Early-Season Weed Control

Why control weeds early?

• Early control helps protect yield potential of the crop.

• Small weeds are easier to control.

• Young weeds absorb and translocate herbicides better.

• Herbicides can be less effective during times of heat and drought stress, which often occur at later application times.

Sequential weed control programs, including preplant / preemergence (PRE) followed by postemergence herbicides, have consistently provided the best weed control and greatest net returns.

Critical period of weed control

• Defined as the growth stages or time during which weeds must be controlled to maintain maximum yield potential. Assumes the field is clean at planting time.

• Corn: weeds can reduce yield as soon as the V2 stage. Control weeds earlier than this and maintain control through at least V14 to help ensure maximum yield potential.

• Soybean: control weeds within the first four weeks. Maintain control through canopy closure. Preventing weed seed production: Control weeds to minimize competitive effects but also to prevent seed production, especially for glyphosate-resistant weeds like waterhemp, Palmer amaranth, and ragweeds.

Take the time to apply preplant / PRE herbicides

• Weeds that germinate, emerge, and grow with the crop cause the most yield loss.

• Preplant/PRE herbicides provide critical early-season weed control when crops are most sensitive to competition.

• Preplant/PRE herbicides can widen the window of application for postemergence herbicide sprays.

• Total post programs are more risky because weather conditions may prevent timely application.

• Control weeds BEFORE they start to compete.

If preplant / PRE herbicides were not applied:

• Apply postemergence herbicides as soon as possible.

• Include residual herbicides to extend control of weeds that are still germinating.

• Do not cut the use rate. Use the recommended rate for the weed size.

• Use high-quality adjuvants as directed on the product labels.

• Be prepared to apply follow-up treatments to control escapes and late-germinating weeds.


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