821.23 Additives and Adjuvants
| MoDOT's Herbicide Database |
Definition: Products designed to increase the effectiveness of herbicides.
Why: Herbicides are formulated for general performance purposes under average conditions. For most jobs they perform satisfactorily but there are many situations where they fall short of the desired effect. For example, the effectiveness of Krenite, used for brush control, is reduced in hard water and the effectiveness of Outrider, used for Johnson grass control, is reduced in water with low pH. If the target species has a very waxy covering on the leaves, such as kudzu, the effectiveness of increasing the wetting ability on the leaf surface enhances the herbicide selected. If drift is a concern, the viscosity or droplet size can be changed so that few fine droplets will be formed and drift will be reduced. Spray additives or adjuvants can be added to solve each of these problems. A substance added to the spray mixture to aid or improve the performance of the main ingredient is an additive.
Method: There are seven principal additives or adjuvants to be considered.
1. Surfactant - Makes the herbicide more effective by breaking down the waxy layer on the leaf surface.
2. Dormant Oils - Helps the herbicide stick to the plant and enter the plant
3. Sodium Gluconate and Water-soft – Softens hard water soft increasing the effectiveness of herbicides
4. Drift Control Agents – Minimizes drift by increasing droplet size
5. Defoamers - Reduces the foam created during agitation with some herbicides
6. Suspension Agents - Helps herbicides remain suspended in solution for longer periods of time
7. Dyes – Highlights treated areas
| Additional Information |
| MSDS Online |
Always check labels before using additives or adjuvants. Adjuvants are highly active materials. In most cases, a very small quantity, often 0.25% or 1 quart per 100 gallons, is all that is needed. Higher quality adjuvants may be considerably less such as 8 ounces per 100 gallons.
Read the label. Be careful to use only the amount needed.
Use only approved additives.