*This content was previously published by Corteva Agriscience
When looking at a weed, its overall height can be deceptively short. How is that possible? Because, to a herbicide, the weed’s height is not a linear measurement from the ground to the top of the plant. When a herbicide is fighting a weed, that fight takes into account every inch of the weed. It includes every point of growth that is on the plant, coming out of the main stem.
Corteva Agriscience Herbicide Trait Specialist Steve Snyder illustrates this in a video on application practices. (Use the QR code to check it out.)
In the video, Snyder measures off a single 8” waterhemp weed and pulls it from the ground. He then breaks off each branch growing from the main stem of the plant and lays them end to end on the ground and measures the length of all the sections of the plant as a whole. The total length comes out to 33″. Snyder explains how, to the herbicide, this is a 33″ weed, not an 8″ weed. He says that this is one reason why it is so important to apply herbicide early and in a timely manner. The herbicide has a much greater chance of being effective when the plant is 6” tall or less, because the weed has far fewer growth points than a larger, more mature weed.
Snyder’s demonstration makes a good point. Weeds that are left to grow taller than 6” make the job of the herbicide just that much tougher. Catching weeds early is an important aspect of good weed control and helps ensure the treatment is as effective as possible.
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