Tag: label

  • Operator Safety: How to Avoid Pesticide Hazards

    Operator Safety: How to Avoid Pesticide Hazards

    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 Pesticide Regulatory Directorate (PRD) 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 PRD. 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
    Degree of Risk and Hazard Symbols

    Two Factors that Determine the Appropriate Level of PPE

    1. The Hazard Rating (above) incorporates the minimum protection generally required for a substance with the rating.
    2. 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.

    A Safety Data Sheet (SDS) is available for each 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 License 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 Pesticide Regulatory Directorate provides workers, employers, and the general public with a wide range of pesticide information. The PRD 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. Also, grab a copy of Health Canada’s “Stay Safe when using Pesticides” factsheet.

    Sources

  • Basic Sprayer Math Demystified

    Sprayer math can be intimidating, but the effort gives solid value. When combined with a calibrated sprayer you reap the following benefits:

    • Estimate how long a job will take.
    • Estimate how much spray mix is required.
    • Estimate how much crop protection product must be ordered for the season.
    • Populate spray records which allow you to review practices, respond to enquiries and satisfy traceability requirements.

    There are many ways to perform sprayer math, and you need only look to local pesticide safety courses, industrial catalogues, and extension resource centres for examples. If you’re already comfortable with your current method, don’t mix and match with others. Sprayer math is a series of related calculations that employ constants to keep the units straight. It’s all or none.

    Walkthrough

    Let’s start with the classic, US Imperial formula for calculating the required nozzle output. In other words, you want to know which nozzle size you need to get the volume-per-planted area you’re aiming for. This is the bread-and-butter formula that seems to be needed most often, so that’s why we list it first.

    In order to determine nozzle size (gallons per minute), you’ll need to know your target volume (gallons per acre), your average travel speed (miles per hour) and your nozzle spacing (in inches). The number “5,940” is a constant that handles all the unit conversions. It is what it is.

    GPM = [GPA x MPH x W] ÷ 5,940

    Of course, this formula can be adjusted to allow you to solve for any factor, as long as you’re only missing one piece of information. Algebra is all about solving for X, or in other words, determining some unknown variable. I know, it’s been a long time since you learned this in school and it doesn’t come easily to most. I propose brushing up on the basics using a series of three great YouTube videos from “Mathantics“

    As we noted earlier, you can do a lot more with sprayer math than just pick the ideal nozzle. But before we continue, a warning: If you live where units are strictly US Imperial, or strictly Metric, then Canada’s odd hybrid “Mock-tric” units can get a little confusing. The rest of this article attempts to be globally-relevant by including examples of both Metric and US Imperial formulae, but watch out for unit conversions. If at any time you don’t see the units you’re looking for, you can consult our exhaustive list of unit conversion tables.

    Grab your calculator or favourite smart phone app – it’s math time!

    Don’t be intimidated. With a little practice, sprayer math gets easier and it’s always worthwhile. The real trick is navigating unit conversions.

    Step 1 – How large is the area you need to spray?

    Multiply the length of the area you plan to spray times the width. If you are using metres, then divide the product by 10,000, which is the number of m2 in a hectare (ha). For feet and acres, divide by 43,560 which is the number of ft2 in an acre (ac):

    Step 2 – How much product is needed to spray the area?

    Consult the rate(s) shown on the label. In Canada, rates are often based on planted area (E.g. hectares). In Australia and New Zealand, they may be based on row length (not covered in this article). If you measure your area in acres, you’ll have to convert the rate by multiplying by a constant: 0.4.

    product-per-area

    Now multiply the area you want to spray (step 1) by the rate (step 2).

    product-per-area2

    Step 3 – How far can you go on a full tank?

    You know your sprayer output (determined through calibration) so you divide that into your tank size. Watch your units:

    full-tank-distance

    Step 4 – How much pesticide per tank? 

    Multiply the area that can be sprayed per tank (Step 3) by the pesticide rate (Step 2). Again, watch your units:

    pesticide-per-tank

    Step 5 – How much area is left to spray?

    Just subtract what you’ve already sprayed from the total area.

    area-left-to-spray

    Step 6 – How much pesticide in the last, partially-full tank?

    Multiply the area you have left to spray (Step 5) by the pesticide rate (Step 2). Yes, watch your units:

    pesticide-partially-full-tank

    Step 7 – How much spray mix will I need for the partial tank to finish spraying the total area?

    Multiply the area you have left to spray (Step 5) by the sprayer output (determined through calibration). Guess what? Watch your units:

    spray-mix-for-total-area

    Sample problems

    Time to test your knowledge. Let’s suppose you want to apply a product rate of 3 L/ha to your blueberries. You calibrate your sprayer and determine your output to be 50 L/ha. Your tank holds 400 L of spray mix. Your planting is 500 m long and 200 m wide.

    Q1 – How large is the area you need to spray?

    area-to-spray

    Q2 – How much product is needed to spray the area?

    product-to-spray-the-area

    Q3- How much area can be sprayed on one tank?

    area-on-full-tank

    Q4 – How much product should be added to a full tank?

    product-needed-full-tank

    Q5 – After the tank is empty, how much area is left to spray?

    area-left

    Q6 – How much product to add to the last, partially full tank?

    product-partially-full-tank

    Q7 – How much spray mix will be needed to finish spraying?

    spray-mix-to-finish-spraying

    Exceptions

    Certain situations aren’t covered in this article. If you are spraying a greenhouse, the math is different. If you are performing a banded application, the math is different. And, if you’re an airblast operator trying to reconcile why a pesticide label uses planted area rather than canopy volume for its rates, you’re in for a lot of additional reading. Some of that latter process can be summed up in this infographic:

    When you find a method that works for you, write it down and keep it with your spray records. Happy spraying!

  • The Label Summary Sheet Proposal

    The Label Summary Sheet Proposal

    We’ve identified and discussed shortcomings in the content and design of today’s pesticide labels in an earlier article. From the perspective of the spray applicator, the information needed most often can be difficult to locate, anachronistic, contradictory, subjective or even missing from the label altogether. To truly encourage an applicator to read and follow the label we need a consistent, concise and clear format that summarizes critical content.

    To that end, we have worked with growers, university/government extension and industry to develop a prototype we’re calling the “Label Summary Sheet”, or LSS for short. We presented the concept in a series of public presentations in western Canada as part of the RealAgriculture TechTour Live event in 2018. You can watch a recording of part of that event at the end of this article.

    The LSS does not replace or interpret the current label, which is a legal document. It is a summary intended to accompany it. At this stage the LSS is simply a proposal. These documents are not intended for use right now; we hope they will grow and change for the better as they stimulate discussion.

    Consider this metaphor: You have just purchased a laptop. When you unbox it, you get an in-depth instruction guide that covers everything from operation to trouble shooting and includes all the legal riders. It’s a daunting technical document that you likely won’t read unless something goes wrong. Knowing that, manufacturers include a graphic and accessible quick start-up guide that summarizes the most common and critical issues. It doesn’t replace the instruction manual, it just augments it. If you can’t find what you need in the quick start-up guide, you are referred to the more fulsome description in the instruction manual. Think of the pesticide label as the instruction manual and the LSS as the quick start-up guide.

    Some agrichemcial companies recognize this need and have developed short documents to summarize key aspects of the label, but they are inconsistent and brand-specific marketing documents that do not always contain the information we are proposing. Here, for example, is the technology sheet for Integrity herbicide.

    We tested the versatility of our LSS format by summarizing four diverse pesticide labels. Our selections are not intended to imply that these labels are particularly deficient. Only that they are commonly used, somewhat complicated and represent the spectrum of pesticide categories and application methods.

    Download and look at the variety of labels we have summarized as examples. They are available here:

    • Pristine (LSS: 3 pages. Pesticide Label: 25 pages)
    • Dual II Magnum (LSS: 3 pages. Pesticide Label: 38 pages)
    • Liberty 150 (LSS: 2 pages. Pesticide Label 20 pages)
    • Traxos (LSS: 2 pages. Pesticide Label: 12 pages)

    Note that each LSS features the same section headings and a relatively consistent layout, no matter the manufacturer. Generic icons are used to illustrate content and make it easier for users to navigate without language barriers. The LSS are black and white to facilitate reproduction and refer back to their respective pesticide labels (i.e. the online PDF, not the booklets that come with the pesticides).

    LSS Sections

    Here is the Pristine LSS broken down by section to highlight the key features.

    1. Banner Section

    The banner is at the top of every LSS. It gives the commercial product name and the date to ensure the LSS reflects the current pesticide label. Four icons represent the most common application technologies: Horizontal boom sprayer, airblast, aerial and handheld. If an application method is prohibited, a banned symbol appears (such as aerial in this case). Note we have left room for RPAAS (UAV’s) anticipating the day we have products registered for that technology. The table notes the type of pesticide (e.g. fungicide, insecticide, adjuvant, etc.). The mode of action and active ingredient(s) are noted, as well as the formulation and the Pest Control Product number.

    2. Resistance Management / Planting Restrictions

    Intended to provide key information on managing pesticide resistance, this section reflects label content about carry over and the rotation of active ingredients. Further, to aid in application decisions, it reflects any restrictions around maximum number of applications, sequential applications or plant back issues following use.

    3. Environmental Conditions


    Any restrictions regarding weather conditions during or after application are noted here. This includes set-backs or buffer zones that reflect method of application and the nature of the adjacent or downwind area in question.

    4. Sprayer Settings

    This section includes the six most commonly asked questions an applicator has when calibrating or adjusting their sprayer prior to use. It is organized by target crop and method of application. When the label provides a high level of detail, the user is referred to the correct page. Note the use of graphics to quickly direct the reader to the information they need. Any additional qualifications found in the label relating to sprayer settings are indicated in the notes beneath the table.

    5. Handling Safety (PPE)

    The concept for this simple and graphic table originated in France, and was communicated to us by Dr. Carol Black of Washington State University. This unambiguous  format encourages the use of PPE while ensuring the handler uses the appropriate level of protection for each activity.

    6. Mixing


    As operators tank mix more products to curtail resistance, improve efficacy or improve productivity, there is a greater chance of chemical or physical incompatibility. This section summarizes any restrictions noted in the label. Learn more by downloading Purdue Universities’ publication “Avoid Tank Mixing Errors“.

    7. Rates and Restricted Entry Intervals

    This table can be quite complicated depending on the pesticide label. It summarizes the rates, volumes and restricted entry intervals by crop. It reflects the broadest range of product rates listed in the label. Restricted entry duration is affected by the post application activity, and this is captured in the REI column. If more detail is required, the user is referred to the appropriate page(s) of the label. Any additional qualifications found in the label relating to rates, volumes or REI are indicated in the notes beneath the table.

    8. Equipment Cleanout

    Finally, equipment cleanout is summarized (where possible) in a sequence of steps. When the pesticide label is silent on the cleanout procedure, the user is provided with the triple rinse protocol, which is generally held to be the industry best-practice.

    Adoption

    To date, this proposal has been made to Croplife Canada, the American Society of Agricultural and Biological Engineers (ASABE), an International Organization for Standardization (ISO) mirror committee (Equipment for crop protection) and more than 1,400 growers and stakeholders across Canada.

    Our suggestion for adoption of the LSS (in its current form or something similar)  is that regulatory agencies commission a working group comprised of representatives from grower groups, industry and government to oversee the process. The working group would support registrants as they populate (or update) the LSS template when a new product is submitted for registration, or as part of the natural review cycle.

    Should the registrant encounter duplicate, missing or contradictory information while completing the LSS, it should be considered an opportunity to remedy the problem on the pesticide label. This will clarify the safest and most effective use of the pesticide for the applicator, who is currently forced to selectively ignore or interpret such errors. To our minds, this was the intent of the original labelling system, and the inclusion of the LSS is a simple and effective way to achieve that goal.

    The Confusicol Sketch

    In 2018 we participated in Real Agriculture’s TechTour Live event that toured four major cities in Western Canada in four days. We presented the “Confusicol sketch” as a light-hearted way to open a discussion with the audience on the strengths and weaknesses of Canadian pesticide labels and how the Label Summary Sheet might be a viable supplement. Here’s one of the live takes, warts and all. Turns out live sketch comedy is tricky…

  • How Canadian Crop Protection Products are Assessed for Safety

    How Canadian Crop Protection Products are Assessed for Safety

    As originally published by The Grower, August 2020.

    Pests such as insects, diseases, and weeds can affect our quality of life in many different ways. Pests can represent a threat to public health and the environment as well as create substantial negative impacts to the economy if they are not sufficiently managed.

    Crop protection products or pesticides play an important role in agriculture and other sectors in managing pests. These products can be very broad in scope; they include, as defined by the federal government:

    “A product, an organism or a substance, including a product, an organism or a substance derived through biotechnology, that consists of its active ingredient, formulants and contaminants, and that is manufactured, represented, distributed or used as a means for directly or indirectly controlling, destroying, attracting or repelling a pest or for mitigating or preventing its injurious, noxious or troublesome effects.”

    While dealing with pests is an important aspect of society, crop protection products can also represent a hazard. If not properly managed, their use has the potential to pose risks to the health and well-being of Canadians and to our environment. As such, crop protection products are highly regulated. So how do we ensure the safety of these products in Canada?

    The federal government has the responsibility of reviewing and registering pest management products before they can be sold or used in Canada. This is covered by the Pest Control Products Act (PCPA). The primary objective of the PCPA is the prevention of unacceptable risks to human health and the environment resulting from the use of these products. The PCPA also recognizes that pest management is an important factor to both the economy and quality of life in Canada; however, these are considered secondary objectives to health and the environment.

    It is the mission of the Pest Management Regulatory Agency (PMRA) based in Ottawa to execute the implementation of the PCPA and its objectives. Of the 450 employees at PMRA, 73% are scientists, including biologists, toxicologists, epidemiologists, and chemists. Evaluations of products by PMRA are extensive and use a weight of evidence approach that considers the nature and quality of scientific sources in their decision making.

    Before the PMRA approves any product for use, regardless of origin, it must undergo a thorough science-based risk assessment and meet strict health and environmental standards. If the proposed use of a product poses unacceptable risks to human health or the environment, it is not registered for use in Canada. It is the responsibility of the company or individual seeking registration to prove their product does not pose unacceptable risks through scientific studies.

    During evaluation or re-evaluation of a product, PMRA considers a comprehensive toxicology database to assess potential health effects. Both shorter term and longer-term effects are considered. These include, but are not limited to, studies to characterize acute and chronic toxicity, carcinogenic potential, reproductive and developmental toxicity, immunotoxicity, neurotoxicity, genotoxicity, and endocrine disruption potential. The PMRA assessments are also informed by epidemiological evidence, general scientific knowledge, and published scientific information.

    In exposure assessments, sensitive populations and life stages are specifically addressed, including infants, children, and women of child-bearing age. Consideration is given to different activities, dietary habits, food intake, and body weight of children versus adults. A product will only be registered if this estimated exposure raises no concerns. Once this is determined, the PMRA will ensure the label directions indicate the appropriate use instructions to best minimize exposure.

    Exposure to a product may occur through different routes (oral, dermal, and inhalation) and pathways (dietary, drinking water, and non-commercial uses). In order to fully assess potential risks, the PMRA conducts aggregate assessments which consider these different pathways and routes. Where it has been demonstrated that a group of pesticides share a common mechanism of toxicity, they are subject to a cumulative risk assessment in which the combined aggregate risks are assessed. In occupational settings such as agriculture and forestry, exposure may occur while handling or applying pesticides. As well, workers re-entering treated areas may be exposed to pesticide residues. These occupational risks are also assessed during the PMRA review.

    The PMRA also sets science-based maximum residue limits (MRLs) on food commodities to ensure the food Canadians eat is safe. These limits are enforced by the Canadian Food Inspection Agency. The MRLs established for each crop are set at levels well below the amount that could pose a health concern.

    Environmental risk assessment integrates the environmental exposure and ecotoxicity information to evaluate the potential for adverse effects on non-target species. This integration is achieved by comparing estimated environmental concentrations (EECs) with concentrations at which adverse effects may occur. The EECs are concentrations of product in various environments, such as in food, water, soil, and air. The EECs can be estimated using standard models, which take into consideration the application rate(s), chemical properties, and environmental fate properties, including the dissipation of the product between applications. In re-evaluations of registered products, EECs can be taken from empirical data.

    Ecotoxicity information includes acute and chronic toxicity data for various organisms or groups of organisms from both terrestrial and aquatic habitats including invertebrates, vertebrates, and plants. Toxicity endpoints used in risk assessments may be adjusted to account for potential differences in species sensitivity as well as varying protection goals such as protection at the community, population, or individual level.

    A vast amount of scientific data is reviewed when evaluating the safety of crop protection products in Canada. These extensive reviews are posted publicly and include consultations where any stakeholders are invited to submit comments. There is good reason to have high confidence that crop protection products are safe for Canadians and the environment under the conditions of registration.

    For those who want a more in depth read, check out the PMRA’s guidance document overview.

  • Crop-Adapted Spraying (CAS) and an Apple Orchard Case Study

    Crop-Adapted Spraying (CAS) and an Apple Orchard Case Study

    An orchard spraying scenario

    Here’s a common situation: An orchardist following IPM identifies a pest that poses an economic threat. It’s an annual pest and spraying is really a matter of when, not if. The operation is 150 acres and runs three airblast sprayers; two have a tower and one does not. Multiple varieties are planted in several blocks on different rootstocks and they are at different stages of maturity. The newer blocks are trellised high density trees and the older blocks are semi-dwarfs on different row spacing. Let’s also imagine the pruning team hasn’t finished yet, so some trees are not pruned.

    The orchardist turns to the pesticide label to decide how to spray such variable targets. It prescribes a range of doses per planted area (not canopy size), depending on the pest pressure. It advises the orchardist to use “enough water” to ensure “good coverage” without incurring “runoff”.

    The orchardist recognizes that the label is vague, and elects to rely on what has worked historically: A water-soluble pouch is dropped into each tank (dose is close enough), and each sprayer operator is instructed to drive at an efficient speed (get it done because rain is coming), spraying until the tank is empty. They say that if a tank is running low before the job is done, speed up and stretch it. If the spray is overshooting a younger planting, they suggest turning off the top nozzles and/or driving faster.

    Airblast operators face this situation regularly. The question is: “Is there a problem with spraying this way if it results in a respectable crop of quality fruit?” Agricultural engineers specializing in application technology in Spain, Australia, Great Britain and the United States say there is a problem, and on behalf of Canada, I completely agree with them.

    Canopy and Sprayer Variability

    The fundamental problem is inconsistent spray coverage and avoidable waste (of time, water and pesticide) due to variability. Our scenario notes multiple sprayer operators, different models of sprayer, and a range of varieties, orchard architectures and canopy management practices. The label does not allow for any of these factors, adhering to a rate based on planted area and remaining silent on water volume.

    International peer-reviewed journal articles stretching back to the sixties have conclusively demonstrated order-of-magnitude differences in the area-density of orchard canopies from one acre to the next. There can even be fold-differences in canopy area-density in the same planting as the season progresses. A label prescribing a fixed dose based on the area planted is not appropriate for any vine, bush, cane or tree crop, and the result is that more crops are over- or under-sprayed than receive appropriate coverage.

    Let us not forget the variability that comes from a poorly adjusted sprayer. I won’t to attempt to quantify the impact (although some researchers have suggested order-of-magnitude differences from sprayer to sprayer). Instead, let’s illustrate it as a conceptual “before and after”:

    Before: Potential spray loss and inconsistency before adjusting sprayer to match the canopy
    After: Coverage variability reduced and unnecessary waste mostly eliminated.

    Beyond the immediate impact on efficiency, variability makes it difficult to diagnose pesticide effectiveness. As an example, there was a scab outbreak in Ontario in 2009 that elicited questions about timing, weather, product choice and resistance. There was very little attention given to spray coverage, which to my mind should have been the first question if only to eliminate it as a potential culprit. This is because each operation interprets labels differently, and very few confirm coverage in any quantifiable way. This practice makes it more difficult to identify a cause when crop protection fails.

    Optimizing pesticide rates

    That was a lot of preamble to describe an issue that many orchardists are already aware of. What is needed is a way to adjust the amount of pesticide per unit ground area (i.e. the label’s prescription) to achieve consistent foliar coverage for canopies of varying shape and density. The concept is visualized in the following figure. In addition, the method has to be simple, intuitive and effective.

    Many models have been proposed to tackle the dose expression issue, including Tree-Row Volume, Leaf Area Index, Leaf Wall Area, PACE+ and DOSAVIÑA. There are advantages and disadvantages to each method. Standing on the shoulders of giants, we combined aspects of each of these models, including incorporating coverage factor research from USDA ARS work in nurseries, to develop the Crop-Adapted Spraying (CAS) method. It is neither complicated nor sophisticated. It formalizes a series of qualitative calibration techniques and the objective is to achieve a target foliar coverage pattern. When achieved with sufficient accuracy, pesticide efficacy is maintained and waste is greatly reduced.

    Caveats

    Perhaps I shouldn’t point out flaws before I describe the model’s effectiveness, but it’s important to understand that CAS relies on a few critical assumptions.

    The first assumption is that the sprayer operator’s typical ratio of formulated product to carrier is appropriate. We need a starting point for adjusting the amount of pesticide per unit planted area, and unless the label specifies a concentration (i.e. a ratio of formulated product to water) or a minimum amount of product per planted area, this is a reasonable starting point. The appropriateness of this assumption is evidenced by a history of satisfactory pest control in the orchard.

    The second assumption lies in defining a threshold for sufficient coverage, and this is a real challenge. Applications can be concentrate or dilute. Some products translocate in the leaf or redistribute on the leaf surface while others do not. Even the droplet size employed (e.g. A mist blower’s fines compared to Medium-Coarse droplets produced by an air induction nozzle) will affect dose, bioavailability and how long residues are active. So, how does one draw a universal line in the sand and say “this much is enough”?

    Our threshold for suitable foliar coverage has evolved through experience, literature review and independent experimentation in several countries and in multiple 3D cropping systems. We propose 10-15 % surface coverage and a minimum of 85 droplets per cm2on a minimum 80% of the canopy. This standard is intended to be practical, versatile and robust in order to safely represent sufficient coverage for most foliar insecticides and fungicides. It is not suitable for ultra-low volume sprayers (e.g. misters, foggers, air-shear), nor is it intended to be a rigorous, scientific absolute.

    For example, a drench application, such as streptomycin or dormant oils, will obviously require more coverage. Plant growth regulators like thinners, stop-drops and foliar nutrients have their own unique criteria. Products that work through vapour redistribution (e.g. some forms of sulfur) and bio-rational products have a minimal dose threshold that must be ensured per planted area, no matter the water volume used. In these cases, Crop-Adapted Spraying may not be appropriate.

    So while it is the nature of models that they may not hold in every situation, this threshold has proved successful in multiple Ontario apple (later in this article) and highbush blueberry operations.

    The method

    The method is a simple and iterative approach that allows growers to adjust the product rate and sprayer output in relation to canopy and sprayer effects on deposits. Follow these steps to adjust the sprayer and optimize coverage. Only do so in conditions you would normally spray in.

    Step 1

    The sprayer should receive all seasonal maintenance prior to first use and undergo a visual inspection before each spray day.

    Step 2

    Park the sprayer in an alley between rows of trees and tie 25 cm (10 in) lengths of ribbon along the air outlet. That would be the deflectors on a low profile axial sprayer, the hubs of multifan systems or the ducted outlets on towers. Turn on the air and extrapolate where the air is aimed. Adjust the air to just overshoot the top of the canopy.

    Step 3

    It is important that the spray slightly overshoot the canopy height. It is less important to spray the lowest point of the canopy as secondary deposition tends to provide sufficient coverage. This may change if fruit weighs down the branches. Ensuring a full swath, turn off any nozzles that are not required. For small and medium canopy sizes, consider using air-induction hollow cones in the top positions of each boom to reduce drift. You may have to increase the rate in those positions to compensate for the fact that nozzles producing larger droplets produce fewer droplets.

    Step 4

    Affix 25 cm (10 in) ribbons to the upwind and far side of one or more trees. At minimum, affix them at the treetop and along the widest portion of the canopy. With the tank half-full of water, drive past in the spraying gear at the ideal RPMs with the air on. A partner in the next alley should see the highest ribbon move. Ideally the other ribbons will waft as well, but in large, dense canopies they may not. In this case, ensure leaves are moving beyond the trunk. No ribbons should strain straight-out.

    This will determine if more/less air is required from the airblast sprayer. The operator can change fan speed (e.g. fan gear), or adjust the sprayer’s travel speed. Lower speed causes air to go higher and deeper and vice versa. In some cases, operators can reduce fan speed by reducing the tractor PTO revolutions by gearing up and throttling down. When air is corrected, determine ground speed in the orchard using smartphone GPS app or a calibration formula.

    Step 5

    Place and interpret water-sensitive papers per this article. If coverage is excessive, reduce output in corresponding nozzle positions (by replacing them with lower rate nozzles). If you see less than ideal coverage, increase the nozzle rates in those positions.

    Be aware that excessive coverage may be unavoidable in the outer edge of the canopy, given that spray must pass through to get to the centre. It is not unusual to see half the deposition mid-canopy when the outside is saturated. Also be aware that ambient wind speed and humidity have significant impacts on coverage. Therefore, only test coverage in conditions similar to your typical spraying conditions.

    Step 6

    When the canopy grows and fills in sufficiently (usually after petal fall), you may have to reassess coverage to reflect a larger, denser canopy with more surface area. Given the critical nature of early season fungicide applications, it may be preferable to have slightly excessive coverage early season and allowing it to self-correct as the season proceeds. If you are suspicious that the spray is being stretched too thin or you are unsatisfied with the coverage, increase the output.

    For high density trees, there may be no need to increase output mid-season. Early in the season, wind travels relatively unimpeded in a high-density orchard and will blow spray off course, reducing coverage and requiring higher water volumes or possibly more air to compensate. As the trees fill in, the average wind speed is reduced and more spray can impact on the target.

    Mixing and Work Rate

    When the correct sprayer settings and volumes have been determined, the operator will mix their spray tank as they would for their typical application. The sprayer will likely cover more orchard than it has in the past, and the operator will have to re-assess how many tanks are required pre and post petal-fall. If your sprayer is employs conventional hydraulic nozzles (that is, it is not a low-volume sprayer), it is not advisable to go below 400 L/ha (~40 gpa).

    This is where OrchardMAX (the free CAS calculator app) can help the operator ballpark the correct rates for each nozzle position and estimate work rate, tanks required, and any potential savings in product.

    Yes. There’s an app for that.

    Apple Orchard Case Study

    Three Ontario apple orchards (and one Nova Scotia orchard) agreed to test the model. A block of trees was randomly selected from each operation to serve as the treatment condition. These trees received spray according to the CAS model. The rest of the orchard was sprayed according to the grower’s traditional methods. The orchards included several varieties and represented both semi-dwarf and high density plantings.

    OrchardTypical spray volume (Control)CAS spray volume (Treatment)% SavingsVarieties (age)Orchard StructureYears in study
    Orchard 1486 L/ha373 L/ha23%Gala + g. Del (~10 yr old)High density3
    Orchard 2748 L/ha478 L/ha &

    608 L/ha = 543 L/ha

    		28%Macs + Empires (~30 yr old)Semi-dwarf3+
    Orchard 3577 L/ha

    (660 L/ha)

    		407 L/ha39%

    (38%)

    		Gala + Fuji (~20 yr old)High density2
    Nova Scotia544 L/ha416 L/ha33%Jonogold (~10 yr old)High density1+

    According to the model, each grower sprayed anywhere from 20-35% less per hectare in the CAS block than in their traditionally-sprayed block. In many cases, the overall canopy coverage was improved in the CAS block compared to the traditional method simply by aiming formally wasted spray into the canopy, and reducing volume in those areas that were unnecessarily drenched.

    A scout was dispatched to monitor insect and disease activity each week for ~15 weeks. They observed a typical IPM scouting protocol and were not informed which block was the traditional control and which was CAS treatment. Data was transformed where appropriate for analysis of variance. In almost every case, there was no significant difference in counts between the CAS treatment and the grower’s traditionally-sprayed control (p=0.05). In those few cases where a pest had higher counts in the CAS block, the counts were so far below a spray threshold as to be insignificant.

    If we look more closely at the three (of 128) ANOVA comparisons of control to treatment, we see that economic thresholds are rarely an issue, and essentially, difference between control and treatment are moot.

    2015_TSSM_O1_Y2
    2015_ERM_O1_Y3
    2015_ERM_O1_Y2

    This study was repeated over three years. Having examined the data to determine if three years of optimized doses had any effect on pest populations, results suggest no such effect.

    Apples were randomly sampled for destructive analysis at harvest and the total counts of any and all damage are shown below. This is simply a tally, and no statistical significance is implied. Note that Orchard 3 was only involved in the study for two years, and unfortunately a killing frost destroyed their harvest in their second year, so we didn’t have much to harvest.

    Apple_data_3_years

    An important part of knowledge transfer is whether or not growers will choose to adopt a method once the instructor is gone. By year two the biggest challenge was ensuring the orchardists in the study continued to spray the control block at their traditional volumes! They were more than willing to adopt the method wholesale and all three did so starting in 2016. Further, colleagues in Nova Scotia performed their own CAS trial for two years, and reported no significant difference in pest activity or apple quality. They accomplished this simply by following a written protocol.

    The orchardist’s enthusiasm, the ability for the study to be replicated without my direct involvement, and the successful results speak to the viability of the method.

    We would like to thank the researchers that developed the methods CAS is based upon, statistician Behrouz Eshani, the orchards that cooperated in the study, my OMAFRA colleagues and the OMAFRA summer students that scouted those orchards for three years.

    More information

    This method of application is really no more sophisticated than the pro rata practice of turning off nozzles that are aiming at the ground or above the target. It will take time for operators to get comfortable with the new volumes (and potentially reduced dosage) and regular scouting is highly encouraged to confirm they are achieving control.

    The maintenance, calibration and operation of an airblast sprayer is an involved process. Collectively, the sprayer setup, weather and crop morphology all influence the coverage obtained from an application. A fundamental understanding of application technology is required before attempting to optimize dosage using the CAS method. We suggest grabbing a copy of the second edition of Airblast101 – Your Guide to Effective and Efficient Spraying. The digital version is a free download, but you can buy a hardcopy as well.

    Finally, take a few minutes to watch this video by AAMS-Salvarani. In many European countries such as Belgium , France and Germany, sprayers must be calibrated regularly. While there is no mention of air speed adjustments, many of the steps in this video correspond with the airblast adjustments relating to Crop-Adapted Spraying.