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How to Use a Pesticide Sprayer

Pesticides come in many different forms – dust, granule, vapor, and more. But generally, the most common form pesticides take is liquid. Spraying liquid pesticides is extremely effective, affordable, and safe when done properly.

While it’s possible to buy pesticides that are ready-mixed and able to be sprayed directly from the bottle you purchase it in, the most powerful and effective pesticides are typically sold in a concentrated liquid form.

“Concentrated” means you need to mix a few ounces of the pesticide with a gallon of water before apply, and to do this you need a pesticide sprayer.

What is a Pesticide Sprayer?

Before we dive right into how to use a pesticide sprayer, let’s give a brief overview of how they generally work. I’ll break it down to the most simple level.

A sprayer has a tank where you mix the concentrated pesticide with regular water.

Once the liquids are in the sprayer, you pressurize the tank by pumping air into it. This is usually by a manual hand pump, but fancier sprayer have powered pressurizers. The air compresses at the top of the tank which puts downward pressure on the liquid.

With the pressure pushing down on the liquid, there’s only one place for it to escape – up the straw that leads to your spraying wand.

Now that you have the gist of how a sprayer works, here’s a guide on how to use a pesticide sprayer, then we’ll get into the different types of sprayers along with their pros and cons.

How to Use a Pesticide Sprayer

1. Check the Equipment

The first thing you should do is check your spraying equipment for damage or leaks. Partially fill the sprayer with water and pressurize it to make sure it maintains pressure.

Spray a little of the water to check for leaks. If your equipment can’t hold pressure or is leaking chemicals, you need to repair or replace it before continuing.

Pesticides are safe to use when applied as directed by the label, but malfunctioning equipment may mean you’re leaking pesticide where you don’t want it to be.

2. Mix the Pesticide

Once you’re satisfied that your equipment is working properly, it’s time to mix in the pesticide. The best way to do this is to fill the tank halfway up, then add the pesticide to the water. Once that’s done, top up the water to get the prescribed level.

For most DIY users at home, this will be a 1 gallon tank. All pesticide labels should have instructions for how many ounces to add to a gallon tank.

The reason for this procedure is to make sure the pesticide mixes thoroughly with the water. It also keeps you safe by helping to minimize splashback while filling.

When filling spraying equipment, you don’t always know just how fast and hard the water is going to come out of the faucet or hose you’re using. If you started with your pesticide and then spray into the tank with a high-pressure hose, you can inadvertently splash highly concentrated pesticide on your face or skin – not good!

Always follow the manufacturer’s instructions on diluting the pesticide. It can be tempting to mix your pesticide stronger than the manufacturer recommends, but it’s unnecessary and unsafe.

Example of a concentrated liquid pesticide

Pesticides are classified as safe for use based on the dilution rate the manufacturer specifies. If you start making stronger mixes, you can’t be sure it won’t be harmful to your health. Plus, it’s a waste of pesticides. Pesticides are diluted to kill bugs, using more won’t make them any more dead!

It’s also worth mentioning here that there is a class of pesticides called “wettable powders”. These powders are added to water and suspended in the liquid. While they are sprayed similar to liquid pesticides, when they dry they revert back to powder form.

If you’re using a wettable powder, make sure that the spray equipment you are using is capable of handling these formulas. Make sure to keep agitating the spray tank as you spray so that the powder stays suspended in the liquid. Some cheaper sprayers have issues with clogging when using powders or heavy oil-based sprays.

3. Pressurize the Sprayer

Most sprayers work by keeping the liquid inside under higher pressure than the outside atmosphere. This high pressure causes the liquid to try to get out of the sprayer via the straw that connects to your spraying wand.

When you press the trigger, the pressurized liquid shoots out of the sprayer and goes where you direct it.

Many sprayers achieve this pressure differential with a manual pump. By pressing down on the handle, you pump air into the sprayer. A specialized valve keeps the air from getting out, so the pressure inside the container builds. These manual sprayers are usually the cheapest and most common option for spray equipment.

If spraying manually, be careful not to pump too much air into the tank. The greater the pressure, the higher the rate at which the pesticide comes out of the container. This can cause the pesticide to splashback off hard surfaces and get onto your skin, where it may be absorbed into your body.

Spraying at too high of pressure causes you to dispense pesticide much faster as well which adds to the cost of any treatment you’re doing.

If the pressure of your sprayer is too high, you have less control over your pesticide, and it can end up in places you don’t want it to go. Many pesticides can be extremely harmful to non-target organisms like fish or honey bees. It’s very important to make sure anything you spray doesn’t end up going down the drain or contaminating the water source.

The best way to avoid this is to make sure you keep the pressure low. If you’re feeling much resistance in the handle as you pump, you’re probably putting too much pressure in it.

3. Adjust the Nozzle

Most sprayers come with an adjustable nozzle. By twisting the nozzle, you can change the spray pattern to best suite your needs. Different spray patterns are useful for different types of applications. For instance:

  • A thin pin stream gives a narrow and highly targeted stream that is great for applying to narrow gaps such as cracks and crevices. Keep in mind that the smaller the pin stream, the higher the pressure will be as the liquid gets forced out of a smaller hole. This can be useful for achieving greater penetration of an underground ant colony or a wasp nest but you need to be more careful for splashback.
  • A fan spray gives a wider, flatter spray that enables you to cover a broad area in less time. This is useful for applying pesticides in an even coat along baseboards, foundations, soffits, and other areas. If you’re performing a preventative pest spray or perimeter treatment, this is the setting you’ll probably use the most.
  • A mist setting allows you to apply pesticide evenly in a very fine spray that travels easily in the air. This can be useful for treating bushes and vegetation with a light coat of pesticide that reaches everywhere. It’s great when you want to coat all sides of a tree or bush, but be careful to only use the setting on days with no wind. It’s very easy for a light mist to travel and end up in places you don’t want it to go.

4. Applying the Pesticide

Finally it’s time to spray! Where you’re spraying the pesticide is going to depend on what pest you’re trying to control. I’d highly recommend looking at our pest specific guides for those tips, which you can easily find in the menu bar or by searching the site.

Application Safety Tips

Always wear safety equipment when applying any pesticide. At the minimum, this should include gloves that are rated to stand up to pesticides and I always recommend glasses/goggles too.

Be aware that some oil-based pesticides can easily dissolve latex gloves. You should also wear long sleeves and pants to protect your skin. Skin absorption is the most common way that people end up sick from pesticide usage.

A respirator or mask will help to protect your lungs, but make sure you use one that’s appropriate for the pesticide you’ve chosen. A dust mask won’t do much to prevent inhalation of pesticide vapor, and you’re better off with a proper respirator that uses canister filters.

Never spray directly above your head. What goes up must come down. If you need to spray an area above you, you should get a ladder and make sure to stand to one side so that dripping pesticide won’t fall down on you.

You should avoid spraying on a windy day as well. Wind can carry pesticides a long way from where you intended to apply them, and this can damage the environment. Make sure the pesticide stays where you want it to go by only spraying on calm days with winds of no more than a couple of miles per hour.

Don’t spray in the rain either. This may seem obvious, but spraying during or immediately before rain causes the pesticide to be washed away and end up in rivers and lakes. It also won’t kill many pests as the rain heavily dilutes it. Ideally, if you’re spraying outside, you want to do it on a day when you can be confident there won’t be any rain for least 24 hours after you’re finished.

5. Cleaning Up

Just because the spraying is over doesn’t mean your work is done. After finishing a treatment, you need to release the pressure in your spray tank. Otherwise, the pressurized pesticide will damage the seals and the tank may start to leak.

A look inside an empty tank. The hose inside leads out to the spraying wand.

Generally, spray tanks have a special pressure release valve to let the air out safely. Don’t simply unscrew the handle of the pump sprayer like you did to fill the tank. The pressurized pesticide will spray out of the tank if you try to depressurize it this way, likely getting you right in the face.

Most sprayer tanks aren’t intended for long-term storage of pesticides, and many pesticides start to quickly lose their potency once they have been diluted inside the spray tank. Also, many jurisdictions have laws regarding the appropriate storage of pesticide that make it illegal to store pesticide in a spray tank. For these reasons it best to make sure you don’t leave any liquid in the tank when finished.

The best way to do that is to calculate how much pesticide you’re going to need to complete the job and only mix that much. That way, by the time the job is done the tank will be empty and ready to be put away.

However, if that’s not possible, you’ll need to dispose of unused pesticides properly. A common way to do this is to empty it out onto soil far away from a water source. Alternatively, you may need to pour it into another container and bring it to a waste disposal facility. Check the manufacturer’s recommendations and the pesticide laws in your jurisdiction to make sure you’re doing things the right way.

Before putting your spray equipment away, triple rinse it with water to remove any pesticide residue. You may also need to clean the outside of the tank to make sure there’s no pesticide or dirt on it. Taking these small steps ensures that your spray equipment will last much longer.

Different Types of Pesticide Sprayers

There are lots of different types of pesticide spray equipment on the market. Which one works best for you is going to depend on the nature of your pest problem and how much spraying you intend to do. Here are the main types.

Hand Pump Sprayers

These sprayers are some of the cheapest and easiest to use. Designed to be carried in one hand while you use the other hand to direct the spray, the capacity of these sprayers is typically in the 1-2 gallon range. You can find sprayers like this at any hardware store, and they are capable of dealing with most household pest problems.

Pros:

  • Cheap to buy and repair
  • Easy to use
  • Easy to find
  • Enough capacity for most home pest problems
  • No motor or other expensive and unreliable parts

Cons:

  • Low capacity means you may need to refill many times if spraying a large area
  • Cheaper construction may not be as durable as more expensive sprayers
  • Low spray rate means treatments take longer

Backpack Sprayers

Backpack sprayers work on the same principle as hand pump sprayers. However, they have greater capacity and can be comfortably carried. Backpack sprayers usually hold around four gallons of diluted pesticide, although some can be a little bigger.

The great advantage of this capacity is that you don’t need to fill up as often, which can cut down on the time it takes to perform the pesticide spray of a large area.

Backpack sprayers are sometimes pressurized by hand just like hand pump sprayers. Some of the more expensive models have a motor that handles the pressurization for you. This motor can be powered by an electric battery or even by gas.

Although these sprayers are more expensive, they cut down on fatigue by saving you from having to pump to pressurize the tank constantly. They also offer a more consistent spray by keeping the pressure at a preset level.

Pros:

  • High-capacity means less time spent refilling
  • More comfortable to use on large sprays
  • Powered models reduce user fatigue
  • Hand powered models can be relatively cheap

Cons:

  • More expensive than hand pump sprayers
  • Powered models are expensive both to buy and maintain
  • Motors add complexity and may require additional maintenance
  • Four gallons of diluted pesticide weighs over 33 pounds, so you need to be physically strong enough to carry that weight while spraying

Hose End Sprayers

These single-use devices come with the pesticide already inside. They’re designed to be attached to the end of a garden hose and sprayed over a large area. The device mixes the pesticide with water at the specific rate as you spray so there’s no measuring. Once the pesticide is all used up, the sprayer can be easily disposed of.

Pros:

  • Extremely easy to use, with no mixing necessary
  • Cheap to buy
  • No maintenance needed

Cons:

  • Less control over the spray rate and pattern
  • Can be hard to find quality pesticides that can be used like this

Large Capacity Sprayers

These sprayers are aimed squarely at professional pesticide applicators. The smallest of these sprayers can look like a small water tank on wheels, while larger ones may be mounted in the back of a truck or on an ATV. These devices are designed to deliver large amounts of pesticide to a broad area and are widely used in agriculture and professional pest control.

Pros:

  • Reduce user fatigue by not needing to be carried
  • High-capacity means less refilling needed
  • Can be used in areas without a reliable water supply, at least until the tank runs out
  • Longer hoses allow treatment of a much larger area.

Cons:

  • Can be very expensive.
  • Maintenance is necessary to keep the motor and hoses in good condition.
  • Filling takes a long time and requires huge amounts of both water and pesticide.
  • Generally only suitable for professionals who spray large areas outdoors.

Spraying tips

  • Never carry a sprayer by its wand or hose. This can damage the sprayer.
  • Never store pesticide inside a sprayer. This may be illegal and can damage the internal seals and valves. Make sure you use all the pesticide you mix for treatment.
  • Avoid extreme temperatures. Heat causes the air inside a sprayer to expand, increasing the pressure beyond the appropriate level. On the other hand, extreme cold can freeze the pesticide inside a sprayer. This causes the liquid to expand, possibly rupturing the wand, hoses, or even the tank itself.
  • Be aware of the wind. You shouldn’t spray on a windy day, but even a light breeze can cause problems. When spraying, make sure the wind is blowing away from you so that it doesn’t blow pesticide back onto you as you spray.
  • Leave an air gap when filling a spray tank. If the water level in a spray tank rises above the end of the hose used to fill it, it’s possible to get backflow. This is a condition where the hose creates a siphon that sucks up the pesticide back into the water source. Eliminate the possibility of backflow by always leaving a gap between the end of the fill hose and the water level inside the tank.

Top Reasons to Use Concentrated Pesticides

Professionals and homeowners both love concentrated pesticides for the following reason –

  • One of the most important is the cost. It’s far cheaper to buy a concentrated pesticide and mix it with water to get the correct concentration than to buy one that’s already been mixed for you. Otherwise, you’re paying a markup for water or whatever else the pesticide is mixed with to make it safe.
  • It’s also much easier to store concentrated pesticides. When you’re performing hundreds of pest treatments per week, the way pest control companies do, you’re going to need a huge amount of pesticide. The less space it takes on a shelf, the better.
  • Concentrated pesticides produce less waste. A quarter gallon bottle of concentrated pesticide could allow you to create hundreds of gallons of usable product from a single small bottle. It’s much more environmentally friendly than going through hundreds and hundreds of aerosol cans to get the same result.

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