Application Systems

A major key to the effective use of chemicals in site preparation is a properly designed application system to insure that the material is deposited evenly over the project area and to minimize drift which might affect adversely neighboring properties. The following outline discusses the general properties of application systems and the specific characteristics of several commonly used types of spray equipment.

1. Herbicides must be applied in carefully calculated dosage, applied evenly.
a. Sprayer must be calibrated to apply known volume of spray in unit time.
b. Sprayer must deliver spray uniformly across pattern.
c. Aircraft must be able to compensate for air turbulence set up by rotor.

2. Volume of carrier is important.

a. Volume determines droplet size and density of deposit, hence coverage.
b. Volume dilutes concentrated chemical, sometimes for greater effect, sometimes lesser, depending on properties of chemical and pest species.

3. Speed of forward motion is important.

a. At a given delivery rate, volume per acre is inversely rated to speed of travel. Must be constant while spraying.
b. Wind shear varies with speed; increased wind shear leads to fine drops.

4. Nozzle configuration will influence spray pattern.

a. Nozzles angles perpendicular to wind give maximum~ shear; 30 degrees to 60 degrees to rear gives minimum because of air vortex from rotor. Not necessary with ground rig.
b. Nozzle orifice will influence fineness of drops, drift. Microfoil.

5. Spray adjuvants can minimize fine droplets, reduce drift. May reduce effectiveness.

a. Thickeners, foams.
b. Choice of carrier.
c. Note: volatility of herbicide cannot be controlled at time of application.

1. Aerial. Almost all rotary wing.

a. Maneuverable, easily adaptable to forest landing sites. Need good support.
b. Applies 15 gallons per acre, maximum, since cost a function of volume delivered.
c. Provides wide swath, overlap, unless drift control used.
d. Versatile and fast.
e. Very touchy with weather (wind speed, rain, temperature).