Ken from Woodinville, Wa writes
Diquat Water Weed and Landscape Herbicide will kill horsetail. Horsetail is very hard to control and it can be tough to properly penetrate through the plant. When using the Diquat you will need to mix it at the rate of 2-4oz per gallon of water and mix it with an 80% Non ionic surfactant.
Answer last updated on: 04/30/2014