This article is based on a presentation by Dr. Melanie Filotas, who delivered it as part of the 2019 agriculture summer student orientation day.
Most crops are sprayed with organic or synthetic pesticides at some point during the growing season. Use caution before entering any area where crops are grown (e.g. corn field, nursery, greenhouse, orchard etc.). Always confirm that it is safe to enter.
Most crops receive some form of chemical input during growth. Be aware of what has been applied.
Even organic operations apply controlled products that may make it unsafe to enter for a period of time.
You can be exposed to pesticides if you enter a treated area before pesticide residues break down and vapours dissipate. The minimal time that must elapse before being permitted to enter is called the Restricted Entry or Re-entry Interval (REI).
REIs are data-driven and established by the federal government. They are defined as: “The period of time that agricultural workers, or anyone else, must not do hand labour in treated areas after a pesticide has been applied.” Hand labour can be any task involving substantial contact with treated plants, plant parts or soil, including planting, harvesting, pruning, and scouting.
Things you should know about REIs:
REIs can range from one hour to several days
If a pesticide label does not indicate a REI, the default is 12 hours
REIs can vary with the product, crop and type of activity (e.g., scouting, harvesting, etc.)
REIs can change over time so always refer to the most recent label
If a tank mix (multiple products) was applied, observe the most restrictive REI
Before visiting an operation to work in the field:
Tell your supervisor where you will be that day
Ask the grower or spray applicator what was sprayed. Records may be posted, but verbal confirmation is preferred
Look up the REI for the product on the crop you will be entering
Check with your supervisor on any products with special instructions beyond the REI
Do not enter the field until the REI has ended. Pesticide REIs can be found in local production guides, or on pesticide labels.
Local production guides summarize REIs.Local production guides list REIs by crop, by product applied, and by activity.
Miscommunication can sometimes happen. Learn to recognize the signs of spraying. When in doubt, leave the planted area and call the grower to confirm or call your supervisor.
In some cases you can look for fresh tracks in the operation, but be aware they may not have been made by a sprayer
Some products have a distinctive odour
It can be difficult to see a sprayer operating, particularly in orchards, but they can be heard. Do not wear earbuds or headsets while in a production area
Look for foliar residue. This is an indicator, but does not always mean it is unsafe to enter
Fresh wheel tracks may indicate recent spraying.
Some products have a distinctive odour.
It may be difficult to see a sprayer operating in the vicinity, such as in this orchard. However, they can often be heard. Do not wear a headset or earbuds in a production area.Residue on leaves may indicate a recent application, as in the left photo. However, it could also be unrelated. On the right is calcium magnesium precipitation from irrigation water. (Photo credit [right]: Jennifer Llewellyn)
There are many potential symptoms of pesticide exposure: headache, fatigue, irritation of the skin, eyes, nose or throat, loss of appetite, dizziness, nausea or vomiting, diarrhea, decreased muscle coordination, and blurred vision. Each product has a Material Safety Data Sheet (MSDS) that will provide details on exposure symptoms and treatments.
While sometimes confused with symptoms arising from sun stroke or dehydration, if you suspect pesticide exposure it is always best to be prudent and get medical help immediately. Contact your local poison centre or 911.
Summer work in crop production can be rewarding and enjoyable, but always use caution and be safe.
This article was co-authored by Kristy Grigg-McGuffin, OMAFA Horticulture IPM Specialist
In view of the frequent heavy rains in many regions this season,
understanding rainfastness, or the ability of a pesticide to withstand
rainfall, is important to ensure proper efficacy. All pesticides require a
certain amount of drying time between application and a rain event. Typically,
residue loss by wash-off is greatest when rain occurs within 24 hours of
spraying. After this point, the rainfastness of a product will depend on
formulation, adjuvants and length of time since application.
Rainfastness of Insecticides
John Wise, Michigan State University has studied rainfastness of common tree fruit insecticide groups and his findings are summarized below. For the complete article, refer here. Note that some products listed in this article may not be registered for use in Canada. Check with your local supplier or in Ontario, refer to OMAFA Publication 360 for a complete list of registered products.
According to Wise, the impact of rain on an insecticide’s
performance can be influenced by the following:
1- Penetration
Penetration into plant tissue is generally expected to enhance rainfastness.
Organophosphates have limited penetrative potential, and thus considered primarily surface materials.
Carbamates and pyrethroids penetrate the cuticle, providing some resistance to wash-off.
Spinosyns, diamides, avermectins and some insect growth regulators (IGR) readily penetrate the cuticle and move translaminar (top to bottom) in the leaf tissue.
Neonicotinoids are considered systemic or locally systemic, moving translaminar as well as through the vascular system to the growing tips of leaves (acropetal movement).
For products that are systemic or translaminar, portions of the active ingredient move into and within the plant tissue, but there is always a portion remaining on the surface or bound to the waxy cuticle that is susceptible to wash-off.
2- Environmental persistence and inherent toxicity
Environmental persistence and inherent toxicity to the target pest can compensate for wash-off and delay the need for immediate re-application.
Organophosphates are highly susceptible to wash-off, but are highly toxic to most target pests, which means re-application can be delayed.
Carbamates and IGRs are moderately susceptible to wash-off, and vary widely in toxicity to target pests.
Neonicotinoids are moderately susceptible to wash-off, with residues that have moved systemically into tissue being highly rainfast, and surface residues less so.
Spinosyns, diamides, avermectins and pyrethroids are moderate to highly rainfast.
3- Drying time
Drying time can significantly influence rainfastness, especially when plant penetration is important. For instance, while 2 to 6 hours is sufficient drying time for many insecticides, neonicotinoids require up to 24 hours for optimal penetration prior to a rain event.
4- Adjuvants
Spray adjuvants that aid in the retention, penetration or spread will enhance the performance of an insecticide.
The following tables can serve as a guide for general rainfastness to compliment a comprehensive pest management decision-making process. They are adapted from “Rainfast characteristics of insecticides on fruit” by John Wise, Michigan State University Extension.
Based on simulated rainfall studies to combine rainfastness with residual performance after field-aging of various insecticides, including carbamates (Lannate), organophosphates (Imidan, Malathion), pyrethroids (Capture), neonicotinoids (Assail, Actara, Admire), IGRs (Rimon, Intrepid), spinosyns (Delegate) and diamides (Altacor), Wise recommends the following re-application decisions for apples. Additional work was done on grapes and blueberries; see Wise’s article for this information. Among the crops, variation in rainfastness of a specific insecticide occurs since the fruit and leaves of each crop have unique attributes that influence the binding affinity and penetrative potential.
½ inch (1.25 cm) rainfall: All products with 1-day old residues could withstand ½ inch of rain. However, if the residues have aged 7 days, immediate re-application would be needed for all products but Assail, Rimon, Delegate or Altacor on apples.
1-inch (2.5 cm) rainfall: In general, most products would need re-application following a 1-inch rainfall with 7-day old residues, whereas Delegate and Altacor could withstand this amount of rain on apples and would not need to be immediately re-applied. Some products such as Imidan on apples could withstand 1 inch of rain with 1-day old residues.
2-inch (5 cm) rainfall: For all products, 2 inches of rain will remove enough insecticide to make immediate re-application necessary.
It is important to note, not all products registered for the
selected pests were included in this study. Refer to Publication 360 for a
complete list of management options.
Rainfastness of Fungicides
There is no comparable research on rainfastness of fungicides
and few labels provide this kind of information. A general rule of thumb often
used is that 1 inch (2.5 cm) of rain removes approximately 50% of protectant
fungicide residue and over 2 inches (5 cm) of rain will remove most of the
residue. However, many newer formulations or with the addition of
spreader-stickers, some products may be more resistant to wash-off. Avoid
putting on fungicides within several hours before a rainstorm as much can be
lost to wash-off regardless of formulation. As well, there are exceptions to
the general rule in regard to truly systemic fungicides such as Aliette and
Phostrol.
The effectiveness of sticker-spreaders with fungicides is
variable and product/crop specific. Penetrating agents don’t help strobilurins;
in fact, some fungicide/crop combinations have been associated with minor
phytotoxicity due to excessive uptake. Captan, which is intended to stay on the
surface, is notorious for causing injury when mixed with oils or some
penetrating surfactants that cause them to penetrate the waxy cuticle. Consult labels for minimum drying times for
individual products and recommendations for using surfactants.
Annemiek Schilder, Michigan State University suggests the
following to improve fungicide efficacy during wet weather:
During rainy periods, systemic fungicides tend to perform better than protectant (or contact) fungicides since they are less prone to wash-off.
Applying a higher labelled rate can extend the residual period.
Apply protectant fungicides such as captan (Supra Captan, Maestro), mancozeb (Manzate, Dithane, Penncozeb) and metiram (Polyram) during sunny, dry conditions to allow for quick drying on the leaves. These types of fungicides are better absorbed and become rainfast over several days after application.
Apply systemic fungicides such as sterol inhibitors (Nova, Fullback, Inspire Super), SDHI (Fontelis, Sercadis, Kenja, Aprovia Top, Luna Tranquility) and strobilurins (Flint, Sovran, Pristine) under humid, cloudy conditions. The leaf cuticle will be swollen, allowing quicker absorption. In dry, hot conditions, the cuticle can become flattened and less permeable, so product can breakdown in sunlight, heat or microbial activity or be washed off by rain.
It happened three times this spring. As is often the case, I was contacted by growers who wanted help with herbicide application. In most of these calls, the discussion revolves around the proper choice of nozzles for a specific task, perhaps some questions on spray pressure, water volume and travel speed.
But these three were different. Instead of being seasoned applicators, all three were new to the business. And more importantly, they had done their homework by looking at product labels before calling.
Labels give us important information on product rates, crop and weed staging, mixing order, sprayer cleaning, and personal and environmental protection. They’re very valuable there. But they also provide application information, and that’s where the problems begin.
Perseverance Required
I have to commend my three clients: they showed great tenacity by actually finding application information on a pesticide label in the first place. This document is so mired in legalese protectionist language at the front that it discourages all but the most persistent.
And often, the application information comes in several parts, interspersed among other information. Mixing instructions. A little later, application. Somewhere nearby, buffer zones. Another paragraph for cleaning. Rainfastness? Keep looking.
It forces the reader to skim through the document, hunting for relevant information.
But once my clients found application instructions, they obviously questioned if they should believe it, or else they wouldn’t have called. The application statements on many labels, simply put, are from long ago, and it’s obvious.
Consider the following two label excerpts, the first from a product initially registered in the mid 1980s and still available, the second from one registered about 30 years later:
1980s:
Application should be made using a minimum of 55-110 litres of water per hectare, at a pressure of 275 kPa, or 310 kPa if using check valves, and at a ground speed of 6-8 kph.
The use of 80° or 110° flat fan nozzles is recommended for optimum spray coverage.
Do not use flood jet nozzles, controlled droplet application equipment or Sprafoil® equipment.
Application of the spray at a 45° angle forward and higher water volumes will result in better spray coverage and penetration of the crop canopy.
Uniform, thorough coverage is important to obtain consistent weed control. Higher water volumes should be used under dense crop and weed canopies to ensure thorough coverage of the target weeds.
2010s:
Apply in a spray volume of 46.8 – 93.5 L/ha unless otherwise specified in tankmix partner section of this label – at 207-345 kPa (30-50 PSI) pressure to ensure proper weed coverage.
Flat fan nozzles of 80° or 110° are recommended for optimum coverage.
Do not use floodjet or controlled droplet application equipment or Sprafoil® equipment.
Nozzles may be oriented 45° forward to enhance crop penetration and to give better weed coverage.
Uniform, thorough coverage is important to obtain consistent weed control. Higher water volumes should be used under dense crop and weed canopies to ensure thorough coverage of the target weeds.
Thirty years apart, but remarkably similar.
Crop protection companies spend about 10 yrs. and $250 million to produce a new pesticide and register it for use. Having made this commitment, it would be most useful to see a small further investment to provide current application information that is relevant to applicators.
After all, these applicators purchase the active ingredient to provide a return on this multi-million dollar investment, to the tune of about 2 billion dollars per year in Canada alone. They deserve good application information.
Imagine this scene:
“Doctor, thank you for this new high tech pharmaceutical engineered to help me with my serious illness. How should I take it?”
“Not sure. Here, read this cough syrup label I found in my drawer. Should be pretty close.”
It’s clearly ridiculous
Let’s dissect these labels to see how they could be improved.
Flat fan nozzles of 80° or 110° are recommended for optimum coverage…
Our sample labels refer to what we assume are conventional flat fan nozzles. While popular in the 80s, these have all but disappeared from sprayers over the course of the past 20 years or so. We haven’t recommended them since then because they drift too much. They’ve been replaced by low-drift nozzles, either pre-orifice, or air-induction.
Nozzle fan angles are now generally 110 degrees or more, and frankly, the difference between 80 and 110 degrees is not that important. What’s important is proper overlap, achievable with a visual assessment followed by boom height and pressure adjustments. Unfortunately the label is silent on that.
Application should be made … at a pressure of 275 kPa, or 310 kPa if using check valves…
A nozzle’s recommended operating pressure depends on the specific nozzle model and on the spray quality (average droplet size) required. With literally many dozens of nozzles now available to each applicator, general pressure suggestions are likely to be wrong, and are more of a liability than a help. And they force label non-compliance when over-ruled by a nozzle manufacturer’s recommendations.
Speaking of spray quality, growers crave to know at what spray quality a product should be applied for best performance and lowest drift. Some labels refer to spray quality (e.g. “apply with a Coarse spray”), but this is with reference to spray drift and buffer zone distances, not efficacy, and that distinction is not made. Knowing the right quality for efficacy would help applicators choose the right nozzle and pressure to meet that criteria.
Higher pressures if using check valves? Nobody has brass screens with check valves anymore. Sprayers have had modern diaphragm check valves for a generation, and those don’t produce pressure losses.
And we all know that six to eight km/h is hardly a common speed these days.
Do not use floodjet or controlled droplet application equipment or Sprafoil® equipment
Sprafoil nozzles have not been produced in Canada for about 25 years, in fact their manufacturer is no longer in business. Controlled droplet atomizers, while becoming more popular again on aircraft, were last seen on ground sprayers in the 1980s. Even then, total installed numbers were probably in the single digits.
As for FloodJet nozzles, those went out of style for herbicides in the late 70s, and were replaced by the very successful TurboTeeJet nozzles shortly after.
Nozzles may be oriented 45° forward…
Nozzles are rarely tilted 45 degrees forward for herbicide application anymore. Maybe that’s because spray booms aren’t built that way today, or because modern booms on self-propelled sprayers are now about 30” (75 cm) above ground, and we travel at about 15 mph (22 km/h). So the forward tilting, though shown to be effective for grassy weeds at 5 mph (8 km/h) and 20” (50 cm) boom heights, as researched in the 1970s, isn’t relevant for herbicides with higher booms.
Uniform, thorough coverage is important to obtain consistent weed control.
Statements advocating for good coverage are nice, but they aren’t useful. Everybody knows we want good coverage. What applicators need to know is how they should measure coverage, and what good coverage actually is. Can we use water-sensitive paper? How much of the target should be covered? How many droplets should be in each square centimetre? How can we measure that in the field, right now? How does it depend on the crop canopy, on weed stage, and on spray quality? The more information an applicator gets, the higher the chance of success.
Apply in a spray volume of 46.8 – 93.5 L/ha…
The only statement that survives our little examination is about water volume. Water volume is important. But even there we have a problem. The volume is in L/ha. This is useful in some parts of Canada, but not in the west, where producers communicate primarily in US gallons per acre. And in the west, provincial guidelines have generated this odd hybrid of L/acre, which few people use for spray volume. But 46.8 to 93.5 L/ha? How is that level of precision justified? (I know that this is a conversion from 5 and 10 US gpa…so why not just say so?)
A Solution
The problem with having outdated or impractical information on labels is that it creates disrespect. Since labels are documents enforceable by federal law, applicators want to comply. At this time, they can’t, and probably shouldn’t, if they want to do the job right.
A vision for a good label should be one that respects the needs of the applicator. Such a label:
places the information that applicators need at the top;
is updated regularly to reflect modern practice and useful advice;
helps a new applicator work out how to apply the product with any equipment;
identifies a spray quality that offers good coverage and low drift;
makes reference to research that supports variations in the application guidelines;
is available electronically, readable on a mobile device, i.e., not pdf.
This label would protect the environment and bystanders, and would foster better pesticide performance.
This label is easy to generate.
This label would be read by applicators.
What’s it going to take?
Additional:
This article created a great deal of discussion. We decided that if we were going to point out issues with the current labelling system, we should also propose a way forward. Read about our Label Summary Sheet proposal.
A Veteran Applicator’s Questions about Pesticide Handling
Time and again, after years of working with dozens of different chemicals, I would wonder to myself “How dangerous is this chemical?”, “Is glyphosate as safe as they say it is?”, “How do I find out what type of safety gear I need while handling this chemical?”
Beyond the agrichemical dealer, ag. consultants, and university or government ag. extension specialists, a quick internet search reveals many sources of pesticide information. Collectively they identify the active ingredient(s) in formulated products, they detail which pests are best controlled by the pesticide, and they provide instruction for application. But it’s more difficult to find consistent, practical information about safe pesticide handling. Sometimes it’s excessive to the point of being impractical (try finding actual “chemical proof” gloves), and sometimes it’s minimal and vague – it depends where you look. No matter the level of precaution, pesticide safety is time consuming and involves some fussing, but it is the hallmark of responsible pesticide use. Just as we ensure that we are applying “safe rates” when spraying chemicals, we must also ensure we are respecting our own well-being while handling chemicals.
In Canada, the Pest Management Regulatory Agency (PMRA) is charged with protecting human health and safety by monitoring pesticides that are sold in this country. According to the Federal Pest Control Products Act all pesticides sold in Canada must be registered with the PMRA. There’s a very nice overview of how that process works here. It is during this registration process that pesticide handling precautions are identified for the label. Further classification may take place under provincial acts.
All pesticides are designed to disrupt, repel, control or kill living organisms, but when it comes to safe handling, insecticides receive the most attention. This is because herbicides and fungicides target biochemical pathways that only exist in plants or fungi. However, most pesticides can be hazardous if they are not handled correctly. The handling precautions that appear on the label are based on five factors.
Five factors that affect handling precautions:
1. Pesticide Family
This factor is the broadest way to categorize potential risk to the handler. Generally, herbicides and fungicides are considered safer than insecticides, but there are notable exceptions. Do not rely solely on the pesticide family when making decisions on pesticide handling.
2. Pesticide Mode of Action
The mode of action gives further detail into how a pesticide should be handled. Modes of action that inhibit biochemical pathways that exist in the target pest, but not in mammals (people, in particular), have lower acute toxicities. Examples include herbicides that inhibit enzymes involved in amino acid synthesis or in photosynthesis – these enzymes do not exist in mammals. However, once again, there are always exceptions. Do not rely solely on mode of action when making decisions on pesticide handling.
3. Pesticide Formulation & Route of Entry
Pesticide formulation affects how a product can potentially be absorbed into the body. Emulsifiable Concentrates (ECs), for example, have higher rates of absorption than solutions or dry products. When it comes to the route of entry, dermal contact is considered safer than inhalation or ingestion. However, not all parts of your skin are created equal, and the point of dermal contact on the body matters a great deal.
4. Pesticide Toxicity
Taken collectively, the first three factors form the overall toxicity of the pesticide. The level of toxicity cannot be predicted – it has to be tested. The LD50 (defined below) values that are reported for a pesticide come from standardized experiments such as animal feeding. Although the chosen species (usually white rats for mammalian endpoints) are known to be similar to humans in their response, there is still the possibility of error. Nevertheless, toxicity forms an important basis for establishing handling precautions.
5. Operator Exposure
People handle toxic substances every day. Household bleach, for example is surprisingly toxic, and yet it can be readily found on kitchen shelves in many homes. The risk of being harmed by a toxic product can only be determined by the likelihood of exposure. While it is possible someone might accidentally consume a hazardous dose of bleach, it’s improbable. Exposure does not just refer to a single exposure to a substance – repeated exposures to small doses of a toxic substance can have a cumulative effect. The goal when handling any pesticide is to minimize exposure, but it becomes even more critical when that pesticide is highly toxic. Together, exposure and toxicity form the basis for risk.
Risk = Hazard x Exposure
Studies have shown that exposure is greatest for handlers of agricultural pesticides during the mixing and loading phase of spraying. During this phase, the risk to the handler may be increased due to:
physical stress
the denial of risk
a negative opinion of personal protective equipment (PPE)
The main method of pesticide exposure is dermal, and many of the surfaces on a piece of equipment are already contaminated.
Health effects of pesticides: Acute and Chronic
Acute: short term
High exposure, resulting in immediate reaction due to a high dosage of pesticide exposure. The severity depends on the toxicity of the molecule and entry into the body (dermal, oral, eyes, etc.). The most common acute reaction is skin irritation, although in certain cases respiratory, digestive, and neurological systems may be affected. Organophosphate (e.g. Lorsban, Malathion) and carbamate (e.g. Sevin, Lannate) insecticides inhibit the cholinesterase enzyme, which is found in humans and affects nerve function. Frequent users of these insecticides undergo regular blood tests to ensure their levels are normal.
Chronic: long term
Chronic affects are more prolonged as they are usually due to lower doses of pesticide exposure over a longer period of time. Although some rare cancers and disruption of the reproductive system have shown to be related to this type of exposure, when the general population and farming population have been compared in studies, the farming population has shown an under-representation in the majority of cancers. In the cases were reproductive malfunctions were observed, a different cause of the malfunction, such as genetic offset, was most often observed in these situations. However, cancer types such as skin cancer and brain cancer were overrepresented in the farming community. A study in France has shown that the onset of neurological disorders in Agriculture communities shows a strong connection between Parkinson’s disease and exposure to pesticides.
Label Information
The majority of information needed to safely handle pesticides is found on the label. Pesticide labels are legal documents, meaning they can be enforced by the federal government. The problem is that most sprayer operators rarely look at the label as they are not very reader friendly and easy to skim through. Most pesticide boxes even have the recommended rate, or acres/case on the side of the box now, so there is even less reason to look at the label.
LD50– the dose of pesticide in mg per kg of the test animals body weight that is lethal to 50 percent of the group of test animals. For example, if the pesticide has an acute oral LD50 value of 1000 mg/kg, and the test animals each weigh 1 kg, then 50 percent of the animals would die if they each ate 1000 mg of pesticide at once. A 100 kg animal would need to ingest 100,000 mg (100 g) of the pesticide for the same effect. LD50 is often expressed by the route of entry – dermal, inhalation, acute oral (ingestion) are the main examples.
Degree of Risk and Hazard Symbols
The appropriate PPE for a job is determined by two factors
The Hazard Rating (above) incorporates the minimum protection generally required for a substance with the rating.
The Label Recommendations will usually give the additional specific protective clothing and equipment needs for an applicator.
Degree of Exposure
This increases as the length of each pesticide application increases. As the number of pesticide applications increases, the time between exposures decreases. If an operator becomes exposed to spray, dust or fumes the degree of exposure increases. Essentially, more protective wear is needed as the degree of exposure becomes greater.
Knowledge
This encompasses all of the above information. In order for a pesticide applicator to avoid injury or the chances of adverse effects on the body, a pesticide applicator must be knowledgeable about pesticides. It can be overwhelming for an applicator to sort through all of the information on the label or on-line regarding pesticides. So much so, that most often applicators avoid the information altogether. Ongoing training and learning will ensure that they are effective in their work. Many aspects of pest control change continuously, as new studies are conducted on the effects of pesticide exposure.
The Material Safety Data Sheet (MSDS) is available for all pesticides registered, and these are usually linked on manufacturers’ websites. It can be eye-opening what types of toxicity tests are done, and what the results are.
Denial that pesticides can potentially cause harm is also a major flaw in the behaviour of applicators. Maintaining a safe work environment and practicing personal safety will reduce the chances of an applicator experiencing serious injury throughout their farming career.
Unknowns
There is very little certainty in toxicology. For one, most testing is done using acute oral and dermal dosing. Basically, toxicologists expose test animals to the neat active ingredient and watch what happens. There is a lot of missing information – what about formulant like solvents, and surfactants? What about synergies in tank mixes? Some, but not all of these, undergo testing. We also have much less information on chronic (long-term) effects, and can only simulate these in quasi long-range tests. In addition, toxicological methodologies and statistical approaches can vary, and we should not be surprised that some reports disagree, and that there are outright conflicts between toxicologists and epidemiologists (scientists that study patterns of health in populations). Regulators are aware of these shortcomings and often use safety factors to account for them. But those of us that use these products regularly, the message is simple: be cautious, and protect yourself.
Avoid Cross-Contamination
Disposable nitrile gloves are the product of choice for handling pesticides. But one of the most common problems with the use of gloves is cross-contamination. You’re handling product with your gloves on, touching containers, hoses, valves, and couplers. When you’re done, you climb back into the cab where you take off your gloves. Later, someone climbs up into the cab to talk to you, using the railing and operating the door handle without gloves. Guess what’s on their hands? Even later, you put away the hose without gloves and return to the sprayer. Now it’s on the steering wheel and all the levers. There are a few solutions:
Double-glove so you can take the dirty outside glove off and still be protected.
Wipe down surfaces that you might touch with gloved or bare hands daily.
If using non-disposable gloves, avoid lined gloves and rinse the insides out daily.
Learn More
If you would like to learn more about pesticide safety, or to obtain pesticide application training, the Pesticide Applicator Licence can be obtained from the Ministry of Agriculture. This course offers in depth, valuable safety information for applicators, as well as general knowledge for pesticide applicators. The Pest Management Regulatory Agency provides workers, employers, and the general public with a wide range of pesticide information. The PMRA can be contacted from anywhere in Canada toll free at: 1-800-267-6315
Download this Quick Reference Guide for commonly used herbicides. Print, laminate and post it at the fill station or pesticide storage area for easy reference.
Biopesticides are a rapidly growing segment in horticultural pest control. While they are often billed as green “miracle cures”, applicators should be aware that they require unique considerations. Issues with lifespan, target specificity, and application technology can all impact their efficacy. However, like any pesticide application, careful planning can minimize wasted time and money.
Typically defined as pesticides derived from “natural” sources, biopesticides contain active ingredients extracted from plants, microorganisms, animals, and/or certain minerals. Given their origin, and the fact that many biopesticides are living organisms (as is the case with most of the microbial-based pesticides), they are often photo-sensitive and quickly break down. This generally means that they need to be re-applied often.
Mixing and handling
Pre-suspending nematodes before inoculating the spray tank.
Consideration should also be given to the lifespan of these products during the application. Many have an optimum pH for both the carrier water and the soil, and a limited temperature range outside of which they may not be active. As already mentioned, direct sunlight can quickly degrade many biopesticides, which means they should be applied either early or late in the day. Timeliness is also a factor: efficacy can be greatly reduced if the product is not used quickly – many biopesticide organisms begin to break down as soon as they are tank mixed. Also, be aware that it can be difficult (or impossible) to find suitable tank-mix partners. For example, a fungal biopesticide obviously shouldn’t be mixed with a fungicide. That also leads the applicator to consider their spray program carefully and clean their sprayers thoroughly between applications.
Efficacy
Applicators should understand how each biopesticide is supposed to control (or more likely, supress) pests. Many biopesticides have to be ingested or physically contact the pest. As such, they often need high application volumes to ensure sufficient coverage of all target surfaces. Many are slow to control the pest, so the applicator may mistakenly think the product is not working, and reapply unnecessarily.
Application equipment
Cleaning a strainer – image courtesy of M. Lanthier.
Applicators may need to reconsider their current equipment when using biopesticides. If the product has to contact the pest, high droplet density is preferred. This can be accomplished with high volumes, but also with higher droplet counts, and that means smaller droplets. Drift issues aside, many biopesticides are actually living organisms (e.g. nematodes) which might be negatively affected by the small nozzle orifice.
The “Spray Guy”, Dr. Jason Deveau, (Application Technology Specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs) suggests using a nozzle with a larger exit orifice and no pre-orifice to minimize clogging or any potential damage to the microorganisms. Clogging can be further reduced by using a minimum of three levels of filtration on a sprayer. With proper agitation, a tank basket, suction filter at the pump and slotted strainers behind each tip should catch any “chunks”. In-line filters at the boom are also potentially helpful. Each filter, from tank to nozzle, should be filter smaller particles than the last. Cleaning screens diligently and inspecting the effectiveness of the agitation system, should be part of every spray day.
Applicators can account for many of these issues by understanding what the biopesticide is and how it is intended to work. Consider these questions:
When is the pest active/vulnerable?
Under what conditions does the product need to be used to be most effective?
Are there special handling or mixing considerations?
What do I need to have in place to minimize the time between mixing and applying the product?
Ultimately, an effective application of biopesticides relies on integrated pest management (IPM). Biopesticides can work as advertised when used thoughtfully and appropriately. Understanding the products benefits and limitations will ensure applicators reap the full benefits of these new and evolving methods of control.
