Mixing and Application
Part 2, Section 1: Pest Management
Pesticides and Their Application
Mixing and application
Be aware that improper sprayer calibration, nonuniform application, calculation errors, or use of the wrong chemicals can cause herbicide injury to the crop. Apply only the recommended amount of herbicide. Slight increases in rates could result in crop injury or leave residues that might injure succeeding crops.
Recalibrate sprayers frequently and adjust them for increased output resulting from normal nozzle wear. Be sure there is sufficient agitation in the sprayer tank to prevent settling of wettable powders, dry flowables, or flowables. Do not stop in the field with the sprayer on, spill herbicide when loading, or dump unused herbicides in anything except a holding tank.
Take the following steps when mixing herbicides:
- Always be sure the sprayer has been checked for uniform application and calibrated properly for application at the recommended rate.
- Calculate the amount of pesticide to add to the sprayer tank based on the active material in each gallon of pesticide concentrate, or the percentage of active ingredient of dry pesticide formulations.
- Read and follow instructions on the manufacturers label pertaining to personal hazards in handling.
- Fill the sprayer tank with at least half the volume of water or fertilizer solution you ultimately will need.
- Start moderate agitation and keep it going.
- Add compatibility agents if needed. For maximum benefit, they must be in solution before pesticides are added. (To determine pesticide compatibility, see next section.)
- Add, mix, and disperse dry pesticides (wettable powders, dry flowables, or water-dispersible granules). These formulations usually contain wetting and dispersing agents that aid in mixing.
- Add liquid flowables and allow thorough mixing. Liquid flowables also contain wetting and dispersing agents.
- Add emulsifiable concentrates (ECs) and allow thorough mixing.
- Finish by adding water-soluble formulations (2,4-D amine, etc.).
- Add any surfactants, crop oil concentrates, etc., last. Crop oils especially do not mix and disperse well if added first.
- Add the remainder of water or liquid fertilizer and maintain agitation while spraying until the tank is empty.
Caution: Never pour concentrated herbicides into a empty tank. Never allow a sprayer containing mixed chemicals to stand without agitation, as heavy wettable powders may clog nozzles or settle into corners of the sprayer tank.