Category: Speciality Sprayers

Main category for all sprayers that are not horizontal booms

  • Closed Transfer Systems – They’re here.

    Closed Transfer Systems – They’re here.

    Closed Transfer Systems (CTS) permit the direct transfer of pesticides from container to sprayer while isolating the process from the operator and the environment. Similar systems are already used with bulk pesticide containers and in other industries to dispense a wide range of liquids from household products to industrial chemicals. In the case of small-volume containers (e.g., up to 20 L), these systems include an integrated container rinsing function.

    The UK’s Iain Robertson testing Pentair’s Cleanload Nexus Coupler

    CTS are comprised of two parts: The Cap (or Adaptor) and the Coupler. The CTS cap is either pre-fitted on the pesticide container, or the user must remove and replace the existing, non-CTS cap with an adaptor. Generically, the container is then locked into the coupler, and a valve in the cap or adaptor opens to permit chemical to be drawn out. If a partial amount is required, the valve can be closed to re-seal the container for safe removal, and the coupler and lines can then be rinsed. If the full amount is required, then the container is also rinsed prior to removal.

    Regulatory Requirements: Canada

    Canada’s Pest Management Regulatory Agency (PMRA) considers the requirement for closed transfer when products go through their natural re-evaluation cycle. They define it as follows:

    “A closed system means removing a pesticide from its original container, rinsing, mixing, diluting, and transferring the pesticide through connecting hoses and couplings that prevent exposure to the pesticide.”

    The requirement is primarily a means of reducing operator exposure and point-source contamination during filling, but can also be used to impose rate restrictions, or in response to reformulation. In recent years, several pesticides have had statements added to the labels regarding the requirement for a closed transfer system. They have stated that there have been three scenarios that they have included closed systems on labels:

    • The registrant requested closed systems be used in the occupational risk assessment.
    • Closed systems were required when triggered by the occupational risk assessment as a form of mitigation to reduce exposure to the mixer/loader. This is the most common reason it gets added.
    • Closed systems were used in the specific exposure study submitted to PMRA that was used in the risk assessment.

    As standardized language is developed, Canadian operators can expect to see statements that vary in their specificity, such as in the following two examples:

    Product 1: “Requirement for additional personal protection equipment (PPE) and engineering controls when mixing/loading and applying to various crops.”
    Product 2: “Closed mixing/loading systems are required. A closed system means removing a pesticide from its original container, rinsing, mixing, diluting, and transferring the pesticide through connecting hoses, pipes, and couplings that are sufficiently tight to prevent exposure of any person to the pesticide or rinsing solution.”

    Questions and concerns have been raised by registrants and growers as these changes have appeared on pesticides with particularly important actives. As of 2025:

    Products with standard CTS label statement:

    • Lorox L Herbicide
    • Ethrel PGR
    • Dibrom Insecticide

    Products that require CTS without standard label statement:

    • Bravo ZN Fungicide (bulk totes only, chlorothalonil in 10 L jugs does not require CTS)
    • Captan 480 SC and Captan L Fungicide (only if open cab AND exceeding a maximum L/day threshold)

    Products that may require CTS but not clear on the label:

    • Sevin XLR Insecticide – “use a closed mixing system”

    In some cases, registrants have avoided the requirement by splitting the label rate and promoting multiple applications to ensure rates do not reach the PMRA’s threshold for closed transfer. Another strategy is to remove small-volume formats and rely on Intermediate Bulk Containers (IBC or totes), which already employ closed transfer. If neither option is available, registrants may face expensive changes (which are currently unspecified) to their injection molding process. This is assuming North American small-volume container packers respond to emerging Canadian requirements.

    Commercial horticultural and specialty crop growers (or field croppers with smaller acreages and diversified crops) are more likely to purchase pesticides in small-volume containers as opposed to a tote. For growers, the practical requirements for compliant closed transfer are not well understood. Most do not currently have CTS and feel a retrofit is overly burdensome (e.g. slow, expensive, complicated), incompatible with their equipment, or redundant with conventional PPE.

    As Canadian agriculture comes to terms with these regulatory changes, the European experience offers valuable insight.

    Regulatory Requirements: Europe

    In Europe, reducing operator exposure and point source contamination during filling has long been a regulatory priority. Regulatory requirements for CTS are slated or already exist. The following dates are “fluid estimates” that will depend on the politics of each country. At the time of writing, the Netherlands are planning to make it compulsory on liquid formulations by 2025. Denmark will follow by 2024-25 and Belgium by 2026. The Czech Republic already stipulates about 12 separate products must be used in combination with CTS, and a blanket requirement is under discussion. In some cases, growers will be granted a three-year transition period before they must show that they have a capable CTS. Currently the UK doesn’t yet have any concrete targets, but they have been testing CTS since 2017 and their experiences have informed product development and the creation of international standards. According to a 2023 article in EI Operator, CropLife Europe stated that Europe is on track to make CTS available to all European farmers by 2030

    Recycling

    According to easyconnect (c. 2024), Germany is on the cusp of agreeing to accept both jugs and caps for shredding. Currently the caps are collected separately (if at all) because they aren’t typically rinsed. This is the same as in Canada.

    Cap and foil collection awaiting disposal.

    However, because the transfer systems also rinse the connection, the caps are down to the same 0.01% residue limit as the jugs, so as long as they’re dry, they’re both recyclable. Discussions are ongoing with France to make the same agreement.

    ISO definitions of CTS

    The 2021 publication of ISO 21191 has greatly facilitated CTS development. The standard defines what a CTS is and specifies the testing methods and compliance criteria for both operator and environment-related safety. Summarizing key points in the ISO:

    The CTS shall

    • connect to containers and application equipment;
    • control flow and measuring of all or a part of the container content;
    • rinse the container into the application equipment;
    • flush the CTS equipment as well as the interface;
    • permit operation while using appropriate personal protection equipment specified on pesticide label and any associated operator’s manual;
    • have clearly labelled controls;
    • be designed to avoid any return of liquid to the clean water supply.

    The CTS shall not

    • cause leakage when the device is connected to the mix tank or application equipment;
    • influence the circulation system of the connected application equipment;
    • allow the introduction of air that promotes foaming or reduces pump performance;
    • leave a residue level of more than 0.01% of the containers nominal volume following rinsing.

    The ISO was reinforced by a 2023 Crop-Life Europe study that tested three systems applying for ISO certification. It demonstrated a more than 98% reduction in operator exposure (while using gloves) for the easyFlow M, GoatThroat, and Cleanload Nexus systems. These systems, and others, are described below.

    Note: when using crop protection products, it remains a legal obligation for operators to wear the personal protection equipment indicated on the product label.

    Commercial Systems

    Pesticide container compatibility is fundamental to the success of any CTS design. There are exceptions, but many agrichemical companies in Europe and North America already employ a 63 mm screw cap for small-volume containers. According to the EPA (EPA 40 CFR Part 165 Subpart B), liquid agricultural pesticides in containers that are rigid and have capacities equal to or larger than 3 liters must have a screw cap either 63 or 38 mm in diameter and at least one thread revolution at 6 threads per inch. Depending on the CTS design, jugs may or may not require a tamper-proof foil. As of 2024, the first available jugs in the U.K. did not have foils.

    The following systems are compatible with the 63 mm cap and are emerging as viable options at the time of writing. Some have been commercially available for several years and others are either new or still in development. Cost and availability will vary based on regional distribution and demand. Interested readers are advised to contact the manufacturer to confirm compatibility with their preferred products.

    easyFlow (agrotop)

    The easyFlow was developed with support from Bayer and has been available for more than 10 years. It requires the operator to remove the existing container cap and replace it with the easyFlow adaptor, which features a built-in knife that automatically cuts any foil seal. It is compatible with container sizes between 1 and 15 L. There are three versions of the easyFlow coupler.

    easyFlow

    The original easyFlow coupler installs directly to the sprayer tank. Once the pesticide container is joined (maximum 10 L format), product pours via gravity straight into the sprayer tank. The container can then be rinsed using an external water source (e.g. via a garden hose) with a min. ¾” diameter, anti backflow valve and water pressure between 3-6 bar.

    easyFlow directly mounted on sprayer tank (image from FreeForm)

    easyFlow M

    The easyFlow M is a standalone coupler that supports containers over 10 L and permits dosing via an integrated measuring unit just below the mounting point. The measuring unit holds up to 2,250 ml with a minimum volume of 60 ml and graduations of 20 ml (50 ml over the 400 ml mark). Product transfer is achieved either by gravity, or by a pump (e.g. Teed to the suction side of the sprayer pump).

    easyFlow M mounted on separate transfer station (image from FreeForm)

    According to agrotop, a 5L container under suction took 2-2.5 minutes to empty and clean during the Croplife study. For reference, some operators claim they are able to drain and triple rinse in less than a minute using a traditional pour into an inductor. An operator in wheat aims to fill in 5-10 min depending and uses 5-10 jugs. On the other hand, CTS users have claimed a “hidden savings” from the overlap in operations where the product from one jug is still entering the system as another is being drained and a third is being prepared. AgroTop sells an optional vent spike called a “Chucker” that makes the process faster still, but penetrating the jug raises questions about ISO compliance.

    Empty containers can then be rinsed before removal, or partial containers removed leaving the adaptor on the jug. While this unit can be mounted on the side of the sprayer, most UK farmers that have trialed this system opted to install it on a portable cart.

    Agrotop’s easyFlow M (Image from Agrotop Website)

    easyFlow QF

    This system is still under development and information is limited. The easyFlow QF coupler reputedly has all the features of the M but is compatible with all manner of container and employs a 12 VDC supply to automatically meter the dose (starting from a minimum 1 L volume). The rinsing process is electronically automated as well.

    Videos of the easyFlow systems in use can be seen here and here. In the United states, these couplers are carried by Greenleaf Technologies. In Canada, it is also carried by FreeForm, a plastic molding company out of Saskatchewan.

    GoatThroat

    US-based GoatThroat has provided industrial liquid transfer solutions since 2001. Their CCS-8600 series requires the operator to remove the existing container cap and replace it with an adaptor with a siphon tube (which also pierces any foil). The container is then pressurized by a hand pump or compressor, forcing chemical into a measuring cylinder before it’s drawn into the sprayer. A clean water line then rinses the container (if emptied completely) and system before decoupling. The adapter can be left on containers if using partial volumes.

    Comparatively, this system transfers and rinses more slowly than other small-format container systems and is entirely manual with multiple steps to transfer product. However, it now has a compressor option to replace manual pumping and it is highly customizable, making compatible with any container from a 1 L jug to a 1,000 L IBC tote. Further, its ability to transfer as little as 5 ml increments makes it a good option for small-acreage horticultural, specialty crop, and research farms where accurate partial loads are prioritized.

    easyconnect cap (and Ezi-connect coupler)

    The easyconnect cap was originally developed by IPN Scholle with the support of BASF and is currently under development by Easy Cap and United Cap. It is compatible with container sizes between 1 and 15 L (possibly 20 L).

    The eascyconnect cap (image from www.easyconnect.tech)

    Because the cap is factory-fitted, it never has to be manually unscrewed or removed and works without requiring a tamper-proof foil. Its success is contingent on major agrochemical manufacturers agreeing to pre-fit it on their products. This has been facilitated by the easyconnect Working Group (ECWG), a consortium of ten major agrichemical companies, including those selling biological products and liquid fertilizers, that are supporting the European implementation of this format.

    BASF displayed their compatible coupler, the ezi-connect at the 2023 Agritechnica in Hanover, Germany. Transfer requires the operator to snap off a dust cover, invert the container, and connect and lock it into the coupler. Another lever advances a probe and allows partial volumes to be dispensed via a vacuum generated by the hopper. Finally, a trigger controls rinsing water and undoing a catch allows the assembly to be rotated to improve cleaning without removing it.

    Easyconnect will be factory installed on 1, 5 and 10 L containers in 2024. This will not be the entire portfolio from all agrichemical companies in the easy connect working group, but will represent a “significant amount” that will demonstrate commitment. In 2022, Syngenta released some information about their new jug format, the Evopac. In November 2024, Syngenta released this short video describing the design, which has the easyconnect cap and several features informed by sprayer operators to make it as safe and convenient as possible. The ezi-connect coupler will be launched in Europe in the 2025-2026 season.

    BASF’s ezi-connect (Image from BASF website)

    Cleanload Nexus (Pentair Hypro)

    The Cleanload Nexus is a JKI-approved coupler designed for use with easyconnect caps on 1 to 15 L containers. The supplied 25 mm x 4 m suction hose can be connected by teeing it directly into the sprayer suction line ahead of the venturi (mounted to sprayer) or using a suitable dry-break coupler (mounted on a portable transfer station). The supplied 16 mm x 2.5 m rinse water hose connects to a clean rinse water source either on or off the sprayer.

    The Cleanload Nexus in use

    It is entirely mechanical and has just two manual controls. The first is a lever that locks the cap in place. Rotating the lever controls the emptying rate, which is between 0.5 and 1 L/sec at 4 bar, depending on liquid viscosity. The time to empty and rinse a 15 L container at 3.5 bar is about 2 minutes, and users have stated that this is as fast or faster than traditional pouring and rinsing methods.

    For dosing, it currently relies on the operator using scale markings on the side of the pesticide container. It has been noted that the plunger mechanism displaces sufficient volume that it must be accounted for when reading graduations. Alternately, the calibrated suction hose connected to the sprayer can be used to assess larger volumes. The hose is, according to many, not a viable method for dosing and improvements are reputedly under development. Neither approach can achieve the ISO +/- 2.5% dosing accuracy, so Pentair has developed a dosing cylinder add-on that sits between the Cleanload Nexus and the sprayer and provides +/-1% accuracy (anticipated launch was in November 2023). A new measuring device, the Ezi-Connect VacTran Measure Unit by Wisdom Systems, was introduced in 2024 and is discussed in this article from EI OPerator.

    Plumbing diagram for the Cleanload Nexus (from Pentair website).
    While this video depicts 4 quarter-turns separated by 10-15 seconds rinses, practical application sees the simultaneous full rotation of the jug during a 30 second rinse. While the unit will rinse itself, some keep a dedicated jug full of clean water on hand and run that through the system last to ensure it’s left in a clean state. Note: operators say they only thoroughly rinse the cap when using a partial volume.

    AccuRite coupler (Tefen)

    Israel’s Tefen has produced dosing pumps and flow products for many years and began field testing the AccuRite CTS coupler in 2022. With a single digital interface to operate the filling process and mobile capabilities for remote management and cloud-based record keeping (e.g., date, time and chemical usage). It is designed to work with the easyconnect cap on containers ranging from 1 to 20 L. This is slow compared with the ~60L/min. from the Pentair system, but Tefen is working to improve the speed.

    Its diaphragm pump can deliver partial volumes at 0.1 L increments with an accuracy of +/- 2.5% of the smallest container used, and a minimum of 0.5 litres remaining in the container. Skip to the 1:50 mark to see the product reviewed (no English) in this video. In 2024, the following instructional video was released:

    We saw one moulded into a Kverneland sprayer (now owned by Kubota) that was designed to couple with the current induction bowl. This is the first time a sprayer company has altered their design to accommodate a CTS and it points to the future.

    Lechler’s LeC Coupler

    Lechler’s Coupler is compatible with the easyconnect cap and features more electrical automation in its design. It requires a 12V electric supply and creates suction (typically from the sprayer’s venturi) to draw out the chemical. A small metering motor automatically moves the probe that enters the container to adjust emptying rate. It employs a pressurized water line running at about 6 bar.

    The system will be controlled via a smartphone app, where the operator can choose partial or full emptying of product containers and control the operating and rinsing processes. Rather than metering flow, the unit employs three load cells with vibration compensation to weigh product. Lechler claims this is more accurate (automatic dosing to a set volume with +/- 2.5% accuracy), because it can compensate for different product densities. The user manually enters these values from product SDS, but likely QR codes will be used in the future.

    The system underwent further testing in 2024 and commercial availability is anticipated for 2025. Farmer’s Weekly covered the details of this system following Agritechnica 2023.

    2025 AgSpray Expo

    References

    • Options expanded for closed-transfer sprayer filling – Farmers Weekly (fwi.co.uk) (May 2022)
    • Aspects of Applied Biology 147, 2022 International Advances in Pesticide Application Review of ISO 21191 Closed Transfer Systems Performance Specifications. Nancy Westcott and Jan Langenakens.
    • Published abstracts from the Association of Applied Biologists’ Closed Transfer Systems Workshop hosted at the Silsoe Research Institute and Silsoe Spray Applications Unit, Bedford MK45 4HP, UK 11th May 2022
    • Pro Operator Magazine, 2017-2023

    This article was originally co-authored by Mick Roberts (Owner/Editor of Pro Operator Magazine) with significant contributions from Jan Langenakens (Principal at AAMS) and informed by insightful communications with both users and manufacturers of CTS. It has been updated as of January, 2025.

  • Tank Mix Compatibility

    Tank Mix Compatibility

    Tank mixing is the practice of combining multiple registered agricultural products in the sprayer tank for application in a single pass.

    The Pros of Tank Mixing

    • Efficiency: If the timing makes sense, a single pass saves time and reduces trample/compaction. E.g. A “weed-and-feed” application of fertilizer and herbicide in corn.
    • Resistance management: Multiple modes of action help prevent resistance development and combat existing problems.
    • Improved performance: Labels may require adjuvants to condition carrier water or reduce drift (utility adjuvants) or to improve the degree of contact between droplets and the plant surface, or enhance product uptake or rainfastness (activator adjuvants).
    Prowl meets Roundup – A beautiful photo by Peter Smith, University of Guelph

    The Cons of Tank Mixing

    Tank mixing requires caution and careful investigation. Should tank mix partners prove to be incompatible, the consequences can be subtle or dramatic, but are always negative. There are two kinds of incompatibility.

    1. Biological or Chemical Incompatibility

    This form of incompatibility may not be immediately apparent following an application. Some level of crop damage or impaired efficacy occurs, which may impact yield or warrant an additional “clean-up” application. This is the result of product synergism or antagonism.

    Synergism (Crop damage)

    When products synergize, the application becomes too potent. For example, an adjuvant could affect crop retention or uptake, exposing it to more active ingredient or overwhelming crop metabolism. The result is damage to the crop we are trying to protect.

    Antagonism (Reduced efficacy)

    When products antagonize, the application becomes less potent. There are several examples:

    • pH adjusters in one product may reduce the half-life of another product (e.g. The fungicide Captan has a half-life of 3 hours at a pH of 7.1 and only 10 minutes at a pH of 8.2.)
    • Active ingredients may get tied-up on the clay-based adjuvants in other products (e.g. glyphosate tied up by Metribuzin).
    • One product changes the uptake/retention of another. For example, a contact herbicide burns weed foliage beyond its ability to take up a lethal dose of systemic herbicide.

    2. Physical Incompatibility

    Physical incompatibility affects work rate and efficacy. Products form solids that interfere with, or halt, spraying. It can also make sprayer clean-up more difficult. For example, weak-acid herbicides lower the pH of the spray mix, reducing the solubility of Group 2 herbicides (i.e. imidazolinones, sulfonylureas, sulfonanilides). The oily formulation then adheres to plastic and rubber surfaces in tanks, connectors and hoses.

    There are many forms of physical incompatibility:

    • Liquids can curdle into pastes and gels that clog plumbing to such an extent that flushing cannot clear it and a manual tear down is required.
    Clogged screens
    • Dry formulations don’t hydrate or disperse, becoming sediment that clogs screens and nozzles. Even if they are small enough to spray, they reduce coverage uniformity. For example, a dry product added behind an oil gets coated, preventing it from hydrating.
    • Certain product combinations may cause settling, or one partner is more prone to settling. If the sprayer sits without agitation, settled products may or may not resuspend. Even if they do resuspend in the tank, they may remain as sediment in lines.
    Residue in hoses – Photo courtesy of Fred Whitford, Purdue University
    Clay-based products may or may not resuspend easily in a tank. Even then, they may not resuspend in plumbing lines.
    • Certain product combinations may cause foaming, or one partner may be prone to foaming, causing overflows or breaking pump suction. When products foam, dry products added through the foam may swell, preventing hydration.
    The Foamover Blues
    • Phase separation occurs when products layer in the tank. Consider oil and water. Even with agitation, the active ingredients may not be uniformly suspended in the tank and coverage uniformity will be reduced during spraying.
    Salad dressing left to rest is a great example of separation and stratification (left). Agitation helps emulsify it (right)

    Due Diligence – Preventing Tank Mixing Errors

    Incompatibility is often a function of the inert ingredients in pesticide formulations (e.g. thickeners, adjuvants, defoamers, stabilizers, solvents, etc.) and not the active ingredients. The more products you add to the tank, the more likely you’ll encounter an issue. It is prudent to perform a jar test to confirm physical compatibility. Remember, even if registered tank mix partners support mixing, your pace, mixing order, and water quality/temperature could cause issues.

    Do not decide to try a new-to-you registered tank mix during loading. Even if you’ve used these products successfully in the past, formulations change without notice. Plan as much as possible off season when there is time to do the following:

    Consult the pesticide labels

    Pesticide labels are always the first point of reference. They should be obeyed even if they contradict conventional practices. Booklet-style labels that come with the products are long, difficult to search and may not be up-to-date.

    In Canada, it is faster and easier to go to the PMRA Label Search website and search labels in PDF format. In other countries, consult the manufacturer’s website for label information. For each tank mix partner, use <CTRL>+F to find the following keywords:

    • Do Not Mix
    • Mix
    • Hours
    • Agitation
    • Fertilizers

    Consult manufacturer and crop advisors

    You’re likely not the first to consider a certain tank mix. Learn from those that have been there already:

    • Consult your chemical sales representative. They know their products best and want to see you succeed. They may have insight that is not found on the product label.
    • Consult local government or academic extension programs for an unbiased opinion.
    • Enlist the help of a professional crop advisor.

    It is a good practice to get tank mix recommendations in writing. If something should go wrong, liability is an important concern.

    If you’ve made a mess – The Reverse Jar Test

    It happens. We’ll use this real-world situation as an example:

    “I mixed up a batch of MCPA 500 A and Glyphosate at ¾ recommended label rate, but then got delayed on application with a stuck drill. I came back to the sprayer and found a nasty chemical precipitate – like waxy chunks. Agitation didn’t break them down. I dumped the tank out as I didn’t want to pump it through the booms. How do I clean up the chunks in the system?”

    We forwarded this question to ag chemists Dr. Eric Spandl (Land of Lakes) and Dr. Jim Reiss (Precision Laboratories) and developed this response:

    “Wearing appropriate personal protective equipment, physically remove the “chunky” material. A lot of time can be wasted (and rinsate water created) by experimenting with various concoctions, but if you do choose to try a compatibility agent, first try it in a mason jar. If it works to dissolve the material, it can be added to the tank with water and agitated. If not, you are down to manual cleaning: hot water under pressure.”

    We dubbed this process “The Reverse Jar Test”. Do not add hot water, cleaners or compatibility agents until the reverse jar test confirms success. You may create a larger problem. Of course, the best advice is to not put yourself in this position to begin with. Once again, don’t make mixing decisions at the inductor bowl – make them before ordering product.

    Tank mixing regulations in Canada (January, 2025 update)

    The following legislative framework is specific to Canada, so readers in other countries should consult their own regulatory authorities.

    Paragraph 6(5)(b) of the Pest Control Products Act (PCPA) states that no person shall use a pest control product in a way that is inconsistent with the directions on the label. In 2020, a public consultation was held to consolidate and clarify tank mixing requirements. This led to Regulatory Proposal PRO2020-01 (Streamlined Category B Submissions and Tank Mix Labelling – July 3, 2020). Essentially, it stated that tank mixing would be allowed if there was text on the product label that specifically permitted it. This could be a specific tank mix combination, a general statement permitting mixing, or both.

    A new general label statement that permits tank mixing was proposed to consolidate tank mixing information in one place on the label and allow greater flexibility in terms of tank mixing options. The prohibition against tank mixing products with the same mode of action was removed, and the reference to tank mixing with a fertilizer is now an optional component of that statement. The general label statement reads as follows:

    “This product may be tank mixed with (a fertilizer, a supplement, or with) registered pest control products, whose labels also allow tank mixing, provided the entirety of both labels, including Directions For Use, Precautions, Restrictions, Environmental Precautions, and Spray Buffer Zones are followed for each product. In cases where these requirements differ between the tank mix partner labels, the most restrictive label must be followed. Do not tank mix products containing the same active ingredient unless specifically listed on this label.

    In December of 2022, Health Canada released a guidance document describing the federal tank mixing policy. This document is not part of the PCPA, but is an administrative document intended to facilitate compliance by all stakeholders. Registrants have until December, 2025 to update their extension material to align with amended product labels and guidance documents. Similarly, users of pest control products will be provided the same transitional period to adjust their purchasing and production practices to align with the provisions of this document. This means the policy will be in full effect on December , 2025. After that, applicators in Canada can only apply tank mixes that appear specifically on a product label, or tank mixes of products whose labels include the new general tank mixing statement.

    Summary of the guidance document

    Tank mixing is not permitted when a potential tank mix partner’s label has some exclusionary statement, such as:

    • Forbidding mixing. E.g. “Do not mix or apply this product with any other additive, pesticide or fertilizer except as specifically recommended on this label.”
    • Limiting tank mixes to only those specifically listed on the product label.

    During the label transition, guidance relating to tank mixing may be found under a section specific to tank mixing, and/or under other sections as in the following examples:

    • Directions for use: E.g. “When tank-mixes are permitted, read and observe all label directions, including rates and restrictions for each product used in the tank-mix. Follow the more stringent label precautionary measures for mixing, loading and applying stated on both product labels.”
    • Buffer Zones: E.g. “When tank mixes are permitted, consult the labels of the tank-mix partners and observe the largest (most restrictive) spray buffer zone of the products involved in the tank mixture and apply using the coarsest spray (ASABE) category indicated on the labels for those tank mix partners.”
    • Resistance Management: E.g. “Use tank mixtures with [fungicide/bactericides/insecticides/acaricides] from a different group that is effective on the target [pathogen/pest] when such use is permitted.”

    If there are no directions on the labels, don’t tank mix them.

    If your situation does not fit these examples, the following table (Appendix A at the bottom of the Guidance Document), lists several other examples examples of different tank mix wording scenarios for registered pest control products.

    Table 1: Permissibility of tank mixing based on various combinations of label statements related to tank mixing

    Product X label saysProduct Y label saysCan I tank mix? (Y/N)
    Nothing (silent on tank mixing)Nothing (silent on tank mixing)N
    General tank mix statementNothing
    (silent on tank mixing)    		N
    Nothing (silent on tank mixing)General tank mix statementN
    General tank mix statementGeneral tank mix statementY
    General tank mix statementTank mix with Product XY
    Tank mix with Product YGeneral tank mix statementY
    Tank mix with Product YNothing (silent on tank mixing)Y
    Nothing (silent on tank mixing)Tank mix with Product XY
    Tank mix with Product YTank mix with Product XY
    Tank mix with Product YExclusionary statement (and label does not include a specific Product X tank mix)N*
    Exclusionary statement (and label does not include a specific Product Y tank mix)Tank mix with Product XN*
    *There may be registered labels that have tank mix scenarios like this. Note that this is not allowed for new tank mix label amendments. Further, any product labels that have tank mix scenarios like this must be amended to alleviate the contradictory scenario. To do this, using the last scenario in Table 1 as an example, one of the following must occur: 1) remove the Product X tank mix from the Product Y label, 2) remove the exclusionary statement from the Product X label, or 3) add a specific tank mix for Product Y on the Product X label. Source: PMRA Guidance Document Tank Mix Labelling 2023

    Tank mixing adjuvants

    According to the PMRA, the rules surrounding the tank mixing of adjuvants remain the same as they have been since 2009, and are not included under the new guidance document. While the PCPA does not reference adjuvants specifically, they are prescribed to be pest control products in the regulations (Pest Control Products Regulations s.2(b)). The general reference in the PCPA that applies is s.6(5)(b).

    Therefore, in the case of activator adjuvants, the label for at least one tank mix partner must specify the use of an adjuvant, and only registered adjuvants labeled for the crop and for tank mixing are permitted. For example, tank mixing the herbicide Reflex with a registered soybean oil adjuvant not labelled for the use, or with an unregistered food grade activator adjuvant, would not be acceptable. Utility adjuvants have registration numbers, but their use is not prescribed or specified on pesticide labels, leaving their use to the discretion of the operator.

    For more information on Canada’s Tank Mixing Policy

    For more information, please contact Health Canada’s Pest Management Information Service.

    Academic Resources

    Even when products are potentially compatible, issues can arise from errors in mixing order, pace, carrier volume, carrier quality and agitation. These are discussed in our article on sprayer loading and jar testing.

    In 2018, Purdue University published “Avoid Tank Mixing Errors”. It is an excellent reference.

    In late 2022, Australia’s GRDC released a comprehensive guide on pesticide mixing and batching (within the context of the Australian agronomic environment, of course), which can be downloaded for free, here.

    Finally, you can watch a 2021 presentation on tank mixing (below). It was delivered to a grape growing audience, but much of the content applies across agriculture. There are a few “oops” moments where I didn’t say quite what I meant. I misread the Sencor dissolution / filtration work. And, I really didn’t answer the last question about mixing herbicides. The answer should have been to consult labels and local resources, such as OMAFRA’s Crop Protection Hub. Note that any discussion of Canadian regulatory policy may have changed in light of the new 2022 Guidance Document.

    This article was co-written with Mike Cowbrough, OMAFRA Weed Management Specialist – Field Crops

  • Think Before Adding Adjuvants

    Think Before Adding Adjuvants

    It’s odd to begin an article by suggesting the reader consult another, but Dr. Tom Wolf wrote a great summary about adjuvants for SaskPulse in 2023 and you can and should download it here. While I’m at it, also grab this article by Rich Zollinger, Emeritus Extension Weed Scientist, North Dakota State University.

    OK, back to the article at hand. An adjuvant is “any substance in a formulation or added to the spray tank to modify the biological activity or application characteristics”. This means they have an array of functions, such as masking pesticide odor, conditioning carrier water, improving mixing and reducing drift (Utility modifier adjuvants). They can also improve the degree of contact between droplets and the plant surface, or enhance product uptake or rainfastness (Activator adjuvants which include a subset of products referred to as Surfactants [SURFace ACTive agENTS]).

    For example, this short video was filmed in 2015 to demonstrate how a sticker surfactant reduces runoff and how a penetrant surfactant can help a product pass through a waxy plant surface. This video was filmed and edited by former OMAFA summer student, Victoria Radauskas.

    Generally, pesticides already come preformulated with the requisite inerts, which include the utility modifier and activator adjuvants that ensure ease of use and optimal product performance. But sometimes the pesticide label requires the operator to add a particular name brand or category of adjuvant. In this case, the pesticide does not include the adjuvant because it might negatively impact product stability, increase bulk and/or increase expense.

    Canada is seeing an increase in the number of adjuvants for purchase (particularly utility modifiers). Claims of improved performance make it tempting to reflexively and proactively throw them in the mix. The grower is free to use any adjuvant provided it is registered for use on the crop and in combination with the pesticide being applied. You can learn more about the regulatory realities in our tank mix article.

    We suggest that adding any adjuvant is an optional last step in optimizing a sprayer’s performance. Dialing in all other aspects tend to reap the greatest rewards. Here are a few general guidelines when using surfactants in horticultural crops:

    • Do not use penetrant surfactants (including oils) with copper, sulphur or captan fungicides.
    • Do not use penetrant surfactants with contact or surface pesticides.
    • Stickers may impede the movement of systemic products.
    • Stickers may prevent redistribution to newly emerging leaves early in the growing season (but they may be desirable during wet springs).
    • Deposition utility modifiers may negatively affect canopy penetration when employing multi row or alternate row traffic patterns.
    • Spreaders are more likely to incur runoff so adjust volumes accordingly.

    Additional Resources

    The following video presentation was recorded for a 2021 adjuvant conference in Argentina. It’s a primer to introduce what adjuvants are and why we might consider using them. You’ll note that I speak slowly during the presentation – that’s because it was being translated and I wanted to make that process as easy as possible. Also, I think I mistakenly said captan was an insecticide – in fact it’s a fungicide. Oops.

    And here’s a 2022 interview from Real Agriculture’s “The Agronomists” featuring Tom Wolf of Agrimetrix, and Greg Dahl of Winfield United. For the adjuvant-related part of the conversation, you can pan ahead to the six-minute mark.

    And here’s a 2025 interview from Real Agriculture’s “The Agronomists” featuring Jason Deveau and and Austin Anderson of Helena.

  • Establishing an Optimal Airblast Carrier Volume

    Establishing an Optimal Airblast Carrier Volume

    North American product labels may or may not include carrier volume recommendations. When they do, it could be based on a two-dimensional value like the planted area, or perhaps on row length which is more appropriate for trellised crops that form contiguous hedge-like canopy walls. Volume may be tied to product concentration, which sets minimum and maximum volumes based on product rates. Or, more commonly, volume recommendations take the form of vague guidelines such as “Spray to drip” or “Use enough volume to achieve good coverage”.

    In all cases, spray efficacy and efficiency can be greatly improved by dialing-in the carrier volume to optimize coverage uniformity and reduce off-target spraying. This is easier said than done because the optimal spray volume is case-specific. It depends on a complicated relationship between:

    • Weather conditions (E.g. temperature, humidity, wind speed and direction)
    • Sprayer design (E.g. air handling, droplet size and flow distribution over the boom)
    • Traffic pattern (E.g. every row or alternate row)
    • Product chemistry (E.g. mode of action and formulation).
    • Target (E.g. Crop morphology, planting architecture)

    It is the final variable, the nature of the target, which is the focus of this article. To learn more about the other variables, grab a copy of Airblast101.

    The plant canopy and planting architecture dictate volume

    Quite often, the target in airblast applications is the plant canopy. The plant canopy is the collective structure containing all plant surfaces. This could be the foliar portion of a single pecan tree, a panel of grapes, or a bay of container crops. The planting architecture describes how those canopies are arranged on the planted area. If we consider the canopy and architecture geometrically, we can make relative statements about the volume required when all other variables are equal.

    Six geometric characteristics of the plant canopy and planting architecture.
    Geometric CharacteristicRelationship to Carrier Volume (per unit planted area)
    Row SpacingThe greater the row spacing, the less volume needed.
    Plant SpacingThe greater the plant spacing, the less volume needed. This assumes gaps between the canopies (I.e. not a contiguous hedgerow).
    *Canopy DepthThe greater the canopy depth, the more volume needed.
    *Canopy WidthThe greater the canopy width, the more volume needed.
    *Canopy HeightThe higher the canopy, the more volume needed.
    Canopy DensityThe denser the canopy, the more volume needed.
    *The product of average canopy depth, width and height is the canopy volume. This value forms the basis for many dose expression models and historic carrier volume calculators such as Tree Row Volume.

    Canopy density

    Let’s focus on a single plant canopy. Research has demonstrated that with the possible exception of canopy height, canopy density has the greatest influence on optimal sprayer settings. Density describes the amount of matter inside a canopy relative to the volume of space it occupies. The denser the canopy, the more surface area there is to cover and the more difficult it is for spray to penetrate. While air handling plays a significant role in improving coverage, a denser canopy will almost always require a greater carrier volume.

    When two physiologically diverse blocks share an alley, use the sprayer settings suitable for the larger of the two. It’s more important to ensure good coverage on the big block than to save on the smaller.
    When two morphologically-diverse blocks share an alley, a two-sided, every-row sprayer should employ settings suitable for the larger of the two. It’s more important to ensure good coverage on the big block than to save on the smaller. Once the hybrid row is sprayed, settings should be modified to suit the block.

    For most perennial crops, canopy density changes over the growing season. The influence of age and staging on canopy size and density will depend on the crop variety, plant health and canopy management practices. The practical implication is that as the canopy grows and fills it typically warrants an increase in spray volume. As illustrated in the figure below, the volume used should reflect the current stage of canopy development. If a volume suitable for the densest and largest stage of development is used all season, it will create a great deal of waste early in the season. However, if volume is increased incrementally to reflect canopy growth, a better fit between coverage and volume will minimize waste. In the image below, volume is increased around petal fall, but the fit could be improved with more increments. Caution is advised to ensure the volume is raised (if required) prior to immediate need, particularly during key developmental stages like bud break or bloom where fungicide coverage is critical.

    The curved line represents the leaf area in a canopy (Y-axis, right) increasing over the growing season (X-axis). The volume of the spray (Y-axis, left) providing effective coverage is indicated in green. Spraying the same volume throughout the season means a lot of over-spray (red) early in the season. The target simply isn’t there yet. Using less volume early season and changing about midway through the season, or as required by canopy development, has the potential to save a lot of spray (blue) without compromising spray coverage. Note that the first volume should give sufficient coverage to reach mid-season, and the second volume should be sufficient to reach the end of the spraying season. Always err on the side of excessive coverage to buffer against the impact of unanticipated variables.

    There are exceptions to this rule. Many nursery crops and mature evergreens often do not require changes to volume. High density apple orchards may or may not require an increase in volume. Early in the season, sparse canopies have low profiles that result in very low catch efficiencies. In other words, a great deal of spray misses the target. The amount of waste is a function of the application equipment design and the weather conditions. Most low-profile axial airblast systems envelop the target in spray with limited means of reducing air energy sufficiently, or to turn off the spray between trees. Further, sparse canopies do not restrict wind, which means ambient wind speed tends to be higher early in the season compared to when the trees become wind breaks. This creates a drift-prone situation and higher volumes are often used to compensate for the loss. The collective result is that excess spray volume is inevitable early season. As the canopies fill, the wind is reduced and catch efficiency increases, so trees intercept more spray without having to raise volumes. This balance eventually tips, however, and an increase in volume may be advisable.

    Watch the following video to see the impact of using excessive spray volume (and poor air adjustment settings) in a young cherry orchard. The waste becomes particularly apparent at ~43 seconds when the sprayer passes in front of the woods and the plume can be seen with higher contrast. While some loss is inevitable in such a sparse canopy wall, this situation could be improved by using less carrier volume, larger droplets, the correct air settings, canopy-sensing optics and/or a tower or wrap-around sprayer design.

    Adjusting spray volume sprayer settings to reflect the canopy can save money and reduce environmental impact during early-season applications and in young plantings. Mix the tank as you normally would to maintain the pesticide concentration on the label, but adjust the sprayer output to match the plant size. Performed correctly, you will be able to go further on a tank without compromising efficacy. This crop-adapted spraying method and the relationship between spray volume, concentration and dose are described further in this article and this article.

    Estimating volume from canopy geometry

    It is challenging to decide on an appropriate spray volume. Many operators resort to historical or regional practices and do not make adjustments to reflect their specific situation. Others refer to models such as Tree Row Volume (a.k.a. Canopy Row Volume) which relates canopy volume per planted area to spray volume. In this case, catch efficacy is expressed as a coverage factor, which is determined through experimentation specific to the crop, environment and sprayer.

    Tree Row Volume = (Avg. Canopy Height × Avg. Canopy Spread × Planted Area) ÷ Row Spacing

    Spray Volume = Tree Row Volume × Coverage Factor

    In New Zealand, coverage factors for dilute applications to deciduous canopies range from 0.007 to 0.1 L/m3 (0.00052 to 0.00075 US gal/ft3). The range captures variation in canopy density and any product-specific coverage requirements. Oil sprays, for example, require more surface coverage than most products. While closer to “the truth”, the Tree Row Volume method is still only an estimate.

    If the operator has no prior experience with the crop or the sprayer and wants a sanity-check on their estimated spray volume, we propose the following guidelines for full canopy dilute application to mature crops using every-row traffic patterns. The volumes may seem high, but recognize we have selected a very challenging scenario.

    • Small canopies (E.g. bush, vine, cane, high-density fruiting wall): 500 L/ha (55 US gal./ac.) to 1,000 L/ha (110 US gal./ac.).
    • Medium canopies (E.g. tender fruit, pome): 750 L/ha (80 US gal./ac.) to 1,250 L/ha (135 US gal./ac.).
    • Large canopies (E.g. tree nut, citrus): >2,000 L/ha (214 gal./ac.) and up tp 7,000 L/ha (748 US gal./ac.).
    • For sprayer operators that think in 100 m row lengths, consider 20 L volume per 100 m row length per 1 m canopy height.

    Further Resources

    No matter the approach to determining spray volume, it is imperative that coverage is assessed. It is amazing what we ask of airblast sprayers. Read this short article for some perspective on the coverage we hope to achieve from a given spray volume. We propose the use of water-sensitive paper to assess spray coverage. We describe its use and evaluation in detail in this article, this article and in this article. Dialing-in an optimal spray volume is an iterative process that requires careful observation and keeping records on what works and what doesn’t for your specific operation.

    Jon Clements (University of Massachusetts) wrote a great blog post on the subject of TRV. He warns about special considerations when it comes to establishing effective volumes for plant growth regulators and links to a factsheet called Spray Mixing Instructions – Considering Tree Row Volume. The factsheet was written in 2021 by Terence Robinson and Poliana Francescatto (Cornell University) and Win Cowgill (Professor Emeritus, Rutgers University).

    Finally, if you really want to get lost the weeds, check out this video recorded in 2021. I had an opportunity to learn from pros like Dr. Terence Bradshaw (University of Vermont) and participants from the Great Lakes region. They’ll tell you all you ever wanted to know about Tree Row Volume. Settle in!

    Thanks to Mark Ledebuhr of Application Insight LLC for his contributions to this article.

  • Determining Airblast Travel Speed – The “Air Displacements” Method

    Determining Airblast Travel Speed – The “Air Displacements” Method

    The concept of Air Displacements was developed by Dr. David Manktelow, Applied Research and Technologies Ltd.

    What is the “right” speed to drive when spraying?

    Airblast sprayer operators must know their average travel speed to calculate how much pesticide and time is required to complete a spray job. Note that it’s an average, not a constant, because travel speed is significantly affected by ground surface conditions (e.g. slippage), grade (e.g. hills) and the weight of the rig (e.g. as spray mix is depleted).

    The pursuit of productivity and the unchallenged status quo of traditional spray volumes, blinds many operators to the fact that travel speed is a critical factor in focusing air energy on the target canopy. As long as droplets are small enough to be entrained and directed by the air, we believe that optimizing the fit between air energy and the target canopy leads to the most frugal and effective use of spray mix and should therefore dictate travel speed. If that speed proves to be painfully slow, or terrifyingly fast, then a mismatch is revealed between the sprayer design and the operational conditions and the overall spraying strategy should be reconsidered.

    This article describes a method for modelling an ideal travel speed. It can be used as a sanity check for existing operations or for those seeking to evaluate the fit of a new airblast sprayer. However, this method can only approximate travel speed. A true optimization of sprayer settings will require fine tuning using the ribbon method and, ultimately, coverage feedback from water sensitive paper (see here and an older article here). We’ll begin with how to measure average travel speed.

    How to measure average travel speed

    Beware the tractor speedometer or rate controller that monitors wheel rotations; both can be fooled by changes in wheel size, tire wear or slippage. GPS or radar-based speed sensors are the most accurate method.

    Those that prefer a manual method can follow this classic protocol for determining average travel speed:

    1. Go to a row that is representative of the terrain in your planting. Measure out a distance of 50 m (150 ft) and mark the start and finish positions with wire marker flags.
    2. Fill the sprayer tank half full of water.
    3. Select the gear and engine speed in which you intend to spray. If using a pull-behind sprayer, ensure the PTO is running or you could introduce errors.
    4. Bring the sprayer up to speed for a running start and begin timing as the front wheel passes the first flag. This is far easier when there are two people.
    5. Stop the timer as the front wheel passes the second flag.
    6. Stay out of any ruts and run the course two more times.
    7. Determine the average drive time for the three runs (i.e. the sum of all three times in seconds divided by three).
    8. Finally, calculate travel speed using one of the following formulae, depending on preferred units:

    Ground Speed (km/h) = Average drive time for 50 m (s) ÷ 13.9 (a constant)

    Those that prefer a less accurate but convenient hack can download any smartphone speedometer app that can calculate an average (similar to a runner’s GPS wristwatch). Fill the sprayer tank half full and drive a representative section of your operation with the fan on and the spray off. Consult the phone for your average speed for each pass. Take a screen shot and email it to yourself as a time-stamped component of your spray records.

    The “Air Displacements” method

    Dwell time

    Airblast sprayers use fans to move a volume of air at a certain speed, often measured in m3/hr or ft3/min. Imagine that volume of air as a three dimensional shape extending from the air outlet over a distance. Likewise, imagine the void between the sprayer outlet and the target canopy as a three dimensional shape penetrating roughly halfway into that canopy (assuming we intend to spray every row).

    How long must the sprayer dwell in one spot before it pushes all the intervening air out of the way and replaces it with spray-laden air? If the sprayer drives too slowly, it will wastefully push spray through and beyond the target (i.e. blow-through). If the sprayer moves too quickly, the spray will not have an opportunity to penetrate the target canopy and most certainly not reach the highest point. This concept of focusing air energy using travel speed is called Dwell Time.

    We want to calculate the volume of air the sprayer generates, compare that to the volume we want displaced, and then determine how fast we must drive to optimize the fit. We can do all this with a tape measure, an anemometer, and a partner to record the data and do a little math.

    1. Measure air outlet area

    With the sprayer safely off, measure the area of the air outlet(s) on one side of the sprayer. We’ll use a Turbomist 30P Low Drift Tower (below) as an example. There are two air outlets that are 5 cm wide by 150 cm high for a total area of 0.075 m2 on each side. Be sure to look inside the outlet for any irregularities like baffles or obstructions intended to block air. Subtract those areas from the total. Don’t worry about small things like nozzle bodies.

    For rectilinear outlets: Height (m) x width (m) = Area (m2)

    For circular outlets: 3.14 x radius2 (m) = Area (m2)

    The air outlet on this Turbomist 30P Low Drift tower sprayer is 5 cm wide by 150 cm tall for a total area of 0.075 m2.

    2. Measure air speed

    First, a few safety warnings: High speed air is loud and can carry debris, so always wear ear and eye protection and respect the hazards inherent to working with air-assist sprayers. Only use an anemometer rated for at least 160 km/h (100 mph) (e.g. here). Do not use a handheld weather meter such as a Kestrel because the impellor could be destroyed and become dangerous shrapnel.

    Use an anemometer rated for at least 160 km/h (100 mph) (e.g. here). Do not use a handheld weather meter such as a Kestrel because the impellor could be destroyed and become dangerous shrapnel.

    Bring the fan up to speed and holding the meter about 25 cm (10 in.) from the outlet, measure the air speed at several locations along the air outlet both vertically and horizontally. We calculate an average speed because many air outlets do not produce uniform air speed or volume along their outlets. For this example, we measured four locations along the air outlet on both sides of the sprayer and saw significant differences. We did this both in low and high gear (see table below).

    High GearHigh GearLow GearLow Gear
    Location Along OutletLeft Side (m/s)Right Side (m/s)Left Side (m/s)Right Side (m/s)
    Top 1/441.180.342.924.6
    Upper34.932.226.430.8
    Lower30.830.024.026.4
    Bottom 1/433.540.226.831.3
    Average35.145.730.028.3
    Anemometer readings from the low drift tower sprayer outlets, on left and right side, in high and low fan gear. Four readings from bottom to top to determine the average. Readings taken 25 cm from edge of outlet and PTO set to 540 rpm.

    Multiple air outlets

    Before we continue with the method, let’s change sprayers to this Turbomist 30P Grape Tower (below). The design is intended to spray adjacent rows from the vertical outlets (5 cm x 150 cm = 0.075 m2) along the tower. The upper, inverted outlets (10 cm x 63.5 cm = 0.0635m2) throw spray over the adjacent rows and cover the outside rows. The intention is to improve productivity by covering four rows of grape (or possibly three) per pass.

    The Turbomist 30P Grape Tower Sprayer is a multirow system intended to drive every third or fourth row.
    Lower, vertical ducts are 5 cm x 150 cm = 0.075 m2
    Upper, inverted ducts are 10 cm x 63.5 cm = 0.0635m2

    However, when we consider this design through the Air Displacement lens, it’s almost like having two sprayers performing two jobs simultaneously. The vertical outlets and the upper, inverted outlets are different shapes. Further, their position (distance and angle, as the top outlets are angled back more aggressively) relative to their respective target canopies are significantly different. How fast must this sprayer drive to optimize the fit? Do we have to compromise coverage and incur drift and waste from one set of outlets to accommodate the other set? The manufacturer has worked to address this potential issue by partitioning the majority of the air energy to the top outlets, but let’s see how that affects travel speed.

    3. Total volumetric flow

    Having already measured the outlet area, we then measured average air speed (see table below).

    High GearHigh GearLow GearLow Gear
    Location Along OutletLeft Side (m/s)Right Side (m/s)Left Side (m/s)Right Side (m/s)
    Top Outlet27.026.527.026.0
    Bottom Outlet12.013.010.512.5
    Average anemometer readings (n=4) for top and bottom outlets, on left and right side, in high and low fan gear. Readings taken 25 cm from edge of outlet and PTO set to 540 rpm.

    Now we can use these two values to determine how much air the sprayer generates by calculating total volumetric flow. We first have to convert air speed from m/s to m/h to make the units work, so just multiply it by 3,600. Then we multiply that by the outlet area and we get the table below.

    Average air speed (m/s) x 3,600 (a constant) = Average air speed (m/h)

    Average air speed (m/h) x Outlet area (m2) = Total volumetric flow (m3/h)

    High GearHigh GearLow GearLow Gear
    Location Along OutletLeft Side (m3/h)Right Side (m3/h)Left Side (m3/h)Right Side (m3/h)
    Top Outlet6,172.06,058.06,172.05,944.0
    Bottom Outlet3,240.03,510.02,835.03,375.0
    Total volumetric flow for top and bottom outlets, on left and right side, in high and low fan gear, with PTO at 540 rpm.

    4. Target volume to displace

    Now that we know the volume of air the sprayer generates, let’s determine the volume of air we need to replace with that spray laden air. This is really the only tricky bit because you have to picture a cross section and then measure the shape. See the illustration below.

    For the bottom outlet, it’s simple. The outlet is 81 cm from the grape panel and the grape panel is 112 cm high. We calculate the area of a rectangle by multiplying length by width, so:

    Length (cm) x Width (cm) = Area (cm2)

    However, the sprayer design makes the top outlet’s job trickier to figure out. This isn’t a rectangle, it’s a “quadrilateral”. We get this odd shape when either the sprayer outlet or the target canopy are significantly taller than the other. Fortunately this one has a right angle so we don’t have to brush off our high school trigonometry textbooks. Instead, we can lean on the internet using this link and plug in the values. As we can see below, the cross sectional areas spanning from the outlets and the middle of the target canopies are 0.9 m2 for the bottom outlet, and 2.35 m2 for the upper outlets.

    This gives us a cross sectional area, but we need to convert that to a volume so we can compare the air generated to the air needed. To do that, we multiply the cross sectional area by 100 m, representing how much air would be needed over 100 m of row length. The formula and the results are presented below.

    Cross sectional area (m2) x 100 m of row length = Target displacement volume (m3)

    OutletTarget Displacement Volume (m3)
    Top Outlet235.0
    Bottom Outlet90.0
    Target displacement volume for each outlet over 100 m of canopy row.

    5. Displacement rate

    We see the target displacement volumes for each outlet are significantly different. Assuming the air from the upper outlet maintains its integrity and reaches its target canopy without being blown off course, it must produce enough air energy to fill more than twice the displacement volume of the lower outlet. We can see from the earlier calculations that it does produce almost twice the total volumetric flow. But is it enough? To know we must calculate the Displacement Rate for each outlet. Let’s just focus on the left side of the sprayer in high gear.

    Total volumetric flow (m3/h) ÷ Target Volume (m3) = Displacement Rate ( displacements/h)

    OutletDisplacement Rate (displacements/h) for left side of sprayer in high gear
    Top Outlet26.25
    Bottom Outlet36.0
    Displacement rates for the outlets on the left side of the sprayer in high gear.

    So we see that the outlets at the top of the sprayer, if stationary, could displace the target volume of air 26.25 times an hour. However, the lower outlet would displace its target volume 36 times in that same hour. We see that we might have a problem. But this is for a stationary sprayer and not a sprayer in motion. The last step gives us what we came here for.

    6. Ideal travel speed

    We can now determine the ideal travel speed for this sprayer using that same 100 m row length.

    [Displacement rate (displacements/h) x 100 m of row length] ÷ 1,000 (a constant) = Ideal travel speed (km/h)

    OutletIdeal travel speed (km/h) based on left side of sprayer
    Top Outlet2.6
    Bottom Outlet3.6
    Ideal travel speed for each outlet on the left side of the sprayer in high gear.

    As we stated at the beginning of this article, this is only a model. It doesn’t account for canopy density and assumes the spray laden volume of air produced by the sprayer can reach the target intact over a given distance. However it does indicate that there is a potential issue that will lead to either over spraying the adjacent row (slower travel speed) or under spraying the distant rows (faster travel speed) which could lead to waste, drift and poor coverage.

    In the image below, we chose to drive close to 2.6 km/h in high gear. No effort was made to adjust the liquid flow (i.e. change the nozzles) so there was too much spray volume here, but we can see the losses on the left (upwind) side, and the blow-through three rows over on the right (downwind) side. Leaving aside the excessive liquid volume, we could drive faster or reduce the fan gear to reduce the blow-through on the adjacent rows, but we may go too fast (or reduce the rate of air displacement) for the upper outlets to reach the target. We can already see the integrity of the upper-left outlet breaking down as it sprays into the wind.

    Testing a travel speed. No effort was made to adjust liquid flow, which is excessive here. Cross wind was from the left to the right in the image. Photo by Corey Parker (Instagram: _parkerproductions)

    Take home

    An ideal travel speed for an airblast sprayer is more than just being productive. The spray must reach and penetrate the target. If this requires dangerously high speeds, or if you simply can’t move slowly enough, it suggests a problem with the spraying strategy. Changes will have to be made to the sprayer, the target canopy, or even the weather conditions you’re willing to spray in. Getting the job done quickly should not compromise the quality of the job. Use this method to re-evaluate your practices, or to assess the capabilities of candidate sprayers if you’re considering a new purchase. Be sure to confirm what this model is telling you using some coverage indicator, such as water sensitive paper.

    Happy spraying.