Category: Spray Basics

  • Fungicides and Integrated Pest Management – An Apple Scab Case Study

    Fungicides and Integrated Pest Management – An Apple Scab Case Study

    Editor’s note: This article originally appeared in the Winter, 2025 ONCore newsletter (Volume 29, Issue 1). We thought it was an excellent description of the integrated pest management process and where fungicide spraying fits in. It’s been modified from the original version.

    Part One: Know Your Enemy

    There is no denying that product efficacy and rotational partners are critical components of effective pest management. A pest is causing damage; we need as many tools as possible to control it. Let’s consider the basics of Integrated Pest Management (IPM). The first step in effective management is understanding the pest biology.

    Figure 1. Foundations of integrated pest management

    Let’s use apple scab as a case study for the IPM process. We’ll start with a deep dive into apple scab 101 by referring to its typical life cycle. Apple scab overwinters in infected leaves on the orchard floor. During the winter and early spring, immature ascospores (primary inoculum) are protected in specialized spore sacs, called pseudothecia.

    Figure 2. Life cycle of apple scab (Image: Cornell University)

    Maturation of ascospores in the leaf litter on the orchard floor usually occurs at the same time the trees are emerging from dormancy. This means mature ascospores are present and ready to infect the first green tissue in spring. However, the percentage of mature ascospores in the orchard generally peaks when apples are at the late pink to petal fall stages of bud development.

    Once the tree breaks dormancy and green tissue is present, a primary infection occurs if the following three conditions are met:

    1. Mature ascospores are present in leaf litter in the orchard.
    2. Weather conditions favour ascospore discharge and infection.
    3. Fungicide protection is inadequate to prevent infections.

    Mature ascospores are discharged from the pseudothecia by rain and splashed up to emerging green tissue by wind. Moisture – dew or rain – is necessary for ascospore discharge and germination, as well as subsequent infection of apple tissue. Olive green, velvety lesions appear 10-28 days after infection by an ascospore, depending on temperature. The lesions initiated by ascospores result in primary infections, and in turn, produce spores called conidia.

    Conidia are spread from primary lesions by rain or wind and initiate further infections when the combination of temperature and leaf wetness enables them to germinate and become established. These are called secondary infections, and generally occur within a tree or between adjacent trees rather than at a long distance.

    The secondary cycle can be repeated many times during the growing season, whereas primary infection only continues until all overwintering spores are depleted. With frequent rainfall, the control of apple scab becomes extremely difficult as the season progresses, particularly if the disease becomes established from primary infections in the spring.

    Early season management (green tip to tight cluster) provides the greatest economic protection against loss from scab control failure. In other words, don’t wait to get fungicide protection on!

    Figure 3. Risk of primary apple scab infection and the probability of economic loss from scab control failure. (Image: Cornell University)

    Part Two: When To Strike

    Just like how understanding the biology of the pest helps to determine appropriate intervention timings, understanding how fungicides work will help determine when best to apply them and ensure maximum efficacy (aka the most bang for your buck).

    Fungicides can be divided into four categories, based on what they do:

    1. Preventative
    2. Curative
    3. Eradicant
    4. Antisporulant

    Preventative

    • Before the plant is even infected
    • Before we can see any symptoms
    • Most fungicides work preventatively
    • If fungicides work in multiple ways, often they work best preventatively

    Curative

    • Stops the mycelial growth inside the plant
    • Still can’t see any symptoms
    • Fungicides with “kickback”

    Eradicant

    • Stops the pathogen during lesion formation
    • Ok, now we can see symptoms
    • Very few fungicides work this way, even though this is how we expect them to work

    Antisporulant

    • Stops the pathogen from sporulating
    • We can see symptoms
    • Several fungicides work this way, but your crop is already infected

    In addition to the timing of a fungicide, efficacy can be affected by residues (or lack of), rains and risky gaps. A general rule of thumb often used is that 1 inch (2.5 cm) of rain removes approximately 50% of protectant fungicide residue and over 2 inches (5 cm) of rain will remove most of the residue. While systemic fungicides tend to perform better than protectant (or contact) fungicides in rainy periods, they do still require a certain amount of time prior to a rain event to be taken into the leaves – which isn’t always as easy as it sounds (see Part three).

    During conditions conducive to disease development, it is important to maintain tight intervals between fungicide applications. Most labels will have the minimum interval listed. For protectant fungicides, a tight interval program would be 5-7 days. Where possible, do not extend intervals beyond 14-21 days if there are any concerns of disease. As a fungicide application ages, the efficacy of that product is reduced.

    Spray coverage can be affected by wind in several ways:

    • Wind direction – can carry droplets away from intended target
    • Wind speed – affects how far the droplets travel
    • Consistency – wind gusts can make coverage inconsistent

    In addition to wind, spray coverage can also be affected by water volume, nozzle orientation, sprayer calibration, alternate row spraying, etc .

    Areas of the canopy that are often missed due to poor coverage are within the tree due to spray not reaching through or at the top of larger trees . Routine monitoring can miss early signs of scab infection in these parts of the tree if not done thoroughly. I saw numerous situations this year (2025) where scab lesions were overlooked.

    Part Three: Fungicide Playbook

    Let’s take a closer look at some common scab fungicides and what is meant by contact and systemic activity and how they might redistribute after application. The rest of this article refers to pesticide brands available in Canada. They may have different names in other countries.

    Figure 4. Movement of fungicide in plant: (A) contact or protectant; (B) xylem-mobile or acropetal; (C) translaminar; (D) phloem-mobile. (Adapted from K. Goldenhar, BCMAF)

    Contact (Protectant) Fungicides

    These products remain on the surface of the plant tissue and provide preventative activity only. Examples of contact fungicides include fluazinam (Allegro, Vantana), coppers, sulphurs, mancozeb (Manzate, Penncozeb, Dithane), captan (Maestro, Supra Captan) and folpet (Folpan, Follow).

    Unfortunately, because these products provide superficial coverage only, they can be prone to UV degradation or run-off and need frequent applications. Stickers/spreaders can help these stay on the plant but always refer to the label before using.

    Systemic Fungicides

    Systemic fungicides get taken up into the plant. Unlike contact fungicides, systemic fungicides tend to have longer duration and are rainfast once absorbed. However, sufficient tissue is needed for absorption so these products are best used after tight cluster in apples. How systemic fungicides move within the plant can vary:

    Xylem-Mobile

    Xylem-mobile, or acropetal fungicides move to the actively growing tips of expanding foliage and protect new growth. Examples of xylem-mobile fungicides include most Group 3 and 11s, as well as some Group 7s (e.g., fluopyram).

    Translaminar

    Translaminar fungicides move from the top of the leaf to the underside. Because of this limited movement, coverage matters. Examples of translaminar fungicides include most Group 7s as well as Cevya and Inspire Super.

    Phloem-Mobile

    Phloem-mobile, or “true” systemic fungicides move into the tissue and are carried to the roots to protect against root rots. There are no examples of phloem-mobile fungicides for apple scab. However, this group includes products such as Aliette and Phostrol which are registered for other diseases of apples. Unlike other systemic fungicides, this group has a short duration of activity (i.e., they move fast).

    Resistance Management

    Fungicides are grouped based on their mode of action, or how the product affects the disease. For example, all products in Group 3 have the same mode of action, so using one product is virtually the same as using all other products within that group. In pre-mix fungicides, both groups need to be considered in all rotation decisions.

    Figure 5. Systemic fungicides registered for apple scab in FRAC Groups 3, 7, 9 and 11

    One key strategy to good resistance management is rotating between products of different chemical groups. Figure 5 shows which fungicides belong to Groups 3, 7, 9 and 11. For instance, since Aprovia Top belongs to Group 3 and 7, it should not be followed by other Group 3 (Cevya, Fullback, Nova), Group 3+9 (Inspire Super), Group 7 (Excalia, Fontelis, Kenja, Sercadis), Group 7+9 (Luna Tranquility) or Group 7+11 (Merivon, Pristine).

    For resistance management:

    • Where possible, include at least half rate protectant fungicide.
    • Do not use products containing the same chemical group in consecutive applications.
    • Limit number of applications per group per season, where possible.
    • Apply preventatively; do not rely on systemic fungicides for post-infection activity
    • Do not use Group 3 (Nova, Fullback, Inspire Super) or Group 11 (Flint, Pristine, Merivon) fungicides after bloom for scab management as they are weak on fruit scab. Trials with Cevya have indicated good efficacy on fruit scab.
    • Research from northeastern US indicates Group 7 fungicides may be weaker on fruit scab as well.

    Part Four: Final Considerations

    In conclusion, take some time to consider the following:

    • Early intervention remains the cornerstone of effective disease management!
    • Use weather monitoring tools to time fungicide applications
    • Adjust spray schedules and product choice according to the weather
    • Dedicate time for regular orchard inspections
    • Train your team to identify symptoms early, accurately and consistently
    • Optimize your spray program
    • Protectant AND systemic fungicides
    • Rotate classes to prevent resistance
    • Select for broad-spectrum efficacy
    • Reduce overwintering inoculum


    The author gratefully acknowledges Katie Goldenhar, OMAFA Pathologist (Horticulture) for providing source material for this article.

  • Alternate Row Spraying

    Alternate Row Spraying

    Alternate Row (aka Alternate Row Middle [ARM]) spraying is an application method where the air-assist sprayer does not pass down every alley during an application. The sprayer operator is relying on the spray to pass through one or more rows and provide acceptable coverage to the entire canopy (or canopies) on a single pass.

    Some state agencies promote this spraying strategy to various degrees, and many sprayer operators (whether they admit it or not) have used this method of spraying. I have advised it myself for very young and/or very sparse vineyard and orchard plantings, but never without confirming coverage. When I tell operators that I have serious reservations about alternate row spraying, they defend it. Here are the most common justifications I’ve heard over the years, and my response:

    JustificationReply
    “I do not have enough spray capacity to spray every row when time is short.”You need more sprayer capacity. Get another sprayer so you can get spray on in time or invest in a multi-row sprayer is possible.
    “ARM spraying saves money and reduces environmental impact because I use less pesticide.”Technically, if you travel every second row with a sprayer calibrated to travel every row, you have indiscriminately reduced your carrier and chemical inputs by half (or more). Without close monitoring you may compromise your efficacy.
    “I only perform ARM spraying early in the season when canopies are empty, or only on young plantings.”I grudgingly grant this one as long as coverage is closely monitored. I’ve prescribed it myself in young or sparse plantings where I couldn’t get the sprayer output low enough to prevent drenching the targets.
    “The spray plume in the alley beyond the target row must mean the spray is providing adequate coverage. More is better!”If the spray is blowing through the canopy, it isn’t landing in the canopy. Further, if the air speed/volume is too high, droplets can ‘slipstream’ past the target without impinging on them. I’ve removed water-sensitive paper from canopies with barely any spray on them despite the plume in the downwind alleys. It looks like a magic trick, albeit an unhappy one.
    “Uncooperative weather doesn’t always leave me enough time to spray the entire crop, and it is the lesser of two evils to spray alternate rows than not at all. I’ll make sure I come back to spray the other rows later.”Choosing to do half a job requires an understanding of the products’ mode of action. If you are spraying an insect at a particular stage of development, there’s no “coming back later” to get that generation – if you missed, your window has closed. If it’s a protective fungicide that offers no kick-back, then once the disease has infected tissue, the damage is done. Get the spray on as best you can, but if it washes away before it has a chance to dry sufficiently, be prepared to reapply at the earliest opportunity as long as the label allows it.
    “ARM has always worked in the past.”Would you mind picking my lotto numbers for me? You’re a very lucky person!

    My reservations about ARM spraying come from published research and personal experience that show that coverage is almost always compromised when spraying from one side of a canopy. The spray must pass through the canopy to reach the far side, and the canopy filters droplets from the air as it passes through. This reduces the number of droplets available to cover the far side. In addition, high velocity spray will create “shadows” where any targets on the immediate far side of a leaf or branch become shielded and receive little if any coverage. Further still, fine droplets slow quickly as they leave the nozzle and take a long time to settle. As the entraining air slows and becomes erratic, the droplets float and change course, making their behaviour hard to predict.

    The cumulative impact can be seen in this infographic I built in 2016. The orchardist was a dyed-in-the-wool ARM applicator and he was resistant to driving every row because it took so much time. I wanted to show that he could claw back some of the lost time by spraying less pesticide every row versus his current volume every second row. He would need fewer refills, and save a LOT of unnecessary pesticide. The water sensitive paper does the talking, and while I’d like to think I’ve convinced him, I’ll bet he’s still out there dicing with fate.

    2016_ARM

    A very popular argument in favour of ARM spraying comes from orchardists that are shifting from semi dwarf to high-density plantings. They ask “How it is different to spray a four foot diameter tree from one side compared to an eight foot diameter tree from both sides”? 

    Well, we know coverage is reduced as a factor of distance. Spraying from one side gives a single opportunity to cover the middle and far side of a canopy, whereas spraying from both sides provides an opportunity for an overlap in coverage. Essentially, the centre of a canopy receives the cumulative benefit of two sprays. Coverage is therefore always improved when spraying from both sides, period.

    Spraying from one side gives a single opportunity to cover the far side of a canopy. However, spraying from both sides provides an opportunity for an overlap in coverage. In other words, the centre of a canopy receives less spray than the outside, but is essentially sprayed twice resulting in a compounding effect.
    Spraying from one side gives a single opportunity to cover the far side of a canopy. However, spraying from both sides provides an opportunity for an overlap in coverage. In other words, the centre of a canopy receives less spray than the outside, but is essentially sprayed twice resulting in a compounding effect.

    Why, then, do some sprayer operators claim that alternate row applications work? Because sometimes, they do! Just because coverage is reduced doesn’t mean it isn’t sufficient to protect the crop. It simply means that the potential for poor coverage and reduced dose is dramatically increased by alternate row applications. A sprayer operator might perform alternate applications successfully for years before conditions conspire to defeat the application: unfavourable wind, poor timing, increased pest pressure, poor pruning practices, excessive ground speed, high temperatures, low humidity, insufficient spray volume, and several other factors might occur simultaneously and reduce coverage below a minimal threshold for control. This confluence of bad luck may not happen the first year, or the second, but eventually…

    Product failure isn’t the only concern. Repeated reduced dosages may play a role in developing resistance. In those situations where the operator recognizes insufficient coverage, they may have to spray more often to compensate, negating any savings in time or product. Reduced dosage is a common error when a sprayer operator elects to use ARM.

    If you still aren’t convinced, at least perform alternate row spraying the “right” way. Here are three situations that I’ve heard operators refer to as alternate row spraying. Situation 1 is most common, but to my mind only Situation 2 would be considered acceptable. Even then, confirming coverage is a must.

    Situation 1:

    The sprayer has a typical calibration for spraying every row, but only drives alternate rows. The first application (solid line) covers different rows from the second application (broken line). The operator will claim to spray more frequently, but generally does not perform the second application unless there is high pest pressure. The result is half-a-dose per hectare per application.

    The sprayer has a typical calibration for spraying every row, but only drives alternate rows. The first application (solid line) covers different rows from the second application (broken line). The operator will claim to spray more frequently, but generally does not perform the second application unless there is high pest pressure. The result is half-a-dose per hectare per application.
    The sprayer has a typical calibration for spraying every row, but only drives alternate rows. The first application (solid line) covers different rows from the second application (broken line). The operator will claim to spray more frequently, but generally does not perform the second application unless there is high pest pressure. The result is half-a-dose per hectare per application.

    Situation 2:

    The sprayer is calibrated for double output compared to a typical every-row situation, and the operator drives alternate rows. The result is that the hectare gets the whole dose per application, but coverage is always inconsistent.

    The sprayer is calibrated for double output compared to a typical every-row situation, and the operator drives alternate rows. The result is that the hectare gets the whole dose per application, but coverage is always inconsistent.
    The sprayer is calibrated for double output compared to a typical every-row situation, and the operator drives alternate rows. The result is that the hectare gets the whole dose per application, but coverage is always inconsistent.

    Situation 3:

    Since the sprayer will only drive alternate rows, the operator mistakenly sets the sprayer to emit half the output compared to a typical every-row situation. The first application (solid line) covers different rows from the second application (broken line). The result is a quarter-dose per application, and if the operator chooses to spray a second time, the hectare will only ever get half-a-dose. Yes, this happens.

    The sprayer has a typical calibration for spraying every row, but only drives alternate rows. The first application (solid line) covers different rows from the second application (broken line). The operator will claim to spray more frequently, but generally does not perform the second application unless there is high pest pressure. The result is half-a-dose per hectare per application.
    The sprayer has a typical calibration for spraying every row, but only drives alternate rows. The first application (solid line) covers different rows from the second application (broken line). The operator will claim to spray more frequently, but generally does not perform the second application unless there is high pest pressure. The result is half-a-dose per hectare per application.

    So, my final word on alternate row applications is that they should be performed with extreme caution. I’ve used them myself in early season applications in new plantings, but never without confirming coverage with water-sensitive paper, and never in conditions that might further compromise coverage to the point that the application does not give control.

    Caveat Emptor!

    Well, I thought it was funny. My apologies to J. Luymes from British Columbia (pictured) and Obi Wan Kenobi (not pictured… or is he?)
    Well, I thought it was funny. My apologies to J. Luymes from British Columbia (pictured) and Obi Wan Kenobi (not pictured… or is he?)
  • Airblast Spraying in Poor Conditions

    Airblast Spraying in Poor Conditions

    Some springs are tougher than others. This article was originally written in 2019, which was particularly challenging. The frequency and duration of rain events left limited opportunity for orchard sprays. Even then, the periods between rains were transitions between warm and moist conditions and cold fronts, which makes wind gusty and changeable. These same periods leave wet alleys prone to rutting and compaction, and conditions that favour spraying may also favour pollinator activity.

    In response, applicators get frustrated. Some may be tempted to spray in sub-optimal conditions and risk drift thinking even a little coverage is better than none. But the adage that “there is no wasted fungicide spray” does not apply here. Some may disagree, but spraying in wet and high-wind situations:

    • greatly reduces coverage and subsequently, crop protection.
    • may result in repeated sub-lethal doses that can encourage resistance.
    • greatly increases the degree of surface run-off and off-target drift, risking environmental, commercial and residential
      contamination.

    The argument itself may be moot because the decision to spray is not strictly a consideration of economics, productivity, and risk tolerance. When environmental restrictions exist on a pesticide label they are inviolate. That is, they are not suggestions but legal requirements. Statements might include:

    • Not spraying when rain is forecast within 12 hours following application. This is, in part, to prevent water-soluble products from moving in surface or channel run-off.
    • Not spraying in calm conditions (generally <3 km/h, as measured at the top or outside of the orchard). This is to prevent airborne spray from moving in unpredictable directions during a thermal inversion, or downhill with stratified air.
    • Not spraying in gusting or windy conditions (generally >10 km/h, but there is no Canadian standard). This is to prevent airborne spray from moving with the wind. This is of particular import when there are sensitive downwind areas that can bring buffer zones into play

    Technologies exist that extend the spray window, but they require long-term planning and may not be economical (or even completely proven). They are generally a combination of orchard architecture and sprayer design. Examples include:

    • Tented orchards (more common in Australia) designed to exclude pests and insulate against hail, wind and inversions.
    • Shrouded vertical booms (e.g. Lipco) designed for trellised orchards.
    • Solid-set emitters (more common in Europe and still experimental in parts of the northern US) that reduce drift and can spray large areas quickly.
    • Vertical towers with downward-oriented fans (e.g. Curtec Proptec or Sardi sprayers) that rely on the orchard itself to filter
      lateral/downward-directed spray.

    Assuming the pesticide label does not prohibit application, there are adjustments that can improve coverage and reduce drift in sub-optimal conditions, but only marginally. These are compromises that sacrifice time, money, effort and/or the level of crop protection. Further, they are only intended for sprayers with towers (i.e. not low-profile axial sprayers):

    • Convert to air induction nozzles (at least in the top two nozzle positions, and likely at one rate higher than you usually use).
    • Be certain to turn off any nozzles spraying excessively over the top of the canopy. A little can’t be helped and is actually a best practice to ensure spray reaches the treetop. Be reasonable.
    • Reduce fan speed to only reach just past the middle of the canopy on the upwind side.
    • Turn off the boom on the downwind side of the sprayer and adjust airspeed and nozzle rates for upwind alternate row spraying only. Especially on the last three downwind rows, which you may have to leave unsprayed entirely.

    The best advice is unpopular: Park the sprayer until conditions improve. Like hail, there are environmental factors that are out of the farmer’s control. They are inconvenient and highly frustrating, but do not be tempted to takes risks on what might ultimately result in poor coverage and accusations of pesticide drift.

  • Sprayer Cleanout and Cleaner Selection

    Sprayer Cleanout and Cleaner Selection

    Editor’s Note: Changes have been made to this article since its original publication in 2015.

    When in-crop spraying is around the corner, sprayer tank clean out is an important topic to address on your farm. Many farms have done the same clean-out routine for years and not had any issues with contaminating residues in the tank resulting in crop damage. Although the old saying “If it ain’t broke, don’t fix it” definitely has some merit, in this case it is good to question whether your cleanout routine is adequate. When you consider the way chemicals have changed over the years, especially the higher reliance on oily surfactants in modern chemicals, it makes sense why we need to pay attention to spray tank cleanout.

    The goal of cleaning the tank is to remove and dilute the previous chemical formulation as much as possible to prevent buildup and carryover of residues which can cause crop damage on non-target crops.

    Safety First

    Always wear safety gear before working around chemicals. Although it can be a hassle, we all know that it is no fun spilling chemical on your clothes and skin. What’s even worse is smelling it all day in the sprayer cab. I use a long waterproof coat, a plastic face shield to prevent back splash when spiking jugs, and of course rubber gloves (No judgment on me looking like a total dork please:).

    Safety First - Are you looking at my headgear? Are you!?
    Safety First – Are you looking at my headgear? Are you!?

    1 – Get the Previous Product Out of the Tank ASAP

    In my experiences spraying, I have always tried to get the previous product out of the tank as soon as possible. Spraying the extra product out of the tank is the safest and most environmentally responsible way to rid your tank of left over product. Dr. Tom Wolf of AgriMetrix Research and Training, states that spraying a crop twice is usually safe, as all herbicides must be registered to be sprayed at twice the rate in order to be registered by the Pest Management Regulatory Agency (PMRA). If one lets the product sit in the tank overnight before beginning the cleanout, there is more time for product to congeal and adhere to the tank and plumbing components.

    Ball valve on main filters.
    Ball valve on main filters.

    I open the valve ends on my filters to empty the buildup in the bottom of the filter canister. There is often chemical residue or green slime from dug-out water in here. Next I like to go along my booms and empty out all the chemical product within the boom plumbing. Our farm runs a Patriot 4420 sprayer, with valves on each boom section to empty out product. Usually I will go to the sprayer and tip the boom ends up so that gravity allows all of the product to drain out. Then I raise the centre rack, and tip end of booms down to force the product to drain out the other way. You would be amazed at how much product comes out by doing this both directions!

    Valves on each nozzle.
    Valves on each nozzle.
    Tipping the boom ends up with the centre rack down.
    Tipping the boom ends up with the centre rack down.

    While the tank is empty and no pump is running, I will remove all the filters on the sprayer, and grab the handy dandy toothbrush – this is the most valuable tool in filter cleanout! This brush is just small enough to get it in the centre of the filter and scrub all of the residue and gunk out of the filters. A pail filled with rinsing solution is an easy way to clean filters and nozzles.

    Possibly the most important cleaning tool. Don't put it back in the bathroom afterwards.
    Possibly the most important cleaning tool. Don’t put it back in the bathroom afterwards.

    2 – Begin Rinsing Process

    I used to always put about 1,000 gallons of water to our 1,200 gallon tank, thinking that a larger volume would clean all areas of the tank better, but I’ve since changed my thinking. Research has shown that two or three smaller rinses *aka triple rinsing) is more effective for rinsing the tank than one large volume rinse. I always crank the agitation up to high and allow the cleaning solution to agitate for as long as possible.

    Nowadays I try to do three 400 gallon rinses.

    1st RinseCleaning product plus 400 gallons water
    2nd RinseCleaning product plus 400 gallons water
    3rd Rinse400 gallons of just water to rinse, and run through plumbing system to check nozzles and for leaks

    Many labels Recommend leaving the rinsing solution in the tank and lines overnight. This will allow more chemical deposits to loosen up. If an operator is forced to speed up the tank cleaning process due to limited time, they must understand that there are risks involved in doing a less thorough tank cleaning.

    Cleaning Products

    Detergent or ammonia? Check the label. If the label doesn’t specify, you can consult this table from Winfield United.

    Detergent CleanerAmmonia
    Solution contains an adjuvantSulfonylureas (SU’s)
    Solution contains a milky looking component (an Emulsion or EC)Thiencarbazone – methyl
    GlufonsinateFlucarbazone
    Imi’s (Group 2)Dicamba
    Simplicity

    Detergent (e.g. All Clear)

    This detergent cleaner is specifically designed to remove pesticide deposits and other debris, including oily substances from booms, filters, and nozzles. Use All Clear (or other detergent cleaner) if the solution is milky-looking (called an emulsion), which means it is oil-based.

    • Label rate is 0.25 L of All Clear/100 L of water.
    • If you are adding 400 gal of water, you will only need 3.78 L of cleaning product.
    • Decontamination rate is double this: 7.57 L of cleaning product. Use this rate if you have had residue issues, or to do a more thorough cleaning.

    pH Increaser (aka Ammonia; e.g. Flush)

    This is an ammonia based cleaning solution. This product is used to raise the pH to increase solubility of most Group 2 products (from FMC, Bayer, and Corteva but not BASF). Flush contains 7% ammonia. Use Flush (or other ammonia based cleaner) for most cleaning, but especially for Group 2 products listed above, such as Varro, and Velocity M3, Express, Refine, Muster, and Spectrum.

    • Label Rate is 0.50 L of Flush/100 L of water.
    • If you are adding 400 gal of water, you will need exactly 7.57 L of cleaning solution.
    A pail and detergent are "must-haves" during sprayer cleanup.
    A pail and detergent are “must-haves” during sprayer cleanup.

    Combo Products

    Alternately, some solutions raise pH without ammonia. FS Rinseout is sodium hydroxide based, not ammonia based. It is a high alkaline solution that elevates and holds the pH combined with strong surfactants to help clean the tank. Another is CleanOut, which uses potassium hydroxide and disodium metasilicate, a detergent. In both cases they are both pH increases and detergents.

    3 – Draining the Rinse Solution

    After I have ensured all nozzles are working correctly, and there are no leaks in the system, I drain out all of the rinse water, fold in the booms, and get ready to fill the tank with chemical solution for spraying!

    More Information

    Learn where residue can hide. This video was filmed for the Environmental Farm Plan with the nice people at Clean Field Services in Drayton, Ontario. Hardly the height of our acting careers, but good messaging nonetheless.

  • Airblast Spring Start-up and Winterizing

    Airblast Spring Start-up and Winterizing

    Any description of airblast sprayer start-up must, contextually, make assumptions on how it was winterized for long-term storage. This cyclic relationship is why I use a chicken-and-egg title slide when giving this presentation.

    Answer: It was the rooster.

    The inability to describe one process without the other is further complicated by the possibility that the sprayer is brand new and was therefore never winterized. So, what follows is an attempt at a logical sequence of pre-season maintenance activities to restore a winterized sprayer, or initiate a new sprayer.

    New Equipment

    If this is a new sprayer, you have an opportunity to perform some preventative maintenance.

    Loosen, lubricate and re-tighten clamps. Always back gears off before tightening to avoid stretching them. (Image from Purdue Extension publication PPP-121: Preparing Spray Equipment for Winter Storage and Spring Startup)
    Use double clamps on pressurized lines for added safety. Wider clamps are better and T-bolt clamps are better than worm-gear.
    Put thread release on bolts and re-tighten with a torque wrench (not an impact tool). Use a paint pen to mark nut, washer and bolt for future visual checks. This is called a “Witness Mark”.
    Protect hoses and wires at rub points. Follow hoses and with a paint pen, number the hose-ends and connections for future reference.
    Using a new tractor? You may have to re-calibrate to account for different gear ratios. When hitching a new sprayer, note that the distance from the ball on the drawbar hitch to the tip of the PTO should be ~14″. Don’t exceed maximum working angles for PTO shafts (usually <25 degrees). If your tractor or implement manufacturer says differently, go with that. And get it in writing.

    Winterizing (Long-term storage)

    If you are preparing the sprayer for long-term storage, follow the normal rinsing process, but don’t reinstall strainers and nozzles.

    Look in the nozzle bodies for debris. Discard worn or broken nozzles.
    Soak, scrub, rinse and store nozzles and nozzle strainers. You may replace them once the sprayer is clean, but I prefer to store them separately since they have to come back off during start-up.

    With the agitation on, circulate undiluted plumbing antifreeze (the sprayer already has 5-10 L (1.25-2.5 gallons) of water in the system from the decontamination process) for five minutes and drain it through the plumbing system (not the booms).

    Disconnect hoses where they attach to the booms and drain as much liquid from the sprayer as possible. (Image from Munckhof Sprayers). Take the time to examine any hose fittings.
    Clean the sprayer (Triple rinse with a detergent) and scrub the exterior. Do not use pressure washers on bearings, fittings, pumps or any lubricated or moving parts.
    Examine fan blades for cracks, build-up or nicks that can cause imbalance. Replace (not just repair) punctured entrance grills.
    Don’t ignore tank damage. Poly tanks are prone to sun damage and cracks. Never climb into a tank to repair it. Quite often, replacement is the best option.
    Clean and inspect wheel assemblies. It’s best to do this during winterization to prevent bearing corrosion as the sprayer sits all winter.
    Remove any rust and repaint (or just touch up). Paint not only looks good, it protects.
    The excellent YouTube channel Ask Tractor Mike proposed storing the PTO shaft indoors in two pieces, and to cut away a portion of the interior guard to facilitate reassembly later on. Also, use a paint pen to mark the splines on the shaft for easier hook-up (see inset top-right of image).
    RV antifreeze is a 50% solution of antifreeze and water with a rust inhibitor. It should not cause phytotoxicity if sprayed or dumped, but be sure to dispose of it away from water sources during start-up. Turn the pump manually to get antifreeze throughout the system. Close the nozzle bodies, loosely fit the tank lid and store indoors. (Image from Purdue Extension publication PPP-121: Preparing Spray Equipment for Winter Storage and Spring Startup).

    Spring Start-up

    Most operators are guilty of neglecting their airblast sprayers and babying their tractors. Sprayers are precision tools that must be kept in good operating order to prevent costly breakdowns, improve their performance, and increase their lifespan.

    Your car is serviced based on distance travelled. Your sprayer should receive regular maintenance based on working hours, per the manufacturer’s recommendations. Daily sprayer inspections are part of regular maintenance since the operator will (hopefully) find small problems before they become big problems.

    Never assume your sprayers is ready to go right out of long-term storage. Parts seize, scale breaks away from surfaces, and small beasties sometimes choose to eat, or make their homes in, cozy sprayers.

    When planning spring start-up, never assume the winterized sprayer is ready for immediate hook-up. Expect a minimum half day per sprayer.
    Attempting to loosen or shift something that hasn’t moved in several months is risky. Pressure gauges snap off, fittings crack, welds break. Expect the unexpected and either have spare parts on hand, or a plan to get them quickly.
    Parts are most likely to seize during the first spray. Bearings and PTO universal joints, especially.
    Start-up is a good time to lubricate parts. Grease the guard ring bearing every 100 hours, the universal joint cross every 25 hours and the shaft and shear bolt regularly.
    Insects, birds and rodents eat, or make homes in, sprayers. Professional rodent bait/traps, steel wool and peppermint oil/gel are possible solutions.
    Check belt tension, alignment and wear. (Image from Purdue Extension publication PPP-121: Preparing Spray Equipment for Winter Storage and Spring Startup).

    Pump specific maintenance is beyond the scope of this article. Hypro recommends changing oil after 40 hours of break-in operation and every 500 hours after that. The diaphragms should be replaced every 1,000 hours. Generally speaking, EPDM (black) diaphragms are a better choice for airblast sprayers, while the Desmopan (amber) diaphragms are really for lawn care sprayers.

    Pump maintenance is beyond this article, but change the oil every 500 hr or 3 months. Use a paint pen to write on the pump what type of oil it requires, and then date the filters. Note the “winterized” sticker.

    At minimum, check the tire pressure. Hard tires drive faster, but leave compacted ruts. Soft tires drive slower, but disperse weight better. Airblast sprayer wheel assemblies should be cleaned and inspected as part of regular annual maintenance. Wheel bearing maintenance before long-term storage may prevent water from corroding the bearings.

    Ensure tire pressure matches the ideal stamped on the tire. Or, if using less pressure to avoid spring soil compaction, ensure both tires have the same pressure.

    The relief valve on your sprayer should always be in the bypass position during start-up. If your gauge spikes then the gauge may always read high afterwards and should be replaced.

    A reminder to always set the relief valve to the bypass position when starting up the sprayer. This is one reason why pressure gauges spike and can eventually fail.

    Replacing leaking, opaque or inaccurate gauges improves sprayer performance. Be sure to use the oil-filled variety of gauge to eliminate a bouncing needle. You can also get suppressors that fit between the gauge and sprayer to prevent pulsing. Consult the article on testing airblast pressure gauge reliability.

    Use a wrench to turn gauges at the nut. Don’t twist them by hand holding the face. Ensure they are not opaque, leaking, plugged or resting above the zero pin.

    Many spray materials do not mix well and one of the common causes of uneven application is poor agitation. If you find deposits at the sump in the bottom of the sprayer after an application, your agitation is insufficient. For mechanical agitators, check for propeller wear and ensure paddles are secure on the agitator shaft. Learn more about agitation here.

    If the agitator shaft is leaking a little, tighten the packing. The packing gland is a common source of leaks. Keep it properly greased. If a leak occurs you can usually repair it by tightening the bolts on the packing gland by ½ a turn, but if that doesn’t work you may have to remove and repack (or replace) it.

    On sprayers with mechanical agitators, look for prop wear and loose or damaged paddles. Fill the sprayer with water and looks for tank leaks. Tighten the bolts 1/2 turn if the packing gland on the agitator shaft is leaking. You may have to remove and repack the gland if the leak persists.
    Look for signs of hose wear and examine the sprayer for leaks while under pressure. Be careful when pressurizing the sprayer for the first time in the spring; this is when lines are likely to come loose or burst. (Image from Purdue Extension publication PPP-121: Preparing Spray Equipment for Winter Storage and Spring Startup).
    Minerals chelate (i.e. scale) more readily on stainless steel than plastic tanks. In either case, the first tank of water and leftover antifreeze should be sprayed from the nozzle bodies with no line or nozzle strainers, and no nozzles. Replace them once the tank is sprayed out.

    The last step is calibrating the sprayer, and that process really depends on your definition. If the preceding steps conflict with those of the manufacturer’s, always follow the manufacturer’s. Do this for reasons of safety and to preserve any warranty.

    Thanks to Fred Whitford (Purdue University), Gail Amos and Mark Ledebuhr (Application Insight LLC) for reviewing the content of this article and for their helpful edits.