Category: Mixing

Articles about mixing and pesticide in horizontal boom sprayers

  • 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.

  • Mode of Action and Spray Quality

    Mode of Action and Spray Quality

    The decision on which application method is best for herbicides boils down to two main factors: (a) target type and (b) mode of action. In general, it’s easier for sprays to stick to broadleaf plants on account of their comparatively larger leaf size and better wettability compared to grassy plants. There are exceptions, of course – at the cotyledon stage, broadleaf plants can be very small and a finer spray with tighter droplet spacing may be needed. Water sensitive paper is a very useful tool to make that assessment. Imagine if a tiny cotyledon could fit between deposits – that could be a miss!

    Some weeds are also more difficult to wet, and those may also need a finer spray or a better surfactant for proper leaf contact. An easy test is to apply plain water to the leaf with a spray bottle. If the water beads off or the droplets remain perched on top in discrete spheres, the surface is considered hard to wet. Most grassy weeds are hard to wet, while most broadleaf weeds are easy to wet.

    Grassy weeds are an especially difficult target because they have smaller, more vertically oriented leaves, and almost without exception are more difficult to wet than broadleaf species. All these factors call for finer sprays for effective targeting and spray retention.

    Broadleaf weeds usually have more horizontally oriented leaves which also happen to be larger. As a result, they can intercept larger droplets quite efficiently.

    There are about thirty mode of action (MOA) groups among the herbicides with about ten accounting for the majority in Canadian prairie agriculture. It’s probably an over-simplification to categorize them into just two groups – systemic and contact.  But that grouping goes a long way to making an application decision.

    Contact products (MOA Group 5, 6, 10, 14, 22, 27) must form a deposit that provides good coverage. Good coverage is an ambiguous term that basically means that droplets need to be closely spaced and cover a significant proportion of the surface area because their physiological effects occur under the droplet, and don’t spread far from there. One way to generate more droplets is to reduce droplet diameter, another is to add more water. A reasonable combination of both is ideal because simply making droplets smaller creates issues with evaporation and drift.

    Systemic products (MOA Group 1, 2, 4, 9) will translocate within the plant to their site of action after uptake. As a result, coverage is less important as long as sufficient dose is presented to the plant. In practice, this means coarser sprays and/or less water may be acceptable.

    When two factors are combined, either in a tank mix or a weed spectrum, the more limiting factor rules. Application of a tank mix or product that is active on both broadleaf and grass plants will be governed by the limitation placed on grass targets. A tank mix comprised of both systemic and contact products is governed by the limitations placed on contact products.

    A factor we should also consider is soil activity and the presence of residue. Studies have shown that soil-active products are relatively insensitive to droplet size. But if they have to travel through a layer of trash to get to the soil surface, more application volume is the best tool.

    Below are some recommended spray qualities and water volumes for use in Canada. The spray qualities listed in the table can be matched to a specific nozzle by referring to nozzle manufacturer catalogues, websites, or apps. Note that Wilger also offers traditional VMD measurements on their site, allowing users to be a bit more specific if necessary.

    Click here to download PDF

  • Evaluating Methods for Controlling Algae in Carrier Water Storage Tanks

    Evaluating Methods for Controlling Algae in Carrier Water Storage Tanks

    This work was performed with Mike Cowbrough, OMAFA Field Crop Weed Specialist.

    In the early summer months, many field and specialty crop operations collect rainwater (or possibly pump water from holding ponds) into storage tanks for use as a carrier in spray applications. These tanks may be stationary, or they may be part of a nurse or tender truck that delivers both water and chemistry to the field as a means of improving operational efficiency.

    Poly tanks. Source: Purdue Extension publication PPP-77 “Poly Tanks for Farms and Businesses“.

    In the case of translucent poly tanks, which are commonly used because of their light weight, custom shape, and low price point, light exposure will grow algae. Algal populations multiply exponentially and will clog spray filters and negatively affect filling. In response, growers use home-grown algicides such as copper sulfate, lengths of copper pipe, household bleach, chlorine, bromine, etc. They do so with little or no guidance and therefore little or no consistency. Beyond the obvious questions surrounding efficacy, it is unknown whether these adjuncts create physical or chemical incompatibilities in the tank mix. If so, there is the potential for reduced efficacy and/or crop damage.

    We tested popular methods for algae control by inoculating a series of 10 L translucent plastic jugs with an algal population sourced from a southern Ontario holding pond. The population was left to acclimate and generally establish itself (aka colonize) before we introduced some form of control. Each jug was then gently stirred and emptied through a sieve for qualitative assessment.

    In a parallel experiment, we introduced the same algicides to fill water and conducted spray trials. 10 L volumes were mixed with a field rate of glyphosate and sprayed on RR soybeans. Weed control was assessed and soybean yield measured for each treatment.

    Algicide Efficacy Experiment

    In each treatment, tap water was mixed with a micronutrient growth media (from the Canadian Phycological Culture Centre at the University of Waterloo). This was an unsterilized 10% WC(ed) solution intended to provide micronutrients for algal growth while minimizing fungal and bacterial growth.

    The source algae were collected from the bottom of a holding pond from a farm in Guelph, Ontario. Algae were homogenized and equal parts added to each jug. The jugs were former 10 L pesticide containers thoroughly rinsed and sprayed with Five Star’s “Star San” non-rinse sterilizer. Tank solutions were gently bubbled (one bubble every 10-15 seconds) with air from an aquarium pump. Air was balanced using a manifold and introduced via diffusion stones at the bottom of each jug.

    Algae sourced from a farm’s holding pond near Guelph, Ontario. Algae was homogenized before inoculating treatment jugs with equal parts.

    Treatments

    Each treatment was tap water plus growth media inoculated with algae and exposed to a natural diurnal/nocturnal cycle unless otherwise indicated.

    1. Control (no algicide)
    2. Left in a shaded area (no direct sunlight)
    3. Household bleach (approximately 5.25% sodium hypochlorite)
    4. Container was spray-painted black to exclude light
    5. Ammonia
    6. “Scotch Bright” copper-coated scour pad. (copper is often introduced as copper sulfate at 1 cup / 1,000 US gal. or a short length of copper pipe)
    7. Bromine (sourced from a local pool supply store)
    Treatment NumberTreatment NameRate
    (/US Gal.)    		Rate
    (% v/v)    		Rate
    (/10 L final volume)
    1Control (no algicide)
    2Shaded
    3*Household bleach1/4 tsp0.000333.3 mL
    4Black container
    5*Ammonia solution1/4 tsp0.000333.3 mL
    6Copper-coated scour pad
    7Bromine1/32 ml0.0000040.04 g
    Table 1. * Bleach and ammonia should never be added together as they produce toxic chloramine gas.

    Method

    On July 12, jugs were loaded with water and growth media and inoculated with algae. They were bubbled gently for one week to establish a stable algal colony. On July 19, algicides were added, or transferred to shade or black-out conditions. On August 31 (approximately six weeks later), jug contents were gently stirred and filtered through white cloth for qualitative assessment.

    Building up algal population for each jug. Note air lines through lids for slow, intermittent bubbling. Algae was not moved to black container or to the shade until after the first week of acclimation.
    Almost six weeks after algicide was added, jug contents were gently stirred and poured through white cloth to collect algae and establish how easily the liquid passed through.

    Observations

    The results of all seven treatments, plus photos of the copper-coated scour pad.

    (1) Control. Liquid poured slowly through cloth. Algae was still alive and healthy. It formed some clumps but was not as thick as other treatments.

    (2) Shaded. Liquid poured fast and easily through cloth. Was particulate in texture rather than clumpy or gelatinous. Very little mass and entirely brown, suggesting it was dead.

    (3) Household bleach. Liquid poured easily through cloth until the clump of algae sitting at the bottom of the jug came out (i.e., most algae were not suspended). Thick mat of healthy-looking algae (note profile photo #3 below). Much greener and thicker than the control (1).

    (4) Black container. Liquid poured fast and easily through cloth. Algae retained a little green coloration (more than the shaded condition (2)) but was particulate and not as healthy as the control (1). We intended for this treatment to exclude all light, but it was still able to enter at the bottom where the jug wasn’t completely painted. This may have kept the algae alive.

    In an oversight, the jug was not completely painted. This left a source of light at the bottom edge that may have helped sustain algae.

    (5) Ammonia. Very difficult to pour liquid through the cloth (note profile photo #5 below). The only condition where a mat of algae was floating at the top of the jug rather than settled at the bottom. It was healthy, green and thick.

    (6) Copper. The most gelatinous of all conditions, the liquid took the longest to pass through the cloth filter. While the algae seemed brown and dead, the gel would be very problematic during sprayer filling and spraying. Note that the copper scouring pad (shown unrinsed) has nothing growing on it.

    (7) Bromine. Like the household bleach condition, liquid poured easily until the healthy mat of algae at the bottom of the jug came out (i.e., most algae were not suspended). Note profile photo #7 below.

    Profile shots of treatment 3 (Bleach), 5 (Ammonia), and 7 (Bromine).

    Spray Efficacy Experiment

    Ideally, adjuncts added to carrier water are inert. That means they don’t reduce a herbicide’s effectiveness on susceptible weeds or increase crop injury. For example, hypochlorite (found in bleach and in chlorinated water) reduces the biological effectiveness of low concentrations of isoxaflutole (the active ingredient in herbicides such as Converge and Corvus). However, when added to higher, agriculturally-relevant concentrations, the reduction in efficacy wasn’t considered significant (Lin et al., 2003). Conversely, bromide has been added to certain herbicides to improve performance (Jeschke, 2009).

    There’s precious little information about synergistic or antagonistic effects from adding bleach, ammonia, copper or bromine to herbicide carrier water. To learn more, we added each of these adjuncts to the standard rate of glyphosate (900 gae/ha – 0.67 L/ac). Using a CO2-pressurized plot sprayer, the solution was applied to <10 cm tall weeds at 150 L/ha (15 g/ac) in glyphosate tolerant soybean at the 2nd trifoliate stage of growth (Elora Research Station, Ontario).

    Visual crop injury was evaluated at 7 and 14 days after application. Weed efficacy was evaluated at 14 and 28 days after application. Soybeans yields were collected using a Wintersteiger plot combine and adjusted to a moisture content of 14%.

    Weed Control

    All treatments provided excellent control (>90%) of the weeds emerged at the time of application. Table 2 (below) presents the % visual control 28 days after application.

    Carrier Treatment
    (glyphosate 540 g/L at 900 gae/ha or 0.67 L/ac)    		Lamb’s-quarterGreen pigweedWitch grassGreen foxtail
    1) Control0000
    2) Shaded100100100100
    3) Household bleach100100100100
    3a) Household bleach – added prior to mixing9597100100
    4) Black container100100100100
    5) Ammonia100100100100
    6) Copper-coated scour pad100100100100
    7) Bromine100100100100
    Table 2. Visual control of lamb’s-quarter, green pigweed, witch grass and green pigweed at 28 days after the application of glyphosate 540 g/L at 900 gae/ha mixed with various carrier treatments intended to prevent algae growth. Treatment numbers correspond with the soybean injury and yield image below.

    Soybean Injury and Yield

    There was no noticeable crop injury from any treatment (figure below) and yields were not significantly different from the control treatment (Table 3). However, when bleach was added prior to mixing, we did observe a trend in reduced soybean yield. We’re unable to explain this observation, but suggest it may be an unrelated issue (such as field variability). There were no obvious signs of crop injury, and the treatment provided excellent weed control.

    Photographs of each plot 14 days after application. The number/letter in each inset image corresponds to treatments in Tables 2 and 3.
    Carrier Treatment
    (glyphosate 540 g/L at 900 gae/ha or 0.67 L/ac)    		Crop Injury
    (%)*    		Avg. Yield
    (bu/ac)    		Significance**
    4) Black container040.0A
    7) Bromine039.6A
    2) Shaded038.1AB
    3) Household bleach037.6AB
    1) Control037ABC
    5) Ammonia036.9ABC
    6) Copper-coated scour pad036.1 BC
    3a) Household bleach – added prior to mixing034.0 C
    Table 3. Visual control of lamb’s-quarter, green pigweed, witch grass and green pigweed at 28 days after the application of glyphosate 540 g/L at 900 gae/ha mixed with various carrier treatments to prevent algae growth. *7 days after application. **Duncan’s multiple range test. Soybean yields that don’t share a letter in common are significantly different.

    Discussion

    We elected to use an extreme situation where a single application of algicide was applied to an established, healthy colony. It’s possible that regular applications of algicide in a volume of water with little or no algae could maintain that condition.

    A treatment was considered effective if it slowed or halted algal growth, especially if it also degraded algal populations, causing them to become brown, thin, and/or particulate. Once in the spray tank, the shear forces created by circulation should disperse any dead or degraded algal masses, making it easier to pass them through filters and nozzles.

    The shade treatment appeared to kill algae as well as cause degradation. Second place went to the black-out treatment, where some light was unfortunately allowed in. This would have continued to fuel photosynthesis in the unpainted portion at the bottom of the jug. Conversely, the black exterior likely raised temperatures above >20 °C, which depresses most algal growth and may have contributed to the degradation.

    Copper appeared to kill the algae but also created a gel that would pose problems to filters. Unlikely to be bacterial, as copper is known to suppress bacterial growth, it could have been caused by diatoms; certain invasive species are known to form brown jelly-like material endearingly referred to as “brown snot” or “rock snot”. Alternately, and according to work by J. Rodrigues and R. Lagoa, alginate polysaccharide can form viscous aqueous dispersions (such as gels) in the presence of divalent cations (such as copper).

    No treatment appeared to reduce herbicide efficacy or affect crop health. However, unexpectedly, the household bleach added prior to mixing may have reduced soybean yield. Given the limited number of replications and the single plot location, we suspect this was a field effect, unrelated to the treatment.

    Take Home

    Based on these results, a combination of shade and light-excluding materials (e.g. black paint) would be the ideal approach to algae control. It’s cheap, effective, and doesn’t require periodic management. Buying black tanks is a good choice, or you can paint them. What you should paint them with is a matter of debate and there’s a very good Twitter thread on the subject if you’re interested.

    An Aside: Algae in Ponds and Dugouts

    We didn’t test this, but the question has come up and the best we can do is share some long-standing farmer wisdom. Some have used Aquashade dye to absorb the photosynthetic wavelengths and reduce algae buildup. Reputedly it is moderately successful. Another option is adding aluminum sulfate to the pond, and with a lot of agitation it should clarify in about 48 hours. Still others have added a few square barley straw bales to the water and found it to work surprisingly well (possibly an allelopathic response). Tie a rope to them and float them in the pond.

    Citations

    Jeschke, Peter. 2009. The unique role of halogen substituents in the design of modern agrochemicals. Pest Manag Sci, 2010; 66: 10–27

    Lin, C.H., Lerch, R.N., Garrett, H.E. and M.F. George. 2003. Degradation of Isoxaflutole (Balance) Herbicide by Hypochlorite in Tap Water. J. Agric. Food Chem. 2003, 51, 8011-8014