Main category for all sprayers that are not horizontal booms
In this, the season three finale of Exploding Sprayer Myths, we join Jason and the Tom-inator as they “tackle” airblast air settings. There are a whole suite of articles dedicated to this topic, linked below the video. It is, arguably, the most important adjustment you can make to an airblast sprayer.
Will there be more Exploding Spray Myths episodes? In the words of a great man: “We’ll be back.”
Special thanks to Don Murdoch and the Simcoe Research Station.
It’s a rainy Friday in 2017 and I decided to deal with the articles, factsheets, manuals and other sprayer-related documents that have been piling up on my desk for a year.
My filing strategy is based on some advice I got from Dr. Bernard Panneton (Application Tech Guru) back in 2009. He said to read each document and then file them according to content, not by author or date. That way when I need something, I can search up the subject and find everything that might be relevant. More than 1,200 files later, the system works. No Dewey Decimals in my office, thank you.
What I’ve noticed as I sift through this eclectic pile of wisdom, is that many of the application methods I experiment with, or generally promote, are rarely entirely novel. Crop protection has evolved considerably (think pulse width modulation, crop sensing and remote piloted aerial application systems), but the fundamentals of spraying haven’t changed that much.
Case in point.
I just found a photocopy of a 1906 book called “Ginseng – It’s Cultivation, Harvesting, Marketing and Market Value, with a Short Account of Its History and Botany“. Great title. We obviously appreciated florid language in technical manuals 100 years ago. Here’s an excerpt that caught my eye:
“When applied to plants, the finest nozzle obtainable must be used. The Vermorel is perhaps the best. Now make no mistake: this spray must be a spray, not a dribble, nor a drizzle, nor a squirt, but a mist. It must look like a little fog at the end of the hose and must reach every part of the plant, particularly the undersides of the leaves, mind, just enough so it won’t trickle off.”
Poetry. And to make my point, it’s similar to what I’d tell a ginseng grower today. Granted, I’d lead them into a lower-range-of-Medium droplet size and help them achieve the described coverage using drop arms. But what on Earth is a “Vermorel nozzle”? That’s not one I have in my motley collection.
I turned to Virginia Tech’s Museum of Pest Management. I hope they’ll forgive me for lifting their content, but it’s too wonderful not to share. They note the contributions of Charles Valentine Riley. Born in London, England in 1843. He was a multi-talented Renaissance man. He was a pioneer of entomology in the United States and is often referred to as the founder of biological control in America.
Two of his greatest contributions to pest management included founding the field of biological control and the invention of the Riley spray nozzle (1889). The Riley nozzle was sold as the Vermorel nozzle. It produced a fan pattern and was the primary nozzle used in pesticide application in the United States and Europe well into the 20th century. The auspicious Mr. Riley died in a bicycle accident in 1895.
It was Riley’s nozzle, and the invention of some other early European pesticide application devices, that inspired W.B. Alwood (publisher of orchard spraying techniques c.1899) to import these devices and adopt them to Virginia conditions. The rest is history.
I tell you this because of what I found beneath the book touting the Vermorel; A 2015 TeeJet brochure for their TXVK hollow cone nozzles. I’m aware that the engineering behind the TXVK molded poly body and ceramic orifice is considerable compared to the humble Vermoral. But on closer inspection the fundamental designs aren’t so different. That realization both surprised and pleased me and compelled me to write this article.
I’m not certain what my point is. I suppose it’s just good to be reminded that the next time you want to invest time, money and effort into a “new idea” you might consider a little historical research. Odds are, you’re not the first person to recognize the problem, or propose a solution. A little time in the archives also instills respect for those that were there first. Let’s not waste time repeating their efforts, but stand on their shoulders and advance what they’ve already pioneered.
And if anyone has one of Riley’s Vermorel nozzles, I’d love to add it to my collection. Drop me a line.
We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run.
–Amara’s Law of Computing
We tend to overestimate the effect of a stewardship mistake in the short run and underestimate the effect in the long run.
–Wolf’s Adaptation of Amara’s Law to Agricultural Stewardship
August 9, 2017
Since June of 2017, we’ve been hearing reports of widespread dicamba damage symptoms in soybeans throughout the US mid-south and midwest. It appears that millions of acres could ultimately be affected, and yield impacts are unknown at this time.
For those new to the issue, dicamba is a broadleaf herbicide in the Group 4 mode of action group, a benzoic acid. It’s an important tool for herbicide resistance management for weeds like palmer amaranth (Amaranthus palmeri) and waterhemp (A. tuberculatus), populations of which have become resistant to Group 2 (ALS inhibitors), Group 5 (triazines), Group 9 (glyphosate), Group 14 (PPO inhibitors) and Group 27 (HPPD inhibitors) in some places.
Dicamba is a volatile herbicide, discovered in 1942 and first registered in the US in 1967. Its primary use was in corn and other cereal crops, lawns, and rights of way, at comparatively low doses, and relatively early in the season.
Calling a pesticide volatile means it can evaporate after application, either from a liquid or a dry deposit, for hours or sometimes days after application. The resulting vapor cloud can move unpredictably, depending on atmospheric conditions, and affect plants long distances away. Higher temperatures increase vapor loss.
Starting this year, dicamba-tolerant soybeans and cotton (Xtend varieties) were sprayed with new lower-volatility formulations of dicamba, XtendiMax, Engenia, and FeXapan, to control certain broadleaf weeds (including the Amaranth species above) without harming the soybeans. Problem is, dicamba can harm non-Xtend soybeans and other plants, even at very low doses. And these registrations were for applications that occurred later in the season, at higher doses than before.
I usually don’t get involved in people’s decision about whether to spray, or what to spray. But I do get involved when it comes down to how to spray. That’s my job. The real question to me is “can this product be used safely in cotton and soybeans?” Right now, the jury’s out on that one.
In my business, our guiding principles are what some people have called the “Three Es of Application”, Efficacy, Efficiency, & Environment.
We use sprays to control pests. That’s the only reason. We have to apply them so that they work, or else it’s a wasted effort. That’s the efficacy part. We also need to use our resources, time, money, etc., efficiently so the whole process doesn’t bankrupt us and we have time left for other important tasks. That’s efficiency. And finally, we need to protect the environment, and that means making sure the product lands where it’s intended.
None of these three priorities trumps the others. All need to be met to the best degree possible. And due to ever-changing conditions, we will typically change our approach to emphasize one or two of these three over the others, to have a working system.
Simply put, pesticides belong on target surfaces covered by the swath of the sprayer, and nowhere else. If they do move elsewhere (something we’ve come to view as inevitable), regulators conduct risk assessments to ensure that this movement does not result in harm. If harm is possible, mitigating tools such as application timing, product rate, spray method, and buffer zones may be imposed. If those tools aren’t enough to ensure safety, regulators deny product registration. That’s their job.
But even if no harm is done by trespass, the products still need to be on-target. That’s stewardship. It’s a principle whose adherence gives license for a technology to be used. It gives others faith in our competence. Practicing this principle when it’s easy prepares us for hard times.
I respect our regulatory process, and know it to be increasingly conservative with regards to risk the less data there are. I worked for the PMRA (the Canadian pesticide regulatory agency) as an application expert for five years. I know the system isn’t perfect and can make mistakes. I know the system can be political. Usually it’s by being too careful. With dicamba, it looks like the opposite happened.
The reason we’re seeing dicamba leaf cupping everywhere isn’t because all applicators suddenly forgot how to spray. They didn’t suddenly get reckless. They didn’t wilfully ignore all the training that the dicamba manufacturers and state and provincial governments developed in preparation for the product launch.
Instead, dicamba drift reports arose from a combination of extreme sensitivity and easily identified symptoms, as well as an unexpected (by some) amount of vapor drift. Even good applications appeared to create problems. Despite warnings from local experts, regulators and registrants didn’t see it coming.
Experienced agronomists have suggested that the observed dicamba trespass of 2017 implicates both temperature inversions and vapor drift. And although the new product labels advise against spraying under inversion conditions, they don’t say a word about vapor drift, the conditions that give rise to it, or how to protect against its occurrence. Not one word. I’ve searched the Xtendimax, Engenia and FeXapan labels. Nada.
Seems that the regulators and registrants felt confident enough in the reduced volatility of dicamba, based on their internal empirical data and modeling, that they didn’t need to mention it on the label. Calling that a mistake is an understatement.
I’d call it the biggest spray application misplay I’ve ever seen.
A part of the problem may be the enormous scale on which this new use of dicamba was introduced, over 25 million acres of Xtend crops. Scale-up errors are common in many industries. Emergent properties related to scale can’t readily be predicted by empirical data and models. Especially when the underlying data are scant.
So what to do? The continued success of agriculture depends to continued access to safe crop production tools. Irresponsible use threatens that. And by irresponsible use, I don’t just mean application. I also mean registration, promotion, sale, and support. The whole stewardship package.
When problems occur, we need to be quick on our feet to acknowledge them, to support those affected, and to try to understand the cause and prevent the situation from continuing or getting worse.
The current industry response appears to be the exact opposite. What I’ve seen is full of denial, downplaying, innuendo, blaming, and entrenchment.
Why is such an important issue in pesticide stewardship handled so poorly?
The immediate victims of this situation are the producers that depend on new technologies. But the long-term victim is agriculture as a whole. The lack of humility and leadership by many of the proponents of this technology, those with no small financial stake in its continued use, hurts not just them, but all of us involved in farming. This is not stewardship. It’s not license. It’s short sighted and reckless.
Over my career, spray application has generally become safer for the operator and the environment. A big part of our success has been the adoption of low-drift nozzles, the de-facto standard for modern pesticide application. The development of less toxic and less persistent pesticides has also been very important. We can avoid a lot of problems with good chemistry. I’ve been proud to tell this story.
I want to stay proud of our story. And in this case, that requires admitting to mistakes that were made and taking corrective action that is in the best interest of our entire industry. Agriculture will persist longer than company brands and titles. It takes priority.
It’s still too early to fully understand all the reasons for the widespread dicamba damage. But it’s not too soon to say that much of this could have been prevented with a smaller rollout, with greater collaboration with government and university experts during registration, and with more honest information on dicamba volatility on product labels. Call it Volatility Humility.
We’ll all pay for the mistakes that were made. We’ll likely have more stringent and expensive registration protocols. More restrictive application parameters. Strained relationships. More distrust of agriculture.
And as always, an ounce of sweet prevention would have been much better than the pounds of bitter cure that will surely be required to make this right.
Some of our biggest struggles in spraying involve the start and end of each spray day.
When starting a new field after the sprayer is cleaned, we need to prime the boom. If it’s full of water, that water has to be purged and the question is always for how long and where to do this (pro tip at bottom of article).
At the end of the day, we should ideally clean the sprayer. During that process, we may struggle with waste disposal, including large rinsate amounts, and course, the uncertainty of whether the job is actually done (since clean water looks exactly the same as contaminated water).
If not cleaning the entire sprayer plumbing, we should at least rinse the boom, even if we’re returning to the same product the following day. It can prevent future problems.
These tasks are complicated by the increasingly convoluted plumbing featured on modern sprayers. Ask someone to explain their sprayer’s plumbing system to you one day. It’s a long story! A bright spot is the well-engineered, compact, and accessible Agrifac system.
Fortunately, virtually any sprayer can be modified to suit your needs. Let’s talk about a few ideas for a winter project:
A word about dumping the tank on the ground. It’s a bad practice for many reasons. Let’s examine just one of those. When you spray a product at 10 gpa, you actually cover each square meter with about 10 mL, or 1/3 oz, of spray mix. When you flush your boom ends on the ground, you’re probably dropping 2 or 3 gallons in the same area. That’s 1000 times the label rate at each boom end, 10 to 26 times per boom. If you dump your tank remainder and all the hoses, say 20 or 30 gallons, that’s 10,000 times the label rate if it covers 1 sq meter. That’s leaching, runoff, residual potential, and not a good story.
Many of the changes we outlined above help prevent that from being necessary.
Pro Tip: To find out how much water your plumbing (from the pump to the boom ends) holds, do this: After cleaning with water and before spraying an EC formulation (white milky appearance in tank, some crop oils are ECs) reset your sprayed gallons on your rate controller. Start spraying and watch for the last nozzle on your furthest and longest section to spray white. Stop spraying and check your sprayed gallons. That’s your volume. No matter the size of nozzle or application volume, it stays constant. To be sure the boom is primed with a new mix, spray until those gallons are reached and you’re set.
Not being able to finish a tank due to weather or any other reason happens to just about everyone. Is it OK to simply leave the sprayer as is, and resume spraying later after some agitation?
In many cases, the answer is yes. Most pesticide mixtures are stable in short term storage. On resuming spraying, an agitation could be all that’s needed to get back to where you started a day or so earlier.
But there are three important exceptions.
When the active ingredient is formulated as a suspension. Suspensions are typically wettable powders and flowables, and rely on a clay carrier to distribute the active in the tank. Because clay is denser than water, these formulations settle out quickly after agitation stops. Sure, they can be brought back into suspension with vigorous agitation. But in lines and booms, boom ends and screens, dislodging a settled clay carrier is much more difficult. It’s also hard to tell if the cleaning has been successful because the problem spots are hidden.
The best solution is to flush the spray boom with water before materials can settle and lodge. A visual inspection where access is possible, such as strainer bowls and boom ends, is part of the process to ensure the formulated product has been removed.
Learn to identify which formulations are suspensions. There’s lots of jargon out there. Look for terms such as DC, DF, DG, DS, F, Gr, SP. Even EC formulations are suspensions (oil in water) and require agitation.
When the active ingredient is chemically unstable. Some pesticides can degrade in the tank, usually due to alkaline (high pH) hydrolysis. The effect is very pesticide specific, but in general, insecticides (particularly organophosphates and carbamates) are more susceptible than other pesticides. This fact sheet by Michigan State University describes the impact of pH on a the half-life of a large number of pesticides.
Note that in the examples in the MSU fact sheets, pesticide half lives are typically days and weeks, and only rarely hours. Also note that while high pH is most often problematic, low pH can lead to faster breakdown in a small number of products.
Ensuring tank mix stability requires a pH meter or paper, and possibly a pH modifier such as citric acid. But do your research first! Here’s an article on pH and water quality.
When the tank previously contained a product known to harm the current crop. This situation is most common and most difficult to address. Some examples from western Canada are Group 2 modes of action sprayed prior to a canola crop. Why are Group 2 products implicated? Many are formulated as dry products on a clay base, and these can settle in boom ends, adhere to tank walls, or get stuck on screens. Their solubility is pH dependent, as we explain in this article.
Canola is particularly sensitive to this mode of action, and the most common canola herbicides, Liberty and glyphosate, are formulated with strong detergents that act as tank cleaners.
Even when applicators think that their tank is clean, they can’t actually be sure and can’t do much about it at that stage. The stripping of tiny amounts of residue off the tank walls, filter screens, or plumbing, can happen during a mid-day stop or an overnight break. Applicators eventually find out that this happened, usually about two weeks after spraying.
Our advice is:
After spraying a herbicide to which a subsequent crop may be sensitive, with the classic case being a Group 2 and moving to canola, be extra diligent with cleaning and pay attention to the tank walls, all screens, and boom ends.
The best way to solve issues is to avoid them in the first place. If the weather looks unsettled and may interrupt your spray operation, consider mixing smaller batches that can be sprayed out completely even if conditions change quickly. This allows you to rinse the tank and spray water through the boom, thus avoiding a contamination problem developing overnight.
If that’s not possible, at least do not let a tank mix sit in the boom overnight. Instead, use your clean water tank to push water through the boom prior to storage and double check the screens. The following day, prime the boom with your tank mix as usual and resume spraying the crop.
If you’re not sure that your sprayer can draw from the clean water tank and push through the booms (the wash-down nozzles are, after all, the intended destination for that water), decipher your system and add the necessary valves that make this possible.
A useful design that helps flush and prime a boom quickly is the recirculating boom offered by some aftermarket boom manufacturers. These booms are also more common on European sprayers. A nice feature of such designs is that the tank contents can be pumped through the entire boom assembly without actually spraying. This ensures that the boom is primed without any soil contamination. It also dilutes whatever residue there may be in the boom plumbing with the entire tank, likely reducing its concentration enough to be of little concern.
An additional feature of recirculating booms is that many offer stainless steel tubing throughout most of their feed and return length, minimizing the black rubber hose products that often adsorb, and later release, herbicide contamination.
Even if a wholesale boom or sprayer change is impractical, consider switching to steel boom lines and tanks tank to minimize residue carryover.
As is often the case in the spraying business, prevention is easier and less costly than solving a big problem later. Spray mix storage is one of those examples where a small amount of extra effort at the beginning can pay big dividends later.