The Benefits of Using the Proper Adjuvant in Pre-Emergent Herbicide Applications

Researchers claim that up to 70% of the effectiveness of pesticide sprays depends on the application.  Controllable application variables include the following:  Proper Sprayer Calibration, Proper Rate and PROPER PLACEMENT OF THE ACTIVE INGREDIENT.  Proper placement can be improved by using the correct adjuvant since it directly influences the placement of the active ingredient on the plant and the soil.  In this article, we will focus on the use of adjuvants in pre-emergent (soil applied) herbicide applications.

There are several classes of adjuvants that have different functions in a spray mix.  Spreaders, Stickers, Penetrants, Wetting Agents, and Deposition Agents to name a few.  The key is to match the adjuvant’s properties with the active ingredient being applied.   For a contact herbicide where maximum coverage and penetration are needed, an adjuvant with spreading and penetrating properties (such as Dyne-Amic or Contingent) is needed.

However, if you are applying a pre-emergent herbicide to the soil, an adjuvant that acts as a deposition agent can improve the application and results.   A deposition agent performs two main functions.  First, it helps keep spray droplets uniform (reducing drift).  Second, it keeps the active ingredient from moving down the soil profile (keeping the active ingredient in the seed germination zone).  The best example of a deposition agent specifically formulated for use with pre-emergent herbicides is Grounded W.  Grounded W is extremely effective in reducing driftable fines (see Example 1) AND helps hold the herbicide active ingredient in the top 3 inches of the soil (the seed germination zone)(see Example 2), effectively maximizing the efficacy of the pre-emergent herbicide application.

Growers often have one opportunity to make a pre-emergent herbicide application before winter rains.  It is critical that the herbicide is applied in a manner that maximizes its effectiveness, reducing the necessity of follow up applications which are costly and less effective.  Adding Grounded W to the pre-emergent herbicide spray mix gives growers the tool necessary to maximize their herbicide dollar and reduce follow up applications.

- Paul W. Crout, CCA, PCA, Coastal Product Manager/Agronomist

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