A Couple of Yearly Reminders Regarding Herbicides

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Acetochlor is a preemergence herbicide for corn that controls annual grasses and some broadleaf weeds. It is in the following products: Harness, Harness Extra, Degree, Degree Extra, Topnotch, Fultime, and Keystone. There are use restrictions related to groundwater quality. The restrictions are based on depth of groundwater within one month of planting and the combination of soil type and organic matter. Do not apply acetochlor if the groundwater depth is within 30 feet and you have sands with less than 3% organic matter, loamy sands with less than 2% organic matter, or sandy loam with less than 1% organic matter.

“Activating” Herbicides
Herbicides applied to the soil surface require rainfall or irrigation to move them into the soil where the plants will absorb them; or mechanical incorporation (field cultivator). Some areas have not received much rainfall lately and you need to be aware if your soil-applied herbicides have been activated. If you have irrigation and your herbicides have been applied but you have not received water, you should consider irrigating to activate those herbicides.

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