Dusty conditions are common in spraying, and in dry springs they are often associated with a further challenge, drought-stressed plants. There is no magic cure for these problems, but here are a few guidelines:
1. Most products are not strongly affected by dust. But two important products are very dust-sensitive, glyphosate and Reglone. The active ingredients in both products are very “charged”, therefore they bind readily and strongly to soil particles, which includes not only dust on plant surfaces, but also suspended soil in spray water that gives the “turbid” appearance.
2. Dust can be viewed as similar to hard water cations, as a game of relative concentration. We try to get the herbicide concentration to be higher, essentially over-powering the antagonist. For glyphosate, two approaches are common: (a) reduce water volume; (b) increase herbicide rate. Reduced volume is tricky if the glyphosate spray contains a tank mix partner such as a Group 6, 14, or 15 to combat resistance. Those products require more water. For Reglone, low water is a bad idea for the same reason.
3. Some specialists recommend the use of higher water volumes to reduce the effects of dust. Although spray volumes are usually too low to actually wash dust off surfaces, the higher water volumes permit the use of larger droplets which may have better absorption characteristics in the presence of dust.
4. Another remedy is to increase the application rate in the spray swath where dust is most severe, usually behind the wheel tracks. Slightly larger nozzles in those regions are widely used by sprayer operators.
5. Even when dust is not a problem, roadside field edges may contain dust from traffic. Higher rates may be justified on the outside rounds for that reason.
6. A report in No-Till Farmer makes the following useful statements: “Greenhouse research conducted by researchers at North Dakota State University in 2006 found that control of nightshade species with glyphosate was reduced when dust was deposited on the leaf surfaces before, or within 15 minutes after, glyphosate application. If the dust was deposited later than 15 minutes after application, phytotoxicity was not reduced. Dust generated from silty clay soil tended to reduce glyphosate phytotoxicity more than dust generated from loamy sand soil.”
7. Several additional management opportunities exist for dusty conditions. Slowing down tends to reduce turbulence and dust generation. Although front-mounted booms apply the spray before the dust is generated, it will deposit before the spray is dry, limiting the benefit, as indicated by the NDSU study.
8. Don’t mistake aerodynamic turbulence for dust. Weed control may be lower behind the tractor unit or near the wheels because the spray is displaced by air currents. The use of water-sensitive paper can help identify if this is part of the problem.
One of the better references on dust and wheel tracks was produced by the GRDC in Australia, and can be found here.
Horticultural crops cannot be produced commercially without the use of pesticides to manage the impacts of insects and pathogens. Growers recognize the importance of pollinators and in some cases, rely on bees for pollination. Growers are practicing due-diligence to try to minimize the effects of necessary pest management activities on bees. There’s a fine balance between managing pests effectively and economically and minimizing the effects of pesticides on pollinators. Impact on pollinators is a major consideration for the registration of pesticides.
Not all pesticides are toxic to honeybees.
Not a honeybee, but a great photo of a pollinator on a spray boom near some nozzles. Too good not to use.
Growers use IPM practices which means that they are spraying only when necessary (monitoring for pest levels) rather than following a calendar-based program. Because each droplet of spray that does not land on the target (the crop) is wasted money, growers are more conscious of drift and are using technology to reduce off-target drift.
The Ontario Bees Act states “No person shall spray or dust fruit trees during the period within which the trees are in bloom with a mixture containing any poisonous substance injurious to bees unless almost all the blossoms have fallen from the trees.” While some crops, like grapes and peaches, do not rely on insects for pollination, bees may still visit their flowers and they are still present in vineyards and orchards before and after bloom, foraging for nectar and pollen on flowering plants in row middles and surrounding vegetation areas. We have been promoting row middle management with flowering plants to encourage the presence of beneficial insects. Honey bees are also attracted to these plants. For this reason, it’s important to recognize that sprays applied to manage pests may have adverse effects on honey bees as well.
One of the most important things to do is to maintain communication between growers/custom operators and beekeepers. While it’s common sense to not allow insecticides to drift directly onto bee hives, bees will usually forage up to 3 km from a hive and when food sources are scarce, they are known to fly as far as 12 km (8 miles) (Download reference).
BeeConnected is an app connecting registered beekeepers with registered farmers and spray contractors, enabling anonymous communication on the location of hives and crop protection product activities. The app is available free of charge through a web browser, the Apple App Store and Google Play.
Here are a few others things you can do:
Read the pesticide label:
Carefully follow listed precautions with regard to bee safety. In some cases a product may not be used while bees are actively foraging.
Product selection:
Pesticides (insecticides and fungicides) are not all equally toxic to honey bees. It is also important to be familiar with the relative toxicity of pest control products to bees. In Publication 360, Fruit Crop Protection Guide, the relative honeybee toxicity is now listed in the fungicide and insecticide activity tables of each chapter. The impact of products that are moderately toxic to bees can be can be minimized if dosage, timing and method of application are correct. Highly toxic products may cause severe losses if used when bees are present at treatment time or within a few days thereafter.
Choose the least hazardous insecticide formulation. Emulsifiable formulations normally have a shorter residual toxicity to bees than wettable powders and flowables which, in addition to having residual characteristics can be more easily picked up from the flowering plant while bees are gathering pollen.
Spray timing:
Whenever possible, apply products with toxicity to bees in late evening, night or early morning while bees are not foraging (generally between 8 p.m. and 8 a.m.). Evening applications are less hazardous to bees than early morning applications. Warm days and nights can extend the foraging period; therefore applications may be necessary later in the evening or earlier in the morning under unusually warm conditions. Do not apply insecticides when cool temperatures are expected after treatment. Residues will remain toxic to bees for a much longer time under cool conditions. Do not apply insecticides that are toxic to bees on crops in bloom, including crops containing weeds or cover crops in bloom. Avoid treating during hot evenings if beehives are very close to the target field and honey bees are clustered on the outside of the hives.
Remove alternate pollen sources:
Where feasible, eliminate weeds or flowers in row middles by mowing at least 2 days before a pesticide with toxicity to bees is to be applied.
Minimize off-target drift:
Drift of spray applications can cause significant bee poisoning problems, particularly when drift reaches colonies or adjacent flowering weeds. In general, sprays should not be applied if wind speed exceeds 10 mph and favors drift towards colonies. Give careful attention to position of bee colonies relative to wind speed and direction. Ensure that there are no colonies directly in the orchard at the time of spray. Select drift-reducing spray nozzle technology, whenever possible. Since fine droplets tend to drift farther, apply spray at lower pressures or choose low-drift nozzles that reduce drift by producing a medium to coarse droplet size.
Calibrate spray equipment often. Air-blast sprayers can produce finer droplets with greater drift potential. When using an air-blast sprayer, consider redirecting or turning off nozzles, or use technologies that reduce drift (for example, towers, multirow, tunnel and target-sensing sprayers). Shut off sprayer when making turns at field ends or gardens, near large puddles, ponds and other sources of water that may be used by pollinators and other wildlife.
There is a precaution to nighttime spraying: you must be aware of inversions. When you spray during an inversion, the larger drops fall quickly (per normal), but smaller lighter droplets fall very slowly (a few centimetres per second). They do not disperse. Instead, they move with the air they were released into, evaporating very slowly, over great distances. These small particles, as well as vapours from volatilizing products, are capable of moving for kilometers and are therefore subject to drift.
The only sure way to know if you are in an inversion is to take two air temperature readings: the first about 10 cm from the ground, and the second about three metres off the ground. If the surface air temperature is cooler, you are in an inversion. The magnitude of the difference indicates how strong the inversion is. Accurate measurements are difficult to manage with conventional thermometers (Although the new Spot-On Inversion Detector makes it possible). It is generally easier for sprayer operators to watch for the following cues:
Large temperature swings between daytime and the previous night.
Calm (e.g. less than 3 km/h wind) and clear conditions when the sun is low.
Intense high pressure systems (usually associated with clear skies) and low humidity where you intend to spray.
Dew or frost indicating cooler air near the ground (fog may be too late).
Smoke or dust hanging in the air or moving laterally.
Odours travelling large distances and seeming more intense.
Daytime cumulus clouds collapse toward the evening.
Overnight cloud cover is 25% or less.
If you suspect a strong inversion, don’t spray. Postpone the application if possible.
Reducing pesticide injury to honey bees requires communication and cooperation between beekeepers and growers and applicators. It is important that beekeepers understand cropping practices and pest management practices used by farmers in the vicinity of their apiaries. Likewise, pesticide applicators should be sensitive to locations of apiaries, obtain a basic understanding of honey bee behavior, and learn which materials and application practices are the most hazardous to bees.
Furthermore a number of native pollinators such as bumblebees, leaf cutter bees, sweat bees and squash bees are also important pollinators in some crops and they too require consideration. While it is unlikely that all poisonings can be avoided, a balance must be struck between the effective use of insecticides, the preservation of pollinators and the rights of all — the beekeeper, farmer and applicator.
In the era of social media and keyboard warriors, it’s easy to feel like someone is always watching and ready to force their opinion on the world. The “tweet first, think later” mentality often adds to misinformation, and worse, it can leave science as a bystander — especially when it comes to modern farming techniques.
Farmers feed the world and they need to ensure they are growing high quality, high yielding crops. One of the most important elements of protecting high-quality crops is spraying. As farmers and custom applicators become more innovative and more knowledgeable about spraying techniques they have to strike a delicate balance, according to Jason Deveau, Application Technology Specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA).
Deveau recently sat down for a Q&A session to discuss tips and tricks for smart spraying, understanding drift, and how important it is for farmers to share smart practices and be champions to others in the community.
V.B.: WHAT ARE SOME OF THE KEY AREAS TO SPRAYING? WHAT ARE THE TOP MUST-DOS? J.D.: First and foremost, the laws of physics have never changed. We may present the facts in different ways to help people understand, or to make them more accessible, but when it comes to spray coverage and spay drift, there are three speaking points:
We want farmers to use the largest droplet size they can without compromising coverage.
We want the boom at the lowest practicable height to the field.
We want farmers to adjust their spraying practices to match weather conditions, and know when spraying isn’t advisable.
V.B.: OK. LET’S START FROM THE TOP. WHY AND HOW DO FARMERS CHOOSE THE LARGEST DROPLET SIZE? J.D.: Droplet size is an effective tool for combating physical drift. Larger droplets have more mass, which means they are more likely to fall rather than be carried away. But, for a given rate, the number of droplets a nozzle produces decreases as average droplet size increases. It’s the same amount of pie no matter how many slices.
Fewer droplets might compromise spray coverage, particularly when targeting small weeds or when using a contact pesticide in a dense canopy. The answer is to use more volume to bring the droplet count back up, but that means more refills for the sprayer operator, which is time consuming. A good operator is always considering the balance between drift potential, coverage, and efficiency. Even with sophisticated technologies, these considerations always lead to nozzle choice.
Traditionally, a grower would choose a nozzle based on the desired rate (e.g. gallons per minute) for a given pressure. As the sprayer changed speed, this would lead to over — or under — application. So, for convenience and consistency, most growers use rate controllers that monitor speed and auto-adjust the rate using pressure. But pressure also changes droplet size and spray pattern. Patterns can collapse at lower pressures (say <30 psi) and average droplet size decreases as pressures increase. You can see that droplet size wasn’t really on the radar. Pulse-width systems have changed this, but they are still few and far between.
And even if a grower chooses a nozzle with a coarse spray quality, they may be surprised to learn it still produces some fine droplets, too. Look at a bell curve. That’s how a nozzle is rated for droplet size — a lot of average sizes in the middle, and then a few smaller or larger sizes. A coarse nozzle does not make you bullet proof; there will still be some drift. That is why we always observe weather and time-of-day restrictions and adhere to the buffer zones that appear on the pesticide label.
V.B.: HOW DO LOW BOOMS IMPACT DRIFT AND WHY DO SOME FARMERS RESIST THIS ADVICE? J.D.: Imagine holding out your arm and dropping a feather. It will move a ways downwind before landing. Now climb a ladder and do the same thing — it goes considerably further. It’s exactly the same for water droplets. To add insult to injury, releasing spray from a higher point also prolongs evaporation, making it even smaller and exacerbating the problem. And if that weren’t enough incentive to lower booms, the high booms create inconsistent spray coverage, undermining the whole reason for spraying in the first place.
The resistance to low booms comes from the desire to drive fast. North American booms sway and yaw, even with boom leveling systems. Higher speeds may get the job done faster, but it requires most farmers to raise the boom to prevent it hitting the ground. It may seem counter-intuitive, but there are several ways a farmer can slow down, drop the boom, and spray more acres in a day — it just requires them to look at their spray operation differently. A great deal of time is spent filling, idling, turning, and travelling between jobs. It’s been demonstrated that saving time on sprayer-related tasks has a big impact on efficiency — more than simply driving faster.
V.B.: HOW DO YOU KNOW WHEN THE WEATHER IS RIGHT FOR SPRAYING? J.D.: Everyone knows the obvious cues. If your hat blows off, it’s probably not the time to spray. But, we’re learning that calm conditions may contribute to chemical trespass even more than wind. There’s no hard and fast rule, but three kilometres an hour to 10 kilometres an hour winds are a good range.
In calm weather, you may find yourself in a thermal inversion, which does not allow fine particles (or volatiles) to disperse and ground. Instead, they hang in a layer of undisturbed air, either moving downhill like water, or eventually moving in an unpredictable direction when the wind picks back up. It’s suspected that this phenomenon has played a significant role in the off target crop damage issues in the U.S. in 2016 and 2017.
In a very telling demonstration, an Ontario agrichemical rep showed that the smoke from a smoke bomb (representing pesticide vapour) travelled 1.7 kilometres during an inversion. In another demo, he showed it moving back and forth across the same field for hours after the application. Learning how to recognize a strong inversion, and knowing when there is too much or too little wind will require a different way of thinking, but will greatly reduce the potential for chemical trespass.
V.B.: WHAT OTHER PRACTICES SHOULD FARMERS BE AWARE OF TO COUNTER DRIFT? J.D.: There are a lot of other considerations, but let’s highlight two.
First – Downwind neighbours (residential and agricultural) can take actions based on your spraying schedule. If there’s a possibility of chemical trespass, it’s a courtesy to let them know your plans, or at least make spray records available and be prepared to answer questions. Quite often explaining what’s happening prevents them getting misinformation elsewhere. It may sometimes be a nuisance, but educating others is part of maintaining the public trust. Ontario farmers are experienced and certified and, frankly, the industry needs them to help educate people on all the good work being done.
Second – Night spraying. Please stop. Time is short and weather can force us to take opportunities where we find them, but calm, clear nights represent the highest potential for a strong thermal inversion. Knowing the weather conditions that affect product performance (for better or for worse), minding pollinator presence, knowing what’s downwind, and STILL following integrated pest management means there seem to be fewer hours left to spray. But, it’s really a matter of understanding which of those factors trumps the others in the decision to spray, or wait. It requires today’s farmer to play an active role when it comes to spraying.
V.B.: YOU MENTIONED PUBLIC TRUST. HOW WILL SPRAYING AND PUBLIC TRUST IMPACT FARMERS’ BUSINESSES? J.D.: We talk about soil, stewardship, and environmental sustainability. But at the core of all those important considerations is the customer driving those agendas. We are getting close to the day (if we’re not there already) where the grocery store dictates farm practices.
Many broad acre farms are still self-regulating to a large degree. They do their best to maintain high standards for safety, transparency, and record-keeping. But, as specialty crop and livestock operations already know, we are moving towards tracing the history of a farm product from the customer all the way back to the seed. Farmers should adopt best practices proactively, before they become mandatory.
So, the level of attention on field crops is more acute than ever before. Many are not used to being under the public microscope. Customers are asking when, how, and what was it sprayed, and they want to know the weather and cleaning practices that were followed. We need to have those answers ready to show what we’ve always known — that farmers are self-aware, are stewards, and are responsible partners in public health and safety.
So spray like everybody’s watching… because they are.
Well, first, understand they are intended for vertical targets, like wheat heads. Here’s a diagram of how they are (ideally) supposed to work:
Here’s is the ideal coverage from fan nozzles on a vertical target. Note that high booms, smaller droplet sizes, high travel speeds, high or changeable wind conditions and uneven emergence can negatively affect coverage.
Here’s our very own Dr. Tom Wolf to tell you all about them.
Now understand they don’t seem improve matters (at conventional pressures) in broad leaf crops. We compared spray coverage from several nozzles in soybean. The lack of any clear cut winner was disheartening, but even messy results can lead to valuable conclusions! Read more about the experiment here and watch the video below:
And finally, understand that choosing a brand or variation of a dual fan nozzle arrangement is likely the least important factor. It falls, in our opinion, last in this sequence of factors:
Spray timing (i.e. crop stage, pest stage)
Product choice
Boom height (Keep ’em low)
Droplet size (Keep ’em Coarse or larger)
Spray volume (Go with more gallons per acre, not less)
Agrifac shunned the Agritechnica show last year, choosing instead to introduce its latest Condor Endurance II alongside a wide range of high-tech controls at the opening of its new factory at Steenwijk, in The Netherlands.
Booms up to 80m wide can be tested in the new 14,000m² factory, which Agrifac has constructed on its existing site at Steenwijk in the Netherlands.
Agrifac has seen quite remarkable growth in recent years, no doubt the result of investment from its owner – the sprayer specialist group, Exel Industries – which bought the struggling manufacturer in 2012.
Since then, sales of self-propelled sprayers have rocketed – from 20/year in 2008 to more than 200 today. The new factory is currently building a machine a day and Agrifac is now looking to boost sales further by expanding operations in Australia, North America as well as central and eastern Europe.
Sales of Agrifac self-propelled sprayers have risen from 20/year in 2008 to more than 200 today. Its new factory has the capacity to build one machine every day.
Indeed the impressive new, architect designed factory is set-up to test booms up to 80m (~262 ft) wide, which is a massive jump from its current 52m (~170 ft) maximum. Unsurprisingly it’s looking at carbon fibre to reach these widths.
While not launched officially, Agrifac made no secret of this at the open day, showing a ‘hybrid’ with carbon fibre outer sections fitted to the existing steel one. While there are few details about this prototype, it uses a lattice-work construction, with the nozzles mounted at the top of a triangle.
Targeting greater precision
Under the banner of ‘Need Farming’ Agrifac is promoting a range of systems to apply products with ultimate precision. Top of the technology tree is AiCPlus, which identifies individual plants and applies a specifically-tailored product rate – on the move.
By the way, Agrifac explains AiC is pronounced ‘I See’, with the AI an abbreviation of Artificial Intelligence.
Cameras, mounted along the boom, scan 3m (~10 ft) wide bands of crop in ‘real time’ and, use special software algorithms to interpret what they detect. This could be individual weeds, diseases or pest damage.
Ultimate spraying precision and control delivered by AiCPlus, which uses boom-mounted sensors to identify areas down to 50cm and deliver targeted treatments with single nozzle accuracy.
Applications are targeted using control to single nozzles, which are operated by Pulse Width Modulation (PWM). This enables the nozzles to be turned on/off at up to 100 times/sec, allowing the system to not only vary and apply the dose for the target, but also maintain the correct droplet size for the product.
Solenoid valves switch nozzles on/off up to 100 times/sec and maintain the application rate without changing pressure. The system also reduces flow to the inner nozzles and increases it to the outside automatically during turns.
To accomplish this degree of precision application, Agrifac has introduced a range of other new technology. Along with the sensors and single control there is another new system, DynamicDosePlus (here’s a smartphone video), which implements control down to a resolution of a single nozzle.
Pesticide rates, rather than just the total application volume, are changed on the move using SmartDosePlus. And to ensure products are applied accurately there is StrictSprayPlus, which includes turn compensation.
Precise prescription maps
For precise applications, without using AiCPlus on the move sensing, Agrifac has developed DynamicDosePlus. This, it claims, is the first system to create application plans to one nozzle precision.
As well as planning applications it also executes the operations, not only controlling applications, turning nozzles on/off, but also varying the pesticide rate between 0-100%. To do this AiCPlus requires high precision prescription maps.
Agrifac has developed a completely new high resolution system for creating prescription maps and executing the instructions on machines equipped with single nozzle control.
Mixing on the move
With AiCPlus varying pesticide rates on the move and to one-nozzle precision, Agrifac says it is difficult, or even impossible, to predict the chemical concentration required before application.
To overcome this, it has developed its SmartDosePlus direct injection system. Just clean water is held in the spray tank with the concentrated chemical stored separately. According to required pesticide rates detected by the sensors or stored on the map, the system’s software then meters the precise quantity of active required for the specific area and mixes it ahead of the boom.
The valve system and full boom circulation and priming ensures each nozzle receives the correct mix. It also doesn’t matter how many nozzles are in operation at the time.
It also enables other active ingredients to be added to treat certain areas and turned off when the patch is passed. Similarly, pesticide rates can be reduced dramatically or even stopped completely in environmentally sensitive areas.
Another big advantage of carrying just clean water in the tank, adds Agrifac, is it significantly cuts cleaning time and the amount of washings. This not only speeds up turnarounds between products, but can also help reduce the risk of cross contamination when working in sensitive crops.
The right rate and droplet size
As well as single nozzle control, StrictSprayPlus also provides application volume control that is unrelated to pressure, which maintains the droplet size regardless of changes in forward speed or pressure.
Automatic controllers normally set the application volume, according to speed by varying the pressure. In most cases as speed rises the droplet size reduces, increasing the risk of drift. As the pressure falls the droplets get larger and this may have adverse effect on efficacy.
Pulse Width Modulation overcomes this by using solenoids to turn the flow to the nozzle on/off up to 100 times/sec to maintain the correct application volume. The pressure is unaltered, so the droplet size remains the same.
StrictSprayPlus nozzle control also delivers turn compensation – to maintain the correct application volume when spraying around corners. As the sprayer turns the nozzles on tip of the outside boom move considerably faster than those on the inside of the turn.
With a fixed application volume, this results in under-dosing on the outside and overdosing on the inside. Agrifac says its system detects the speed differences and calculates the rate required for each nozzle across the boom.
But, experts warn, it’s important to note that PWM currently does not work with many of the popular Air-Inclusion (AI) nozzles in use today.
On the level
Regardless of the other technology on board, setting and maintaining the best boom height is crucial to maintaining spray efficacy and cutting drift.
For its new StrictHeightPlus auto-boom height control, which works in conjunction with the BalancePlus and variable geometry on its J Boom, Agrifac has developed new ‘wide view’ sensors.
Three sensors are fitted into four separate clusters, mounted across the boom that, it adds, scan a wider area than other systems. This is said to provide a better overview of the crop as well as help to distinguish between irregularities, misses and tramlines, which can affect performance.
A new auto-boom height control system, developed in house, uses three sensors in a cluster to scan a wider crop area. Four clusters are used on the boom.
The system is also now fully integrated into the firm’s own EcoTronic terminal, eliminating the need for another box in the cab.
More power and control for Endurance II
The Endurance II is powered by a 420hp engine and is equipped with a new, advanced control panel and joystick.
The sleek new EcoTronicPlus II joystick and touch-pad clusters commonly used controls into areas, providing finger-tip control of operations.
While the manufacturer sticks with the Claas Vista cab, inside operators will find a sleek new, modern control panel. Called EcoTronicPlus II, it is designed solely for use on a sprayer and incorporates a stylish joystick ahead of the armrest pad, which is surrounded by touch buttons.
These are accompanied by a single touch-screen, which is used for both the sprayer and the GPS-controlled equipment, such as section control, mapping and even road navigation. The screen changes automatically to display only information that is required for the current operation.
Elsewhere the Endurance II retains familiar equipment such as the existing StabiloPlus chassis, GreenFlowPlus multi-stage centrifugal pump and spray system as well as the 8,000 litre (~2,110 gal.) capacity tank and booms from 24m (~80 ft) to 55m (~180 ft).
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