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How to Kill Whitetop Weeds

Whitetop weed also goes by the names Cardaria spp. and hoary cress and is a member of the mustard family. The plant is an invasive weed that grows in tall vertical stalks and develops clusters of small, white flowers at the top in the spring. Whitetop is a perennial weed that will regrow each year unless measures are taken to kill it. Killing whitetop is best accomplished using repeated applications of herbicides.

Wait until the fall to kill the whitetop weed if it is located in a crop or other area that will be harvested. Otherwise, you can kill the weed any time of the year that they appear.

Fill a hand-held or industrial crop sprayer with an herbicide containing 2, 4-D as the main ingredient. Add in water as instructed on the product label to dilute the mixture to the proper concentration.

Spray the entire area where the whitetop weeds are growing with the herbicide solution until all plant stems and leaves are saturated.

Monitor the area once per month and reapply additional herbicide to any new green whitetop weeds that sprout. You must continue spot treating in this manner for at least three years, which is how long the seeds remain viable in the soil.


If you are treating land not used for crops or grazing, you can use herbicides containing chlorsulfuron or metsulfuron. However, these herbicides increase the soil pH levels for two to three years after application.

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