EquipmentSelecting the right equipment and using the proper application techniques when applying herbicides is important for several reasons: it minimizes the risk of off-target damage, it reduces waste of product, it increases worker safety and much more.

Before starting an application, always refer to the product label of the herbicide(s) you are using for usage requirements and directions. Specifically, the label will outline helpful guidelines around equipment as well as instructions for each application technique that the product is labeled for. Always carefully read and follow label instructions.

Tank-mixing herbicides

Correctly tank-mixing herbicides ensures product efficacy. But beyond just herbicides, applicators tend to mix adjuvants, drift control agents, surfactants and/or dye with herbicides to increase efficacy and accuracy when making applications. However, the wrong combination can result in clogged nozzles, scum and precipitates in the tank, and can even damage the area you are treating. Avoid incompatibility, damage to desirable vegetation and other negative scenarios by following a few basic guidelines:

  • Always refer to the product label for product-specific tank-mixing instructions.
  • Incompatibility occurs when one or more components of the mix create a chemical reaction, reducing the effectiveness of one or all of the herbicide components. A jar test is the most practical method to visually check for incompatibility. Fill a quart jar with the correct ratio of the materials in the mix. This should show you if your mixture is compatible.
  • Start with a clean tank. If a tank is not clean, the jar test won’t help. Vigorously agitate the tank contents while mixing and applying the products. If you take a break, leave the agitator running.
  • Even with proper agitation, never start spraying on the desired target. Apply the herbicide mixture to a small test area before broadcasting.
  • Always follow the correct filling order for products.
  • Be aware of all mixing requirements and procedures indicated on the product labels.
  • Keep containers below eye level when opening and pouring.
  • Keep fill hoses above water level in the spray tank to prevent back-siphoning.
  • Be aware of wind direction before pouring to minimize exposure downwind.
  • Never use your hands to stir the mixture or retrieve an item dropped into the tank.

Spray equipment calibration

Hand-held and backpack sprayers are inexpensive tools used to apply pesticides on small acreages to protect them from weeds, brush, trees and vines. Effective vegetation management depends on applying the proper amount of herbicide, and this can only be done if the spray equipment is calibrated accurately for the desired rate.

There are a number of techniques for using a backpack sprayer when spraying an area or plot. Hold the nozzle tip steady at a suitable height above the target surface, usually within a range of 14 to 18 inches. Or, swing the wand back and forth in a pendulum motion as you walk. With either technique, it is essential that you achieve uniform coverage of the treatment site. Use the same pressure, speed and technique in the application that was used to calibrate the herbicide.

Below are resources appropriate for reference when calibrating all types of herbicide spray equipment:

Virginia Tech Bulletin Number 456-502
National Science Foundation for Integrated Pest Management (CIPM)

Video: Calibration

Calibrating spray equipment before applying herbicides offers numerous benefits. This video goes over calibration techniques, as well as important points to remember when calibrating spray equipment.

Video: Equipment for low-volume basal

This video reviews the proper equipment needed for a low-volume basal application, which can be very effective for selective control of unwanted trees.