Pennsylvania: Post Herbicide Applications – Mistakes Are Happening

Pesticide Sprayer Nozzles. Photo: Ken Chamberlein, Ohio State University

Pesticide Sprayer Nozzles. Photo: Ken Chamberlein, Ohio State University

As the growing season rapidly progresses, many are harried, and we are receiving reports about herbicide application mistakes being made. These mistakes can range from lack of weed control to crop injury or even complete death. In the end, these can be costly for various reasons.

Keep these things in mind when spraying post herbicides:


Contact herbicides such as Liberty, Reflex/Flexstar, Cadet, Cobra, Ultra Blazer, etc. need to be applied through nozzles that produce medium-sized droplets. In general, air induction nozzles produce too large of droplets for these types of herbicides.

Good spray coverage is critical for effective control. Use higher spray volumes (15-20 gallons per acre or more) for best results.

Use of necessary and correct adjuvants

Most post herbicides require spray additive to be included in the spray tank for optimal control. Make sure to understand which product(s) should be used whether it be a non-ionic surfactant (NIS), crop oil concentrate (COC), methylated seed oil (MSO), and/or nitrogen fertilizer (AMS or UAN).

Read the label or refer to the Agronomy Guide for information on which adjuvants to use. Adjuvants are more critical, especially in droughty conditions.

Use the correct product

I know this sounds simplistic, but we are hearing about incorrect products being applied to the wrong crop, e.g., Engenia (dicamba) being applied to Enlist (2,4-D) soybeans.

Sometimes this is due to mistaking similar sounding product names; while other times, it is a misunderstanding of what products can be applied to the GM crop. Make sure to know what product can be applied to the crop.

Be cautious of these and other possible errors that can happen while spraying herbicides.

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