- 1). Fill the sprayer with water and the needed chemicals to treat the tree, such as an insecticide or fungicide. Follow the directions on the chemical to get the right mix based on the water quantity.
- 2). Adjust the pressure on the sprayer to fit with the tree height. The taller the tree, the more pressure is needed to force the water to the top. For example a 65-foot tree or greater is going to need 800 psi, while a 45- or 50-foot tree only needs 400 psi.
- 3). Adjust the nozzle based on the height of the tree as well. A taller tree will not be coated if the nozzle is on a fine mist; it needs larger droplets so that they can push through the air. Fine droplets means that less water, or gallons per minute, are flowing through the nozzle. For tall trees you need a higher gpm. For example trees at a height of 65 feet need 20-gpm, 85 need 35-gpm and above 100 need 60-gpm or more.
- 4). Turn on the hydraulic tree sprayer and aim the gun up the tree. You don't want to stand directly under the tree, but several yards away. Wall around the tree to coat it on all sides, and have someone help with the hose. The angle you aim the hose, and how far away you stand depends on the height of the tree. Extremely tall trees are sprayed with only a slight angle, which means you have to be closer in. With shorter trees, or as you work the sprayer down lower on taller trees, you need to adjust to a greater angle and step back further so as not to damage the branches and leaves.
- 5). Continue to soak the tree down until it is dripping to ensure full coverage.
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