From that point, the applicator can choose travel speeds that maintain the necessary pressure range.

    Summary

    It is up to applicators and industry representatives to ensure that herbicide products are applied according to label requirements. We expect significant scrutiny on spray drift from new products and need to ensure that proper application methods are used at all times. It’s important that everyone understands just how to do it.

    Dr. Scott Bretthauer (U. Illinois) gives a nice summary in this video by Precision Labs:

  • Agrifac Condor: A Wake-up Call For North American Sprayer Manufacturers?

    Agrifac Condor: A Wake-up Call For North American Sprayer Manufacturers?

    agrifac-condor-endurance
    Agrifac Condor Endurance (Source: Agrifac)

    I like good ideas.  And at Canada’s Outdoor Farm Show in Woodstock this fall, I saw a sprayer that puts a lot of them in one place.  I’m talking about the Agrifac Condor Endurance.  I’ve seen European sprayers before, even operated a few.  And although they are all well-engineered machines, the Netherlands-based Condor might be the first one to gain traction in North America. Why this one? Let me explain.


    Size:      If you thought European machines are too small for North American conditions, this one breaks the mold.  Sporting an 8000 L (2100 US gal) tank, track widths up to 4.6 m (15 ft), a 320 hp Tier 4 engine, and booms up to 55 m (180 ft) wide, it’s a monster. The smaller Condor offers tank sizes of 1050 or 1300 US gal and is a smaller machine overall.

    Agrifact Condor Sump
    The tank sump design ensures minimal remainders.

    Tank and Pump:  The large tank has a molded funnel sump that feeds directly into the pump.  Net result is a design that empties the tank completely, leaving a tiny remainder amount, less than 2 gallons according to Rob Blijdorp, with Agrifac North America.  Because most of us clean tank remainders by diluting them with clean water, this small remainder needs less water to dilute residues to safe levels, saving time when switching products.  The machine is equipped with a Hypro centrifugal pump as standard equipment in North America. A diaphragm pump is optional. This pump type is unusual for North America, but it is self-priming, can run dry, and can produce very high pressures.

    Agrifac Condor Boom
    Wide booms with recirculating plumbing boost productivity and minimize waste (Source: Agrifac)

    Boom: The boom widths available on the Condor are astounding, and there’s no easier place to use them than the North American Great Plains.  Wider booms are one of the most effective efficiency boosts in spraying, and allow slower travel speeds while creating fewer tracks.  The Condor boom has a recirculating design with a pressure feed from both ends, eliminating boom ends and increasing cleanout speed.  Since it uses the boom as part of its circulation system, the boom primes at filling so the new product is at the nozzles right away. Sectional control is flexible, with nozzle-by-nozzle control available.

    Agrifac Condor 4-wheel steer
    Four wheel steer on a walking beam chassis

    Chassis:  The frame and suspension system looks like a walking-beam setup, and is claimed to give a smoother ride with less transfer of bumps to the boom. The system has four-wheel steer capability for less tracking in turns, and a tight turning radius. The weight of the smaller Condor machine equipped with a 120’ boom is 24,500 lbs, the Condor Endurance with the same boom is 31,000 lbs.

    HighTechAirPlus nozzle
    The HighTechAirPlus atomizer is a twin fluid design that uses air to control flow and atomization.

    Nozzles: I saved the best for last.  Since 1989 (yes, I remember the year!), I’ve been a fan of “twin fluid” nozzles, but have not seen them take hold anywhere.  The HighTechAirPlus nozzles are Agrifac’s version.  Here’s how they work:  Liquid is delivered to the nozzle in the usual way, by pressure.  But air is also delivered, created by a dedicated air pump that has modest volume and pressure requirements.  Both air and liquid make their way through the same nozzle (a deflector style, similar to the TeeJet FloodJet).

    HighTechAirPlus
    HighTechAirPlus installed. Note the air supply and the air-activated shutoff for individual nozzle sectional control.

    The advantage?  Liquid flow and droplet size can be adjusted independently, with air and liquid pressure.  More air results in lower liquid flow. It also reduces droplet size.  More liquid pressure increases flow, and also reduces droplet size.  Clever combinations of both can keep droplet size fairly constant over a wide flow rate range.  Alternatively, the nozzles can change droplet size while keeping the same flow rate, depending on the drift or coverage needs at the time. The travel speed range achievable is similar to that with PWM.

    Verdict.  The jury’s out.  As a newcomer to North America, the Agrifac faces a few challenges.  Many say it needs a dealer network, inventory and parts.  It needs to prove its reliability. It needs to be able to service its machines, especially if parts are non-standard.  It needs field cred out here.

    But I’m a bit tired of our North American sprayers adding horsepower, speed, and weight to their sprayers each year, and little else.  They leave applicators to struggle alone with equally important productivity factors such as quick and thorough cleanout, drift management, nozzle selection and others.

    The things that strike me with this new sprayer are Agrifac’s innovative design, and its emphasis on issues that matter to applicators:  productivity and excellent control over application rate and droplet size. The company has the right priorities in my books.

  • When is Fungicide Coverage Critical? Always!

    When is Fungicide Coverage Critical? Always!

    Introduction

    A local strawberry producer was just beginning his harvest when the entire field was suddenly stricken with anthracnose. He would have done almost anything to save it, but he could only watch in frustration as the disease quickly devastated his crop. While he was telling me this story, he was wringing his hands; I’m sure he didn’t realize he was doing it. It had been more than a month since the crop was lost and he was obviously still very upset. Let’s put on our deerstalker hats and consider what might have caused the trouble.

    Strawberry anthracnose. Photo by Pam Fisher, OMAFRA.
    Strawberry anthracnose. Photo by Pam Fisher, former berry specialist with OMAFRA.

    Most of the fungicides we apply in horticulture are protectants, not curatives. What that means is that the fungicide has to be in place before disease has a chance to take hold. Once it establishes a beachhead, you can typically only hold it at bay, not eradicate it. So, if you’re guilty of waiting too long between fungicide applications, the problems may have already begun. This is exacerbated when you don’t achieve the necessary spray coverage. Put the two together and mix in rainy and warm conditions and diseases like anthracnose can spread at alarming speed.

    Method

    I focus on the sprayer part of disease management, so I have to assume that inoculum is being controlled as much as possible (e.g. culling infected plants, drip irrigation, etc.). I asked the grower about his sprayer and his spraying schedule. He admitted to pushing the limits between fungicide applications, and being uncertain about the spray coverage he was achieving with his conventional flat fan nozzles.

    Strawberry Sprayer
    Strawberry Sprayer

    In cases like this I try to find gentle ways of introducing the idea of using more water, increasing the frequency of applications, or buying new nozzles, because there is time and expense involved and many growers don’t want to hear that. However, when I started my soft sell routine, he looked me straight in the eye and said he’d lost tens of thousands of dollars in revenue so a few nozzles or a couple more applications were not a pressing concern. There’s a point in any endeavour when you’ve committed so much time and money that you’ll do pretty much anything to see it come to fruition (pun intended). He was willing to do whatever it took. This was my kind of guy.

    So, in preparation for next year, we diagnosed spray coverage from five different sprayer set ups. Let me point out, as I always do, that spray coverage analysis does not necessarily extend to control. They correlate well, but if you aren’t using the right product or your timing is off, even the best coverage won’t help you. Caveats aside, here’s what we tested:

    Setup1:

    Broadcast application using a horizontal boom with TeeJet Twinjet 8006’s at 8.3 bar (120 psi) on 50 cm (20 in) centres. We calculated a nozzle rate of 3.9 L/min (1.03 gpm), so at 5.0 km/h (3.1 mph) that’s 923 L/ha (98.7 g/ac).

    Setup 2:

    Banded application on a horizontal boom equipped with a row kits suspending three TeeJet XR 8002’s at 8.3 bar (120 psi). We angled the two side nozzles so the fans were not perpendicular or parallel with ground. This kept more spray on the raised row and out of the alleys. The swath covered 50 cm (18 in) and we calculated a nozzle rate of 1.29 L/min (0.34 gpm), so at 5.0 km/h (3.1 mph) that’s 1,016 L/ha (108.6 g/ac).

    Setup 3:

    Banded application on a horizontal boom equipped with a row kits suspending three TeeJet XR 8002’s at 6.2 bar (90 psi). We angled the two side nozzles so the fans were not perpendicular or parallel with ground. This kept more spray on the raised row and out of the alleys. The swath covered 50 cm (18 in) and we calculated a nozzle rate of 1.14 L/min (0.3 gpm), so at 5.0 km/h (3.1 mph) that’s 896 L/ha (95.8 g/ac).

    Setup 4:

    Broadcast application using a horizontal boom with TeeJet Twinjet 8004’s at 6.2 bar (90 psi) on 38 cm (15 in) centres. We calculated a nozzle rate of 2.27 L/min (0.6 gpm) so at 5.0 km/h (3.1 mph) that’s 717 L/ha (76.5 g/ac).

    Set up 5:

    Broadcast application using a horizontal boom with TeeJet Twinjet 8006’s at 6.2 bar (90 psi) on 38 cm (15 in) centres. We calculated a nozzle rate of 3.4 L/min (0.9 gpm) so at 5.0 km/h (3.1 mph) that’s 1,076 L/ha (115 g/ac).

    Protocol and Conditions

    It was late September, so the weather was a cool 8 °C, humidity was low and winds averaged 5 to 15 km/h. We timed our passes to correspond with lighter wind wherever possible. Three sets of water-sensitive paper were placed in a single row, but only one pass was made per sprayer setup. One paper was placed at the top of the canopy which is always very easy to hit, so we oriented it sensitive-face-down. The second paper was placed midway down the canopy, oriented facing up. The final paper was also oriented facing up, but placed at the very bottom of the canopy, more or less on the ground. Collectively, we spanned the depth of the canopy.

    Following each application, papers were collected for digital analysis using “DepositScan” which determines the percent of the paper covered with spray, and the droplet density. Both of these factors contribute to overall coverage. This wasn’t intended to be a rigorous experiment, so the means are presented here with standard error for the sake of comparison. There was no statistical analysis. In the case of papers located face-down, when only trace amounts of spray were discernible they were assigned a percent coverage of 1% and droplet density of 25 droplets/cm2.

    Results

    A few observations before we get to the results. Research has demonstrated that row kits and higher volumes improve spray coverage, and that’s why we tried banding the applications using row kits in Setups 2 and 3. However, this grower didn’t use GPS to plant his rows, and while they weren’t too crooked, they made it challenging to apply in a band. Further, there is some concern that a banded application would miss any inoculum in the alleys. These are important points to factor in when considering methods to control disease.

    The keen reader might notice we sprayed using pressures that exceed the manufacturer’s recommendations. In fact, none of these tips were rated over 60 psi and I used a formula to calculate their output at our high pressures. I have been heard to say (many times) never to exceed the manufacturer’s rates because it makes a mess out of the spray quality: droplets get much finer and pressure does not cause finer drops to penetrate a dense canopy. Better to switch to larger nozzles and stay within the pressures indicated on the manufacturer’s rate tables. I maintain that assertion. However, the grower was assured by fellow growers and custom applicators that this was the way to go and he wanted to try it. So, that’s where Setups 1, 4 and 5 came from.

    Be aware that a small sprayer like the one in this study needs considerable pump capacity to support such high pressure and flow to the boom and maintain effective agitation. For more information on pumps, check out this article.

    The following table expresses the coverage obtained by setup:

    Set upPaper PositionMean % Coverage (±SE)Mean Deposits/cm2 (±SE)
    Setup 1 – Broadcast XR 8006’s on 20” centres at 120 psi for 98.7 gpaTop1.0 ± 025.0 ± 0
    Middle23.6 ± 4.5253.5 ± 72.9
    Bottom15.2 ± 2.1423.2 ± 35.3
    Setup 2 – Three banded XR 8002’s at 120 psi for 108.6 gpaTop2.1 ± 1.178.9 ± 53.9
    Middle54.8 ± 12.1275.2 ± 145.3
    Bottom29.1 ± 2.7544.5 ± 70.4
    Setup 3 – Three banded XR 8002’s at 90 psi for 95.8 gpaTop7.4 ± 5.9134.4 ± 52.2
    Middle31.6 ± 15.9203.6 ± 108.5
    Bottom8.1 ± 3.9224.4 ± 102.3
    Setup 4 – Broadcast Twinjet 8004’s on 15” centres at 90 psi for 76.5 gpaTop1.0 ± 025.0 ± 0
    Middle33.3 ± 5.0240.7 ± 70.9
    Bottom12.9 ± 6.0263.9 ± 95.2
    Setup 5 – Broadcast Twinjet 8006’s on 15” centres at 90 psi for 115 gpaTop2.3 ± 1.3105.6 ± 80.6
    Middle48.9 ± 5.5194.3 ± 25.6
    Bottom19.5 ± 10.3246.8 ± 40.4

    The results may be easier to compare and contrast in the following graph.

    Strawberry coverage results for all five setups.
    Strawberry coverage results for all five setups.

    Observations

    According to the results, Setup 2 appeared to provide the best overall coverage. This is no surprise given that it was the second highest volume and employed a row kit. This corresponds with findings that have been published elsewhere. However, the excessively high pressure did create a lot of drift and the row kit didn’t always line up with the planted row. Further still, there’s the potential for missing anything that might harbour inoculum in the alleys, like runners. This setup wasn’t appropriate for this particular situation.

    The second-best overall coverage was obtained from Setup 5. This represented the highest volume, and a preferably lower pressure on twinjets, which may have allowed the spray to penetrate the canopy from multiple angles. This broadcast application is more reliable for hitting meandering rows and covers the alleys as well. So, the grower plans to employ this setup for the 2016 season, spraying at shorter intervals and confirming his coverage with water-sensitive paper. Let’s hope it works out.

    End-of-Season Update

    The grower that volunteered his time to this study has reported that his strawberries at the end of the 2016 season were absolutely beautiful. Granted, it is always difficult to draw a direct correlation between sprayer calibration and control. For example, 2016 was a very dry growing season and disease pressure was lower than in 2015. Nevertheless, spray coverage plays an important role in crop protection and our work to improve sprayer performance definitely played it’s part. His success is great news!

  • Exploding Sprayer Myths (ep.3): Nozzle Pressure

    Exploding Sprayer Myths (ep.3): Nozzle Pressure

    Here’s the third in our series of short, educational and irreverent videos made with Real Agriculture.
    We wanted to explain where pressure readings are taken on a sprayer and why it’s so important to know what pressure your nozzle is experiencing, rather than what the screens in your cab are telling you. Not only does pressure affect your application rate, but it affects your spray quality, which can be critical if your rate controller allows the pressure to drop below 30 psi.

    IT’S MY TURN TO DRIVE!