Tag: productivity

  • Question of the Week: Fine Sprays for Fungicides?

    Question of the Week: Fine Sprays for Fungicides?

    The following question arrived from one of our prairie clients last week:

    “A retailer is promoting the use of hollow cone nozzles to be used on field sprayers (20” spacing) to apply fungicides which he claims out-perform any regular and twin fan tips. Claims:

    • create an extra fine droplet for maximum coverage on the canopy
    • use less water, less time spent filling
    • apply at 3.5 gpa
    • add vegetable oil to reduce drift

    “So his direction to a specific customer was to use the TEEJET CONEJET TXA8001VK nozzle at  80 psi – travelling at 10 – 12 mph to achieve a 3.4 gpa application rate with a ‘very fine’ droplet size.

    “What are your thoughts?”

    Here’s how I answered (edited for clarity):

    That recommendation sounds familiar – it originates from a consultant with experience in South America, where this idea is promoted to improve (aerial) spray productivity.

    I fundamentally disagree with his approach. Adopting and promoting it is not only illegal (contravenes every modern label’s water volume and spray quality requirements), it also puts a generation’s worth of stewardship efforts on drift management at risk.

    To be balanced, let’s explore the attractiveness of this approach. Finer sprays do provide superior coverage and save water. Every child knows this. Finer sprays also go places in the canopy where the coarser sprays can’t, for example very dense lentil canopies.

    Over the years, we’ve explored the performance of fine fungicide sprays in canola, pulses, and cereals in research trials with the U of S and AAFC. To our surprise, droplet size played only a small role in fungicide performance. Water volume was much more important. Droplet size management with pressure through a low-drift nozzle was enough to get the best disease control.

    The main drawbacks of very fine sprays are:

    1. The fine droplets evaporate to dryness very quickly, in seconds. As they shrink, their drift potential is increased even more, and once dry, the remaining particles work much less well. The proponent corrects for this by adding an oily adjuvant as an evaporation retardant. With oil, the fines remain liquid much longer. Although many products become more effective this way, they also become more phytotoxic and less safe for the applicator and bystander. Completely off label, completely risky for crop safety, unknown effects on MRLs, extremely unsafe for the environment and humans. Remember when people dissolved 2,4-D ester in diesel, back in the 40s and 50s and sprayed it with their brass 6501 tips? That’s what this is.
    2. Cone nozzles are designed for airblast sprayers and do not produce good pattern overlaps for boom sprayers. The proponent of this method actually recommends that the boom be raised to overcome the bad patterns and to (believe it or not) simulate aerial application. If this were done, the spray would be re-distributed by air-currents and come down wherever the wind blows it. Probably far away.  The concept of on-target, uniform application, the practice that makes product use acceptable, and the thing we try to achieve with flat fans at a low boom height, is completely lost.
    3. Producers will not have the support of pesticide manufacturers should a performance issue arise. Even worse, if regulators find out about this off-label practice, significant fines (fines for fines, get it?) can be charged under the Pest Control Products Act.
    4. Airborne spray drift with an air-induced spray like the AirMix, GuardianAir, AIXR and the like, applying 10 gpa, is about 1% of the applied amount, measured at 5 m downwind of the downwind edge of the swath in a 20 km/h wind. We’ve never measured hollow cone drift from a boom sprayer, but when we used a flat fan at 5 gpa, drift increased to about 8% of applied. I’d guess a high pressure hollow cone would easily double or triple that. Illegal and irresponsible.
    5. Travel and boom turbulence is a part of faster travel speeds. This would affect the finer droplets much more than the coarser ones, as we can imagine. It’s similar to drift. With a low-drift spray, the proportion of the total spray volume that is “fine”, say less than 150 microns, is about 5%. For a very fine hollow cone, it might by 50 to 75%. So a much greater proportion of the sprayed dosage would be susceptible to uncontrollable movement. This could be good, when turbulence redirects the spray to places that are unreachable by larger droplets. Or it could be bad, as turbulence pushes droplets away from an important target, creating a miss. On balance, bad. Very bad.

    These types of recommendations are concocted by people who want to tell a unique story that is popular with some. Their approach differentiates them from the rest of the crowd, an old and effective marketing trick. But these proponents do not have the best interests of the industry in mind.

    Our individual and collective agricultural practices must be respectful of others. Of safety. Of the law. Of the environment. We have lots of opportunities to make shortcuts…nobody’s watching most of the time. But that doesn’t make it right. It’s certainly not in ag’s long-term interest.

    When considering our agricultural practices, imagine describing them to a young non-farming person. Can you justify your actions? Do your practices make you proud? If not, you have work to do.

    Here’s a task: If your boom sprayer has nozzles that produce very fine sprays, take them off and throw them in the garbage. Might sound radical, but it’s the right thing to do.

  • Deciding on the Right Way to Spray

    Deciding on the Right Way to Spray

    “What is the right way to apply this pesticide?” It’s one of the classic questions. Applicators know that spray method determines the efficacy of the application as well as its environmental impact. And it has to use time and water resources efficiently to make sense.

    To answer the question properly, we need to take things one step at a time.

    1. Canopy: To start, we need to look at the canopy that our application will go into. If it’s an early season spray into a seedling crop, then the canopy won’t be much of a barrier. Lower water volumes can be possible. Droplet size will only depend on the target type and the pesticide mode of action.
    Small weeds require more smaller droplets to secure effective targetting

    If it’s a later application into the bottom of a maturing canopy, the foliage may intercept the spray before it reaches the target area. More water will likely be needed, and droplet size may become more critical for getting the spray to its destination. Dense canopies are a real challenge and lower-canopy deposition usually benefits from finer sprays because the small droplets can turn corners better.

    Dense canopies are very difficult for a spray to penetrate. Higher water volumes and smaller droplets are the key tools that help.

    2. Water Volume: Regardless of canopy, the range of application possibilities will depend on the water volume and spray quality combination. It’s math: assuming some constant amount of coverage on each leaf, more layers of foliage will require more water. Using less water volume will make it necessary to use finer sprays to keep droplet numbers constant. More water will allow coarser sprays. This decision has implications for drift, and by extension, affects the number of hours we can spray in a day. More drift tolerance means better application timing and overall productivity.

    The tradeoffs between water volumes and droplet sizes are seen in this figure. Once a certain threshold of coverage has been reached, a further increase in coverage may not provide any additional control.

    3. Target Type and Droplet Behaviour: Whatever spray we use, the target plant or insect needs to intercept, collect, and retain the spray droplet. This is where the fun begins. Target leaves may be vertical or horizontal, large or small. Their waxy surface may be easy-to-wet or difficult-to-wet. The general rules of thumb are that larger, more horizontal and easy-to-wet surfaces are better suited for coarser sprays – these are intercepted more efficiently and stick readily. That is a reason why most broadleaf weeds and crops are very compatible with low-drift sprays.

    Large targets (left) are most efficient at intercepting larger droplets (provided droplet bounce is not a problem) because smaller droplets may evade capture. Smaller targets are usually missed by larger droplets but are very capable of capturing smaller droplets.

    On the other hand, smaller, vertically oriented and difficult-to-wet plants require finer sprays for effective targetting. Larger drops tend to miss these targets or bounce off them. Most grassy, and some broadleaf weeds (especially at early growth stages) fall into this category.

    4. Mode of Action: There are nearly 30 modes of action on the herbicide world, and another ten modes for insecticides and fifteen for fungicides. The effect of droplet size and water volume on their uptake and translocation varies, and it’s probably not correct to generalize too much. There is one notable product, glyphosate. For this product, research has consistently shown that large droplets and more concentrated mixtures provide better uptake. But we’ve also seen problems when this is over-done, causing localized toxicity and limiting translocation.

    With many products, we’ve sometimes seen better performance with finer sprays due to improved coverage, yet at other times less performance due to rapid evaporation. On the whole, it’s probably still fair to say that contact modes of action require finer sprays and higher water volumes, even if there is the occasional exception. And systemic products can typically handle coarser sprays. We’ve always been surprised just how coarse we seem to be able to push the system before any loss of efficacy.

    What does it all mean? In spraying, we need to accommodate a lot of diversity. The average application is broad-spectrum, targeting large and small broadleaf and grassy plants. Many sprays are tank mixes of several modes of action. It’s impossible to prescribe a specific spray for each situation. We need a little bit of everything. And the spray should not be drift-prone. It’s easy to see that we need to aim for the middle to accommodate everything.

    The traditional flat fan nozzle, either in its conventional or low-drift form, generates a wide range of droplet sizes that can range from 5 µm to about 2000 µm. If we need fine droplets, they’re there. If we need larger droplets, they’re also there. The proportion of the total spray volume in each specific size fraction depends on the nozzle choice and size, the spray pressure, and the adjuvant mix in the tank. Overall, the system is very robust, and although it requires some tweaking, a well chosen average spray can achieve most tasks well enough.

    A typical spray quality chart shows the expected spray quality for a range of nozzle sizes and pressures. Spray quality measurements follow standards set by the ISO and ASABE, these change from time to time and therefore charts tend to become outdated.

    Our research has repeatedly shown that a Coarse spray is a good starting point that does most things well. It is acceptable to move into a Very Coarse or coarser category provided water volumes are also raised, and provided the target types and modes of action are suited for this change.

    It is rarely necessary to spray finer than Coarse, and when this is done, we recommend against spraying finer than a Medium spray. There is simply no advantage from product performance, and drift risk becomes unacceptable.

    Tweaking the System. In order to maximize the performance of your spray, and the efficiency of your overall spray program, here is some advice:

    1. Know the spray quality of your nozzles, and their response to spray pressure. Manufacturers publish this information in their catalogues and on-line. Make this your homework assignment.
    2. Use the coarsest spray that you can afford to. This will make the application safer, it will widen the weather window, and it will simply let you get more done in a day or a season. Coarse sprays work.
    3. Use spray pressure and water volume to fine tune the application for a specific purpose. If using a contact product, you can keep the same nozzle you used for a systemic product. Apply more water or use more spray pressure to generate more droplets.
    4. Do not skimp on water. Higher water volumes tend to make an application more uniform, robust, and crop-safe. Spray coverage improves. Canopy penetration improves. Coarser sprays are possible. The only exception to this rule is glyphosate, which works better in lower water volumes. But with higher glyphosate rates and more tank mixing, even that exception is disappearing.
    5. Learn as much as you can about how your pesticides work and where they need to be in your canopy. Apply your knowledge to select optimal water volumes and spray qualities.
    6. Be wary of people who advise very low water volumes in conjunction with fine sprays. They want to appeal to your need for efficiency, but do so at the cost of consistency and environmental stewardship. Plus these types of applications are illegal for many of our products.
  • My Sprayer Santa Wish List

    My Sprayer Santa Wish List

    Dear Sprayer Santa,

    “I tried to be good this year.  It was hard, though.  Yes, I know that fast driving causes drift and lots of other problems.  But I couldn’t help it – the 375 horses under the hood needed the exercise.  I honestly didn’t mean it.  I’d have stopped had the air-ride not cushioned all the impacts so well.  I had no idea, really.  The cab was so quiet.  I’m sure that plume of spray and dust behind my sprayer didn’t cause any damage.  I mean, nobody called me, anyways.  I had no choice, after spending 2 hours cleaning out the tank and having to do another three quarters before the forecast rain.  So please, Santa, can I have a bigger sprayer?  Please? I think I need it…to, errr…to…to feed the world.  Yeah, that’s right, Santa Baby.  I need it to grow food for others.  So how about it?”

    I wake up in a cold sweat.  Well, if there was a Sprayer Santa, he’d hear lots of excuses about these sorts of things from applicators afraid of getting a lump of coal on Christmas Day, a black nozzle so to speak.

    So why don’t we stop making excuses and solve the problem by making sprayers that focus on the right things?

    Here’s my “no more excuses” wish list:

    1. Increase transport speeds, reduce field speeds. Let’s establish gear ranges which save time getting to the field, and ensure a better quality job once we get there. Let’s focus on productivity without resorting to the easy, but bad option.  Speed comes at a cost.  More horsepower.  More fuel. More structural stength. More weight.  None of it cheap. Or good.
    2. Increase boom width. This one’s a productivity powerhouse.  It’s every bit as good as travel speed, on a percent gain basis, and much cheaper.  Where else in the world is there a better opportunity for wider booms?  The earth’s temperate plains are almost without exception wide, and more or less flat.  With the help of autosteer and automatic boom height, why should 120 ft be the limit? Many aftermarket manufacturers offer booms at 150 ft.  But why stop there?  Sure, we’ll need some engineering to make it work.  But the fact is that wide booms, coupled to slower speeds that require less horsepower, can have the same productivity.  Not a bad tradeoff.
    3. Explore lighter materials. Sure, Ford was ridiculed by GM for offering aluminim trucks.  But when weight is important, alternate materials can make the impossible possible. Booms that weigh many thousands of pounds require so much strength just to carry their own weight, there are diminishing returns.  And the result is that we are stuck with narrow booms.  Let’s get inventive with alloys and composites.
    4. Focus on time saving features. On any given day, we are given maybe 6 hours of good spraying conditions, some in the morning, some in the evening, and perhaps a few in between. This can be interspersed with several days of bad conditions.  What a waste to spend this precious time not actually spraying, but rather filling, cleaning, transporting, getting un-stuck, figuring. In a business where timing is so important, and where a late application can have serious yield implications, we should be spending a greater proportion of time spraying. We need help to minimize downtime.
    5. Dedicated clean water pumps and small sumps. Want to clean out the tank faster? Rather than relying on batch mode, reducing concentration by serial dilution, consider adding a dedicated pump to your clean water saddle tank.  Introducing clean water through the wash-down nozzles while at the same time spraying out the sump dramatically increases dilution power with less water. And of course, the smaller the sump and recirculating reservoir, the faster the job will get done.
    6. Recirculating booms. I initially wrote these off as a bad idea when they offered a single pressure entry point (on one end) followed by an exit on the other. Over 120 ft, you’d surely see pressure drops of 10 psi – unacceptable. But with modern designs offering up to four pressure entry points (both ends and middle) these issues appear to have been eliminated. And with clever plumbing, the boom can act as an extension of the tank, making priming and cleaning faster and easier.  Sectional control is now governed by individual shutoff valves, offering customizable, fast, positive shutoff.
    7. Better flow and droplet size control. 2016 promises to be one of the most exciting years for new atomizers, with new entries in the twin fluid, pulse-width modulation, and multiple nozzle markets. But there’s still lots of room for improvement. To the young engineers reading this, give us a nozzle that provides a 10-fold range of flow rates, each at the same pattern angle and droplet size.  Let this nozzle offer easy control of droplet size from Medium to Ultra Coarse at each flow rate. How hard can this be? Make it affordable and reliable, with consistent flow rates and a long wear life.  I think we’re ready to pay for this.
    8. Easy cleaning materials. Every year, it’s a guessing game. Are all the Group 2 residues removed from the tank and booms before you spray your LibertyLink canola? How can you be sure?  Well, by checking your canola two weeks later, of course!  In the meantime, all we can do is offer hope with ever more rigorous cleaning protocols, one-upping last year’s efforts to ensure that nothing got left behind.  How about tank, fitting, hose, boom, and nozzle body designs engineered to eliminate these problems?  How about a guarantee to that effect by the sprayer manufacturer?  It’s going to take more than the occasional stainless steel component.  If we have enough knowledge in fluid dynamics to send an F1 sports car into a turn at 250 km/h, then surely we can design a hydraulic system that self-cleans!
    9. Better aerodynamics. Let’s face it, we can’t control drift just by making sprays coarser. Eventually we’ll reduce coverage too much and this will hurt our important contact products the most. Instead, we need sprayer and boom designs that facilitate the transport of droplets towards their target, avoiding drift. Maybe the shape of our tractor units and boom components will play a role here, maybe the nozzle pattern needs a re-evaluation. Maybe shrouds will return. One thing’s for sure – we can’t simply drive faster and expect coarser sprays to solve the problem.

    So that’s my list.  I’m sure it’s just a beginning.

    What’s on your list?

    Lee Valley Safety Goggles

    *I have a confession to make.  I’m secretly hoping for those Lee Valley German Safety Goggles for Christmas.  Protecting your eyes has never been cooler.

  • The 2015 in Review: 8 Points Evaluation of Your Spray Program – Tips with Tom #12

    The 2015 in Review: 8 Points Evaluation of Your Spray Program – Tips with Tom #12

    During post-harvest down-time, it’s important to take a much needed breather.
    Then, before you know it’ll be time to start the shop projects and equipment maintenance for next year, if you haven’t started already. Before you get started, though, Tom Wolf has a handy list of things to evaluate, clean up, fix or replace on the sprayer.

    In this final installment of Tips with Tom, Wolf runs through key areas of the sprayer that could potentially use upgrading or just maintenance, plus lists some quality parameters that could be improved for next year that may take some footwork through the busy winter season.

  • Increase Sprayer Productivity Without Driving Faster

    Increase Sprayer Productivity Without Driving Faster

    Timing trumps most things in crop protection. A great spray applied at the wrong time isn’t nearly as valuable as a mediocre spray at the right time. So how do we improve our ability to get things done at the right time?

    Often, we try to win races by driving faster. In our last article, we looked at driving speed and concluded that faster speeds can lead to more drift and less uniform deposition. Driving slower can be viewed as a sort of insurance policy: You may not notice the benefits right away, but on days when that extra bit of performance is required, you’re covered.

    So how do you get the job done quickly if you can’t drive faster?  To answer, we have to look to other opportunities for boosting productivity.

    Recently, we built a model to capture all the elements of a normal spray operation that affect timeliness. These were:

    • travel speed
    • boom width
    • tank size
    • water volume
    • field length
    • number of headlands
    • turning speed
    • fill time

    First, we identified a reasonable base condition. For the sprayer, that was a travel speed of 14 mph, a 90’ boom, an 800 gal tank, a 10 gpa water volume, and a 20 minute fill time. Then, we set up a typical field situation, which was spraying a half-mile run on a quarter with two sprayed headlands and a turning speed of 8 mph. Finally, we changed one factor at a time to determine its relative importance.

    Before we discuss the results, let’s make it clear that just because changing some of these factors improves productivity doesn’t mean we’re recommending them! For example, adequate water volume remains an important input that improves coverage and permits the use of low-drift sprays. Larger tanks increase compaction and take more power, and so forth.

    Here’s what we found:

    All productivity values were expressed as acres per engine hour. For this reason, our numbers will be lower than what a typical sprayer monitor reports, most of which calculate acres per spraying hour.

    For the base condition, the sprayer spent 15% of its driving time turning, and 37% of its on-field time stationary (i.e. filling).  For every hour spent on the field, less than half the time (48%) was spent spraying. This resulted in an average productivity of 82 acres/h.

    Increasing the spray speed to 18 mph increased average productivity to 93 acres/h, but it also increased the proportion of time spent turning and loading, resulting in just 40% of the field time spent spraying.

    Decreasing the loading time from 20 to 10 minutes reduced the proportion of field time spent stationary to 23%, covering 100 acres/h at 14 mph. Surprisingly, this was the productivity-winner, resuling in 62% of on-field time spraying.

    We discovered other powerful productivity factors, and chief among them was boom width. A 33% increase in boom width from 90’ to 120’ gave a productivity boost to 94 acres/h, close to the same result as increasing the travel speed to 18 mph earlier. Similar side effects occurred: more time turning, and a greater proportion of time filling, as we saw with faster travel speeds.

    Boom width seems to have some room for growth.  Many smaller European counties use wider booms than we do in North America, for example.  With gps guidance and large fields, we have excellent conditions for their implementation.

    Two other factors that had similar effects to fill time were water volume and tank size. Less water and larger tanks increased productivity by decreasing the fill frequency, with effects similar in magnitude to speeding up the fill time. Decreasing the water volume from 10 to 5 gpa increased productivity to 100 acres/h by decreasing the proportion of time the sprayer was stopped from 37% to 23%. Increasing from an 800 to a 1,200 gallon tank increased productivity to 94 acres/h, again by decreasing the proportion of time spent filling to 28%.

    Taken together, a sprayer with a 120’ boom, a 1,200 gal tank, applying 10 gpa and filling in 10 min had an average productivity of 132 acres/h. And this was achieved without driving faster than 14 mph. If you can string two quarters together and drive a whole mile before turning, that number rises to 145 acres/h, a surprisingly large 13 acres/h gain.

    The perspective of minimizing downtime extends to other tasks, too:

    • Be more prepared for the job by reviewing the product label in advance, noting the correct mixing order.
    • Keep extra nozzles, clamps, and nozzle bodies in the cab.
    • Don’t clean plugged nozzles, replace them.
    • Use low-drift nozzles so a small increase in wind doesn’t shut you down.
    • Ensure all the products needed are on the tender truck (e.g. pesticide, adjuvant, tank cleaner, anti-foamer, etc.).
    • Consider switching to 3” plumbing (pump rates of 300 – 400 gpm are possible).
    • Make sure your inductor won’t be the limiting factor. For example, product pumps can be awfully slow when the product is cold. It might be worthwhile to explore a venturi system.

    Speeding up the fill process is a good idea, but be careful with certain products. Dry materials such as the sulfonyl ureas (e.g. Refine, Express SG, etc.) and some fungicides (e.g. Astound, etc.) require time to hydrate in water so they mix properly. Some operators pre-hydrate these in a smaller tank, while others get an extra tank to pre-mix whole loads and simply transfer them over.

    Also think about the time spent cleaning the sprayer. Thoroughness is important, but perhaps there are efficiencies to be gained there as well, like never letting a sprayer sit after spraying. We’ve written about continuous rinsing, for example, to improve cleaning speed and effectiveness.

    So, the quicker we can spray, while ensuring a quality job, the more effective our crop protection practices will be. We encourage you to use our to determine your best configuration.

    Got a productivity tips to share? Let us know! And remember: In spraying, the race is won in the pits.

    Factor

    Base

    Drive Faster

    Fill Faster

    Spray Wider

    Less Water

    Bigger Tank

    New Sprayer

    Travel Speed

    14 mph

    18 mph

    14 mph

    14 mph

    14 mph

    14 mph

    14 mph

    Fill time

    20 min

    20 min

    10 min

    20 min

    20 min

    20 min

    10 min

    Boom Width

    90 ft

    90 ft

    90 ft

    120 ft

    90 ft

    90 ft

    120 ft

    Water Volume

    10 gpa

    10 gpa

    10 gpa

    10 gpa

    5 gpa

    10 gpa

    10 gpa

    Tank Size

    800 gal

    800 gal

    800 gal

    800 gal

    800 gal

    1200 gal

    1200 gal

    Field Length

    0.5 mile

    0.5 mile

    0.5 mile

    0.5 mile

    0.5 mile

    0.5 mile

    0.5 mile

            

    Time Turning

    15%

    19%

    15%

    20%

    15%

    15%

    20%

    Time Loading

    37%

    42%

    23%

    42%

    23%

    28%

    19%

    Time Spraying

    48%

    39%

    62%

    38%

    62%

    57%

    61%

    Acres/h

    82

    93

    100

    94

    100

    94

    132