How do you determine which type of additive to use? Also, since a large number of additives are available for use with herbicides, how do you know whether a specific product will perform adequately? Herbicides differ widely in chemical properties, therefore they differ in requirements for spray additives. Improper selection of an additive for a specific use may reduce weed control or increase crop injury. The best source of information to determine the type of additive to use is the herbicide label. Herbicide manufacturers conduct extensive research to determine how to achieve the most consistent performance with their products, thus label recommendations should be followed. However, there are many situations where the user will need to make a decision among different additive options provided on the label.