Bob from Apple Valley, Mn writes
Tenacity is not labeled to kill Quackgrass. We recommend using a glyphosate product like Glyphosel Pro and spot treating. You can also use a product a selective herbicide like Certainty if you have warm season grass. Please make sure to always review the product label to make sure you are using the right product and mixing ratio for your needs.
Answer last updated on: 05/14/2013