Part 2, Section 1: Pest Management
Pest Management
Pesticides and Their Application
Liquid pesticide mixes
Solutions are homogeneous mixtures of two or more substances. A solution may be either clear or colored and cannot be separated by mechanical means. An example is 2,4-D amine dissolved in water.
Emulsions are formed when one liquid is dispersed in another, as 2,4-D esters dispersed in water. Emulsions appear milky when dispersed in water and without agitation, the liquids may separate.
Suspensions are mixtures of finely ground insoluble particles of pesticide, such as atrazine 80W, suspended in the water or liquid fertilizer carrier. Since these formulations have a specific gravity greater than water, they tend to settle to the bottom of the tank; therefore, continuous mixing (agitation) is required to maintain a uniform mixture.
Fumigants are gases at room temperature when not pressurized. They commonly come as liquids in pressurized containers as, for example, liquid ammonia. The liquid must be injected or released under a gas-tight tarp to prevent its being lost to the air. Specialized application equipment is required.
Premixes are not formulations, but combinations of two or more herbicides premixed by the manufacturer. Premixes commonly combine two or more herbicides that are used together anyway, and they may contain any of the herbicides discussed above. The primary reason for using premixes is convenience. Since 1980, about 30 premixes have been released for use on corn and soybeans, and the future surely will bring more.
Water-soluble bags (WSB) are available for a number of pesticide products and formulations. Pesticides (generally DF or WDG) are packaged in polyvinyl alcohol-based bags that readily dissolve in water. WSBs offer improved handling safety, reduced waste disposal, and unit-dose convenience.