Can You Use a Power Washer to Spray Insecticide on Insect Infested Tree?

Its normal for trees to get Infested by insects and pests. At that moment, you only think of one thing, to spray it with insecticide or pesticide. However, you don’t know how.

We all know how powerful a power washer is. That is why it’s called a power washer in the first instance right? In less than a few minutes, the power washer must have removed whatever that is on a surface, making it look like brand new. However, can you use a power washer to spray insecticide on insect-Infested tree? Let’s find out if it’s okay.

Is It Okay to Use a Power Washer on Trees?

Power or pressure washers are extremely powerful. They are 10 to 15 times more efficient than a garden hose. A garden hose has a water flow of 50 PSI, so you can imagine what a power washer will deliver.

At 700 PSI, which is among the lowest setting can be very powerful for trees and may hurt it. That force can eradicate grime, debris, dirt, and mildew from any vehicle, furniture, etc. It’s even powerful to remove aphids and other insects from trees, but the effects are usually more harm than good.

When you decide to use a power washer to spray insecticide on insect-Infested tree, the force will not only get rid of the insects, but will remove chunks of the barks. The force may also damage the tree cells and remove so many leaves in the process.

Besides, the chemicals inside power washer is also dangerous. If you start to spray an insecticide high up, the droplets will pour down on you and anything that is close by. If it happens that you have a small garden close by,  overspraying can kill the vegetation. Wearing gloves, goggles, and other safety gears may not completely shield you from getting touched by the insecticide.

Remember, most of these insecticides are made of dangerous chemicals, so that they become instantly harmful when they come in contact with the skin. So unless you are extremely careful, spraying insecticides into treetops is dangerous.

If you still insist on spraying with a power washer, ensure that you are using the least possible settings. Also, be wary of the type of nozzle you intend to use. The nozzle should be able to deliver at a wider range, and not deliver focused spray. The yellow-colored nozzle, for example, can deliver at a wider range. The same goes for the white and black. Red nozzles should be avoided because they spray water on a specific area.

What You Should Instead of a Power Washer

Power washers can deliver an effective insecticide spray to trees, irrespective of how high it is, but it comes with consequences. Hence, may not be the best tool or equipment to use.

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A garden hose or expandable garden hose will work as an alternative, but it will be time consuming. It is equally effective and will get rid of aphids and other insects on your insect-infested tree. Attaching the hose to a fertilizer sprayer or insecticide sprayer will do just fine if you are spraying some feet away and not something as high as a tree. If you are not acrophobic, you can climb the ladder and spray on parts that are insect-infested.

Another alternative to power washers are tree sprayers. Tree sprayers work by generating pressure from the pump and using this same pressure to power the spray through the nozzle. Tree sprayers are efficient hydraulic sprayers that provide excellent spray coverage on trees, without damaging the foliage or trunk. Tree sprayers can be mounted on a truck, if you don’t want to be carrying the tank around.

Components of a Tree Sprayer

A tree sprayer consists of a tank, pump, and a nozzle.


A tank is where the mixture is contained. That is, the chemical mixture. Tanks that are coated with materials that does not rust easily are best, since it will be containing lots of chemical concentrations. It’s important that the tank is washed to prevent accumulation of chemical residues that can clog the opening.


Pumps excite the chemical mixture so that it produces a stable flow to the spray nozzles. It moves the liquid from the tank to the nozzle. A pump is a major part of a tree sprayer. You should never operate it above the recommended pressure by the manufacturer. Else, you will be damaging the pump.


Nozzles are made of different materials such as brass, steel, aluminum, etc. Using the right type of nozzle is critical in the operation of a tree sprayer and the formulation of the insecticide. The nozzle determines the amount, uniformity, and coverage of spray you intend to apply on the targeted area.

Nozzles turn the liquid concentration into droplets and propel the droplets in the right direction. They determine the right pressure at which they discharge the concentration.

There are common nozzle angles which are 65°, 80°, and 110°. Each of these angles have an effect on the spray pattern. For example, 65° will narrow the spray to a specific area at an increased height, while the 100° nozzle angle will stay at wide angles, but at a closer range to the targeted area.

There are five major parts of a nozzle – the nozzle body, the strainer, gasket, spray tip, and the cap. The nozzle body holds the other four parts from the bottom. The strainer prevents the nozzle from getting clogged and worn out. It can remove the dirt and rust even before it teaches the nozzle.

Gaskets hold the spray tip to the strainer. The spray tip determines the pattern of droplet and the flow rate. The cap holds the other parts from the top and ensures that they are in place.

You should choose a nozzle that is adjustable. Adjustable nozzles have a wide area coverage, and are suitable for spraying insecticide on tall trees.

Tree Sprayer Maintenance

  • The tree sprayer should be cleaned after you are done spraying. Do not wash the sprayer in areas where it might contaminate water supplies or even plants.
  • Clean nozzle tips with a soft brush.
  • Use nozzles that are made of ceramic or stainless steel. These materials reduce the chances of wear and tear.
  • Avoid exposing the tank to sunlight as it can shorten its lifespan.
  • If you are not clear about how to flush out chemicals from the tank, check the label of the chemical for further information.

How to Spray Insecticide on Trees

If you have a small to medium-size trees, taking care of it is easier. With the aid of ladders, you can decide to prune, spray insecticide on portions that are diseased or pest infected, and do other things high up.

However, it’s different with tall trees. You can’t stand on a ladder and expect to reach high up when the tree is above 20 feet. You will need something efficient, like a powerful spraying equipment to reach that high level. In this case, you will need a tree sprayer with some powerful nozzle.

Things that you will need

  • Goggles
  • Gloves
  • Face masks
  • Overall or good protective clothing
  • Insecticide
  • Bucket
  • Water
  • High-pressure sprayer
  • Adjustable hose nozzle of about 400 – 500 PSI water flow.


  1. Wear your overall or protective clothing. Put on your goggles, mask, and ensure that you have your gloves worn as well.
  2. Prepare the chemical you intend to use for treatment and put it into the tank of the high-pressure sprayer. This is done by mixing the insecticide or chemical in a bucket of water. Follow the chemical’s label instructions for proper mixture. After that, pour the mixture into the tank. The sprayer, whether it’s hydraulic or an air-blast sprayer should have between 30 – 60 GPM pump.
  3. Stay some meters away and direct the sprayer away from the base of the tree. Set the sprayer towards the direction of the Infested area at an angle where the droplets will not likely rain on you.
  4. Once you are done setting, start the sprayer and watch it’s nozzle spraying pattern. While spraying, adjust the nozzle by twisting it as you would with a hose nozzle. This is to focus the stream on the appropriate height of the tree before it becomes mist.
  5. Walk your way through while spraying so that all portions of the tree, including the leaves and branches would get touched.
  6. Remember to read the chemical’s directions to know how to get the best of your spray effectively. The label should be able to tell you how often you should spray on your insect-infested tree. Also, the chemical could affect vegetation if the droplets should pour back. So it’s crucial that you read the manual to know how to possibly protect your vegetation.

You should note that there are moments where you should and should not spray insecticide on your Infested tree. If there is wind or low humidity, you should avoid spraying because the chemical will evaporate rapidly. If it’s going to rain, spraying should also be avoided as the rain would wash away the insecticide from the tree.


If you were thinking of using a power washer to spray insecticide on your infested tree, I’m sure this article has cleared your doubts. It’s effective, yet not without its consequences. However, there is an alternative, which is the tree sprayer.

A tree sprayer is efficient to deal with whatever insects and pests that may be hanging on the leaves of your trees. Unlike power washers that may destroy the foliage, tree sprayers are gentle. With the right nozzle and PSI, you can get those insects off your precious leaves.

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