The decision on which application method is best for herbicides boils down to two main factors: (a) target type and (b) mode of action. In general, it’s easier for sprays to stick to broadleaf plants on account of their comparatively larger leaf size and better wettability compared to grassy plants. There are exceptions, of course – at the cotyledon stage, broadleaf plants can be very small and a finer spray with tighter droplet spacing may be needed. Water sensitive paper is a very useful tool to make that assessment. Imagine if a tiny cotyledon could fit between deposits – that could be a miss!
Some weeds are also more difficult to wet, and those may also need a finer spray or a better surfactant for proper leaf contact. An easy test is to apply plain water to the leaf with a spray bottle. If the water beads off or the droplets remain perched on top in discrete spheres, the surface is considered hard to wet. Most grassy weeds are hard to wet, while most broadleaf weeds are easy to wet.
Grassy weeds are an especially difficult target because they have smaller, more vertically oriented leaves, and almost without exception are more difficult to wet than broadleaf species. All these factors call for finer sprays for effective targeting and spray retention.
Broadleaf weeds usually have more horizontally oriented leaves which also happen to be larger. As a result, they can intercept larger droplets quite efficiently.
There are about thirty mode of action (MOA) groups among the herbicides with about ten accounting for the majority in Canadian prairie agriculture. It’s probably an over-simplification to categorize them into just two groups – systemic and contact. But that grouping goes a long way to making an application decision.
Contact products (MOA Group 5, 6, 10, 14, 22, 27) must form a deposit that provides good coverage. Good coverage is an ambiguous term that basically means that droplets need to be closely spaced and cover a significant proportion of the surface area because their physiological effects occur under the droplet, and don’t spread far from there. One way to generate more droplets is to reduce droplet diameter, another is to add more water. A reasonable combination of both is ideal because simply making droplets smaller creates issues with evaporation and drift.
Systemic products (MOA Group 1, 2, 4, 9) will translocate within the plant to their site of action after uptake. As a result, coverage is less important as long as sufficient dose is presented to the plant. In practice, this means coarser sprays and/or less water may be acceptable.
When two factors are combined, either in a tank mix or a weed spectrum, the more limiting factor rules. Application of a tank mix or product that is active on both broadleaf and grass plants will be governed by the limitation placed on grass targets. A tank mix comprised of both systemic and contact products is governed by the limitations placed on contact products.
A factor we should also consider is soil activity and the presence of residue. Studies have shown that soil-active products are relatively insensitive to droplet size. But if they have to travel through a layer of trash to get to the soil surface, more application volume is the best tool.
Below are some recommended spray qualities and water volumes for use in Canada. The spray qualities listed in the table can be matched to a specific nozzle by referring to nozzle manufacturer catalogues, websites, or apps. Note that Wilger also offers traditional VMD measurements on their site, allowing users to be a bit more specific if necessary.
One of the fastest moving new agricultural technologies is spray drones. Hardly a month goes by without some sort of new capability, some new features. It’s truly an exciting space to watch.
As with all things, there are good news and bad news to share. First the good news.
Drone capacity is on the rise. The early drones shipped with hoppers of 8 to 10 litres. Part of the reason was to keep weight below 25 kg. Below this weight, pilot licensing requirements and flight restrictions are easier. Anyone with a Basic RPAS license (RPAS is the official term for drones, Remotely Piloted Aircraft Systems) can operate drones up to 25 kg. Above this weight, one requires an Advanced license, which is much more difficult to obtain. Current drones like the DJI T40 have a hopper capacity of 40 L, allowing more area to be covered per flight.
The new DJI T40 holds 40 L of liquid and has a claimed swath width of 36 feet (Source: DJI)
Swath widths are increasing with drone size. The limiting factor for electric drones is still battery power. Flight times of 15 to 20 minutes are possible, depending on the ferrying distance. As a result, larger drones don’t necessarily fly longer, but they spray wider, up to a claimed 30 feet for the DJI T30, and 36 feet for the T40.
Atomizers are improving. The trusty flat fan nozzle certainly works on a drone, but its proper operation depends on spray pressure. And spray pressure is not currently reported by drones. Instead, their application software relies on flow rate, and pressure is adjusted in the background in response to changes in travel speed, swath width, or nozzle size. Although drone flow meters are remarkably accurate, the operator could inadvertently operate the drone at a pressure that produces the wrong spray quality for the conditions.
Enter the rotary atomizer. Long a darling of the thinking applicator, these atomizers use centrifugal energy to create a spray with a tighter span, meaning fewer fine and fewer large droplets. Spray quality still depends on pressure-generated flow rate, but droplet size can additionally be altered with rotation speed. This means that if a faster travel speed increases the spray pressure, the effect on spray quality can be counteracted with a changed rotational speed to keep everything more uniform.
Rotary atomizers, like this one from XAG generate more uniform droplet sizes and can alter droplet size without changing spray pressure.
Hybrid systems are entering the market. Rotary wings allow for precise positioning of aircraft and they provide downwash that helps spread the spray pattern out. Downwash also improves canopy penetration and could reduce drift, like air-assist, if used properly. But rotary wings use a lot of energy, limiting battery life. When flown at the wrong height or speed, deposit patterns, drift, and swath width will change. That has to be managed and requires experience.
In comparison, hybrid drones have fixed wings for flight and rotary wings for take-off and landing. The rotors just rotate into the position needed at the time. Fixed wing drones will fly faster, possibly improving capacity and also reducing the effect of the downwash. These systems are new, and much needs to be learned before we understand their various characteristics. But they offer a nice avenue into more productivity.
Hybrid drones like this one from Advanced Robotics can cover more ground with less turbulence than a rotary wing drone.
Drones are multi-purpose. Virtually all drones have interchangeable wet and dry hoppers so they can be used to apply dry nutrients or seed as needed. That makes them quite versatile. But the newest spray drones have scouting-quality cameras on board and can be asked to take high resolution images while they’re spraying. At the end of the mission, a very detailed picture of the crop emerges, with much higher resolution than the higher-elevation scouts produce. Other sensors on the drones can be used for variable rate application of nutrients, or even for spot spraying weed patches.
Scouting camera takes pictures while conducting a spray mission (Source: DJI)
Now for the bad news. It’s still not legal to apply mainstream pesticides using drones in Canada, and it may stay that way for a while yet.
Pesticide application by drones remains illegal in Canada. The main reason is that the Pest Management Regulatory Agency (PMRA) has declared drones to be unique application method, separate from ground sprays and aerial sprays from piloted aircraft. This has triggered the need for risk assessment data for spray drift, efficacy, bystander exposure, crop residue. It’s a fair decision – drones produce finer sprays than any other existing system, they potentially use lower water volumes by necessity, and they create a less predictable deposit due to rotor downwash. The majority of current pesticide formulations are designed for 5 to 10 gpa, this creates a certain concentration of surfactants and products that interact with plant surfaces or that change the potency of drift. Altering this by a factor of 5 can have undesirable outcomes. Yes, aircraft also use lower volumes, but more in the area of 2 to 5 gpa. Drones could cut that in half again, and that warrants study.
Registrants haven’t rushed to study drones. Most major manufacturers of pesticides have a small drone program to get their feet wet, and most have applied for Research Authorization (RA) from the PMRA to study them. But the decision to register a drone use for a pesticide has much to consider. Is it worth it to generate the required dataset for the regulators? Will drones amount to a lucrative new market for product? Do we have the resources and expertise to service this new market? The answers to such questions are clearly complex and much remains unknown. The registrants’ caution is understandable.
There may be a small portfolio of available products. Anyone thinking that a fleet of inexpensive, nimble drones will replace their ground sprayer is banking on the registration of the products they need in their operatioin by the registrants. The most likely products to be registered are fungicides, for which drones would offer several advantages in canopy penetration and spraying in tight time windows due to, say, wet weather.
Another obvious use is in industrial vegetation management where rough terrain or remote locations make it difficult to use wheeled sprayers. Or vector control with larvicides, which, incidentally, comprise the first pesticide registrations for drones in Canada (two microbial mosquito larvicides were approved for drone use in October 2022).
But it seems unlikely in the short term that a producer would have their pick of products to apply by drone anytime soon. And this means that a drone would remain a supplemental tool on the farm, not the main workhorse.
Regulatory hurdles are substantial. Not only is a pilot required to be licensed to use drones, a pesticide application also requires a Specialized Flight Operations Certificate (SFOC). In general, SFOCs are required if:
you are a foreign operator (i.e., not a Canadian citizen or permanent resident);
you want to fly at a special aviation event or an advertised event;
you want to fly your drone carrying dangerous or hazardous payloads (e.g. chemicals);
you want to fly more than five drones at the same time.
SFOC applications are fairly easy to fill out. Aside from identifying the drone and the pilot, the application needs the purpose of the mission, the location of the mission, and the time period of the mission. The problem is that it may take up to 30 days to hear back for simple missions, 60 days for complex mission. And if the SFOC is not granted, you can’t fly. You can’t decide to spray a field at the last minute.
The news is clearly a mixed bag. We have it all – exciting technology, obvious niche in the marketplace, significant regulations, slow process. In the meantime, spray drones are legal to purchase and relatively inexpensive. And we know they are being purchased. Canada doesn’t have a strong compliance system within the PMRA, so it’s hard to know how much pesticide spraying is being done illegally, or how perpetrators will be treated by the law.
The reputation of the industry once again rests with hope that good decisions are being made by conscientious individuals.
If you read this site, you know we’re fans of recirculating booms. We love them for three reasons:
They save money and waste by recovering spray back to the tank during priming and rinsing
They make boom cleaning easier by eliminating boom-ends
Most require individual nozzle shutoff, which makes for better sectional control
If you’re new to the concept of recirculating booms, read more here.
Until recently, these booms were only available on sprayers imported from outside North America (Horsch, Amazone, Agrifac to mention three), or via France’s Pommier booms that have been available as retrofits for many years. In 2018, Agco introduced their Liquid Logic system on the Rogator line, becoming the first North American manufacturer to offer a recirculating boom at the factory. Pattison Liquid also offers Recirculating booms as standard equipment on their Connect Sniper pull-type sprayer.
In the meantime, three boom retrofit kits and one sectional conversion kit have become available.
Arag Australia‘s BRS (Boom Recirculation System)
The first was developed by Arag Australia, and is available there via Nozzles Online, and in Canada through Nozzle Ninja. Designed for John Deere R-Series and Case Patriot sprayers, the kit uses the existing line that feeds liquid to the outermost section and simply extend that line to the end where it enters the boom via two installed elbows. The liquid returns to the centre via the installed boom sections which are connected together by removing the boom end cap (or “aspirator” for John Deere) and replacing the gap with a section of hose. Back at the centre rack, the liquid from both booms meet in the middle. At this point, a three-way valve gives the choice to return the spray to the tank, or to receive pressure from the pump. There is also a manual valve that allows the return to be dumped for safe disposal.
Arag Boom Recirculation System (Spray Mode)Arag Boom Recirculation System (Recirculation Mode)
The system does not tie into the sprayer’s electronics. instead, it adds a switch in the cab that the operator uses to switch from spray mode to recirculation mode. The switch is not activated at the end of each swath, but instead to prime or flush the boom.
A switch is added so the user chooses recirculation or spray mode. The boom would recirculate to prime or flush, and remain in spray mode during the spray operation.
Raven
Raven offers a recirculation kit for 3000, 4000, and 5000 series Case Patriot sprayers with Aim Command HD and an ISOBUS terminal. The approach is slightly different, as they retain the pressure feed through individual sections but also tie the sections together so the spray is returned to the tank. By including a shutoff valve between each section, the system retains the option to use conventional sectional control for high flow situations, or to isolate a section should a leak occur. The system can be configured and controlled from the sprayer monitor, either a Viper 4+, CR7, or CR12.
Raven Boom Recircualtion System schematic (from Raven manual). Note the retention of section valves and the addition of manual valves between sections.
John Deere
On March 2, 2021, John Deere announced a 2022 factory option called Pressure Recirculation and Product Reclaim. The system keeps several existing sections and adds two steel lines the flull length of each boom wing. One is for supply, the other return. As these lines approach a section, the supply is fed to one end of the section and the return is connected to the other end. On a 120′ boom, there are five recirculating sections, two on each wing and the centre.
This approach adds one more line than the other designs, and this line will hold materials that ultimately need to be cleaned, flushed, and possibly dumped or sprayed out for cleanout. A possible reason for the extra line is the ability to deliver 220 gpm to the boom, an advertised feature of John Deere high flow booms that may come in handy for topdressing liquid fertilizer. These levels of volume are not needed for pesticides.
John Deere Boom Recirculation and Reclaim. Top two lines are supply and return and extend the length of each boom wing. These connect to the existing sections on each wing, creating several smaller recirculating sections.
Latitude Ag
This Wisconsin company has developed an innovative product that converts any existing plumbed section that contains boom ends into a recirculating section. It does this by incorporating a boom recirculation valve” (the “Merlin IC System“) into the original section feed line. Boom end caps are removed and replaced with sweeps and hoses that return flow to these boom valves. The flow from the boom ends is incorporated back into the sectional feed thanks to a venturi design in the recirculation valve.
A prototype of the Merlin IC System valve made by Latitude Ag
Advantages of this design include simplicity. No moving parts are required, the valve simply recirculates the flow from the boom ends automatically whenever that section operates. Existing sectional control, whether it’s by plumbed section or individual nozzle bodies, is unaffected. Flushing the boom with water is done with normal spraying. It takes some extra time to incorporate and dilute the contents of the boom end return lines but results in a clean boom and no section end residue. We’ve seen the results of testing and agree that it works.
This product does not allow boom priming without spraying. However, a key advantage is that it can be used with direct injection since no product is returned to the tank. Latitude Ag says it will provide the necessary flow sensor and software to make this possible. As of 2025, this system may no longer be commercially available.
Precision Planting ReClaim
ReClaim is capable of operating on a sprayer with or without individual nozzle shutoff. For conventional nozzle bodies containing the original spring-loaded diaphragm check valves, the concept is to drop the liquid pressure below the cracking point of the check valves so flow continues through the sections and back to the tank without engaging the nozzles.
Recirculation fittings are added to the end of each boom section. These feed into 3/4″ lines are installed on section ends, which in turn feed increasing diameter collector lines that eventually return all flow to the tank. Flow reaches the sections as before. When recirculation is turned on, flow exits the boom section through the new fittings and returns through 3/4″ lines to the centre of each section, where it enters 1” lines that take the flow to the center of each boom wing. There the flow in the 1” lines is combined moves to the center of the sprayer on 1.5” lines where it meets the flow from the other wing. From there, the flow returns to the tank through an electronic ball valve and 2” line. This system ensures no back-pressure and balanced flow from each section.
For some sprayer rate control systems such as John Deere, the pump won’t operate below about 20 psi despite operator settings. This means the priming or flushing procedure would trigger nozzles to spray if the bodies were fitted with spring-loaded diaphragm check valves. A pressure reduction kit (a second restrictor valve) is required to reduce the pressure sufficiently for ReClaim to work in these instances. More here.
ReClaim operates independently of any electronic control systems, relying on a toggle switch to initiate recirculation. When flow back to the tank is detected, a light indicates that recirculation is working, and the operator waits approximately 60 sections for a 120’ boom to circulate all volume back to the tank. Download the operator’s guide, here.
This system requires a lot of additional lines. A 120’ boom would require 120’ of additional 1” line and 60’ of 1.5” line. The manufacturer states that ReClaim adds about 14 gallons of volume that would need to be displaced back to the tank, adding to the standing volume. This volume can be circulated using solution from the main solution tank, or displaced back to the tank using flow from an existing clean water tank, or displaced using compressed air via an optional pneumatic port. It is not clear how spray mix in the ReClaim system can be removed from lines without returning it to the tank and draining it from there. Users should consider the additional surface area and volume that will have to be addressed during cleanout.
Do It Yourself
If none of the available options work for your sprayer, consider building your own system. Sprayer plumbing parts are available from the major manufacturers Banjo, Hypro, TeeJet, and Wilger. Wilger, in particular, has developed a nice suite of parts well suited to recirculating booms, including flanged sweeps and thin gauge steel booms, punched for nozzle bodies or unpunched to move product. See their support for DIY projects on this dedicated page: Wilger Retrofit.
Take Home
All these recirculation options improve the status quo of plumbed boom sections with boom ends. They should be considered essential equipment on sprayers.
No matter where you live, it’s been a long time since the last “normal” ag trade show. The pandemic forced a break in this long-standing tradition, and it wasn’t easy. Trade shows are an integral part of doing farm business. At a time when there are fewer equipment dealers offering a lower diversity of makes, a trade show may be the only place to see and thoroughly inspect what other manufacturers offer. With that in mind, I spent a full three days at the 2022 Ag in Motion Show near Langham, Sask. to see the sights.
On the sprayer front, a lot has happened in the last few years. The strength within the “new kids on the block,” the Netherlands’ Agrifac sprayer and Germany’s Horsch Leeb, is noteworthy. Even with fledgling dealer networks, they’ve managed to sell dozens of units based on the strength of convincing features. These go beyond exceptionally wide booms and large tanks, and include smart plumbing designs with recirculating booms and easier cleanout. They also weigh less than their North American counterparts despite standard features like four-wheel steering and superior boom stability. Most importantly, both manufacturers are committed to innovation and offer quick iterations within their models, incorporating new ideas constantly. Often, it’s the small thoughtful things that save time and create endearment.
The Horsch-Leeb sprayer
Case IH showed their new generation 4450 series sprayer. The machine has many improvements over the 4440 edition, focusing on operator comfort, digital integration and hydraulic capabilities. It weighs more than its predecessor, as to be expected. The Millennium spray boom is great, but unfortunately, there is no factory-designed recirculation, leaving owners to go to the after-market for solutions–a missed opportunity.
The Case 4450 with Millennium boom
Since acquiring Miller Sprayers in 2014, New Holland has had a unique front-mount boom design, and one was on display. Nicely engineered, I’ve always liked the concept of a front-mounted boom for better visibility of the things that matter. But again, there’s no recirculation. Did they consider it yet feel it wasn’t a high priority? We know that recirculating booms perform a waste-free prime while avoiding cleanout problems with boom-ends. These are important issues for applicators. I’m also curious why NH hasn’t gone to the Wilger boom components and nozzle bodies for IntelliSpray, since the Wilger tips are still the best choice for PWM.
Front-mounted boom on New Holland SP410F
John Deere’s newly named sprayers were at the show, the new models also offering improvements in operator comfort. The one on display was fitted with its recirculating boom, a nice addition to the feature set. Like the Raven retrofit kit, it appears to be designed with 200 gpm flow needs in mind, necessitating additional pipes and hoses that other systems avoid. Such high flows are very rarely needed except for 28-0-0 topdressing. Still, kudos for having a factory installed, controller integrated option.
AGCO showed off its Fendt Rogator and my heart went pitter patter as I approached it, recalling seeing its namesake at Agritechnica 2019. At the time, I felt it was one of the top sprayers at the German show owing to its innovative frame and suspension systems (independent wishbone), unique pump system (centrifugal pump that can run dry and never lose prime) and efficient plumbing. But this Fendt Rogator was a traditional Rogator frame with a Fendt tractor hood and cab to fool the passer-by. It’s no slouch, with optional four-wheel steering, adjustable clearance, and Liquid Logic recirculating booms. I felt cheated, nonetheless.
Fendt Rogator, sort of.
A visit to the Apache display showed why they remain a valid sprayer option. Built on mechanical two-wheel drive, they save weight and have better fuel economy than their hydrostatic counterparts. Yet, they still offer large tanks and aluminum Pommier booms when requested. Like most other brands, Pulse-width Modulation (PWM) is an available option. Personally, my soft spot for lighter sprayers is due to analysis of logistical efficiency–fill, clean and transport times. These create competent productivity values even with smaller sprayers that are more affordable to own and operate.
Light and nible Apache with strong Pommier aluminum boom
That led me to PhiBer Industries, creators of the DASH tender system. The family-owned firm from Crystal City, Man. creates custom solutions for hauling water and metering pesticides to sprayers. Thoughtful designs and use of air-driven product pumps with volumetric metering creates an efficient system that’s easy to understand and use. PhiBer joins existing products from Pattison Liquid, Free-Form Plastics or The Handler to offer a basic inductor and pump system. They will also build a complete custom trailer incorporating numerous additional features.
Phiber DASH tender system
Weed detection was shown by three exhibitors, but only one demonstrated it in action. Croplands had its field-proven green-on-brown WEEDit unit installed unit on a customer’s John Deere R4045, available for a test drive, as well as offering technical support at a booth. WEEDit remains the standard for green-on-brown and works very reliably out of the box. John Deere had an installed See & Spray Select, also green-on-brown, on a sprayer, but did not run it.
The most exciting new item sat at the Agrifac booth with their AiCPlus feature courtesy of Bilberry. Bilberry is a small French company, recently acquired by Trimble, selling green-on-green spot spray retrofits in Australia for over a year now. In Canada, they offer four algorithms at this time: green on brown for general burndown or desiccation; green-on-green for broadleaf weeds in cereals; grassy weeds in canola; and, both broadleaf and grassy weeds in corn. Powered by colour cameras and NVIDIA processors, continuous advancements in the software will improve performance as more weeds are added to its list of capabilities. Two AICPlus machines are running in Manitoba, and it’s good to see the company focusing on this market. John Deere and Greeneye, for example, are focused on the US row-crop market for the time being.
Weed detecting cameras and processors by Bilberry, featured on Agrifac AIC Plus
Perhaps the most ambitious spray technology was shown by Precision AI. Utilizing a large-fixed wing drone, the company aims to detect and spray weeds while operating at 60-to-70 km per hour. A hybrid power unit has an internal combustion motor that generates electrical power for rotors. This type of design offers significantly longer flight times than the 15 minutes currently possible with battery-driven units. Fascinating.
Precision AI concept spot spray drone, fixed wing with vertical take-off and landing
Spray drones also featured in the demonstration space at Ag in Motion despite the fact that this application method remains illegal for pesticides in Canada. It’s astounding what types of advancements each year brings. DJI is the global leader with three models available in Canada, including the 8-litre capacity T10, the 20-litre T20, 30-litre T30, and soon, the 40-litre T40. XAG, another leading manufacturer, showed a new two-rotor unit with rotary atomizers for excellent droplet size control. Flow management is nicely handled by accurate flow meters, but pressure sensors and displays are lacking in all units I’ve seen. Given that pressure is a big determinant of spray quality for hydraulic nozzles, that’s an oversight. We’ll continue to wait for this application method to be legal for pesticides in Canada.
XAG drone with two rotors and two rotary atomizers
As always, the show was full of old friends and catching up was welcome after the recent isolation. The opinions and advice from our peers play a big role in agriculture, where relationships and reputation still govern business alongside product features and cost. Trade shows are the perfect place for all of that to come together. Welcome back, old friend.
A version of this article was originally written by @nozzle_guy as a guest blog for Farm At Hand, and is reproduced with permission.
One of the smartest decisions a grower could make is to consider a late-season harvest-aid application. Particularly in years with thinner stands, weeds can maintain a foothold. Late season moisture can give new life to late emerging plants or branches. When the crop is ready to cut, this could mean all sorts of cutterbar, pickup reel, feederchain, and sieve headaches.
A desiccant or pre-harvest herbicide application can help avoid those problems. The challenge is to get the spray into, or through, a mature crop canopy. Here are some pointers to do it right.
Evaluate where within the canopy the spray needs to go to do its job. If you’re considering a pre-harvest herbicide, are you looking to control dandelions or buckwheat near the bottom of the canopy, or are you trying to get thistles or quackgrass, whose leaves are near the top? If you’re mostly trying to accelerate drydown with a contact product, where in the canopy are the green stems and leaves that you need to contact?
Take a bird’s eye view of your canopy. That’s how the spray sees it. If you can clearly see your target, the spray application is pretty straightforward because most droplets will make their way there easily. But if the target is obscured by a lot of foliage, or if it’s vertical, the job is much more challenging and will require some combination of more water, slower speeds, angled tips or finer sprays.
To hit plant parts that you can’t see, one of the main tools is finer sprays. The smaller droplets have an easier time changing direction to get around obstacles like leaves, and they are also much more likely to be intercepted by petioles and stems, and to stick to them. This can be both an advantage and disadvantage – for example, the awns in bearded cereals are notoriously effective at capturing the smallest droplets before they can do any good further down. If you don’t want to install a different nozzle to get a finer spray, simply increase the spray pressure of your low-drift nozzle to 80, 90, even 100 psi. This will create enough fine droplets. But don’t expect the higher pressure to push the spray into the canopy. Only air-assist can do that.
To get more spray deeper into the canopy, slow down, add water, and point nozzles backward. The backward orientation helps offset the forward travel speed, giving the droplets a slower net forward velocity that helps their downward movement.
If you’re using contact products like diquat, paraquat, saflufenacil or carfentrazone, use generous amounts of water, and slightly finer sprays. Make sure that spray drift control remains a priority and pay attention to water quality.
Test your water and make sure your water doesn’t have turbidity (suspended clay or other organic matter), for glyphosate and diquat or paraquat, and hardness, for glyphosate. Aluminum sulphate can help get rid of turbidity in a pond, but it takes time (treat turbid water at least 24 to 48 h before you need it). If treating a storage vessel, expect a layer of sediment. Ammonium sulphate (AMS) and other water conditioners can remove antagonizing hard water ions like magnesium and calcium. This is especially important as we increase water volumes with glyphosate to get better coverage. The higher water volumes give a concentration advantage to the hardness minerals.
Diquat and paraquat’s mode of action benefits from being applied in the evening. The absence of the sun allows it to be taken up and slightly moved (by diffusion, not true translocation) within the leaf before morning sunlight activates it. Once activated by the sun, these products exert their activity and movement stops. If you’re not careful, the tighter window of evening-only applications could get you behind. And of course, be aware of the signs of inversions and know when to quit.
Plan ahead and make sure you give yourself enough time, because to do the job right you’ll be using more water and driving a bit slower. Focus on productivity tools like a fast, efficient fill to make up the lost time.
A good job with a pre-harvest herbicide or a harvest-aid can save many harvesting headaches, and can help dry down during less than ideal conditions. It’s another reason why the sprayer may be the most important implement on the farm.
