Treating tall trees for pests and diseases is challenging because it requires moving the chemical solution high into the canopy for effective coverage. This process necessitates specialized equipment and precise techniques to manage the physical demands of vertical application. Homeowners or property managers seeking to protect mature trees must adopt professional-grade methods to ensure the health and longevity of these valuable assets. The following methods focus on practical, safe, and effective strategies for reaching the highest points of a tree from the ground.
Selecting Equipment for Vertical Reach
Achieving adequate vertical reach requires a system capable of generating both high pressure and significant flow. Standard backpack or hand-pump sprayers are insufficient, demanding a high-volume pump system, such as a hydraulic or air-blast sprayer. A hydraulic sprayer uses water to propel the chemical, while an air-blast sprayer utilizes water and air for projection. These systems typically require a pump with a flow rate between 20 and 60 gallons per minute (GPM) to be effective for significant heights.
The pump and engine are the heart of this operation. Medium to high-pressure diaphragm pumps are often recommended, capable of pressures up to 500–700 pounds per square inch (psi). This pressure is necessary to atomize the droplets and achieve the required lift, often reaching 50 to 100 feet. The entire fluid path must be properly sized, including a high-pressure agricultural hose and a large tank capacity. A sufficient tank prevents cavitation, or air in the lines, which occurs if the pump’s flow rate exceeds the tank’s supply.
The final component is the specialized spray gun, often featuring a long barrel to straighten the stream. These guns have adjustable nozzles that transition between a highly focused, solid stream and a broad, fine mist. The focused stream provides the initial momentum to reach the canopy. The nozzle must then convert this stream into a fine mist at the target height to ensure the chemical coats the branches and leaves without causing damage. Some long-range spray guns can handle flow rates up to 30 GPM and pressures up to 850 psi.
Preparation and Safety Protocols
Before application begins, the most important step is carefully reading and adhering to the product label. The label specifies the correct mixing ratios, the mandatory Personal Protective Equipment (PPE), and the precise application rate, which is legally binding. PPE requirements for high-reach spraying often include:
- Long-sleeved shirts and long pants.
- Rubber boots (not leather).
- A hat and safety glasses to protect against drift and splash-back.
- A respirator, often necessary depending on the chemical’s toxicity.
The chemical solution must be mixed accurately in a well-ventilated area, following the manufacturer’s directions exactly. It is best to mix only what will be used immediately. Environmental conditions must be checked before spraying; application should only occur during calm periods. Wind can cause significant drift and reduce coverage, while high temperatures or the immediate forecast of rain can also compromise the effectiveness of the treatment.
Securing the application area is necessary to protect non-target organisms and surrounding property. Position the sprayer to allow spraying the tree limbs at an angle, avoiding directing the spray directly above your head. Non-target plants, especially low-growing vegetation, should be covered with plastic sheeting to prevent accidental contact with the chemical solution.
Mastering the Application Technique
Effective application hinges on maximizing coverage while minimizing waste and drift, requiring a deliberate approach to spraying. Begin by aiming the focused stream high into the canopy to achieve the necessary vertical distance. As the stream reaches the target height, the adjustable nozzle should break the stream up into a fine, coating mist. This technique ensures the solution reaches the top of the tree before dissipating, providing a uniform film on the foliage.
To ensure the entire canopy is treated, the operator must walk around the trunk and spray the tree from multiple angles, penetrating the foliage from all sides. When targeting pests or diseases that reside primarily on the leaves, aim to coat the underside of the leaves. This is where many insects hide and where the stomata (pores) are located. Applying the spray at an angle, rather than straight up, helps the solution penetrate the dense branch structure.
The goal of the application is to “spray to runoff,” meaning the foliage and branches are thoroughly coated until the solution just begins to drip off. This saturation point indicates that maximum coverage has been achieved without excessive waste. It is crucial to monitor the wind continuously; if conditions become breezy, stop spraying immediately to prevent chemical drift outside the treatment zone.
Alternatives to High-Reach Spraying
For extremely tall trees or when high-volume spraying is impractical, systemic treatments offer an effective alternative. Systemic methods introduce the treatment directly into the tree’s vascular system, distributing the product throughout the entire plant. This protects the tree from the inside out, eliminating the challenge of vertical reach and significantly reducing the risk of chemical drift.
One common method is soil application, where the chemical is applied around the tree’s base and absorbed by the roots. This relies on the tree’s natural water uptake process to move the product into the xylem, the water-conducting tissue. For successful uptake, the soil must be adequately moist, so deep watering prior to and after application is often necessary.
Another alternative is trunk injection, where the treatment is injected directly into the tree’s trunk, bypassing the soil entirely. This technique delivers the chemical straight into the vascular system, resulting in rapid distribution and long-lasting protection, often up to two years. Trunk injections are particularly effective for pests like wood borers, which are difficult to control with surface sprays. They also minimize exposure to non-target insects and the environment.